In this paper, we investigate a multitone simultaneous wireless information and power transfer (SWIPT) based modulation scheme for battery-less Internet of Things (IoT) nodes that works in the ultra high frequency (UHF) region. The conventional SWIPT system is assumed to have power-consuming communication modules. Having such modules on to the IoT nodes whose power is harvested from radio frequency (RF) power sources is too unrealistic. In addition, waveform design from the aspect of power harvesting through SWIPT still has room for consideration. Recent studies have explored multitone based SWIPT to increase the power conversion efficiency (PCE). In these schemes, information is modulated by changing each tone's nature or varying the number of tones. Among these methods, we focused on modulation schemes known as frequency-shift multitone based SWIPT, which shifts frequencies among the tones for information encoding. Unlike previously proposed methods where demodulation requires some power-consuming fast Fourier transfers (FFTs), especially under small communication bandwidths, we applied a signal detection method by measuring output peak to average power ratios (PAPRs) for frequency-shift multitone based SWIPT to reduce power consumption. Based on our analysis, different tone configurations in the frequency domain would yield varieties of nonlinear outputs during the rectification process. In addition, these specific nonlinear output patterns depend on the tone configurations. With this feature, it is possible to demodulate in the time domain at the receiver side using PAPR based measurements, which could eliminate FFT operation. This paper describes how measuring PAPRs enables the detection of signals in theory and validates this through simulations and experiments. We also estimate the communication rates. Based on our results, we achieved 0.46 bits/s/Hz when the number of tones was 6 and estimated that there were (N − 1)(N − 2)/2 + 1 different PAPRs from a given multitone waveform whose number of tones was N .INDEX TERMS Energy harvesting, frequency shift keying, multisine based waveforms, peak to average ratio, simultaneous wireless information and power transfer.
This Paper describes small-sized multichip modules (MCMs) for 10Gbps optical transmission systems. We have developed three kinds of MCMs. MCMs include LSIs we have newly developed by employing SiGe bipolar process. Each kind of MCM is composed of an alumina substrate with flat lead frames, LSIs mounted by flip chip mount technology, passive SMT components, and a heat spreader. To achieve wide-band characteristics of MCMs, the grounded coplanar waveguide design is adopted for the transmission lines on MCMs. The heat spreader is attached to the backside of each LSI through thermally conductive silicone compound for highly effective cooling. These MCMs have been applied for our 10Gbps optical transmitter and receiver modules in the wavelength division multiplexing (WDM) system, and achieved 1.6Tbps (10Gbps x 160 channels) of transmission capacity.
IntroductionRapidly increasing demand for lightwave transmission capacity drives wider bandwidth-use of optical fiber cables and higher line rate per channel for spectral efficiency improvement in WDM optical transmission. In the large capacity WDM system, high line rate as 10Gbps and small footprint are required for a transponder.The block diagram of WDM system is shown in Fig.1. WDM system provides the ability of multiplexing the multiple light wavelengths on a single fiber and increase the carrying capacity. This WDM system includes pairs of a transmitterside transponder (TxPND) and a receiver-side transponder (RxPND). The 10Gbps transponder in our WDM system has a forward-error-correction (FEC) function in order to realize the long span optical transmission. The 10Gbps TxPND consists of an optical receiver module (indicated as O/E) for 9.95Gbps (OC-192), a forward error correction encoder (FEC COD) LSI, and an optical transmitter module (indicated as E/O) operating at 10.66Gbps (optical channel for 10Gbps). The RxPND consists of another optical receiver module for 10.66Gbps, a forward error correction decoder (FEC DCOD) LSI, and another optical transmitter module (indicated as E/O) for 9.95Gbps.A large amount of the optical transmitter and receiver modules are applied in the WDM system, so that small-sizing of these optical modules is indispensable for small footprint of the whole systems.To realize the small-sized optical transmitter and receiver modules, we adopted the following approaches for packaging of LSIs.
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