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Personal comfort systems (PCSs) that are energy efficient have been widely used indoors to improve occupant thermal comfort and acceptability under a variety of thermo-hygrometric conditions. Although numerous studies have shown that the use of PCSs has beneficial effects, definitive conclusions on the effectiveness of PCSs on thermal comfort enhancement have yet to be drawn. Furthermore, detailed analyses of specific indoor conditions that may be the most promising are lacking. As a result, a comprehensive meta-analysis review was conducted to summarize, analyze, and compare findings from eligible documented studies on the effects of various PCSs on occupants’ perceptual responses. Besides, the energy performance of various PCSs was examined. The effects of total cooling or heating area as well as types of PCSs, on occupants’ perceptual responses were specifically addressed. This systematic review and meta-analysis serve as a foundational reference source for the selection of highly energy-efficient and effective personal comfort systems to improve thermal comfort of indoor occupants.

We propose a novel method to generate photonic quadrature-phase-shift-keying (QPSK) orthogonal frequency division multiplexing (OFDM) vector signal using only one Mach-Zehnder modulator, in which the OFDM signal is phase precoded and amplitude precoded according to the square-law characteristic of the photodetector. We theoretically analyze and experimentally demonstrate that this concept of the generation of the QPSK OFDM vector signal can be employed in our system architecture based on our proposed scheme. The results show that the bit-error ratios of the transmission system are less than the forward-error-correction threshold of $3.8\times 10^{-3}$ . By this scheme, we simplify the configuration and reduce the cost of the OFDM transmission system.

In this paper, we propose and experimentally demonstrate a W-band fiber–wireless–fiber integration transmission system with directly-modulated laser (DML) for electrical-to-optical (E/O) conversion. In this system, 20-Gb/s quadrature phase shift keying (QPSK) signal is transmitted for 20-km single-mode fiber-28 (SMF-28), then delivered over 160-m wireless link and finally transmitted for 40-km SMF-28 under BER of 3.8×10 −3 . Our experimental results show that a simple and cost-effective DML is suitable for E/O conversion. Its transmission performance can be improved once the DML's nonlinear saturation effect is compensated.

We numerically and experimentally investigate and compare photonic constant- and multi-amplitude quadrature-amplitude-modulation (QAM) vector signal generation at radio frequency (RF) bands enabled by a Mach-Zehnder modulator (MZM)-based optical carrier suppression (OCS) modulation. In order to attain an electrical vector RF signal displaying multi-amplitude QAM modulation, such as 8 QAM and 16 QAM, after square-law photodiode detection, the driving RF signal carrying multiamplitude QAM transmitter data, should be both amplitude- and phase-precoded before used to drive the MZM. However, for constant-amplitude QAM modulation, such as quadrature-phase-shift-keying (QPSK), only phase precoding is needed. We experimentally demonstrate 1-GBd vector signal generation at 12 GHz enabled by an MZM-based OSC modulation, adopting QPSK, 8 QAM, and 16 QAM modulation, respectively. We also experimentally compare the bit error rate performance of the three different vector signals, and the QPSK case is the best, while the 16 QAM case is the worst.

We propose a novel scheme for photonic multiamplitude quadrature-amplitude-modulation (QAM) vector signal generation at microwave/millimeter-wave bands enabled by Mach-Zehnder modulator (MZM)-based adaptive photonic frequency multiplication. In order to attain an electrical millimeter-wave vector signal displaying multiamplitude QAM modulation, such as 8QAM, after square-law photodiode detection, the driving radio-frequency (RF) signal, carrying multiamplitude QAM transmitter data, should be both amplitude- and phase-precoded before used to drive the MZM. We experimentally demonstrate 8QAM vector signal generation at W-band adopting photonic frequency octupling (x8) enabled by our proposed scheme. The MZM is driven by a 12-GHz precoded RF signal carrying 1-GBaud 8QAM transmitter data. The generated 1-GBaud 8QAM vector signal at W-band is air transmitted over 2-m distance. To the best of our knowledge, it is the first time to realize the generation and reception of multiamplitude QAM vector signal by one external modulator at W-band.

We experimentally demonstrate an optical-wireless transmission system at W band, which can support long-distance wireless transmission and tolerate some frequency difference of the local oscillators (LOs) at the receiver. The generation of millimeter-wave signal is based on the photonic technique by heterodyne mixing of an optical polarization division multiplexing quadrature phase shift keying (PDM-QPSK) signal and an optical LO signal. After 20-km fiber transmission, tens of gigabit-per-second millimeter-wave signals are delivered over multiple-input-multiple-output (MIMO) wireless links by different polarization antennas. Then, analog downconversion is performed before the received signal is demodulated by coherent detection and advanced digital signal processing. Using this system, we experimentally demonstrate the transmission of 18.7-, 29.9-, and 37.4-Gb/s PDM-QPSK wireless signals at W band over 80-, 40-, and 20-m wireless links, respectively, with bit error rate less than the forward error correction threshold of 3.8 × 10-3. In addition, we investigate the effect of different frequency LOs on the MIMO system performance, finding that the system can tolerate about 1.25-GHz frequency difference for a 10-Gbaud signal. The proposed system can be suitable for the building-to-building broadband connection, in-building hybrid fiber-wireless access networks, and some scenarios that bridge natural obstacles and difficult-to-access terrain.

We proposed and experimentally demonstrated a novel architecture for the downlink of satellite-ground communication system at W-band (75–110 GHz). Radio-frequency transparent demodulation technique and polarization multiplexing technique are used to reduce the ground system complexity. Quadrature phase shift keying signals (30 Gbaud/s) are transmitted over 15 m wireless link and 50 km fiber. The net bit rate of the whole system is 100 Gb/s while 20% overhead forward error correction (FEC) code is used. Bit-rate-error under FEC limit of 2 × 10−2 is achieved at the optical signal noise ratio of 21 dB. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:409–414, 2015

In this letter, we propose and experimentally demonstrate a W-band (75-110 GHz) full-duplex transmission fiber-wireless-fiber system with the rate up to 60 Gb/s for the first time. Both the uplink and downlink in our proposed system consist of two spans of 80 km single-mode fiber-28 (SMF-28) and a 1-m wireless link. We experimentally demonstrate that our proposed system can simultaneously transmit a 60 Gb/s upstream quadrature-phase-shift-keying (QPSK) signal carried by 99 GHz carrier frequency over the uplink and a 60 Gb/s downstream QPSK signal carried by 101 GHz carrier frequency over the downlink. Both millimeter-wave generation and demodulation are enabled by photonic techniques. Wireless crosstalk that occurs between the uplink and the downlink is effectively avoided because the pair of antennas adopted in the uplink is polarization orthogonal to that adopted in the downlink. With the optical signal-to-noise ratio (OSNR) of 20 dB, the bit error ratios (BERs) for 60 Gb/s signal transmission are less than the third-generation forward-error-correction (FEC) limitation of 2 × 10 -2 .

We propose and experimentally demonstrate a W-band seamlessly integrated fiber-wireless-fiber transmission system enabled by photonic millimeter-wave generation and demodulation techniques, in which up to 128-Gb/s (16-Gbd) polarization division multiplexing 16-ary quadrature amplitude modulation (16QAM) signal can be first transmitted over 50-km single-mode fiber-28 (SMF-28), then delivered over 1-m × 2 multiple-input multiple-output wireless link at 100 GHz and finally transmitted over another 50-km SMF-28 with a bit-error ratio less than the third-generation soft-decision forward-error-correction threshold of 2 × 10 -2 . The proposed system can be well compatible with high-level QAM and is suited to large-capacity high-spectral-efficiency fiber-wireless integration communication.

We analysis the temporal and power evaluation of an ultrawideband (UWB) signal based on monocycle Gaussian pulse and experimentally verify it. With optimized design, 1.25 Gb/s UWB signal with good Gaussian shape is successfully generated with dark return-to-zero based on the nonlinear polarization rotation in semiconductor optical amplifier and the −10 dB bandwidth is larger than 10 GHz with a fractional bandwidth close to 200%. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1492–1495, 2014

We propose a novel scheme to expand the inherent limit in the product of the optical delay and the transmission bandwidth in resonator-based delay lines, with the optical orthogonal frequency division multiplexing (OOFDM) technique. The optical group delay properties of a single ring resonator were theoretically studied, and double-carrier OOFDM signals were transmitted through such a device in the experiment, where the subcarrier-frequencies matched those of the resonant modes in the device. The results show that, although the delay-bandwidth product (DBP) is limited in the order of 50 ps×10 Gb/s for signals on each of the sub-carriers, the total DBP of the system is doubled to 2×50 ps×10 Gb/s due to the double-carrier transmission.

In this paper, we propose a novel and simple method to generate millimeter-wave vector signals using only one phase modulator (PM) and phase-precoding technique, in which the precoded microwave vector signal is used for the drive of the single PM. We experimentally demonstrate that this concept of the generation of quadrature-phase-shift-keying-modulated vector signal can be employed in our radio-over-fiber (RoF) system architecture based on our proposed scheme. By this scheme, we simplify the configuration and reduce the cost of the RoF system.