Protocol and transceiver for cordless/cellular telephone service

• US 5,212,684 A
• Filed: 08/30/1990
• Issued: 05/18/1993
• Est. Priority Date: 09/01/1989
• Status: Expired due to Term

• Current Assignee: IPG Electronics 503 Limited (Coller IP Capital Limited)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: MacNamee, Robert J. G., Vadgama, Sunil K.
• Primary Examiner(s): Chin, Wellington
• Application Number:
  US07/575,116
• Time in Patent Office: 992 Days
• Field of Search: 370/24, 370/29, 370/32, 370/79, 379/59, 379/60, 379/61, 455/33.1, 455/54.1, 455/53.1, 455/54.2, 455/56.1, 455/33.2
• US Class Current: 370/280
• CPC Class Codes: H04M 2250/08 home cordless telephone systems using the DECT standard
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A communications system suitable for use with hand portable radio telephones operating in a cellular mode, the typical cell size being between 500 m and 3 km radius. Each cell comprising at least one primary or base station (10) connected to the PSTN and one or more secondary portable stations (14) which are capable of roaming within the cell. Radio communication between the stations can be initiated by either station. Each primary and secondary station having radio transceiving means for time division duplex communication between the stations, a codec operating at 32 kbits/second or 11.4 kbits/second and means for transmitting digitised speech in accordance with a framed structure comprising 3 full rate or 6 half rate channels per carriers, the carrier being modulated at a carrier bit rate of substantially 270.8333 kbits/second. Provision is made for internal and external handover, if required. Also, if required, the secondary station can be constructed to operate in the DECT system as well as in the above described system.

Claims

1. A communications system comprising a dual mode hand portable transceiver for metropolitan cellular and cordless telecommunications use, forming a secondary station, and a primary station, the primary and secondary stations each comprising respective radio transceiving means for duplex radio communication between the stations, said primary and secondary stations each further comprising:

a single encoding means for digitizing speech to form transmitter digitized speech signals, and a single decoding means for recovering speech from received digitized speech signals, and

means for formatting said digitized speech signals to produce a modulation signal according to a selected one of first and second protocols, selection of the protocol being responsive to control by a user of the transceiver, said first protocol using 3 full rate channels per carrier, with each channel carrying signals at substantially 32 kbits per second; and

said second protocol using 2 half rate duplex channels carrying signals at substantially 11.4 kbits per second, and

each respective transceiver comprising a single transmitter means for modulating a carrier with said modulation signal at a carrier bit rate of substantially 270.8333 kbits per second, and transmitting the resultant formatted transmitter digitized speech signals over a duplex channel system.

2. A system as claimed in claim 1, characterised in that the frame length is substantially 10 milliseconds.

3. A system as claimed in claim 1 characterised in that communication between the primary and secondary stations is by single frequency time division duplex.

4. A system as claimed in claim 3, characterised in that each channel comprises two slots and the message structure for each slot comprises successively a preamble, a training sequence, a signalling field, a data field and tail bits.

5. A system as claimed in claim 3 characterised in that broadcast, common and dedicated control channels are provided on the same radio carrier.

6. A system as claimed in claim 3 characterised in that broadcast and common control are provided on a reserved radio carrier.

7. A system as claimed in claim 1 characterised in that the modulation parameter (bandwidth x time) BT is 0.3.

8. A system as claimed in claim 7, having at least two carriers and characterised in that adjacent carriers are spaced apart by substantially 200 KHz.

9. A system as claimed in claim 1, characterised in that the primary station is connected to a public switched telephone network (PSTN).

10. A system as claimed in claim 1, characterised in that the primary and secondary stations each operate in accordance with a protocol which permits either station to initiate a call to the other station.

11. A system as claimed in claim 10, characterised in that each secondary station includes a channel equaliser.

12. A system as claimed in claim 1, characterised in that each primary station includes a channel equaliser for equalising a digital signal from the secondary station.

13. A system as claimed in claim 12, characterised in that each channel comprises two slots and the message structure for each slot comprises successively a preamble, a training sequence, a signalling field, a data field and tail bits;

and the channel equaliser pre-distorts a digital signal to be transmitted to a secondary station, the degree of pre-distortion being determined on the basis that the channel is a reciprocal channel and that the adjustment of the equaliser coefficients using the training sequence is such that the signal received at the secondary station is substantially undistorted.

14. A system as claimed in claim 1 characterised in that the primary station has means to practise antenna diversity.

15. A system as claimed in claim 1 further comprising means for permitting internal and external handover.

16. A system as claimed in claim 1 characterised in that GSM signalling protocols are adapted to work on DECT channels.

17. A system as claimed in claim 1 having a signalling protocol comprising a physical layer, a link layer and network layer protocols, characterised in that at least some of the signalling messages for the link layer comprise short form messages which are contained in a single message frame.

18. A dual mode hand portable transceiver for metropolitan cellular and cordless telecommunications use, comprising:

a single encoding means for digitizing speech to form transmitter digitized speech signals, and decoding means for recovering speech from received digitized speech signals,

a single means for formatting said digitized speech signals to produce a modulation signal according to a selected one of first and second protocols, selection of the protocol being responsive to control by a user of the transceiver, said first protocol using 3 full rate channels per carrier, with each channel carrying signals at substantially 32 kbits per second; and

said second protocol using 2 half rate duplex channels carrying signals at substantially 11.4 kbits per second, and

a single means for modulating a carrier with said modulation signal at a carrier bit rate of substantially 270.8333 kbits per second, and transmitting the resultant formatted transmitter digitized speech signals over a duplex channel system.

19. A transceiver as claimed in claim 18, characterized in that said transceiver is arranged to communicate with a primary station by single frequency time division duplex.

20. A transceiver as claimed in claim 19, characterised in that each channel comprises two slots and the message structure for each slot comprises successively a preamble, a training sequence, a signalling field, a data field and tail bits.

21. A transceiver as claimed in claim 19, characterised in that the primary and secondary stations each operate in accordance with a protocol which permits either station to initiate a call to the other station.

22. A transceiver as claimed in claim 18 characterised in that the modulation parameter (bandwidth×

time) BT is 0.3.

23. A transceiver as claimed in claim 18, for responding to a signalling protocol comprising a physical layer, a link layer and network layer protocols, characterised in that at least some of the signalling messages for the link layer comprise short form messages which are contained in a single message frame.

24. A transceiver as claimed in claim 18, characterized in that said transceiver comprises means for operating in a DECT system mode, said single means for modulating comprising means for setting the modulation rate to 1.152 Mbits/S, and said single means for formatting comprising means for setting the multiplexing rate to 12 duplex channels in a 10 mS frame, and for selecting the appropriate protocol.