Multiplex communications – Communication over free space – Combining or distributing information via code word channels...
Reexamination Certificate
1999-03-12
2003-02-25
Chin, Wellington (Department: 2664)
Multiplex communications
Communication over free space
Combining or distributing information via code word channels...
C370S343000, C370S320000, C370S330000, C370S335000
Reexamination Certificate
active
06526036
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a mobile communication system sharing of a frequency channel or a time slot and using a time division multiple access system (hereinafter referred to as TDMA) and/or a time division, code division multiple access system (hereinafter referred to as time divided CDMA), and in particular, it relates to a mobile communication system comprising a function in which a set of links, an up-link and a down-link, having different communication capacities from each other may be handled as a single communication channel (hereinafter referred to as an asymmetric communication channel).
BACKGROUND ART
A mobile communication system is mainly constituted with a mobile communication equipment or a portable communication equipment and a base station which communicates with mobile stations through radio channels. In such a mobile communication system, the common use of a radio frequency spectrum by different radio systems may be executed in a frequency division multiple access system (hereinafter referred to as an FDMA) or between a TDMA system and a CDMA system.
The common use of a frequency channel by different code systems has been put into an actual operation concerning the CDMA system.
A mobile communication system of a time slot common use type in which at least a TDMA signal and at least a time divided CDMA signal coexist in a time slot is disclosed in U.S. application Ser. No. 08/524,974 which is separately applied by the same applicant as the present invention, however, an asymmetrical communication channel is not all at referred to in the application.
Technologies for mobile communication systems in which a time slot is commonly used and a frequency channel is also commonly used, and further, technologies for synchronizing radio base stations by a wireless local loop (hereinafter referred to as WLL) using semi-fixed communication equipment are known in the art. However, in these technologies, an asymmetric channel in which capacities of an up-link and a down-link are different is not known.
The U.S. Pat. No. 5,363,403 is known as a system in which a plurality of CDMA signals are commonly used. However, in the specification, nothing is described concerning the way of handling a time divided CDMA. The U.S. Pat. No. 5,511,068 is also known as another mobile communication system, however, it is related to an adaptive filter in a time divided CDMA system and in the specification nothing is nothing refers to the common use of a frequency channel of a CDMA signal and a TDMA signal in a single time slot.
As a communication system in which a TDMA technology is applied to a CDMA communication system, the U.S. Pat. No. 5,410,568 is known. In the patent, a synchronization code is placed at the head of a burst signal. The patent does not refer to a system in which a time divided CDMA system is introduced using a TMDA control channel for setting frame synchronization, and nothing refers to coexistence with a TDMA system. In other words, it is not a patent in which TDMA system and a time divided CDMA system are to be used in common using a TDMA frame. Further, no consideration is paid for an asymmetrical channel in which the capacity of an up-channel is different from that of a downchannel.
Besides the above-mentioned ones, JP-A-63/175526, JP-A63/175527, JP-A-5/145477, JP-A-7/154866, and JP-A-8/186533, and so on are known.
However, in the above-mentioned JP-A-63/175526 and JP-A63/175527, it is intended to send more signals under the condition that the transmitting power of a transponder in a satellite communication is limited, but in the case of a mobile communication on land, such a limitation does not exist. Furthermore nothing describes a time divided CDMA system or a high speed TDMA. JP-A-5/145477 is related to the control of transmitting power of a signal in a TDMA time slot, and nothing refers to the time divided CDMA and TDMA communication systems.
The above-mentioned JP-A-7/154866 and JP-A-8/186533 are applications in which a set of links, an up-link and a down-link of having different capacities from each other may be handled as a communication channel. In the former, however, there is no concrete description about a high speed TDMA data transmission or a low speed time-divided CDMA data/voice frequency signal transmission, and nothing refers to a control information channel for intermittent connection which connects a user and a database during the consideration of the user or to the increase or decrease of a guard time in the unit of a micro time slot in a high speed TDMA data transmission channel. In the latter, as understood from the explanation of an aloha with a slot, it is premised on a packet communication system, and the time ratio of an up-link to a down-link in a time division duplex communication system can be variable, but it does not vary the time ratio of the up-link to down-link in a TDMA-TDD frame. Therefore, nothing refers to the coexistence of a plurality of TDMA signals, high speed TDMA data transmission and time divided CDMA in a time slot.
As mentioned in the above, there are many kinds of systems being constituted of one or more base stations which communicate with a plurality of mobile stations through radio channels using a TDMA system and a time divided CDMA system have been known. In these mobile communication systems, there has been a demand to introduce a high speed data communication system, however, a mobile communication system which is able to correspond such a demand has not been realized.
In order to make a mobile communication system to be able to correspond to a multimedia communication, it is needed to introduce a communication channel in which the communication capacity in an up-link and that in a down-link are different.
The present invention was made to solve the problems as mentioned in the above, and the object of the present invention is to realize a mobile communication system which is able to correspond to a multimedia environment, wherein a high speed TDMA channel is introduced to a mobile communication system in which a TDMA signal and a time divided CDMA signal coexist, and furthermore, communication links having different communication capacities in an up-link and a down-link may be handled as a single communication channel.
DISCLOSURE OF THE INVENTION
A mobile communication system described in claim
1
according to the present invention is the one in which a high speed data channel is introduced and the communication channel is made to be an asymmetric one in which the communication capacity of the up-link and that of the down-link are different from each other. Thereby, it is made possible to change over the communication speed in the unit of a frame length, which has been needed by customers, and to realize a mobile communication system which is able to flexibly adapt to the variation in communication capacity, which has been required by the multimedia environment.
A mobile communication system described in claim
2
according to the present invention is one in which the ratio of the communication capacity of an up-link to that of a down-link is varied by shifting a frame time, a TDD line in a frequency axis, in the direction of the time axis.
A mobile communication system described in claim
3
according to the present invention is the one comprising an asymmetric communication channel in which the down-link is assigned a high speed TDMA data channel and the up-link is assigned a low speed TDMA data channel.
A mobile communication system described in claim
4
according to the present invention is an asymmetric communication system in which the down-link is assigned a high speed TDMA data channel and the up-link is assigned a low speed time divided CDMA data channel.
A mobile communication system described in claim
5
according to the present invention is an asymmetric communication system in which the down-link is assigned a low speed TDMA data channel and the up-link is assigned a high speed TDMA data channel.
A mobile communication system described in claim
6
according to the present
Matsumoto Shinji
Uchida Yoshinori
Chin Wellington
Rothwell Figg Ernst & Manbeck
Schultz William
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