Cellular cordless telecommunications system

Details Cellular cordless telecommunications system Cellular cordless telecommunications system

1997-11-19

2001-05-01

Tsang, Fan (Department: 2746)

Telecommunications

Radiotelephone system

Zoned or cellular telephone system

C455S560000, C455S561000, C455S462000, C455S554100, C455S555000, C455S502000, C370S350000, C370S524000, C370S329000

Reexamination Certificate

active

06226515

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a cellular cordless telecommunications system.
The cordless telecommunications system with the best performance of the moment, based on the DECT Standard [Digital Enhanced (previously: European) Cordless Telecommunications; cf. Nachrichtentechnik Elektronik [Electronic Information Technology] 42 (January/February 1992), No. 1, Berlin; U. Pilger:
33
“Struktur des DECT-Standards” [Structure of the DECT Standard]; pages 23 to 29 in conjunction with the ETSI Publication ETS 300175-1 . . . 9, October 1992; Siemens Components 31 (1993), No. 6; S. Althammer and D. Brückmann: “Hochoptimierte IC's für DECT-Schnurlostelefone [Highly optimized ICs for DECT cordless telephones]”, pages 215 to 218; telecom report 16 (1993), No. 1, J. H. Koch: “Digitaler Komfort für schnurlose Telekommunikation—DECT-Standard eröffnet neue Nutzungssgebiete [Digital convenience for cordless telecommunications—DECT Standard opens up new fields of use]”, pages 26 and 27), transmits the radio messages, inter alia, using the TDMA method (Time Division Multiple Access).
However, the present invention is not limited to the TDMA transmission method. The invention thus also extends to those systems which are described in the document TIB-RO9067(5)-P. Bauer-Trocheris: “UMTS-Integrator für die mobile Kommunikation—ein Ausblick auf die Mobilfunklandschaft nach dem Jahr 2000 [UMTS integrator for mobile communications—a summary of the mobile radio situation after the year 2000]”, Report on the Convention “European Mobile Radio, 5th annual meeting of the German and European mobile radio section, FIBA Congress, Munich, Feb. 24 to 26, 1993”.
The DECT-specific cordless telephone system is a digital system which, according to
FIG. 1
(cf. tec 2/93—Technical Magazine from Ascom “Wege zur universellen mobilen Telekommunikation [Ways for universal mobile telephone communication]”, pages 35 to 42) can be used in the private area (for example house, apartment, garden etc.), in the small public area (for example companies, office building etc.) and as a telepoint application.
The basic structure of the cordless telephone system comprises a base station BS (FP=Fixed Part with FT=Fixed Termination and a mobile unit MT (PP=Portable Part with PT=Portable Termination with the capability for telecommunications with the base station BS. This basic structure can be extended in accordance with the DECT Standard in such a manner that up to twelve such mobile units MT are assigned to a single base station BS.
FIG. 2
shows such a cordless telephone system STS, in which a maximum of 12 links using the TDMA/FDMA/TDD method (Time Division Multiple Access/Frequency Division Multiple Access/Time Division Duplex) are set up on one DECT base station BS in parallel to DECT mobile units MT1 . . . MT12 via a DECT radio interface designed for the frequency band between 1.88 and 1.90 GHz. The
FIG. 12
results from a number “k” of time slots or telecommunications channels (k=12) available for duplex operation of a DECT system. The links may in this case be internal and/or external. In the case of an internal link, two mobile units registered at the base station BS, for example the mobile unit MT
2
and the mobile unit MT
3
, can communicate with one another. For setting up an external link, the base station BS is connected to a telecommunications network TKN, for example in wire-based form via a telecommunications access unit TAE or a private branch exchange NStA is connected to a wire-based telecommunications network or, in accordance with WO 95/05040, in wire-free form as a repeater station to a higher level telecommunications network. In the case of the external link, it is possible to communicate with a mobile unit, for example with the mobile unit MT
1
, via the base station BS, and for the telecommunications access unit TAE and a private branch exchange NStA to communicate with a subscriber in the telecommunications network TKN. If, as in the case of the Gigaset 951 (Siemens cordless telephone, cf. telecom report 16, (1993), issue 1, pages 26 and 27—the base station BS has only one connection to the telecommunications access unit TAE or the private branch exchange NStA, then only one external link can be set up. If—as in the case of the Gigaset 952 (Siemens cordless telephone, cf. telecom report 16, (1993), issue 1, pages 26 and 27—the base station BS has two connections to the telecommunications network TKN, then, in addition to the external link to the mobile unit MT
1
, a further external link is possible from a wire-based telecommunications terminal TKE connected to the base station BS. In this case, it is in principle also feasible for a second mobile unit, for example the mobile unit MT
12
, to use the second connection for an external link, instead of the telecommunications terminal TKE. While the mobile units MT
1
. . . MT
12
are operated using a battery or a rechargeable battery, base station BS, which is designed as a small cordless switching system, is connected via a mains connecting unit NAG to a power network SPN.
The cordless telephone system according to
FIG. 2
is preferably used in the private area, according to FIG.
1
.
In the small public area—in accordance with FIG.
1
—a plurality of such cordless telephone systems according to
FIG. 2
can be operated in a cellular system on a private branch exchange (Private Automatic Branch Exchange), the private branch exchange PABX controlling a plurality of base stations A-BS, B-BS, C-BS and, if required, supporting a handover from one base station to another.
FIG. 1
also shows six mobile units MT
a
. . . MT
f
which are assigned to the three base stations A-BS, B-BS, C-BS. This results in a cellular cordless telephone system in which the telecommunications link as a rule passes via that base station A-BS, B-BS, C-BS with which the mobile unit MT
a
. . . MT
f
has the best radio contact.
Based on the document “Nachrichtentechnik Elektronik [Electronic Information Technology]”42 (1992) January/February, No. 1, Berlin, DE; U. Pilger: “Struktur des DECT-Standards [Structure of the DECT Standard]”, pages 23 to 29 in conjunction with the ETS Publication ETS 300175-1 . . . 9, October 1992,
FIG. 3
shows the TDMA structure of the DECT system STS. In terms of multiple access methods, the DECT system is a hybrid system in which radio messages can be transmitted on ten frequencies in the frequency band between 1.88 and 1.90 GHz using the FDMA principle and, according to
FIG. 3
, in a predetermined time sequence using the TDMA principle, from the base station BS to the mobile unit MT and from the mobile unit MT to the base station BS (duplex operation). The time sequence is in this case governed by a multiple time frame MZR, which occurs every 16 ms and which has 16 time frames ZR, each having a time duration of 10 ms. Information is transmitted separately in these time frames ZR to the base station BS and to the mobile unit MT, this information relating to a C, M, N, P and Q channel defined in the DECT Standard. If information for a number of these channels is transmitted in one time frame ZR, then the transmission takes place based on a priority list where M>C>N and P>N. Each of the 16 time frames ZR in the multiple time frame MZR is in turn split into 24 time slots ZS each having a time duration of 417 &mgr;s, of which 12 time slots ZS (time slots
0
. . .
11
) are reserved for the transmission direction “base station BS→mobile unit MT” and a further 12 time slots ZS (time slots
12
. . .
23
) are reserved for the transmission direction “mobile unit MT→base station BS”. Information having a bit length of 480 bits is transmitted in each of these time slots ZS, in accordance with the DECT Standard. Of these 480 bits, 32 bits are transmitted as synchronization information in a SYNC field, and 388 bits as wanted information in a D field. The remaining 60 bits are transmitted as additional

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