Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1997-12-17
2001-10-23
Nguyen, Chau (Department: 2663)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S477000, C370S337000
Reexamination Certificate
active
06307865
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radio communication method and a radio communication system between a base station and a mobile station which are applied to a digital cordless telephone system which makes use of a personal handyphone system (PHS) and by which communication by a modem modulation signal such as a facsimile modem signal or a data modem signal or a speech signal is performed by demultiplexing of a PCM (Pulse Code Modulation) signal of 64 kbps and an ADPCM (Adaptive Differential PCM) signal of 32 kbps.
2. Description of the Related Art
A digital cordless telephone system which makes use of a handyphone system (PHS) is conventionally used. An exemplary one of such digital cordless telephone systems is disclosed, for example, in Japanese Patent Laid-Open Application No. Heisei 5-328425.
The cordless telephone system disclosed in the document mentioned above is directed to realization of talking of a high quality by an ADPCM signal of 32 kbps. Further, as a multiplexing system for a speech signal, a circuit having a transmission speed of 64 kbps such as an ISDN (Integrated Services Digital Network) is used. In the multiplexing system, an ADPCM signal of 32 kbps is multiplexed to allow duplex communication by 32 kbps.
In this instance, a mutual exchanging apparatus between a &mgr;-law, A-law system of 64 kbps as a digitalization sampling system for a speech signal and an ADPCM system of 32 kbps is provided to allow setting of which one of the systems should be used. By such mutual exchanging processing, if, during communication using the ADPCM system of 32 kbps, a new request for communication to the same communication destination is received, additional communication using the same circuit is possible.
However, in the conventional cordless telephone system described above which is directed to realization of talking of a high quality by an ADPCM signal of 32 kbps, when a base station connected to a public network performs data transmission through a radio circuit regarding a modem modulation signal from a facsimile (FAX) modem or a data modem as a speech signal, a PHS mobile station which receives the ADPCM signal of 32 kbps by the transmission converts the ADPCM signal of 32 kbps having a narrow bandwidth once into an analog signal and sends out the analog signal to the facsimile machine or data terminal.
Consequently, the data quality is deteriorated considerably and besides the transmission speed is dropped. In this instance, the transmission speed of 9,600 bps is guaranteed for practical use. This also applies to another case wherein a base station is connected to an ISDN network.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a radio communication method and a radio communication system which allow, where they are applied to a digital cordless telephone system or the like which makes use of a handyphone system (PHS) connected to an analog circuit or an ISDN network, data transmission in a wide band regarding a modem modulation signal from a modem of a facsimile machine or a data terminal as a speech signal and allow communication at a high transmission speed without deterioration of the data quality.
In order to attain the object described above, according to an aspect of the present invention, there is provided a radio communication method for a radio communication system which includes a base station connected to an analog network and a mobile station connected to the base station by a radio circuit, wherein the base station performs, when an analog signal which is a modem modulation signal such as a facsimile modem signal or a data modem signal is received from the analog network, PCM/CODEC processing of the analog signal, modulates the analog signal into a PCM signal of a high transmission speed, separates the PCM signal into two ADPCM signals of a low transmission speed, allocates the two ADPCM signals of the low transmission speed to two time slots by channel CODEC processing and performs data transmission as two radio communications through the radio circuit, and the mobile station demodulates the data received from the base station into an analog signal by a processing procedure reverse to the processing procedure by the base station and performs communication of the analog signal with a wide bandwidth of the high transmission speed regarding the analog signal as a speech signal.
The base station may perform, when a speech signal which is an analog signal is received from the analog network, ADPCM/CODEC processing for the speech signal, allocate the one ADPCM signal to one time slot and perform data transmission through the one radio circuit.
According to another aspect of the present invention, there is provided a radio communication method for a radio communication system which includes a base station connected to an ISDN network and a mobile station connected to the base station by a radio circuit, wherein the base station separates a modem modulation signal such as a facsimile modem signal or a data modem signal which is a PCM signal of a high speed sent thereto from the ISDN network into two ADPCM signals of a low transmission speed, allocates the two ADPCM signals of the low transmission speed to two time slots by channel CODEC processing and performs data transmission as two radio communications through the radio circuit, and the mobile station demodulates the data received from the base station into an analog signal by a processing procedure reverse to the processing procedure by the base station and performs communication of the analog signal with a wide bandwidth of the high transmission speed regarding the analog signal as a speech signal.
The base station may perform, when the PCM signal of the high transmission speed sent thereto from the ISDN network is a speech signal, PCM/ADPCM processing to convert the speech signal of the received PCM signal into an ADPCM signal of the low transmission speed, allocate the one ADPCM signal to one time slot and perform data transmission through the one radio circuit.
A radio communication system according to the present invention may have two forms including a form wherein it comprises a radio base station connected to an analog network and a mobile station connected to the base station by a radio circuit and another form wherein it comprises a radio base station connected to an ISDN network and a mobile station connected to the base station by a radio circuit. Where the radio communication system has the former form, the base station includes a main control section for controlling components of the base station, an analog circuit interface section for receiving an analog signal from the analog network, a signal type discrimination section for discriminating whether the analog signal received by the analog circuit interface section is a modem modulation signal from a facsimile modem or a data modem or a speech signal, a PCM/CODEC section for modulating the analog signal from the analog circuit interface section into a PCM signal of 64 kbps and for conversely demodulating a PCM signal of 64 kbps into an analog signal, an ADPCM/CODEC section for modulating the analog signal from the analog circuit interface section into an ADPCM signal of 32 kbps and for conversely demodulating an ADPCM signal of 32 kbps into an analog signal, a switch section for switching connection of the analog circuit interface section alternatively to the PCM/CODEC section or the ADPCM/CODEC section, a demultiplexing section for demultiplexing a PCM signal of 64 kbps and an ADPCM signal of 32 kbps, a channel CODEC section for performing allocation of communication channels to time slots of the radio circuit and performing framing and deframing of radio frames of a control channel and a communication channel, and a radio interface section for receiving data from the radio circuit and transmitting data through the radio circuit.
Meanwhile, the mobile station includes a main control section for controlling components of the mobile station, a radio interface se
Adachi Tsukasa
Ogasawara Hiromichi
NEC Corporation
Nguyen Chau
Nguyen Phuongchau Ba
LandOfFree
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