Joint Optimization of IRS Location and its Phase Shift for Received Power Maximization

AbstractThis work clarified the conventional/phase shift dual Mach–Zehnder modulation measured technique for upgrading radio over fiber (ROF) systems. Four levels of pulse amplitude modulation and non-return to zero code scheme are employed in different previous studies for upgrading ROF systems. The possible transmission distance is extended to 150 km and a bit rate of 40 Gb/s for achieved acceptable max. Q factor of 13.7498 and minimum bit error rates of 1.82×10–43. The total optical received power is measured at fiber cable length for maximum distance. Also, in the same way, the signal power levels are measured after fiber optic cable and avalanche photo detector optical receiver. The proposed model has presented the enhancement percentage ratio of 13.654% over the previous models in signal quality enhancement.

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A Deep Reinforcement Learning Approach to IRS-assisted MU-MIMO Communication Systems

10.36227/techrxiv.17868425.v1 ◽

2022 ◽

Author(s):

Dariel Pereira-Ruisánchez ◽

Óscar Fresnedo ◽

Darian Pérez-Adán ◽

Luis Castedo

Keyword(s):

Reinforcement Learning ◽

Phase Shift ◽

Communication Systems ◽

Mimo System ◽

Multiple Input Multiple Output ◽

Joint Optimization ◽

Mimo Communication ◽

Continuous State ◽

Policy Gradient ◽

Sum Rate

<div>The deep reinforcement learning (DRL)-based deep deterministic policy gradient (DDPG) framework is proposed to solve the joint optimization of the IRS phase-shift matrix and the precoding matrix in an IRS-assisted multi-stream multi-user MIMO communication.<br></div><div><br></div><div>The combination of multiple-input multiple-output(MIMO) communications and intelligent reflecting surfaces(IRSs) is foreseen as a key enabler of beyond 5G (B5G) and 6Gsystems. In this work, we develop an innovative deep reinforcement learning (DRL)-based approach to the joint optimization of the MIMO precoders and the IRS phase-shift matrices that is proved to be efficient in high dimensional systems. The proposed approach is termed deep deterministic policy gradient (DDPG)and maximizes the sum rate of an IRS-assisted multi-stream(MS) multi-user MIMO (MU-MIMO) system by learning the best matrix configuration through online trial-and-error interactions. The proposed approach is formulated in terms of continuous state and action spaces, and a sum-rate-based reward function. The computational complexity is reduced by using artificial neural networks (ANNs) for function approximations and it is shown that the proposed solution scales better than other state-of-the-art methods, while reaching a competitive performance.<br></div>

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Performance evaluation of hybrid modulation techniques for high speed radio over fiber communication system

International Journal of Modern Physics C ◽

10.1142/s0129183119500700 ◽

2019 ◽

Vol 30 (09) ◽

pp. 1950070 ◽

Cited By ~ 1

Author(s):

R. Shantha Selva Kumari ◽

K. Seyatha

Keyword(s):

Phase Shift ◽

Amplitude Modulation ◽

Communication System ◽

Phase Modulation ◽

Pulse Amplitude ◽

Q Factor ◽

Phase Shift Keying ◽

Fiber Communication ◽

Received Power ◽

Shift Keying

In Radio over Fiber (RoF) technology, the optical network capacity is integrated with the wireless network. The main objective of this work is to enhance the performance behavior of optical fiber communication system in terms of BER, Received Power and Q-Factor. The proposed combined modulation technologies, such as Pulse Amplitude Frequency Modulation (PAFM), Differential Phase Shift Keying Amplitude Modulation (DPSKA), Offset Quadrature Phase Shift Keying Amplitude Modulation (OQPSKA), Quadrature Amplitude Frequency Modulation (QAFM), Frequency Phase Modulation (FPM) and Pulse Amplitude Phase Modulation (PAPM), are used to meet this objective. The input data are used for modulating the electrical carrier signal with a frequency of 250 and 255[Formula: see text]GHz. This hybrid modulation technique obtained the minimum BER of about [Formula: see text] in FPM technique. The maximum Q-Factor of 33 is obtained in QAFM technique. The obtained maximum received power is 0.79[Formula: see text]mW in OQPSKA technique.

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A Deep Reinforcement Learning Approach to IRS-assisted MU-MIMO Communication Systems

10.36227/techrxiv.17868425 ◽

2022 ◽

Author(s):

Dariel Pereira-Ruisánchez ◽

Óscar Fresnedo ◽

Darian Pérez-Adán ◽

Luis Castedo

Keyword(s):

Reinforcement Learning ◽

Phase Shift ◽

Communication Systems ◽

Mimo System ◽

Multiple Input Multiple Output ◽

Joint Optimization ◽

Mimo Communication ◽

Continuous State ◽

Policy Gradient ◽

Sum Rate

<div>The deep reinforcement learning (DRL)-based deep deterministic policy gradient (DDPG) framework is proposed to solve the joint optimization of the IRS phase-shift matrix and the precoding matrix in an IRS-assisted multi-stream multi-user MIMO communication.<br></div><div><br></div><div>The combination of multiple-input multiple-output(MIMO) communications and intelligent reflecting surfaces(IRSs) is foreseen as a key enabler of beyond 5G (B5G) and 6Gsystems. In this work, we develop an innovative deep reinforcement learning (DRL)-based approach to the joint optimization of the MIMO precoders and the IRS phase-shift matrices that is proved to be efficient in high dimensional systems. The proposed approach is termed deep deterministic policy gradient (DDPG)and maximizes the sum rate of an IRS-assisted multi-stream(MS) multi-user MIMO (MU-MIMO) system by learning the best matrix configuration through online trial-and-error interactions. The proposed approach is formulated in terms of continuous state and action spaces, and a sum-rate-based reward function. The computational complexity is reduced by using artificial neural networks (ANNs) for function approximations and it is shown that the proposed solution scales better than other state-of-the-art methods, while reaching a competitive performance.<br></div>

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Object Wave Determination by Single-Sideband Methods

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071776 ◽

1973 ◽

Vol 31 ◽

pp. 266-267

Author(s):

Kenneth H. Downing ◽

Benjamin M. Siegel

Keyword(s):

Phase Shift ◽

Carbon Films ◽

Object Wave ◽

Electron Wave ◽

Phase Object ◽

Heavy Atoms ◽

Single Sideband ◽

Thin Carbon ◽

Additional Phase Shift ◽

Additional Phase

Under the “weak phase object” approximation, the component of the electron wave scattered by an object is phase shifted by π/2 with respect to the unscattered component. This phase shift has been confirmed for thin carbon films by many experiments dealing with image contrast and the contrast transfer theory. There is also an additional phase shift which is a function of the atomic number of the scattering atom. This shift is negligible for light atoms such as carbon, but becomes significant for heavy atoms as used for stains for biological specimens. The light elements are imaged as phase objects, while those atoms scattering with a larger phase shift may be imaged as amplitude objects. There is a great deal of interest in determining the complete object wave, i.e., both the phase and amplitude components of the electron wave leaving the object.

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A Many-Beam Technique for Enhanced Resolution of Partial Dislocations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096485 ◽

1972 ◽

Vol 30 ◽

pp. 646-647

Author(s):

J. M. Oblak ◽

B. H. Kear

Keyword(s):

Phase Shift ◽

Field Method ◽

Dark Field ◽

Bright Field ◽

Field Technique ◽

Weak Beam ◽

Partial Dislocations ◽

Enhanced Resolution ◽

Nickel Base ◽

Beam Technique

The “weak-beam” and systematic many-beam techniques are the currently available methods for resolution of closely spaced dislocations or other inhomogeneities imaged through strain contrast. The former is a dark field technique and image intensities are usually very weak. The latter is a bright field technique, but generally use of a high voltage instrument is required. In what follows a bright field method for obtaining enhanced resolution of partial dislocations at 100 KV accelerating potential will be described.A brief discussion of an application will first be given. A study of intermediate temperature creep processes in commercial nickel-base alloys strengthened by the Ll2 Ni3 Al γ precipitate has suggested that partial dislocations such as those labelled 1 and 2 in Fig. 1(a) are in reality composed of two closely spaced a/6 <112> Shockley partials. Stacking fault contrast, when present, tends to obscure resolution of the partials; thus, conditions for resolution must be chosen such that the phase shift at the fault is 0 or a multiple of 2π.

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Observation of surface morphology by reflection electron holography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154652 ◽

1989 ◽

Vol 47 ◽

pp. 536-537

Author(s):

N. Osakabe ◽

J. Endo ◽

T. Matsuda ◽

A. Tonomura

Keyword(s):

Phase Shift ◽

Surface Morphology ◽

High Sensitivity ◽

High Energy ◽

Path Difference ◽

Transmission Mode ◽

Electron Holography ◽

Dynamical Process ◽

High Vertical Resolution ◽

Amplification Technique

Progress in microscopy such as STM and TEM-TED has revealed surface structures in atomic dimension. REM has been used for the observation of surface dynamical process and surface morphology. Recently developed reflection electron holography, which employes REM optics to measure the phase shift of reflected electron, has been proved to be effective for the observation of surface morphology in high vertical resolution ≃ 0.01 Å.The key to the high sensitivity of the method is best shown by comparing the phase shift generation by surface topography with that in transmission mode. Difference in refractive index between vacuum and material Vo/2E≃10-4 owes the phase shift in transmission mode as shownn Fig. 1( a). While geometrical path difference is created in reflection mode( Fig. 1(b) ), which is measured interferometrically using high energy electron beam of wavelength ≃0.01 Å. Together with the phase amplification technique , the vertivcal resolution is expected to be ≤0.01 Å in an ideal case.

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