Katsuhiko Kawazoe

Ultra-high-speed and universal-coding-rate Viterbi decoder VLSIC-SNUFEC VLSI

An ultra-high-speed (higher than 60 Mb/s) Viterbi decoder VLSIC with coding rates from one-half to fifteen-sixteenths and a constant length of seven for forward error correction (FEC) is developed using 0.8-/spl mu/m semi-custom CMOS LSIC technology. To reduce the power consumption of the one-chip high-coding-rate Viterbi decoder, a newly developed universal-coding-rate scarce-state-transition (SST) Viterbi decoding scheme and low-power-consumption burst-mode-selection (BMS) path memory are employed. A new maximum-likelihood-decision, (MLD) circuit for the SST Viterbi decoder is developed to reduce the path memory length without coding-gain degradation. The developed Viterbi decoder VLSIC achieves a maximum data rate of 60 Mb/s with a power consumption of 2.5 W and achieves near theoretical net coding-gain performance for various coding rates.<<ETX>>

A reliable channel control method for wireless multimedia communications

This paper proposes channel control sequences and a reliable channel control signal transmission method for wireless multimedia communications employing TDMA for multiple access. The proposed methods allow multiple traffic bursts to be assigned between a base station and a personal handy phone with low hardware and software increase compared to single burst assignment. They improve the layer 2 frame error rate by about 25% for two control channels, FACCH/SACCH (fast/slow associated control channel).

Novel packet transmission scheme for personal communication systems

This paper proposes a novel packet transmission scheme for personal communication systems in the slow fading environments. The throughput of personal communication systems using packet data transmission can be decreased by the bit errors caused by the slow fading generated when the portable sets (PS) are used while walking. The proposed selective reject protocol with acknowledgment (ACK) transmission (SR-A) protocol employs ACK packet transmission for all received data packets to realize higher packet data transmission throughput. Computer simulation results confirm that the proposed SR-A protocol improves the data throughput performance by 30% compared to conventional selective reject (SR) protocol. Moreover, application of reception diversity (for higher Eb/No (>15 dB)), and combination of reception diversity and forward error correction (FEC) improve the data throughput performance of the SR-A protocol by about 20%.<<ETX>>

Universal-coding-rate scarce-state-transition Viterbi decoder

The authors propose a universal-coding-rate scarce-state-transition Viterbi decoder that permits the realization of a high-speed high-coding-rate one-chip forward error correction CMOS LSIC. To reduce the power consumption of high-coding-rate Viterbi decoders, the proposed decoder expands the scarce-state-transition (SST) Viterbi decoding scheme from a coding rate of one-half to any higher coding rate. To employ the SST Viterbi decoding scheme for high-coding-rate convolutional codes, a universal predecoding scheme for convolutional codes is introduced. Computer simulations showed a drastic reduction in CMOS gate on-off switching. A low-power-consumption path memory is proposed to reduce the power consumption. A pilot chip was fabricated and its total power consumption was reduced by 27% for rate three-fourths coding rate Viterbi decoding.<<ETX>>

Low-power and high-quality signal transmission baseband LSIC for personal communications

This paper presents a very low power consumption one-chip baseband large-scale integrated circuit (LSIC) for personal communication terminals. It comprises a /spl pi//4-shift QPSK modem, an adaptive differential pulse code modulation (ADPCM) codec, a time division multiple access time division duplex (TDMA-TDD) controller and a link access procedure for a digital cordless (LAPDC: Layer-2 protocol) controller. The developed LSIC meets all the specifications of the personal handy-phone system (PHS) standard. By employing a novel coherent demodulator and an ADPCM codec with a click noise suppressor, a higher quality voice transmission has been achieved in a fading environment. In addition, it has 61-kb/s data transmission capability to achieve wireless multimedia services based on PHS. Moreover, the novel circuit configurations of the modem, the ADPCM codec, the TDMA-TDD controller, and the LAPDC controller achieve significant power reduction of the baseband circuits (57.4 mW) of personal communication terminals. It enables very low power consumption wireless multimedia terminals to be achieved based on the PHS common air interface.

A reliable and low power consumption personal terminal architecture for wireless multimedia communications

This paper presents an advanced architecture for a wireless multimedia communication personal terminal ; variable bit rate channel assignment method and optimum function assignment of hardware and software to improve channel control reliability and to reduce power consumption which are important requirements for TDMA wireless multimedia communications. The proposed burst diversity method improves the layer-2 frame error rate by about 25% for two control channels, FACCH/SACCH (Fast/Slow Additional Control CHannel). The power reduction improvement has been confirmed by developing a PHS terminal in which the CPU power consumption is reduced to about one third of conventional one.

Direct-Multicasting Satellite Communications System Using a new Multi-carrier and Multi-rate Modem

The Internet has become a global medium for communication, entertainment, and e-commerce. And there is increasing demand to deliver multimedia contents, such as audio and video data, from web sites to many customers simultaneously. The size of data to be delivered and the number of transmission points has been increasing recently. In this context satellite communication is thought to be effective network and communication infrastructure because it covers large area and easily provides high-speed service with great many reception points. A direct-multicasting satellite communications system was previously proposed to achieve a full mesh type satellite network economically and we developed the group modem, the efficient channel assignment control program, and the highly reliable multicasting program for it. This paper presents the architecture of the group modem that is used for direct-multicasting satellite communications system as a key technology of it.

Channel Assignment Control Method for Direct-Multicasting Satellite Communications System

The Internet has become a global medium for communication, entertainment, and e-commerce. And there is increasing demand to deliver multimedia content, such as audio or video data, from web sites to many customers simultaneously. The size of data to be delivered is growing and the number of transmission points has increased recently. Satellite communications that provide simultaneous reception capability, expanded service area, and high-speed transmission is thought to be effective as a communication infrastructure. To realize the direct-multicasting satellite communications system to achieve a full-mesh-type satellite network economically, the group modem and the channel assignment control program have been developed. This paper describes the highly effective channel assignment control program that has scale flexibility and high functionality for this system.

Bit significance selective frequency diversity transmission-voice quality improvement in fading channels

This paper proposes a frequency diversity transmission scheme that obtains a frequency diversity effect and does not deteriorate spectrum efficiency by utilizing multiple carrier frequencies alternatively, not simultaneously. This scheme improves the bit error rate (BER) or significant information bits by sacrificing that of insignificant bits in fading channels. Simulation results show that the error floor of significant information bits is improved by more than 80% while that of insignificant bits is doubled. Computer simulation results show that the proposed scheme improves the ADPCM voice signal-to noise ratio (SNR) by approximately 4 dB even when the frequency correlation is 0.5. The transmission scheme, TDMA-TDD, can be applied to various types of data transmission in personal communication systems.

Double side information concatenated coding scheme for fading environments-experimental evaluation employing SNUFEC VLSI

In order to realize a high-coding-gain forward error correction scheme for fading environments, a novel concatenated coding scheme employing soft decision decoding with channel-status-information (CSI) for inner codes and also soft decision decoding for outer codes (double side information concatenated coding scheme) is proposed and its performance is clarified by a hardware experiment employing the developed ultra-high-speed (operation speed up to 60 MHz) and universal-coding-rate (from coding rates one-half to fifteen-sixteenths) Viterbi decoder VLSIC (SNUFEC VLSI). The proposed scheme improves the Pe performance to 1/3 of conventional one by employing the SNUFEC VLSI which can output the path memory circuit status 1,0 ratio as the soft-decision decoding data for likelihood information.<<ETX>>