Yukou Mochida

A High Performance LSI Digital Signal Processor for Communication

This paper describes a newly developed CMOS LSI DSP (FDSP3). It has a powerful multiplier, which operates at a rate of 10 M-operations/s, almost twice as fast as the fastest existing LSI DSPs. Some key techniques to attain these high performance characteristics of the DSP are described. Suitable memory capacities of the RAM and ROM were analyzed as a function of the operational capability of the DSP. These were reflected in the design of the FDSP3. To assist in the development of the program, support tools have been developed. A Pascal based cross compiler and an on-line debugging tool are described in some detail.

Technology-oriented review and vision of 40-Gb/s-based optical transport networks

Research and development of 40-Gb/s-based technologies are very significant for not only increasing the total capacity of wavelength-division multiplexing transmission systems but also providing higher speed interfaces to routers and Ethernet devices in order to create new services in the twenty-first century. The technologies of digital and analog integrated circuits are progressing steadily, and the LiNbO/sub 3/ Mach-Zehnder external modulator has already reached the performance level required for practical use. Adaptive, intelligent compensation for problems such as chromatic dispersion and polarization-mode dispersion can make the design of optical transport networks more flexible. As an example, we achieved 3.5-Tb/s (43 Gb/s/spl times/88 ch) transmission over a 600-km nonzero dispersion-shifted fiber by using LiNbO/sub 3/ modulators and virtually imaged phased array variable-dispersion compensators.

Technologies for local-access fibering

The authors describe passive optical networks (PON), optical wavelength allocation, device and system technologies. Some examples of PON systems are given including SDM, WDM, FDM, and TCM. The authors go on to discuss optical modules LSI and optical amplifiers. The paper concludes with a discussion of upgrading PONs.<<ETX>>

A 16 kbps ADPCM with multi-quantizer (ADPCM-MQ) codec and its implementation by digital signal processor

This paper describes an implementation of a new 16 kbps speech codec using commercially available DSPs and its performance. The coding algorithm chosen here is ADPCM with Multi-Quantizer (ADPCM-MQ) which selects the optimum ADPCM coder frame by frame and switches to it dynamically. To implement this coding algorithm, we used two Fujitsu DSPs (MB8764), 1.5 chips for the encoder and 0.5 chip for the decoder. Reconstructed speech with a 21 dB segmental SNR was obtained. With error correction, this codec provides good speech quality even with a bit-error rate of 10^-2 to 10^-3. To improve the subjective quality of the reconstructed speech, adaptive postfiltering was also applied. Since the processing delay of this codec is less than 10 ms, no echo-canceller is needed. Moreover, 2400 bps voice band data (CCITT Rec.V. 26) could be transmitted with a data error rate from 10^-7 to 5×10^-6, and G.III facsimiles were successfully transmitted using this codec.

The Photonic Technologies Impact on the Next Generation Network

This paper describes the possible impact of photonic technologies on the next-generation network. With the explosion of the Internet (IP), the capacity demand is increasing exponentially, which exceeds Moors law. The next-generation IP network should sustain this increase. This paper shows the possible node processing bottleneck even the transmission capacity can be supported by the use of WDM technology. Based on this analysis, the paper proposes a virtual router network as a solution, which applies a logical full-mesh connection based on salient features of photonic network technology. Development of the WDM technology sets the target at 1000 wavelengths on a fiber so that a dynamic wavelength routing function is becoming available. The increase in wavelengths, transparency among wavelengths, and the wavelength routing function can provide an optical path, which forms the base of a logical full-mesh structure and also provides an easy migration scenario from the current network to the next-generation IP network. The possibility is examined by calculation using a bi-directionalloop network as an example. As the foundation of the proposal, the current statusof photonic network technologies is described with future projection.