Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1999-01-15
2003-07-08
Kizou, Hassan (Department: 2662)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S342000, C370S347000
Reexamination Certificate
active
06590878
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a mobile communication system that is capable of realizing the use in combination of a wireless local loop (WLL) communication system and a mobile communication system using frequency channel sharing and time slot sharing based on a time-divided multiple access (TDMA) method, or a code division multiple access (CDMA) method, or a time-divided CDMA method.
BACKGROUND ART
A mobile communication system mainly comprises for example a mobile vehicle communication apparatus or mobile portable communication apparatus (hereinafter referred to as mobile stations) and base stations that communicate with the mobile stations through radio channels or wireless channels. In mobile communication systems, sometimes a radio frequency spectrum using different radio communication methods is shared between FDMA (frequency division multiple access)/TDMA method and a CDMA method. CDMA methods sharing frequencies between different codes have been performed. In the prior art, the technique in a mobile communication system with time slot sharing in which TDMA signals and time-divided CDMA signals are shared in a same time slot is known. In addition to this, there is a technique in mobile communication systems with time slot sharing, in which TDMA signals and time-divided CDMA signals are commonly used in a same time slot, and with frequency sharing. Furthermore, there is the conventional system that shares a plurality of CDMA signals disclosed in the United State patent U.S. Pat. No. 5,363,403, Spread Spectrum CDMA Subtractive Interference Canceller and Method, by D. L. Schilling et al. However, this US patent does not disclose any method handling time-divided CDMA signals.
In addition, in U.S. Pat. No. 5,511,068, Mobile Communication system capable of transmitting and receiving radio signals obtained by TDMA and CDMA methods without Interference, T. Sato discloses the Adaptive Filter in a time-divided CDMA signal system. However, in this literature, there is no description of frequency sharing of a time-divided CDMA signal and a TDIMA signal in a time slot.
Furthermore, the Japanese laid open publication number JP-A-6-268575 has disclosed a technique in which a receiving level of a radio signal transmitted from mobile stations to base stations is measured by a base station located in an uplink and the base station divides the received uplink signal into groups and each group is assigned into each time slot.
In addition, the Japanese laid open publication number JP-A-8-228375 discloses a technique to handle outer cells and inner cells in a concentric circle, but, there is no explanation about a technique to assign time-divided CDMA radio waves to different time slots inside and outside of a concentric circle zone of a mobile station or a Wireless Local Loop (WLL) station. In addition, in this literature, there is no description about interference in which a large power radio waves generate noise in small power radio waves in the demodulation of the CDMA method or about anti-interference.
As described above, in the prior art, in the conventional mobile communication systems formed; by WLL stations or mobile stations and base stations communicating them through radio wave channels, there is the requirement to expand time slot sharing and frequency channel sharing using different radio communication methods to WLL communication and mobile communication sharing systems performed between TDMA signals, time-divided CDMA signals, and synchronous word identification sharing TDMA signals.
Furthermore, the prior art entails the problem that it has been necessary to determine the function of the mobile switching station that manages the communication of the entire system in which different transmission power signals are assigned into different time slots when TDMA signals, time-divided CDMA signals, and synchronous word identification sharing TDMA signals are assigned into a mobile station positioned in a concentric-circle zone in a cell.
Moreover, the prior art entails the problem that operators in different mobile communication systems need to be able to perform a frame synchronization in each system described above.
The present invention is proposed to overcome the above drawbacks in the prior art. It is an object of the present invention to provide a mobile communication system enable TDMA signals or time-divided CDMA signals, and synchronous word identification sharing TDMA signals to perform time slot sharing and frequency sharing. mobile communication system is capable of avoiding the masking of TDMA signals, time-divided CDMA signals, and synchronous word identification TDMA signals by larger power transmission signals provided to mobile stations located in different zones. This is performed in a shared same time slot and frequency channel in which TDMA signals, time-divided CDMA signals, and synchronous word identification sharing TDMA signals are shared. For example, radio waves in a downlink transmitted from the base station are divided into different groups according to the magnitude of the radio wave transmission power. Each of the groups is assigned into a different time slot. It is thereby possible to obtain the mobile communication system that enables the shared use of frame synchronization of the same system by base stations belonging to a plurality of operators and capable of avoiding to mask the weak downlink and uplink radio waves.
DISCLOSURE OF THE INVENTION
According to the present invention, there is provided a mobile communication system comprising mobile stations of a plurality of mobile vehicle communication apparatus or mobile portable communications apparatus, semi-fixed WLL stations, at least one base station, and mobile switching centers connected to the base station. Radio communication among the above is performed based on FDMA or multi-carrier TDMA, or CDMA method, or time-divided CDMA method which are digital modulation methods such as FSK, BPSK, QPSK, QDPSK, p/4-DQPSK, QAMSK, QGMSK. The mobile communication system shares time slots and frequency channels having shared channels which are time-divided CDMA signal channels that share time slots and frequencies on a frequency axis with FDMA/TDMA digital signals. The TDMA signal on a same frequency channel and a same time slot comprises a plurality of signals, and the mobile stations, the WLL stations, the base stations identify each of the TDMA signals by setting a different synchronous word to each of the TDMA signals under the control of the mobile switching centers, and the radio communication is performed by using the time-divided CDMA signals that share the time slots and the frequencies with the TDMA signals or share the time slots with the TDMA signals.
This results in the effect that the time slot and frequency are shared in the TDMA signals and/or the time-divided CDMA signals and/or the synchronous word identification sharing TDMA signals. In addition, in the same time slot and frequency channels in which the TDMA signal, the time-divided CDMA signal, and the synchronous word identification sharing TDMA signal are shared, the masking of radio waves by radio waves of a large transmission power, transmitted to mobile stations located in different zones is avoided. It is thereby possible to reduce communication errors.
According to the present invention, there is provided a mobile communication system in which the mobile switching center comprises a memory. The mobile switching center identifies the WLL station belonging to the base station connected to the mobile switching center, stores radio information about the WLL station and relationship information about station identification information. The mobile switching center uses the relationship information of the WLL station stored in the memory when initiating communication to the WLL station.
According to the present invention, there is provided a mobile communication system in which when completing the radio communication with the WLL station, the mobile switching center updates the relationship information of the WLL st
Matsumoto Shinji
Uchida Yoshinori
Kizou Hassan
Levitan Dmitry
Mitsubishi Denki & Kabushiki Kaisha
Rothwell Figg Ernst & Manbeck
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