Fan Changxin

A novel variable-rate MELP speech coder

In MELP coder, LPC coefficients are quantized to 25 bit/frame by MSVQ. The overall bit of MELP is 54 bit/frame, so more than 45% of the required bandwidth is spent on transmission of LPC coefficients. In this paper, based on LPC adaptive forward-backward quantization, a novel variable-rate MELP coder is proposed, in which linear prediction is done by using either the currently (forward LPC) or previously decoded (backward LPC) speech frame. The backward LPC scheme shall be applied, i.e., the LPC coefficients based on the previously decoded optimal speech frame are used to encode the current frame and only the time delay shall be transmitted to the decoder, so, average LPC bit number becomes smaller. Computer simulation shows significant average overall bit rate reduction is achieved without compromising the decoded speech quality.

BCSM switch for B-ISDN a new high-performance switching element

This paper proposes a new high-performance switching element with the new shared-memory queuing policy, which is called blocked-cell shared-memory (BCSM) queuing. As the name means, instead of buffering all cells through them, the BCSM switching elements only buffer the blocked cells at their input ports. Theoretic analysis results under the uniform traffic model prove that BCSM switching elements have better performance than shared-memory switching elements.

Rotated Barnes-Wall lattice based vector quantizer and its application in image-sequence coding

A new scheme is presented to design a rotated Barnes-Wall lattice based vector quantizer(LVQ). The construction method of the LVQ and its, fast quantizing algorithm are described at first. Then gain-shape lattice vector quantizer (GSLVQ) with LVQ as shape quantizer is discussed. Finally the GSLVQ is used in image-sequence coding and good experimental results are obtained.

The architecture and experiment of the customer premises network for a microwave ATM network

The paper discusses the architecture of an experimental research prototype for a microwave ATM customer premises network (CPN). Based on the architecture of the CPN, some of the key technologies for realizing the CPN functional blocks are discussed and part of the application specific integrated circuit (ASIC) design results are reported.<<ETX>>

Development of telecommunications undertakings in China

A brief history of telecommunications in China is given. The current status of telecommunication services, administration, technology, and policy is reviewed. Future plans are discussed. >