GB2324442A - Cordless telephone operating in public and private telephone systems - Google Patents
Cordless telephone operating in public and private telephone systems Download PDFInfo
- Publication number
- GB2324442A GB2324442A GB9801934A GB9801934A GB2324442A GB 2324442 A GB2324442 A GB 2324442A GB 9801934 A GB9801934 A GB 9801934A GB 9801934 A GB9801934 A GB 9801934A GB 2324442 A GB2324442 A GB 2324442A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- receiving
- receiving mode
- telephone system
- reception
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/18—Selecting a network or a communication service
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/02—Terminal devices
- H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
Landscapes
- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
A base station of a private telephone system transmits incoming call signals intermittently at a frequency f1 and timing t1. A base station of a public telephone system (for example PHS) transmits incoming call signals intermittently at a different frequency f2 and timing t2. A cordless telephone operating in the private system performs intermittent reception at the frequency f1 and timing t1. If reception quality deteriorates then in the periods between intermittent reception the cordless telephone scans for the intermittent signals from the public system. The quality of reception of the public system is compared with that of the private system and if better the cordless telephone switches to the public system and intermittently receives at a frequency f2 and timing t2. Switching is also executed in a period between intermittent reception. Switching back to the private system is achieved in the same way.
Description
2324442 TELEPHONE APPARATUS The present invention relates to cordless
telephone apparatus, and more particularly to a digital cordless telephone apparatus which receives signals intermittently transmitted from base stations of a private telephone system and a public telephone system (for example, PHS) with different timings and at different frequencies in order that the apparatus can be used in both systems. The invention can be applied, for example, to a radio telephone system such as a network, which includes base stations that communicate with mobile telephones, communication being handed over when the mobile telephone crosses a boundary.
This type of digital cordless telephone apparatus waits for an incoming call in a receiving mode in which an incoming signal from a base unit can be received in a service area of the base unit of a private telephone system, and the apparatus waits for an incoming signal in a receiving mode in which an incoming call from a base station of a public telephone system can be received when the apparatus is moved into a service area of the public telephone system.
For example, according to Japanese patent laid-open publication No. Hei 7087565, if a calling code of the private system can not be read when the apparatus operates in the receiving mode of the private system, the mode is automatically switched to the receiving mode of the public system after a predetermined time lapses. Further, 2 according to Japanese patent laid-open publication No. Hei 8-079829, the mode is set to the receiving mode of the private system if the apparatus receives a signal from the public base station or a signal from the private base station and there is a private base station which is capable of performing communication when a power supply of the apparatus is turned on or it is detected that the apparatus is out of communication area, while it is set to the receiving mode of the public system if communication with the private base station is impossible but that with the public base station is possible.
In the former conventional example described above, however,. sinee the mode is switched tA> tbe-receiving mode of the public system when a predetermined time lapses after a calling code of the private system fails to be read, an error for detec.ting an incoming signal from the base station occurs. Furthermore, in the latter example, there is not described the relationship between a receiving timing and a retrieving timing when retrieving signals from the private base station and the public base station, and an error for 'detecting an incoming signal may be likely to occur. SUMMARY OF THE INVENTION
The' present invention seeks to orovide a digital cordless telephone apparatus being capable of switching a receiving mode of a private system and that of a public system so as not to generate an error for detecting is 0 3 an incoming signal without being adversely affected by frequencies and timings of the private system and the public system.
To this end, the present invention executes signal retrieval of the other telephone system for changing over the receiving mode in a period between the current receiving timing and the next receiving timing in the receiving mode.
Further, when changing over to the receiving mode of the other telephone system, the changeover operation is performed in a period between current receiving timing and the next receiving timing of that telephone system.
Preferably, the present invention comprises: a circuit for Judging the quality.of reception in the current receiving mode, i.e., a private receiving mode in which a signal which is intermittently transmitted from a base station of a private telephone system with a predetermined timing is intermittently received or a-public receiving mode in which a signal which is intermittently transmitted from a base station of a public telephone system with a predetermined timing is intermittently received; a circuit for retrieving a signal of the other telephone system when the quality of reception is degraded; and a circuit for switching to the receiving mode of the other telephone system in accordance wj:th a result of retrieving the signal of the other telephone system the quality of reception, the signal retrieval circuit retrieving a signal of the other 0 4 telephone system in a period other than a receiving timing in the current receiving mode. In addition, the receiving mode switching circuit switches the receiving mode in a period other than a timing for receiving a signal from the other telephone system.
Another aspect of the invention comprises receiving apparatus for use in a system in which communication is handed over from one base station to another when the receiving apparatus crosses a boundary, the apparatus comprising:
means for switching to a receiving mode in which the digital signals from the base stations are received and means for selecting a period duri ng which the digital signals are intermittently received before the handover, the selecting means being responsive to the qualj7ty of reception in- said receiving mode.
These and other objr:cts, features and advantages of this invention will become more fully apparent from the following detailed description taken with the accompanying drawings by way of example only and in which:
Fig. 1 is a view showing an example of the structure of a digital cordless telephone system; Fig.2 is a block diagram showing a preferred embodiment according to the present invention; Fig. 3 is a flowchart showing the operation of a reception controller illustrated in Fig. 2; and Fig. 4(a) 4(c) are timing charts showing the operation of the reception controller illustrated in Fig. 2.
in the drawings, the s ame reference numerals denote the sarne structural elements.
A preferred embodiment according to the present invention will now be described with reference to the accompanying drawings.
Fig. 1 shows an example of the structure of a digital cordless telephone system, in which a digital cordless 0 1 telephone apparatus 1 moved from a service area of a base station 2 of a private system to a service area of a base station 3 of a public system and it is positioned in an area 4 where the service areas of the both systems overlap one on another. For example, the private system has such a configuration as that a base unit connected with an exchange or the like through a wire line is placed in a home and a portable unit connected with the base unit through a wireless line is included. Further, in the public system, a portable unit which is connected using a wireless line with a base station provided outside is included.
The digital cordless telephone apparatus 1 enters the receiv-in- mode for receiving an-incom3Pg signal from the base station 2 of the private system and waits for an incoming call in a service area of the base station 2. When the apparatus moved into the service area of the base stat.ion 3 of the public system, the apparatus 1 is automatically switched to the receiving mode for receiving an incoming signal from the base station 3 and waits for an incoming call. The receiving mode is switched in the area 4.
Fig. 2 is a block diagram of the digital cordless telephone apparatus according to a preferred embodiment of the present invention.
In Fig. 2, a radio section 11 is controlled by a reception controller.12 in order to intermittently receive a 0 6 signal sent from the base stations of the private telephone system and the public telephone system. A private receiving mode controller 13 sets the receiving mode for intermittently receiving a signal with a timing for intermittently transmitting an incoming signal from the base station of the private system and controls this mode. A public receiving mode controller 14 sets the receiving mode for intermittently receiving a signal with a timing for intermittently transmitting an incoming signal from the base station of the public system and controls this mode. A receiving mode changeover switch 16 is controlled by the reception controller 12 and selects either the private --receiving mode 13 or the public receiving mode 14.
A retrieval mode controller 15 sets a mode for retrieving a signal of the other telephone system in advance when switching the receiving mode and controls this mode. For example, when receiving a signal in the private receiving mode, the receiving frequency is set for a signal supplied from the base station of the public telephone system. A retrieval changeover switch 17 is controlled by the reception controller 12 and selects either'the receiving mode controller or the retriev al mode controller 15. At the same time it supplies the received output from the radio section 11 to either an incoming signal detector 18 or a signal retriever 19. Here, the received output from the radio section 11 is fed to the signal retriever 19 when the 0 7 r, 4 is retrieval mode controller 15 is selected, and the received output from the radio section 11 is supplied to the incoming signal detector 18 when the receiving mode controller is selected. The signal retriever 19 detects a timing for receiving a receive signal and informs the reception controller 12 of the detected timing.
A reception quality judging section 20 detects a reception level of the receive signal and judges the quality of reception based on a.mean value of the reception levels. obtaining the mean value in this manner can eliminate-the erroneous judgment caused due to fading or the like.
The operation of the reception Controller 12 will now be described --ithrefe-rence to Ficrs. 3 and 4. It is assumed that the apparatus moves from the service area of the private system to the service area of the public system and operates in the private receiving mode.
Fig. 3 is a flowchart showing the operation of the reception controller 12. Fig. 4 is a timing chart showing the operation of the reception controller 12.
Incoming signals transmitted from the base stations of the private system and the public system are intermittently sent at di f ferent frequencies fl and f2 and with different timings '(periods Tl and T2 as shown in Fig. 4(a), respectively. Each of the periods Tl and T2 is approximately one second. The digital cordless telephone apparatus 1..performs intermittent reception with the 8 0 is- transmission timings of the private/public system and waits for the incoming call while suppressing consumption of the battery.
The digital cordless telephone apparatus 1 performs intermittent reception in the private system receiving mode and wait s for the incoming call (step 101 in Fig. 3), as shown in Fig. 4(b). As shown in Fig. 4(c), the apparatus 1 controls the retrieval changeover switch 17 to selects the retrieval mode in the period immediately after the receiving timing of the private system and before the next receiving -timing, and supplies the received output from the radio section 11 to the signal retriever 19 in order that the signal retriever 19 execu-'Les sj_gna-3_._r6-trieval(st-ep 103) The quality of reception of the public system is compared with that of the private system and, if the quality of reception of the public system is better (step 104), the receiving mode changeover switch 16 is caused to select the private receiving mode to change over to the receiving mode of the public system (step 105).
It is-to be noted that the similar operation is possible by replacing the term "private" with the term "public" and vice versa if the digital cordless telephone apparatus moves from the service area of the public system to the service area of the private system.
As described above, according to the present invention, retrieval of the signal of the other telephone 6 9 system for switching the receiving mode which is executed in a period between the current receiving timing and the next receiving timing inthe receiving mode does not adversely influence the current reception, and hence the receiving mode can be switched between the private system and the public system without causing an error for detecting the incoming signal.
Further, in case of changing over to the receiving mode of the other telephone system, the error for detecting the incoming signal of the other telephone system can be avoided by switching the mode in the period between the receiving timing and the next receiving timing of the other telephone system.
While the invention has been de scribed with reference to a specific embodiment thereof, it will be appreciated by those skilled in the art that numerous variations, modifications, and imbodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the invention. Each feature disclosed in this specification (which term includes the claims) and/or in th draw b inco orated in the invention independently of other disclosed sUVW.U I-LU61a U-LL.Y 11 and/or illustrated features.
The text of the abstract filed herewith is repeated below as part of the specification:
A signal of the other telephone system is retrieved within a period other than receiving timing in the current receiving mode in order to switch the receiving mode. Further, when switching to the receiving mode of the other telephone system, the switching operation is carried out within a period other than the receiving timing of the other telephone system.
1
Claims (19)
1. An apparatus for selecting one of base stations which 1 intermittently transmit incoming signals with timings different in accordance with respective,base stations in o..izder to switch to a receiving mode in which the incoming signals are intermittently received with the timing, the apparatus characterized by utilizing a period other than the timing for receiving the incoming signals to perform signal retrieval and receiving mode switching.
2. An apparatus capable of being used in both a private telephone system and a public telephone system, comprising: means for judging the quality of reception in the current receiving mode, i.e., a privat.e receiving mode for intermittently receiving a signal which is intermittently transmitted from a base station of the private telephone system with a predetermined timing or a public.receiving_ mode for intermittently receiving a signal which is intermittently transmitted from a base station of the public telephone system with a predetermined timing; means for retrieving a signal of the other telephone system when the quality of reception is deteriorated; and means for switching to the receiving mode of the other telephone system in accordance with a result of retrieving a signal of the other telephone system and the quality of reception, the signal retrieving means performing retrieval of a signal of the other telephone system within a period other than the receiving timing in the current receiving mode.
3. The apparatus according to claim 2, wherein the receiving mode switching means switches the receiving mode within a period other than the timing for receiving a signal of the other telephone system when the quality of receiving a signal of the other telephone system is better than that in the current receiving moe.
4. The apparatus according to claim 2, wherein the means for judging the quality of reception makes judgment based on a mean value of the reception levels.
1
5. The apparatus according to claim 2, wherein the apparatus is a digital cordless telephone.
6. A method for controlling an apparatus for selecting.one of base stations'which intermittently transmit incoming is signals with timings different in accordance with respective base stations in order to switch to a receiving mode in.
which the incoming signals are intermittently received with a. timing, the method characterized in that signal retrieval and receiving mode switching are performed by utilizing a period other than the timing for receiving the incoming signal.
7. A method for controlling an apparatus which can be used in both a private system and a public telephone system, the method comprising the steps of: judging the quality of reception in the current receiving mode, i.e., a private receiving mode for intermittently receiving a signal which 12- is intermittently transmitted from a base station of the private telephone system with a predetermined timing or a public receiving mode for intermittently receiving a signal which is intermittently transmitted from a base station of the public telephone system with a predetermined timing; retrieving a signal of the other telephone system when the quality of reception is deteriorated; and switching to the receiving mode of the other telephone system in accordance with a result of retrieving a signal of the other telephone system and the quality of reception, thereby performing retrieval of a signal of the other telephone system within a period other than the receiving timing in the current receiving mode.
8. Receiving apparatus for use in a system in which communication is handed over from a current base station to another base station comprising: means for detecting signals from at least one other base station in a plurality of base station in a plurality of intervals between digital pulses of the currently received signal; means for selecting one of the detected signals; and means for switching to a receiving mode in which the selected digital signal is received.
9. An apparatus as claimed in claim 8, wherein the detection means is controlled by the quality of the currently received signaL
10. An apparatus as claimed in claim 8 or 9, wherein the selecting means is responsive to the quality of reception from the detected signal.
11. An apparatus as claimed in claim 8, 9, or 10, wherein the switching means switches to the receiving mode of the detected base station when the quality of reception of the current base station deteriorates below a predetermined value.
12. An apparatus as claimed in any of claims 8 to 11, wherein the switching occurs at a boundary between the service area of different telephone providers.
13. An apparatus as claimed in any of claims 8 to 12, wherein the different telephone service providers are private telephone systems and public telephone systems.
14. A method for changing the receiving mode of a portable receiving apparatus comprising the steps of. searching for signals from other base stations in a plurality of intervals between digital pulses of the currently received signal; selecting one of the detected signals; switching to a receiving mode in which the selected digital signal is received.
Is. A method as claimed in claim 14, wherein searching for other signals is controlled by a deterioration in the quality of the currently received signal.
16. A method as claimed in claim 14 or 15, wherein selecting the other base station is dependent on the quality of the reception of the signals received from that base station.
17. A method as claimed in claim 11 or 12, wherein searching for signals from other base stations occurs at a boundary between the service areas of the base stations.
18. An apparatus for selecting base stations substantially as described hereinbefore and with reference to the accompanying drawings.
19. An method for controlling apparatus selecting base stations substantially as described hereinbefore and with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1536697A JPH10215484A (en) | 1997-01-29 | 1997-01-29 | Digital cordless telephone system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9801934D0 GB9801934D0 (en) | 1998-03-25 |
| GB2324442A true GB2324442A (en) | 1998-10-21 |
Family
ID=11886807
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9801934A Withdrawn GB2324442A (en) | 1997-01-29 | 1998-01-29 | Cordless telephone operating in public and private telephone systems |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH10215484A (en) |
| CN (1) | CN1201347A (en) |
| GB (1) | GB2324442A (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0318033A2 (en) * | 1987-11-27 | 1989-05-31 | Nec Corporation | Handoff method for cellular digital mobile communication system and mobile station |
| GB2271039A (en) * | 1992-02-06 | 1994-03-30 | Motorola Inc | Apparatus and method for alternative radiotelephone system selection |
| WO1994013113A1 (en) * | 1992-11-30 | 1994-06-09 | Nokia Telecommunications Oy | Method of measuring adjacent base stations in tdma radio system and tdma radio system |
| WO1994029981A1 (en) * | 1993-06-14 | 1994-12-22 | Telefonaktiebolaget Lm Ericsson | Non-continuous transmission for seamless handover in ds-cdma systems |
| GB2292286A (en) * | 1994-08-06 | 1996-02-14 | Motorola Inc | Method of handoff between time divided communications systems |
| EP0727915A2 (en) * | 1990-03-19 | 1996-08-21 | Fujitsu Limited | Mobile radio communication system |
| WO1998009461A1 (en) * | 1996-08-30 | 1998-03-05 | Telefonaktiebolaget Lm Ericsson (Publ) | Methods and systems for concurrent receipt of incoming calls from a wide area cellular network and a private radio communications network |
| WO1998009468A1 (en) * | 1996-08-30 | 1998-03-05 | Telefonaktiebolaget Lm Ericsson (Publ) | Radio communications systems and methods for mobile assisted handover between a private network and a public mobile network |
-
1997
- 1997-01-29 JP JP1536697A patent/JPH10215484A/en active Pending
-
1998
- 1998-01-27 CN CN 98105642 patent/CN1201347A/en active Pending
- 1998-01-29 GB GB9801934A patent/GB2324442A/en not_active Withdrawn
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0318033A2 (en) * | 1987-11-27 | 1989-05-31 | Nec Corporation | Handoff method for cellular digital mobile communication system and mobile station |
| EP0727915A2 (en) * | 1990-03-19 | 1996-08-21 | Fujitsu Limited | Mobile radio communication system |
| GB2271039A (en) * | 1992-02-06 | 1994-03-30 | Motorola Inc | Apparatus and method for alternative radiotelephone system selection |
| WO1994013113A1 (en) * | 1992-11-30 | 1994-06-09 | Nokia Telecommunications Oy | Method of measuring adjacent base stations in tdma radio system and tdma radio system |
| WO1994029981A1 (en) * | 1993-06-14 | 1994-12-22 | Telefonaktiebolaget Lm Ericsson | Non-continuous transmission for seamless handover in ds-cdma systems |
| GB2292286A (en) * | 1994-08-06 | 1996-02-14 | Motorola Inc | Method of handoff between time divided communications systems |
| WO1998009461A1 (en) * | 1996-08-30 | 1998-03-05 | Telefonaktiebolaget Lm Ericsson (Publ) | Methods and systems for concurrent receipt of incoming calls from a wide area cellular network and a private radio communications network |
| WO1998009468A1 (en) * | 1996-08-30 | 1998-03-05 | Telefonaktiebolaget Lm Ericsson (Publ) | Radio communications systems and methods for mobile assisted handover between a private network and a public mobile network |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9801934D0 (en) | 1998-03-25 |
| JPH10215484A (en) | 1998-08-11 |
| CN1201347A (en) | 1998-12-09 |
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| REG | Reference to a national code |
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