다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Direct-current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) is used in visible light communications (VLC) for high rate transmission. Due to the unipolarity of optical signals, a direct current (DC) offset along with proper clipping is adopted in DCO-OFDM. A high DC-offset causes a waste of power and a low DC-offset causes a severe clipping distortion. Thus, the DC-offset and information-carrying power shall be jointly optimized to balance clipping distortion and power consumption. We consider the offset and power optimization problem under the optical and/or electrical power constraints over flat and dispersive channels. In the flat case, we analytically characterize the optimal solution, based on which several important insights are provided. We also investigate the relation and impact of the two constraints, and propose efficient algorithms to obtain the optimal solution. In the dispersive case, we identify the scope of the optimal solution, and provide efficient algorithms to jointly optimize the offset and power. The optimality and superiority of the proposed methods are validated by numerical results.

Offset and Power Optimization for DCO-OFDM in Visible Light Communication Systems

We conduct a two-dimensional study of pulse design for electromagnetic time-reversal (TR) imaging as applied to ultrawideband (UWB) breast cancer detection. We consider the situation when a tumor located in the human breast is surrounded by a large number of small tissue inhomogeneities that create strong signal clutter. When applying the TR algorithm, the excitation pulse should be properly designed such that there are distinguishable differences between the tumor and clutter responses. In this paper, we propose four pulse design criteria for the TR-based tumor detection. The modulated and modified Hermite polynomials (MMHPs) that fit well into the real pulse shapes are used as a general waveform template for the design process. Finally, numerical examples are used to demonstrate the usefulness of the proposed analytical framework. This paper can be a guide in the selection of suitable waveforms for which the tumor response can be enhanced and/or the clutter interference can be suppressed. The investigation is also well suited for applications to surface-penetrating radar using UWB signals

Pulse Design for Time Reversal Method as Applied to Ultrawideband Microwave Breast Cancer Detection: A Two-Dimensional Analysis

A novel multi-user modulation technique is proposed by using Manchester Coded Code Shift Keying (MC-CSK) system along with Double Padded-Modified Prime Code Sequence (DP-MPCS) in the visible light communication (VLC) In the VLC link, MC-CSK employed to enhance the bit rates and reduce BER includes effective fluctuation In this work, the direct current in modulated signal, which includes a series of 0’s or 1’s are decreased by using Manchester coding The proposed MC-CSK technique, however, uses M signaling waveforms which are mostly derived from a single pseudo random noise circular shift code The proposed MC-CSK, system performance is compared with conventional modulation technique Eventually, the results indicate that the MC-CSK coding focus on DP-MPCS outperforms the system BER performance, mitigate the interference, and, improve the system throughput over the conventional modulation techniques

Novel multi-user MC-CSK modulation technique in visible light communication

We discuss herein whether an optical wireless communication (OWC) system can be a candidate for post 5G or 6G cellular communication. Almost once per decade, cellular mobile communication is transformed by a significant evolution, with each generation developing a distinctive concept or technology. Interestingly, similar trends have occurred in OWC systems based on visible light and light fidelity (Li-Fi). Unfortunately, OWC is currently relegated to a limited role in any 5G scenario, but the debate whether this is unavoidable has yet to be settled. Whether OWC is adopted post 5G or 6G is not the vital issue; rather, the aim should be that OWC coexists with 5G and 6G communication technologies. In working toward this goal, research and development in OWC will continue to extend its benefits and standardize its systems so that it can be widely deployed in the market. For example, given that a standard already exists for a visiblelight beacon identifier and Li-Fi, a service using this standard should be developed to satisfy user demand. Toward this end, we propose herein a method for visible-light beacon identification that involves using a rolling shutter to receive visible-light communications with a smartphone camera. In addition, we introduce a rotary LED transmitter for image-sensor communication. key words: post 5G/6G, visible light communication, Li-Fi, IEC 62943 visible light beacon, rolling shutter, rotary LED transmitter

Optical Wireless Communication: A Candidate 6G Technology?

The paper discusses the construction of UWB pulses on the basis of B-splines under the following conditions: (i) the B-splines are time-limited piecewise polynomials; (ii) the pulses are rectangular when their order is one and they converge to band-limited functions at the limit that their order tends to infinity; (iii) an analog circuit and a fast digital filter exist for the generation of B-splines. A constrained minimization technique is proposed for designing pulses so as to comply with the FCC spectral mask and satisfy basic requirements for UWB pulses.

Design of UWB pulses based on B-splines

In this paper, the throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences which combines the ALOHA system with Code Shift Keying using nonorthogonal sequences is analyzed. In this system, the nonorthogonal sequences are constructed by concatenating Mcon orthogonal sequences. The throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences is analyzed in consideration that the number of packets changes at intervals of one orthogonal sequence. Moreover, the throughput performance of our system with Channel Load Sensing Protocol (CLSP) is also analyzed. We also examine the influence of unreachable control signal of CLSP. Consequently, it is found that the throughput performance of our system decreases significantly by this analysis. It is also found that the throughput performance of our system improves greatly by using CLSP. However, the unreachable control signal affects the throughput performance of this system, seriously.

A Reasonable Throughput Analysis of the CSK/SSMA Unslotted ALOHA System with Nonorthogonal Sequences *

In this paper, to increase Normalized throughput of the optical wireless code-division multiple-access (CDMA) system, modified pseudo orthogonal M-sequences (MPOMS) are considered as optical pseudo-Noise (PN) code. Moreover, the bit error rate (BER) performance of the optical wireless CDMA system using multi-pulse pulse position modulation (MPPM) is also derived in the presence of the scintillation, background-Noise, avalanche photo-diode (APD) Noise, thermal Noise and signal dependence Noise. Consequently, the BER performance in consideration of Normalized throughput of the MPPM system with MPOMS is superior to that of the MPPM system with conventional pseudo orthogonal M-sequences in the single-user case and multi-user case.

Theoretical Analysis of Optical Wireless CDMA with Modified Pseudo Orthogonal M-Sequence Sets

In this paper, atmospheric optical DS/SS systems with on-off orthogonal m-sequence pairs are considered The bit error rates of the on-off keying (OOK) DS/SS and the antipodal DS/SS are analyzed by taking into account the scintillation, background-noise, avalanche photo-diode (APD) noise, thermal noise, and multiple access interference (MAI) Moreover, the optical DS/SS systems using on-off orthogonal M-sequence pairs are compared with those using the extended prime code sequences Consequently, the optical DS/SS using the on-off orthogonal m-sequence pairs is superior to the optical DS/SS using extended prime code sequences

Theoretical analysis of atmospheric optical DS/SS with On-Off Orthogonal M-sequence Pairs

In this paper, the CSK/SSMA ALOHA system with nonorthogonal sequences which combines the ALOHA system with Code Shift Keying (CSK) using nonorthogonal sequences is proposed. The throughput performance was evaluated by theoretical analysis. Moreover, the throughput performance of the system is compared with those of the DS/SSMA ALOHA and M-ary/SSMA ALOHA systems. It is found that the throughput performance of our system to be better than those of the other two systems.

Hiromasa Habuchi

Papers

Design of UWB pulses based on B-splines

A Reasonable Throughput Analysis of the CSK/SSMA Unslotted ALOHA System with Nonorthogonal Sequences *

Theoretical Analysis of Optical Wireless CDMA with Modified Pseudo Orthogonal M-Sequence Sets

Theoretical analysis of atmospheric optical DS/SS with On-Off Orthogonal M-sequence Pairs

CSK/SSMA ALOHA System with Nonorthogonal Sequences