Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1998-04-14
2001-07-03
Ngo, Ricky (Department: 2664)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S341000, C370S437000, C370S493000
Reexamination Certificate
active
06256298
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile telecommunication system, and in particular to a mobile telecommunication system in which a sound signal is transmitted after being coded and compressed according to the ADPCM (Adaptive Differential Pulse Code Modulation) scheme.
2. Description of the Related Art
Conventionally, as a mobile telecommunication system in which sound data are transmitted after being coded and compressed according to the ADPCM scheme, there is a personal-handyphone-system transmission system (hereafter referred to as “PHS transmission system”) which is disclosed in JP-A-7-30645, for example. The PHS transmission system is used in the communication scheme for transmitting sound and image signals using the S interface of an ISDN (Integrated Services Digital Network). For example, a compressed signal produced by encoding and compressing the sound signal according to the ADPCM scheme is assigned to a first channel
15
, which consists of four bits among eight bits of B
1
channel (B
1
-ch) as shown in
FIG. 3A
, to be transmitted as a signal of 32 kbps. An uncompressed signal (non-sound signal) containing other information is assigned to a second channel
16
, which consists of the remaining bits of the B
1
channel and eight bits of B
2
channel (B
2
-ch) as shown in
FIG. 3B
, to be transmitted as a signal of 96 kbps.
In the PHS transmission system, however, it is necessary to use two channels (i.e. the B
1
and B
2
channels) in order to simultaneously transmit and receive the compressed signal (sound signal) and the uncompressed signal (non-sound signal). Furthermore, in the case where the data amount of the uncompressed signal (non-sound signal) is small, the circuit utilization factor between PHS terminals reduces.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a mobile telecommunication system capable of improving the circuit utilization factor and of simultaneously transmitting and receiving a compressed sound signal and a non-sound signal over one channel.
A first mobile telecommunication system according to the present invention is a mobile telecommunication system for transmitting a sound signal from a first terminal to a second terminal over a channel with a predetermined number of bits, each of the first and second terminals being a mobile telecommunication terminal, which comprises: a first base station to which the first terminal and a third terminal for transmitting a non-sound signal are connected; and a second base station connected to the first base station via a digital network, the second terminal being connected to the second base station, wherein the first terminal comprises: means for coding and compressing the sound signal to convert the sound signal into a compressed sound signal; and means for transmitting an answer signal in response to receiving a notice signal which informs that the second terminal is the mobile telecommunication terminal, and upon receiving the answer signal from the first terminal, the first base station transmits the compressed sound signal, which is transmitted from the first terminal, and the non-sound signal, which is transmitted from the third terminal, to the second base station via the digital network by assigning the compressed sound signal to several bits of the channel and assigning the non-sound signal to remaining bits of the channel.
A second mobile telecommunication system according to the present invention is a mobile telecommunication system for transmitting a sound signal from a first terminal to a second terminal over a channel with a predetermined number of bits, each of said first and second terminal being a mobile telecommunication terminal, which comprises: a first base station to which the first terminal and a third terminal for transmitting a non-sound signal are connected, the first base station having a first modulation rate conversion device for converting a signal modulation rate; and a second base station connected to the first base station via a digital network, the second terminal being connected to the second base station, the second base station having a second modulation rate conversion device for converting a signal modulation rate, wherein the mobile telecommunication terminal comprises: means for coding and compressing the sound signal to convert the sound signal into a compressed sound signal; means for transmitting a first notice signal which informs that the first terminal is the mobile telecommunication terminal; and means for transmitting a control signal, which brings the first and second modulation rate conversion devices into a non-operational state, in response to receiving a second notice signal which informs that the second terminal is the mobile telecommunication terminal, and upon receiving the answer signal from the first terminal, the first base station transmits the compressed sound signal, which is transmitted from the first terminal, and the non-sound signal, which is transmitted from the third terminal, to the second base station via the digital network by assigning the compressed sound signal to several bits of the channel and assigning the non-sound signal to remaining bits of the channel.
A third mobile telecommunication system according to the present invention is a personal-handyphone-system transmission system for transmitting a sound signal from a first telecommunication terminal to a second telecommunication terminal via a circuit switching service of an integrated service digital network over a channel with a predetermined number of bits, which comprises: a first base station to which the first telecommunication terminal and a data terminal for transmitting a non-sound signal are connected, the first base station including a first adaptive-differential-pulse-code-modulation signal/pulse-code-modulation signal conversion device for converting an adaptive differential pulse code modulation signal, which is obtained by coding and compressing the sound signal according to an adaptive differential pulse code modulation scheme, into a pulse code modulation signal which is obtained by coding the sound signal according to a pulse code modulation; and a second base station connected to the first base station via said circuit switching service of the integrated service digital network, the second telecommunication terminal being connected to the second base station, the second base station including a second adaptive-differential-pulse-code-modulation signal/pulse-code modulation signal conversion device for converting the adaptive differential pulse code modulation signal into the pulse code modulation signal, wherein the first telecommunication terminal comprises: means for converting the sound signal into the adaptive differential pulse code modulation signal by coding and compressing the sound signal according to an adaptive differential pulse code modulation scheme; means for transmitting a first notice signal which informs that the first telecommunication terminal is a personal-handyphone-system terminal; and means for transmitting a control signal, which brings the first and second adaptive-differential-pulse-code-modulation signal/pulsecode-modulation signal conversion devices into a non-operational state, in response to receiving a second notice signal which informs that the second telecommunication terminal is a personal-handyphone-system terminal, and upon receiving the control signal from said first telecommunication terminal, the first base station transmits the adaptive differential pulse code modulation signal, which is transmitted from the first telecommunication terminal, and the non-sound signal, which is transmitted from the data terminal, to the second base station by assigning the adaptive differential pulse code modulation signal to several bits of the channel and assigning the non-sound signal to remaining bits of the channel.
REFERENCES:
patent: 5479480 (1995-12-01), Scott
patent: 5781538 (1998-07-01), Ganesan et al.
patent: 5812951 (1998-09-01), Ganesa
Matsushita Electric - Industrial Co., Ltd.
Ngo Ricky
Stevens Davis Miller & Mosher LLP
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