Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1998-10-20
2002-10-08
Marcelo, Melvin (Department: 2663)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S524000
Reexamination Certificate
active
06463077
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a PHS data communication terminal adapter, and in particular, to a PHS data communication terminal adapter which performs data communication with a data communication terminal on the side of a PHS (Personal Handy-phone System) via a digital network by executing protocol conversion and switching the data transmission bit rate between a high data transmission bit rate and a low data transmission bit rate.
DESCRIPTION OF THE PRIOR ART
In Personal Handy-phone System (PHS) which has been developed in Japan, data communication terminals which can be connected to PHS handy phones are widely used in order to communicate data, and PHS data communication terminals having radio transmission/reception capability are also utilized. Therefore, communication of data can be executed between data communication terminals which are connected to PHS handy phones, between a PHS data communication terminal (having radio transmission/reception capability) and a data communication terminal which is connected to a PHS handy phone, or between PHS data communication terminals (having radio transmission/reception capability). In the data communication in the PHS, data is transmitted mainly at a bit rate of 32 kbps based on CCITT-I430, and a data transmission bit rate of 64 kbps is also utilized. In Japan, the Personal Handy-phone System is connected with ISDN (Integrated Services Digital Network) and PSTN (Public Switched Telephone Network), and thus data communication between a data communication terminal which is connected to a PHS handy phone (or a PHS data communication terminal having radio transmission/reception capability) and a data communication terminal on the side of the ISDN or PSTN is also possible.
With regard to the Personal Handy-phone System, proposals for standardization of data transmission protocols etc. have been done in order to make data transmission and access to Internet using PHS handy phone easier, in which “PIAFS” (PHS Internet Access Forum Standard) has been standardized in March 1997 by PHS Internet Access Forum (JAPAN). In the PIAFS, methods for controlling synchronized systems in PIAFS data transmission protocol conversion, full-duplex data communication, measurement of answer delay time, flow control, data link establishment/release, data assembing(framing)/disassembling functions, data compression function, etc. have been standardized. Frame types such as negotiation frames, synchronization frames, control frames, data frames, etc. have also been standardized.
As mentioned above, when a data communication terminal on the side of an Integrated Services Digital Network (ISDN) communicates with a data communication terminal on the side of a Personal Handy-phone System (PHS) via the ISDN, data communication is executed at a data transmission bit rate of 32 kbps or 64 kbps in information channels (2Bch) according to the CCITT-1430. The 64 kbps data transmission bit rate is utilized when radio wave conditions for the PHS handy phone are good, and the data transmission bit rate is switched to 32 kbps if the radio wave conditions are not good. The switching of the data transmission bit rate between 32 kbps and 64 kbps is determined and executed exclusively by the data communication terminal on the side of the PHS, since the radio wave conditions are detected on the side of the PHS.
Data transmission from a data communication terminal on the side of a PHS network to a data communication terminal (such as a personal computer) on the side of an ISDN is executed, for example, via a PHS handy phone, a radio base station of the PHS network, the PHS network, the ISDN, an NCU (Network Control Unit), and a PHS data communication terminal adapter to which the data communication terminal on the side of the ISDN is connected. Data transmission from the data communication terminal on the side of the ISDN to the data communication terminal on the side of the PHS network is executed reversely.
Data communication between a PHS handy phone (to which the data communication terminal on the side of the PHS is connected) and the PHS network is executed using (2B′+D) channels. The data transmission bit rate of the B′-channel is 32 kbps or 64 kbps as mentioned above, and the data transmission bit rate of the D-channel is 16 kbps.
The ISDN communicates data utilizing (2B+D) channels (2× (32 kbps or 64 kbps)+16 kbps). Here, in the ISDN, the basic data transmission bit rate is fixed to 64 kbps, in which 8-bit B-channel transmission data is transmitted at a frequency of 8 kHz (8 bits×8 kHz). Therefore, the 32 kbps (4 bits×8 kHz) B-channel transmission data of the ISDN is transmitted utilizing front 4 bits of the 8-bit B-channel transmission data, and rear 4 bits of the 8-bit B-channel transmission data is filled with dummy data such as “1111”.
When the 32 kbps B′-channel data is sent from the PHS handy a phone, an exchange (switch) of the PHS network converts the 32 kbps B′-channel data to the 32 kbps B-channel transmission data (in which the front 4 bits of the 8-bit B-channel transmission data are utilized and the rear 4 bits of the 8-bit B-channel transmission data are filled with the dummy data), and sends the 32 kbps B-channel transmission data to the ISDN.
The PHS data communication terminal adapter (TAP) (to which the data communication terminal on the side of the ISDN is connected) which communicates data with the data communication terminal on the side of the PHS network via the ISDN utilizing data transmission bit rates of 32 kbps and 64 kbps operates as follows.
(1) When the PHS data communication terminal adapter is in a SETUP status (when the PHS data communication terminal adapter and the data communication terminal on the side of the PHS have just been established connection, by communicating control information using setup signals on the D-channel), the data communication terminal on the side of the PHS which is going to transmit data to the PHS data communication terminal adapter on the side of the ISDN can not inform the PHS data communication terminal adapter whether its data transmission bit rate is 32 kbps or 64 kbps. Therefore, the data-receiving PHS data communication terminal adapter on the side of the ISDN has to execute the following PIAFS protocol conversions at once or successively, in order to judge whether the data transmission bit rate of the datasending data communication terminal on the side of the PHS is 32 kbps or 64 kbps and set protocol conversion mode of itself at a “high rate protocol conversion mode” which corresponds to the high data transmission bit rate (64 kbps) or a “low rate protocol conversion mode” which corresponds to the low data transmission bit rate (32 kbps) based on the judgment.
(a) The PHS data communication terminal adapter executes 64 kbps PIAFS protocol conversion to all the bits of the 64 kbps B-channel transmission data.
(b) The PHS data communication terminal adapter executes 32 kbps PIAFS protocol conversion to the front 4-bit data of the 64 kbps B-channel transmission data composed of 8 bits.
(2) When data transmission bit rate is changed from 64 kbps to 32 kbps by the data communication terminal on the side of the PHS by channel switching during data communication, the PHS data communication terminal adapter has to execute the following PIAFS protocol conversions at once or successively, in order to judge whether the data transmission bit rate of the data-sending data communication terminal on the side of the PHS is 32 kbps or 64 kbps and set the protocol conversion mode of itself at the high rate protocol conversion mode corresponding to the high data transmission bit rate (64 kbps) or the low rate protocol conversion mode corresponding to the low data transmission bit rate (32 kbps) based on the judgment.
(a) The PHS data communication terminal adapter executes 32 kbps PIAFS protocol conversion to the front 4-bit data of the 64 kbps B-channel transmission data composed of 8 bits.
(b) The PHS data communication terminal ada
Dickstein , Shapiro, Morin & Oshinsky, LLP
Marcelo Melvin
Mehra Inder Pal
NEC Corp.
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