Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-03-15
2003-03-11
Le, Thanh Cong (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C370S347000, C370S332000, C370S342000
Reexamination Certificate
active
06532364
ABSTRACT:
TECHNICAL FIELD
This invention relates to a mobile -communication system which allows hand-over including a function by which a set of links including an up-link (Up-link) and a down-link (Down-link) having different communication capacities can be used as one communication channel (hereinafter referred to as an asymmetrical communication channel) using frequency channel sharing or time slot sharing in which a multiple connection system such as a TDMA (TDMA; Time divided Multiple Access; time divided multiple access) system or a time divided CDMA (CDMA; Code Division Multiple Access; code division multiple access) system is used.
BACKGROUND ART
A mobile communication system is principally composed of mobile stations such as, for example, mobile car-carried communication apparatus or mobile portable communication apparatus, and radio base stations which communicate with the mobile stations by radio channels. In such a mobile communication system as just described, sharing of the same radio frequency spectrum by different radio systems hereinafter referred to as frequency channel sharing) is sometimes effected between an FDMA (FDMA; Frequency Division Multiple Access; frequency division multiple access) system or a TDMA system and a CDMA system. It is to be noted that, in the CDMA system, frequency channel sharing between different codes has already been put into practical use. Further, hand-over in those systems is known already.
Here, a mobile communication system of time slot sharing wherein a TDMA signal and a time divided CDMA signal are shared in a same time slot is disclosed in the official gazette of Japanese Patent Laid-Open Application No. Hei 8-130766 already filed for patent separately and so forth. However, those documents do not describe an asymmetrical communication channel between up- and down-links or hand-over in high speed data transmission.
Meanwhile, a technique of a mobile communication system of time slot sharing and frequency channel sharing wherein a TDMA signal and a time divided CDMA signal are used in a same time slot and synchronization between radio base stations in which a semi-fixed communication apparatus (hereinafter referred to as WLL station) by a wireless local loop (Wireless Local Loop; hereinafter referred to as WLL) and so forth have already been filed for patent by Japanese Patent Application No. Hei 9-188356 and so forth. However, those documents do not recite an asymmetrical communication channel wherein an up-link and a down-link have different communication capacities or hand-over in high speed data transmission.
Furthermore, also a technique of a mobile communication system suitable for a multi-media radio environment having an asymmetrical communication channel is filed for patent separately by Japanese Patent Application No. Hei 9-164817. However, in the document, hand-over in high speed data transmission is not taken into consideration.
Meanwhile, as a mobile communication system wherein a plurality of CDMA signals are shared, U.S. Pat. No. 5,363,403 is known. However, the specification of the patent does not recite a method of handling a time divided CDMA signal. While also U.S. Pat. No. 5,511,068 is known as another mobile communication system, the document relates to an adaptive filter for a time divided CDMA signal system, and the specification of it recites neither that frequency channel sharing of a CDMA signal and a TDMA signal is performed in one time slot nor hand-over in high speed data transmission.
Further, as a document which handles hand-over, International Publication No. WO96/06512 is known. However, the invention of the document handles hand-over in a cellular (Cellular) communication system, and does not recite a case wherein time slot sharing of a time divided CDMA signal and a TDMA signal is performed in one time slot or a mobile communication system which has an asymmetrical communication channel.
Furthermore, as a document which relates to a communication system wherein a TDMA technique is applied to a CDMA communication system, also U.S. Pat. No. 5,410,568 is known. This patent places a synchronization code (Synchronization-code) at the top of a frame of CDMA communication, that is, at the top of a burst, but does not introduce a time divided CDMA system using a TDMA control channel in order to effect frame synchronization setting, nor recites coexistence with a TDMA system. In other words, the patent does not intend sharing between a TDMA system and a time divided CDMA system using a TDMA frame. Further, in this patent, no attention is paid at all to a communication channel wherein the communication capacities of an up-link and a down-link are asymmetrical, and hand-over in high speed data transmission is not recited either.
It is to be noted that, in addition to the documents mentioned above, the official gazette of Japanese Patent Laid-Open Application No. Hei 6-22364, the official gazette of Japanese Patent Laid-Open Application No. Hei 7-322332, the official gazette of Japanese Patent Laid-Open Application No. Hei 8-154269, the official gazette of Japanese Patent Laid-Open Application No. Hei 8-280056 and so forth are known.
However, while the official gazette of Japanese Patent Laid-Open Application No. Hei 6-22364 mentioned above discloses a technique of hand-over for a TDMA cellular system, it is quite silent about an asymmetrical channel wherein an up-link and a down-link have different transmission capacities or a matter regarding hand-over in high speed data transmission.
In the meantime, while the official gazette of Japanese Patent Laid-Open Application No. Hei 7-322332 discloses a technique regarding reception of other base station signals in a silence period in a cellular system of the FDMA system, the TDMA system or the CDMA system or hand-over based on such reception, it does not recite an asymmetric channel wherein an up-link and a down-link have different transmission capacities or hand-over in high speed data transmission.
On the other hand, while the official gazette of Japanese Patent Laid-Open Application No. Hei 8-154269 discloses a technique wherein, in a mobile communication system, strengths of radio signals from radio base stations are measured and order numbers are applied to the radio signals in the descending order of the radio signal strengths and then the order is correlated with the order of hand-over and a candidate for hand-over is selected based on the correlation, it does not recite a communication system of an asymmetric channel wherein an up-link and a down-link have different transmission capacities or hand-over in high speed data transmission.
Further, while the official gazette of Japanese Patent Laid-Open Application No. Hei 8-280056 discloses a technique wherein, in a cellular system of the TDMA system or the CDMA system, a data buffer is provided in a radio base station and synchronism is established between the radio base station and an adjacent base station to realize instantaneous disconnection-free hand-over, it does not recite mobile communication having an asymmetric channel wherein an up-link and a down-link have different transmission capacities or hand-over in high speed data transmission.
Such various mobile communication systems which include one or more radio base stations which communicate with a plurality of mobile stations by radio channels and use the TDMA system and the time divided CDMA system as described above are conventionally known. Also in such mobile communication systems as described above, the demand for introduction of high speed data transmission is increasing. However, a mobile communication system which can sufficiently meet the demand has not been realized as yet.
Also it is demanded to introduce a communication channel wherein an up-link and a down-link have different communication capacities in order to make a mobile communication system cope with multi-media.
Furthermore, also in such a mobile communication system as described above, it is necessary to introduce hand-over means for allowing smooth hand-over in high speed data t
Fujio Hiroyuki
Uchida Yoshinori
Cong Le Thanh
Le Lana
Mitsubishi Denki & Kabushiki Kaisha
Rothwell Figg Ernst & Manbeck
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