Jawad A. Salehi

In this paper, we introduce a stochastic shape optimization technique for base-station placement in cellular wireless communication networks. We formulate the data-driven facility location problem in a gradient-based framework and propose an algorithm that computes stochastic gradients efficiently via nearest-neighbor evaluations on Voronoi diagrams. This enables the use of Shannon-entropy objectives that promote balanced coverage and yield more than two orders of magnitude reduction in per-iteration runtime compared to a conventional integral-based optimization that assumes full knowledge of the underlying density, making the proposed approach practical for real deployments. We highlight the requirements of facility location balancing problems with the introduction of the Adjusted Entropy Ratio and show a significant improvement in load balancing compared to the baseline algorithms, particularly in scenarios where baseline algorithms fall short in subdividing crowded areas for more equitable coverage. A downlink telecom evaluation with realistic propagation and interference models further shows that the proposed method configuration substantially improves user-rate fairness and load balance. Our results also show that Self-Organizing Maps (SOMs) provide an effective initialization by capturing the structure of the users’ location data.

In this paper, we explore the general principles of time-division multiple-access passive optical networks (PON) through the lens of quantum light signals. We investigate the optimal quantum receiver for various quantum light signals and delve into the fundamental constraints imposed by their quantum nature. This paper evaluates the optimal error probability for the Fock, coherent and phase-randomized coherent states. Furthermore, we investigated the power splitter/combiner channel, which is the main element in a PON, from the quantum viewpoint using the scattering matrix formalism. We demonstrated that under the low-loss condition, the error probability of the Fock quantum passive optical network (QPON) can surpass the coherent QPON.

A cost-effective global quantum Internet may be developed using the existing communication infrastructure. This article examines the quantum version of three conventional wavelength-division-multiplexing and multiple-access (WDM) communication systems and networks. They are Lambdanet-based broadcast WDM networks, quantum routers based on a waveguide grating router, and fiber-to-the-quantum nodes that are fed by two opposing and extreme quantum light signals, namely the coherent (Glauber) and number (Fock) states. Using the coherent states, we identify the classical behavior of the quantum WDM (QWDM) networks. Furthermore, employing quantum single-photon sources and exclusive quantum results, such as quantum correlations occurring in the receivers's states, are studied in these WDM communication systems and networks. Finally, we provide secure-key rate estimation for Lambdanet- and waveguide grating router (WGR)-based quantum key distribution networks leveraging the developed QWDM. As compared to Lambdanet, WGR obtains a higher rate of secure keys.

This paper describes the fundamental principles and mathematical foundations of Quantum Direct-Sequence Spread-Spectrum Code Division Multiple Access (QDSS-CDMA) communication systems. The evolution of quantum signals through the quantum direct-sequence spread-spectrum multiple access communication system is carefully characterized by a novel approach called the decomposition of creation operators. In this methodology, the creation operator of the transmitted quantum signal is decomposed into the chip-time interval creation operators each of which is defined over the duration of a chip. These chip-time interval creation operators are the invariant building blocks of the spread-spectrum quantum communication systems. With the aid of the proposed chip-time decomposition approach, we can find closed-form relations for quantum signals at the receiver of such a quantum communication system. Further, the paper details the principles of narrow-band filtering of quantum signals required at the receiver, a crucial step in designing and analyzing quantum communication systems. We show that by employing coherent states as the transmitted quantum signals, the inter-user interference appears as an additive term in the magnitude of the output coherent (Glauber) state, and the output of the quantum communication system is a pure quantum signal. On the other hand, if the transmitters utilize particle-like quantum signals (Fock states) such as single photon states, entanglement effect can arise at the receivers. The important techniques developed in this paper are expected to have far-reaching implications for various applications in the exciting field of quantum communications and quantum signal processing.

This paper addresses the challenge of enhancing energy efficiency in Visible Light Communication (VLC) networks through Space Division Multiplexing (SDM) and smart lighting integration. We mathematically formulate the problem of energy-efficient multi-user VLC networking with SDM and smart illumination, tailoring the light output according to the users’ demands. To address the arising intricate optimization problem, we propose Clustered Light Emitting Diode (LED) Assignment and Power optimization (CLAP). This heuristic approach leverages density-based spatial clustering for efficient user grouping and employs a greedy sequential algorithm for LED assignment. The constrained optimization by linear approximation technique is employed to determine transmitted optical power levels. By incorporating density functions of achievable rates into precise transmitter models, our study accurately assesses power consumption in VLC system optimization, significantly enhancing energy efficiency. A comparative analysis of three popular VLC network transmitters shows that precise power consumption determination is superior to using common approximations. The proposed methodology showcases remarkable improvements, achieving up to a 55% increase in energy efficiency and up to a 58% reduction in power consumption for a VLC network, with best results observed when utilizing bias-T transmitters, which can accommodate DC biasing, equipped with class AB amplifiers, known for their efficiency.

This paper investigates the mathematical model of the quantum wavelength-division-multiplexing (WDM) network based on the entanglement distribution with the least required wavelengths and passive devices. By adequately utilizing wavelength multiplexers, demultiplexers, and star couplers, N wavelengths are enough to distribute the entanglement among each pair of N users. Moreover, the number of devices employed is reduced by substituting a waveguide grating router for multiplexers and demultiplexers. Furthermore, this study examines implementing the BBM92 quantum key distribution in an entangled-based quantum WDM network. The proposed scheme in this paper may be applied to potential applications such as teleportation in entangled-based quantum WDM networks.