Industrial Technology Research Institute

Itri Limited

Shian-Ming Tzeng

Chi-Chang Chen

Chen-Chi Fan

An adapter for connecting a first low bit rate transmission link and a second high bit rate transmission link is disclosed. The adapter receives frames transmitted via the first link. The frames are of variable length and include a flag, an address field, a control field, a variable length data field and a frame check sequence. Each frame also includes after the flag a length code indicative of the frame length, which length code does not alter a frame check sequence of the frame. The adapter includes a processor which determines for each frame in response to the length code a specific time at which the adapter begins transmitting the frame out onto the second transmission link. The specific time is chosen for each frame so that the completion of the transmitting of the frame out on the second link substantially coincides with the completion of the receiving of the frame from the first transmission link. The length code of each frame is removed when it is transmitted out over the second transmission link. The inventive adapter is especially useful is certain kinds of ISDN networks. For example, a fractional terminal equipment (F-TE) may generate the frames with the length codes and transmit these frames in a sub-B channel which runs on an ISDN S/T interface bus at a rate of 64/N kbps, where N is an integer greater than two. The adapter forms part of a fractional network terminator (F-NT) which adapts the frames for transmission on a 64 kbps link, for example, to a central office.

Adapter for transmission lines using HDLC frames

A system and method are disclosed for adapting the rate of a data terminal equipment having a V-series type interface connected to an integrated services digital network which supports more than two simultaneous communications. A V.110 rate adapter is provided which receives user data at a user data rate from the data terminal equipment and outputs a bitstream containing the user data at a B-channel data rate. A fractional rate adapter is also provided which receives this bitstream and outputs a second bitstream at a lower subchannel data rate using a bit discarding technique.

Growing community of inventors

Yangmei, Taiwan

Shian-Ming Tzeng