JP2001285186A - Communication channel switching method for relay - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: To smoothly switch to another communication channel when wireless communication is used, and when communication quality deterioration is detected in a communication channel used for one communication. SOLUTION: In a PHS communication network, a wireless repeater 20 relays between a public base station 21 and a portable station 22 using different time slots. If the communication quality deteriorates due to interference or the like with the wireless repeater 20, (s
3), a communication channel TCH switching instruction is given from the public base station 21 to the wireless repeater 20 (s4). When the communication channel TCH of the switching destination is a time slot used for communication with the mobile station 22, a switching instruction is given to the mobile station 22 (s5), a switching sequence is executed (s6), and the switching is performed. Succeeds (s7), the public base station 2
Then, the switching sequence between the two is executed (s8), and the relay is continued (s2). If switching is not successful (s
7) Continue relaying while maintaining the original state (s2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a PHS (Personal
The present invention relates to a relay communication channel switching method for switching a TCH as a communication channel used as a wireless channel when a plurality of wireless channels are simultaneously controlled for one call by a repeater of a handy phone system.

[0002]

2. Description of the Related Art Conventionally, a PHS communication network as shown in FIG. 5 has been used. In the PHS, a plurality of public base stations (CS) 1, 2, 3,... Are distributed and arranged in an area where PHS services are provided. Public base stations (CS) 1, 2,
Are connected so as to be able to communicate with each other via a public communication network such as the ISDN network 10. In the PHS communication network,
A plurality of mobile stations (PS) 11, 12, 13, 14, 15,
16, ... is in principle any public base station (CS)
Are wirelessly connected to 1, 2, 3,... Public base stations (CS) 1, 2, 3, ... and mobile stations (PS) 11, 12,
, 13, 14, 15, 16,...
May be provided.

FIG. 6 shows a PHS communication network shown in FIG. 5 in which radio repeaters 19 are used as mobile stations (PS) 11, 12, 13, 14,.
, And public base stations (CS) 1, 2, 3,... Indicate the use status of time slots when relaying is performed. In PHS, "Digital Telecommunication Industry Association STD-28"
It is performed according to the air interface established as. The PHS radio access method is TDMA (Time
A time division multiple access system called Division Multiple Access is adopted, and public base stations (CS) 1, 2, 3,.
Allocates a slot for each specific time interval and communicates different information for each slot. In the PHS, a minimum frame to be transmitted and received in eight slots is defined as a TDMA frame, and is repeated in units of 5 msec. One TDMA frame is composed of four slots allocated for transmission (TX) and four slots allocated for reception (RX) transmitted by the wireless repeater 19.

Generally, the radio repeater 19 performs conversion between a public radio wave and a private radio wave, and transmits a private control radio wave while waiting for communication from a public base station (CS). The mobile station (PS) as a plurality of registered terminal stations waits for communication. When a call via the wireless repeater 19 starts, the wireless repeater 19
Communicates with a mobile station (PS) using private radio waves and communicates with a public base station (CS) using public radio waves. The communication contents between the mobile station (PS) and the public base station (CS) are interchanged, and the public base station (C
S) 1, 2, 3, ... and mobile stations (PS) 11, 12, 1
Wireless relay between 3, 14, 15, 16,... Is performed. In PHS, a data transmission rate of 32 kbit / s can be obtained by using one time slot. The PIAFS (PHS Internet A) was established by the Radio Industries and Businesses Association, which succeeded the Radio System Development Center (RCR) in April 1996, as the secretariat.
ccess Forum Standard), a transmission speed of 64 kbit / s is obtained using two time slots. FIG. 6 shows a method of performing communication by occupying two time slots in one call for the purpose of improving data communication speed. That is, the first and second time slots TS1 and TS2 are used as communication channels with the portable station (PS), and the third and fourth time slots TS3 and TS4 are used between the public base station (CS) and the third time slot. To use as a communication channel.

As shown in FIG. 5, in a PHS communication network, many public base stations (CS) and terminal stations (PS) communicate via radio waves. In addition to PHS, radio waves are widely used. There is also noise generated from various electronic devices and the like. Therefore, in the time slot used by the wireless repeater 19, there is a case where the communication quality deteriorates due to interference with other radio waves or the like. When the quality of communication deteriorates, it becomes impossible to perform communication, or it is necessary to repeat communication many times before correct communication becomes possible.

When the quality of wireless communication is degraded, interference may be avoided by changing the communication channel. The conventional PHS wireless repeater 19 attempts to change the time slot when the quality of wireless communication is degraded. However, if the time slot to be switched is already in use, the time slot cannot be switched. For example, when relaying is performed using two time slots as shown in FIG. 6, all the time slots are used, and even if one of them is switched to another time slot, , The time slot to be switched has already been used.

FIG. 7 shows a sequence in which quality degradation occurs in one time slot, and a time slot in use at the time of moving the time slot is simultaneously switched. That is, as shown in FIG. 6, the first and second time slots TS1 and TS2 are used for communication with the portable device (PS), and the third and fourth time slots TS3 and TS2 are used.
4 is used for communication with the public base station (CS), the public base station (CS)
3 is detected and the second time slot TS is detected.
2 is given to the wireless repeater 19, the wireless repeater 19 sends a TS to the public base station (CS).
At the same time, the mobile station (PS) issues an instruction to switch the second time slot TS2 to the third time slot TS3 to the portable station (PS), and executes a switching sequence for switching the communication channel TCH from TS3 to TS2 on TS2. The communication channel TCH switching sequence is executed on the time slot TS3.

[0008]

If the communication channel used by the wireless repeater 19 deteriorates in communication quality, smooth relay cannot be performed. As shown in FIG. 6, when relaying between a PHS mobile station (PS) and a public base station (CS), and when communication is performed using two time slots at a time. Even if one time slot is to be switched to another time slot, the time slot cannot be switched as it is because the destination time slot has already been used.

If the switching of the destination time slot is performed at the same time according to the procedure shown in FIG. 7, the switching can be performed even if there is no vacant time slot.
However, in the procedure as shown in FIG. 7, TS3 of the time slot between the public base station (CS) and the wireless relay is used.
To TS2, wireless repeater and mobile station (PS)
When the switching of the time slot from TS2 to TS3 at the same time is performed at the same time, if the switching of any one of the time slots fails, the contention of the communication channel used for the communication is continued for a long time, and as a result, Has the problem that the call is disconnected.

For example, referring to FIG. 7, a wireless repeater and a portable station (P
S) on the third time slot TS3 between
If the H switching sequence fails, then the second time slot TS2 will be the radio repeater and the public base station (CS).
This is because it has already been successfully occupied by the TCH switching sequence as a communication channel between the communication channel and the communication channel, so that it is impossible to return to the original communication channel.

As described above, in the prior art, when the TCH of a communication channel is switched by a wireless repeater used in a PHS or the like, the time slot of the switching destination is used in the other wireless communication being relayed. It is necessary that the relationship does not overlap with the time slot being used. Also, in order to enable switching of the communication channel TCH even in the case of overlapping, the communication channel
After the switching of H, there is no problem if the switching succeeds in switching the other competing communication channel, but if the switching fails, the contention of the communication channel will continue, and as a result, The probability of a call being disconnected increases.

An object of the present invention is to provide a relay capable of smoothly switching wireless communication via a communication channel in which quality degradation occurs to another communication channel when performing wireless relay using a plurality of communication channels. To provide a method for switching communication channels for communication.

[0013]

SUMMARY OF THE INVENTION The present invention is connected to a first wireless device and a second wireless device via a first communication channel and a second communication channel selected from a plurality of communication channels set in advance. When relaying communication between the first wireless device and the second wireless device, monitors the quality of communication between the first wireless device and the first wireless device via the first communication channel; When the quality of the communication with the wireless device deteriorates, the communication with the second wireless device is changed to the second wireless device.
Switching from the communication channel to another communication channel, securing the second communication channel as an empty channel, and then switching to perform communication with the first wireless device via the second communication channel. This is a method of switching a relay communication channel.

According to the present invention, the first wireless device communicates with the second wireless device via the first communication channel, and the second wireless device communicates via the second communication channel. When the communication between the first wireless device and the first wireless device via the first communication channel deteriorates when relaying the communication between the first wireless device and the first wireless device, the communication channel used for the relay is switched. Switching of the communication channel is performed by first switching communication with the second wireless device from the second communication channel to another communication channel, securing the second communication channel as an empty channel, and then switching to the first communication channel.
Since the communication with the wireless device is switched to be performed via the second communication channel, the switching can be smoothly performed while avoiding contention of the communication channel.

Further, according to the present invention, when it is failed to secure the second communication channel as an empty channel, communication between the first wireless device via the first communication channel, and communication between the second wireless device and the second wireless device. And the communication via the second communication channel during the communication is continued.

According to the present invention, in order to switch the communication with the first wireless device from the first communication channel to the second communication channel, the communication with the second wireless device is switched from the second communication channel to another communication channel. If switching to the channel fails to secure the second communication channel as an empty channel, communication with the first wireless device is continued without changing to the second communication channel. If the securing of the vacant channel succeeds, it is expected that the communication quality is prevented from deteriorating. Even if the securing fails, the communication can be continued in the original state, so that the continuity of the call can be improved.

Further, according to the present invention, in order to secure the second communication channel as an empty channel, another communication channel for switching communication with the second wireless device from the second communication channel is the first communication channel. Channel.

According to the present invention, when the channel for performing communication with the first wireless device is switched from the first communication channel to the second communication channel, the second communication channel is set to an empty channel. Since the communication with the wireless device is switched from the second communication channel to the first communication channel, the switching is performed within the range of the communication channel used for relaying the communication between the first wireless device and the second wireless device. be able to.

Further, according to the present invention, the first wireless device includes
S, and the second wireless device is a PHS
Wherein the communication channel is a time slot set by a PHS time division multiple access method.

According to the present invention, when relaying the communication between the PHS mobile station and the public base station, the time slot set in the PHS time division multiple access system is switched to improve the communication quality due to interference or the like. Deterioration can be avoided.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows, as an embodiment of the present invention, a configuration for switching a time slot as a communication channel relayed by a PHS and a switching procedure. FIG.
As shown in (a), the PHS wireless repeater 20
A communication such as a call is relayed between a public base station (CS) 21 as a wireless device and a mobile station (PS) 22 as a second wireless device. Time slot (TS) in the wireless repeater 20
Is used in the same manner as in FIG. That is, transmission (TX) and reception (R) set in the time division multiple access system.
X) for each of the four time slots TS1, T
Of the S, TS3, and TS4, two time slots are occupied and relayed for the purpose of improving the data communication speed. As in FIG. 6, the radio repeater 20 assigns the first and second time slots TS1 and TS2 to the mobile station (PS) 22.
The third and fourth time slots TS3 and TS4 are used for communication with the public base station (CS) 21.

As shown in FIG. 1 (b), the procedure is started from step s1, a wireless relay is performed between the public base station 21 and the portable station 22 in step s2, and quality deterioration is monitored in step s3. If no quality deterioration has occurred, step s
Return to 2 and continue the wireless relay. Quality degradation is determined by the number of frame errors in a certain section. Such determination of quality deterioration is performed by all of the mobile station (PS) 22, the radio repeater 20, and the public base station (CS) 21. The function of judging quality deterioration has been conventionally provided. When quality deterioration is detected in step s3, TCH switching for switching a time slot as a TCH which is a communication channel used for communication between the public base station (CS) 21 and the wireless relay device 20 in step s4. Instructions are given. Before switching the communication channel TCH with the public base station (CS) 21, the wireless repeater 20 uses the wireless repeater 20 for communication between the wireless repeater 20 and the portable station (PS) 22. The switching instruction of the communication channel TCH is performed. In step s6, a communication channel TCH switching sequence is executed between the mobile station (PS) 22 and the wireless repeater 20.

In step s7, it is determined whether or not the switching of the communication channel TCH between the portable station (PS) 22 and the wireless repeater 20 has been successful. The determination as to whether or not the switching has been successful is made according to whether or not the TCH switching sequence has been normally completed to the end. Success / failure judgment
This is performed in all of the mobile station (PS) 22, the radio repeater 20, and the public base station (CS) 21. Communication channel TCH
When it is determined that the switching of the communication channel TCH is not successful, the switching of the communication channel TCH is not performed, and the process returns to step s2 to continue the wireless relay using the communication channel TCH as it is. If it is determined in step s7 that the switching with the terminal station (PS) 22 has been successful, the communication channel TCH switching sequence is executed with the public base station (CS) 21 in step s8. Return to s2,
The wireless relay is continued in a state where the communication channel TCH is different from the original state.

Generally, the radio repeater 20 performs mutual conversion between public radio waves and private radio waves. The radio repeater 20 itself waits for an instruction from the public base station (CS) 21,
A control radio wave for private use is transmitted, and a plurality of registered portable stations (PS) 22 are set as slaves to stand by in a signal waiting state. When a PHS call starts, communication with the mobile station (PS) 22 is performed using private radio waves, and communication with the public base station (CS) 21 is performed using public radio waves. . Therefore, the mobile station (PS) 22 performs the same operation without distinguishing between the case where the mobile station 22 is connected via the wireless repeater 20 and the case where the mobile station is directly connected to the public base station (CS) 21. The public base station (CS) 21 also makes no distinction between the case via the wireless repeater 20 and the case directly connected,
Perform the same operation.

FIG. 2 shows a schematic system configuration of the radio repeater 20. The wireless repeater 20 includes a wireless unit 31, a channel codec unit 32, and a control unit 33. The wireless unit 31 performs transmission and reception of wireless signals. The channel codec unit 32 assembles and disassembles signals for each time slot. The control unit 33 executes a communication channel TCH switching sequence and the like, and manages connection and maintenance of the call.

As described with reference to FIG. 6, the PHS is divided into a plurality of sections on the time axis at the same frequency of the assigned radio wave, and in the case of the PHS, it is divided into four time slots (TS). It uses a time division multiple access scheme in which slots are assigned to different users. Recently, a method of allocating two time slots to the same user has been adopted for the purpose of improving the data communication speed. FIG.
Then, the signal received from the portable station (PS) 22 in the first and second time slots TS1 and TS2 in the reception (RX) section is transmitted in the third and fourth time slots TS3 and TS4 in the transmission (TX) section. By transmitting to the public base station (CS) 21, the radio wave from the portable station (PS) 22 is relayed to the public base station (CS) 21. Similarly, reception (R
X) Third and fourth time slots TS3 and TS in the section
4 from the public base station (CS) 21 in the first and second time slots TS in the transmission (TX) section.
1 and TS2 to the mobile station (PS) 22 to transmit radio waves from the public base station (CS) 21 to the mobile station (P).
S) Relay to 22.

FIG. 3 shows a communication channel TCH performed in accordance with the procedure shown in FIG. 1B when interference occurs during the third time slot TS3 in the time slot allocation as shown in FIG. 7 shows a switching sequence.
The public base station (CS) 21 monitors the communication quality, gives a “TCH switching instruction” message (A) to the wireless repeater 20 for the time slot in which the quality is deteriorated, and moves the channel in which the interference occurs. Request. The "TCH switching instruction" message includes the time slot information of the movement destination and the communication channel information. Here, an operation when the communication channel of the third time slot TS3 is moved to the second time slot TS2 will be described.

Since the second time slot TS2 is used as a communication channel with the mobile station (PS) 22 in the radio repeater 20, the communication channel with the public base station (CS) 21 is moved as it is. I can't let it. Therefore, the wireless repeater 20 is connected to a mobile station (PS).
22 and transmits a “TCH switching instruction” message (B). The content of this message is an instruction to move the second time slot TS2 used as a communication channel with the mobile station (PS) 22 to the third time slot TS3. The mobile station (PS) that received the message
At 22, the sequence for switching the communication channel TCH is executed on the third time slot TS3. When the TCH switching sequence (C) on TS3 is completed, the second time slot TS2 becomes empty.
By executing the TCH switching sequence (D) on S2, the movement of the communication channel causing interference with the public base station (CS) 21 can be completed. The TCH switching sequence is performed by transmitting and receiving “synchronous burst” and transmitting and receiving “TCH burst”.

FIG. 4 shows a public base station (CS) as in FIG.
In response to the communication channel TCH switching instruction (A) from the communication relay 21, the wireless repeater 20 gives a communication channel TCH switching instruction (B) to the mobile station (PS) 22, and the wireless relay 2
0 fails when the TCH switching sequence for switching the communication between the mobile station (PS) 22 and the second time slot TS2 from the second time slot TS2 to the third time slot TS3 is performed on the third time slot TS3. 1 shows an overall communication sequence of the first embodiment. The wireless repeater 20 and the mobile station (P
If the communication channel TCH switching sequence (C) on the third time slot TS3 with the S) 22 fails, the wireless repeater 20 and the mobile station (PS) 22
The return sequence (D) is performed on the second time slot TS2. In this return sequence (D), the communication between the wireless repeater 20 and the mobile station (PS) 22 returns to the original second time slot TS2. A third time slot TS between the wireless repeater 20 and the mobile station (PS) 22
3 has failed in the TCH switching sequence (C), the communication channel TCH between the radio repeater 20 and the public base station (CS) 21 remains unchanged from the third time slot TS3, When the return sequence (D) on the time slot TS2 ends, the public base station (CS)
Returning to the state before the communication channel TCH switching instruction (A) from 21 is performed, the communication is continued.

In the embodiment described above, in the PHS radio relay, the data communication speed is improved by using four time slots two by two. However, the relay may be performed by using one time slot one by one. it can. When the time slots are used one by one, there is a high possibility that the time slots are switched to unused time slots. However, even when all of the four time slots are used as in the above-described embodiment, the time slot used for the relay for one and the time slot used for the relay for the other are eventually exchanged. Switching is possible. When interference occurs in wireless communication, the wireless repeater 20, the public base station (CS) 21, and the mobile station (PS)
Since the geographical position of the time slot 22 may be affected, if the time position of the time slot is changed, the degree of interference is reduced, and there is a possibility that communication quality degradation is avoided. Further, although one of the two time slots used at the same time is switched, the two time slots can be switched at the same time. However, when interference occurs in a specific time slot among the time slots obtained by dividing the same frequency, it is better to switch the time slots one by one and check whether switching is successful or not to avoid interference. It can be achieved reliably.

Although FIG. 1 illustrates the case where the time slot is switched by the PHS, even when the relay is performed using a channel having a different frequency band in the wireless relay, interference due to interference occurs in one frequency band. When quality degradation occurs, the frequency can be switched to the other frequency to reduce interference.

[0032]

As described above, according to the present invention, when the first communication channel used for communication with the first wireless device is degraded in communication quality due to interference or the like, the second wireless device The second communication channel used for communication with the first wireless device can be switched to an empty channel and then used for communication with the first wireless device. The second communication channel is a communication channel used for communication with the second wireless device, and it can be expected that communication can be performed in a state in which quality degradation due to interference is smaller than in the first communication channel. . Since the second communication channel is switched after being an empty channel, communication with the first wireless device can be smoothly and reliably switched from the first communication channel to the second communication channel.

According to the invention, the communication with the first wireless device is switched from the first communication channel to the communication with the second wireless device from the second communication channel to another communication channel. When the communication fails, the communication with the first wireless device is not switched from the first communication channel to the second communication channel, so that at least the communication state can be continued, and the relay state is not further deteriorated. can do.

According to the present invention, the communication channel for performing communication with the first wireless device is changed from the first communication channel to the second communication channel.
When switching to the communication channel, the communication channel with the second wireless device is switched from the second communication channel to the first communication channel. Since the communication is switched to be performed via the second communication channel, when the communication channel used for communication with the first wireless device is switched, the communication channel of the switching destination is an empty channel, and the switching is performed smoothly. It can be performed.

Further, according to the present invention, in order to switch communication with the first wireless device from the first communication channel to the second communication channel, the second communication in which communication with the second wireless device is performed. If switching the channel to another communication channel and failing to set the second communication channel to an empty channel fails, the relay is continued without switching the communication channel, so that the state of the wireless relay is prevented from further deteriorating. be able to.

According to the present invention, the first communication channel and the second communication channel used for wireless relay can be exchanged to cope with communication quality deterioration due to interference or the like.

Further, according to the present invention, it is possible to switch the time slot set in the time division multiple access system of the PHS to avoid the quality deterioration even if the communication quality deteriorates due to interference or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a wireless relay system of a PHS that implements a relay communication channel switching method according to an embodiment of the present invention, and a flowchart illustrating an outline of the communication channel switching procedure. .

FIG. 2 is a block diagram illustrating a schematic system configuration of the wireless repeater 20 of FIG. 1;

FIG. 3 is a communication sequence diagram showing a procedure for switching a time slot used for relay in the PHS communication network of FIG. 1;

FIG. 4 is a communication sequence diagram showing a procedure until switching of a time slot used for relay in the PHS communication network of FIG. 1 fails and the original communication state is continued.

FIG. 5 is a block diagram showing an outline of a conventional PHS communication network.

FIG. 6 is a diagram illustrating a use state of a time slot by the wireless repeater 19 illustrated in FIG. 5;

FIG. 7 is a communication sequence diagram showing a procedure for switching one time slot to another time slot in a time slot usage state as shown in FIG.

[Explanation of symbols]

 Reference Signs List 20 radio repeater 21 public base station 22 mobile station 31 radio section 32 channel codec section 33 control section

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Nakamura Within NTT Mobile Communication Network Co., Ltd. 2-1-1 Nagatacho, Chiyoda-ku, Tokyo (72) Inventor Akihiko Uchiyama Mayor of Abeno-ku, Osaka-shi, Osaka 22-22 Ikemachi F-term in Sharp Corporation (reference) 5K067 AA26 BB04 CC04 EE02 EE06 EE10 EE71 HH01 JJ35 5K072 AA13 BB13 BB25 CC15 EE23 FF25 FF26 GG11 GG14

Claims (4)

[Claims] 1. A first wireless device connected to a first wireless device and a second wireless device via a first communication channel and a second communication channel selected from a plurality of communication channels preset for wireless communication, respectively. When relaying communication between the device and the second wireless device, the quality of communication between the device and the first wireless device via the first communication channel is monitored. When the quality degradation occurs in the communication between the second wireless device, the communication with the second wireless device is switched from the second communication channel to another communication channel.
A method for switching a relay communication channel, comprising: securing a communication channel as an empty channel, and then switching to perform communication with a first wireless device via a second communication channel. 2. When securing the second communication channel as an empty channel fails, the communication between the first wireless device and the second wireless device via the first communication channel is performed. 2. The relay communication channel switching method according to claim 1, wherein communication with the second communication channel is continued. 3. Another communication channel for switching communication with the second wireless device from the second communication channel in order to secure the second communication channel as an empty channel,
2. The communication channel according to claim 1, wherein the first communication channel is the first communication channel.
Or the relay communication channel switching method according to 2. 4. The first wireless device is a PHS public base station, the second wireless device is a PHS mobile station, and the communication channel is set by a PHS time division multiple access system. 4. The relay communication channel switching method according to claim 1, wherein the time slot is a time slot.