Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1997-09-22
2002-02-26
Yao, Kwang B. (Department: 2664)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S335000
Reexamination Certificate
active
06351458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wireless transmitter, a wireless receiver, and wireless communication equipment of CDMA system for digital cellular mobile communication or the like, and more particularly, to ones with which both FDD (Frequency Division Duplex) and TDD (Time Division Duplex) can be operated in a simplified construction and efficient manner.
2. Description of the Related Art
In digital cellular mobile communication, multiple access systems in which a plurality of mobile stations simultaneously connect with a circuit using the same frequency band are adopted. CDMA (Code Division Multiple Access), one of the multiple access systems, is a technique for carrying out multiple connection utilizing spread spectrum communication where a spectrum of an information signal is spread over a sufficiently wide band compared with the original bandwidth in transmission. Thus, CDMA is sometimes referred to as Spread Spectrum Multiple Access (SSMA). As a method of spreading a spectrum, Spread Spectrum-Direct Sequence (SS-DS), that is, a system where an information signal is multiplied directly by a spread series code to spread the spectrum of the information signal.
It is an object of the present invention to provide a CDMA cellular mobile communication system in which both FDD (Frequency Division Duplex) and TDD (Time Division Duplex) methods can be used for transmission and reception of communication signals.
SUMMARY OF THE INVENTION
In wireless communication, there are two systems: a system where transmission and reception are allotted to different radio frequencies (FDD: Frequency Division Duplex); and a system where the same frequency is used and transmission and reception are allotted according to time sharing (TDD: Time Division Duplex). As shown in
FIG. 9
, in FDD, a radio frequency F
1
(
801
) for a down circuit (from a base station to a mobile station) is different from a radio frequency F
2
(
802
) for an up circuit (from a mobile station to a base station). On the other hand, in TDD, which is sometimes referred to as the ping-pong system, the same radio frequency F
3
(
803
) is time shared to transmission/reception to carry out communication.
In FPLMTS (Future Public Land Mobile Telecommunication Systems) which is now being standardized as systems for mobile communication in the next generation with ITU being at the center, 1885-2025 MHz and 2110-2200 Mhz are allotted as radio frequencies for FPLMTS bands. For example, the above two frequency bands are to be allotted to the FDD band and the TDD band, it may be considered that 2110-2200 MHz and 1885-1975 MHz, each having a bandwidth of 90 MHz, are allotted to the FDD band and the remaining low frequency band, that is, 1975-2025 Mhz having a bandwidth of 50 MHz is allotted to the TDD band. In this case, as a cellular wireless system, it may be considered that the two communication systems, FDD and TDD, are operated in the same area and by the same base station.
Accordingly, the present invention provides a CDMA cellular wireless communication system which can operate both FDD and TDD.
According to the present invention, there is provided a CDMA cellular wireless communication system which comprises a base station, a plurality of mobile stations for communicating with the base station, FDD (Frequency Division Duplex) communication means between the base station and the mobile stations using different radio frequencies for transmission and reception and TDD (Time Division Duplex) between the base station and the mobile stations using a same frequency for transmission and reception between the base station and the mobile stations.
REFERENCES:
patent: 5602836 (1997-02-01), Papadopoulos et al.
patent: 5689502 (1997-11-01), Scott
patent: 5732076 (1998-03-01), Ketseoglou et al.
patent: 5793757 (1998-08-01), Uddenfeldt
patent: 5802046 (1998-09-01), Scott
patent: 5850393 (1998-12-01), Adachi
patent: 5933421 (1999-08-01), Alamouti et al.
patent: 5943362 (1999-08-01), Saito
patent: 5956326 (1999-09-01), Magana
patent: 6175744 (2001-01-01), Esmailzadeh et al.
Kato Osamu
Miya Kazuyuki
Matsushita Electric - Industrial Co., Ltd.
Stevens Davis Miller & Mosher LLP
Yao Kwang B.
LandOfFree
CDMA cellular wireless communication system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with CDMA cellular wireless communication system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and CDMA cellular wireless communication system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2961556