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28 results on '"Siddiqi, Umair F."'

1. On the Achievable Max-Min User Rates in Multi-Carrier Centralized NOMA-VLC Networks

Author

Maraqa, Omar, Siddiqi, Umair F., Al-Ahmadi, Saad, and Sait, Sadiq M.

Subjects
Computer Science - Information Theory, Electrical Engineering and Systems Science - Signal Processing
Abstract

Visible light communications (VLC) is gaining interest as one of the enablers of short-distance, high-data-rate applications, in future beyond 5G networks. Moreover, non-orthogonal multiple-access (NOMA)-enabled schemes have recently emerged as a promising multiple-access scheme for these networks that would allow realization of the target spectral efficiency and user fairness requirements. The integration of NOMA in the widely adopted orthogonal frequency-division multiplexing (OFDM)-based VLC networks would require an optimal resource allocation for the pair or the cluster of users sharing the same subcarrier(s). In this paper, the max-min rate of a multi-cell indoor centralized VLC network is maximized through optimizing user pairing, subcarrier allocation, and power allocation. The joint complex optimization problem is tackled using a low-complexity solution. At first, the user pairing is assumed to follow the divide-and-next-largest-difference user-pairing algorithm (D-NLUPA) that can ensure fairness among the different clusters. Then, subcarrier allocation and power allocation are solved iteratively through both the Simulated Annealing (SA) meta-heuristic algorithm and the bisection method. The obtained results quantify the achievable max-min user rates for the different relevant variants of NOMA-enabled schemes and shed new light on both the performance and design of multi-user multi-carrier NOMA-enabled centralized VLC networks., Comment: May, 2021: Accepted for publication in Sensors Journal, MDPI Publisher

Published
2021
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7. Simulated Evolution (SimE) Based Embedded System Synthesis Algorithm for Electric Circuit Units (ECUs)

Author

Siddiqi, Umair F., Shiraishi, Yoichi, El-Dahb, Mona A., Sait, Sadiq M., Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Dobnikar, Andrej, editor, Lotrič, Uroš, editor, and Šter, Branko, editor

Published
2011
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28. PARALLEL INVERSE HALFTONING BY LOOK-UP TABLE (LUT) PARTITIONING.

Author

Siddiqi, Umair F. and Sait, Sadiq M.

Subjects
*ALGORITHMS, *IMAGING systems, *LOGIC devices, *ELECTRONIC equipment, *PIXELS
Abstract

The Look-Up Table (LUT) method for inverse halftoning is not only computation-less and fast but yields good results. The method employs a single LUT that is stored in a ROM and contains pre-computed contone (gray level) values for inverse halftone operation. This paper proposes an algorithm that can perform parallel inverse halftone operations by partitioning the single LUT into N smaller Look-Up Tables (s-LUTs). Therefore, up to k (k≤N) pixels can be concurrently fetched from the halftone image and their contone values fetched concurrently from separate s-LUT. Obviously, this parallelization increases the speed of inverse halftoning by up to k times. In this proposed method, the total entries in all s-LUTs remain equal to the entries in the single LUT of the serial LUT method. Some degradation in image quality is possible due to pixel loss during parallel fetching. This is because some contone values cannot be fetched in the same cycle because some other contone value is being fetched from that s-LUT. The complete implementation of the algorithm requires two CPLDs (Complex Programmable Logic Devices) for the computational portion, external content addressable memories (CAM) and static RAMs to store s-LUTs. [ABSTRACT FROM AUTHOR]

Published
2008

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