Makoto Hamaminato

A 0.33 nJ/bit IEEE802.15.6/Proprietary MICS/ISM Wireless Transceiver With Scalable Data Rate for Medical Implantable Applications

This paper presents an ultra-low power wireless transceiver specialized for but not limited to medical implantable applications. It operates at the 402-405-MHz medical implant communication service band, and also supports the 420-450-MHz industrial, scientific, and medical band. Being IEEE 802.15.6 standard compliant with additional proprietary modes, this highly configurable transceiver achieves date rates from 11 kb/s to 4.5 Mb/s, which covers the requirements of conventional implantable applications. The phase-locked loop-based transmitter architecture is adopted to support various modulation schemes with limited power budget. The zero-IF receiver has programmable gain and bandwidth to accommodate different operation modes. Fabricated in 40-nm CMOS technology with 1-V supply, this transceiver only consumes 1.78 mW for transmission and 1.49 mW for reception. The ultra-low power consumption together with the 15.6-compliant performance in term of modulation accuracy, sensitivity, and interference robustness make this transceiver competent for various implantable applications.

Data conflict resolution for layered LDPC decoding algorithm by selective recalculation

Layered LDPC decoding algorithm is known to achieve high Bit Error Rate (BER) performance and high throughput for LDPC decoders. However, for ISDB-S2 (Integrated Services Digital Broadcasting via Satellite - Second Generation) LDPC decoder, applying layered algorithm directly will result in data conflict problem. In this paper, a novel selective recalculation method is proposed to solve the data conflict problem. It determines the inaccurately calculated values based on a recalculation decision rule, and correct them accordingly. By applying this selective recalculation method, the layered algorithm can achieve conflict free BER performance. Simulation results demonstrate that the proposed method can achieve 0.1dB gain for the code with most conflicts in ISDB-S2, under the same BER performance compared to the previous strategy to solve data conflict problem.

Radio channel characterization for 400 MHz implanted devices

The wireless communication channel around/in the human body is a difficult propagation environment. This paper presents measurement and simulation results to characterize such a channel. A fluid human body model is employed to emulate the inside of a human body. The paper details the fluid human model and path loss model parameters at 400 MHz (MICS band). It is shown that the simulated and measured results are in a close agreement, for instance at a distance of 20 cm and a implant depth of 10 cm, the measurement results in a path loss of -42.1 dB and the simulation in -43.0 dB. The effect of human model shape on measured path loss is analyzed. Furthermore, simulations are employed to characterize this effect. Using the path loss model a top-level link budget is evaluated to determine the feasibility of a given implant device compliant to IEEE802.15.6-WBAN-400 MHz standard.

Self-adjustable offset min-sum algorithm for ISDB-S2 LDPC decoder

In this paper, a novel self-adjustable offset min-sum LDPC decoding algorithm is proposed for ISDB-S2 (Integrated Services Digital Broadcasting via Satellite - Second Generation) application. We present for the first time a uniform approximation of the check node operation through mathematical induction on Jacobian logarithm. The approximation theoretically shows that the offset value is mainly dependent on the difference between the two most unreliable inputs from the bit nodes and the algorithm proposed can adjust the offset value according to the inputs during the iterative decoding procedure. Simulation results for all 11 code rates of ISDB-S2 demonstrate that the proposed method can achieve an average of 0.15dB gain under the same Bit Error Rate (BER) performance, compared to the Min-sum based algorithms, and consumes only 1.21% computation complexity compared to BP-based algorithms in the best case.