## Design of Permutation-Based Sparse Code Multiple Access System

SCMA codebook based on permutation design.

## Uniquely Decodable Ternary Codes for Synchronous CDMA systems

Code set design and simple decoding algorithm.

## Design of low-complexity detection for faster-than-Nyquist (FTN)

Outperforms symbol-by-symbol detector.

## Improved Soft Decoding of Reed-Solomon Codes on Gilbert-Elliott Channels

New soft decoding of RS codes.

## Fast Decoder for Overloaded Uniquely Decodable Synchronous Optical CDMA

Novel low-complexity detection scheme.

## Design of low-Density Spreading Code Based on Gaussian Separability

Novel LDS design outperforms existing constructions.

• 2015 2015

#### Instructor

Carleton University, Canada, Department of Systems and Computer Engineering

• 2011 2008

#### Research Assistant

University at Buffalo, USA, Department of Electrical Engineering

• 2008 2006

#### Teaching Assistant

University at Buffalo, USA, Department of Electrical Engineering

• 2005 2005

#### Research Assistant

University at Buffalo, USA, Department of Electrical Engineering

### Education

• Ph.D. 2012

Ph.D. in Electrical Engineering

University at Buffalo, USA

• M.S.2007

Master of Science in Electrical Engineering

University at Buffalo, USA

• B.S.2005

Bachelor of Science in Electronics Engineering

The American University in Cairo, Egypt

### Honors, Awards and Grants

• 2012-2014
NSERC Industrial R&D Fellowship

· Studies and categorized the field failure data for various subsystems

· Modelled the ultra rugged wireless network with Quality of Service (QoS)

· Designed and developed a tool based on the model that would help design ultra rugged products

• 2008-2011

· Developed spread-spectrum steganography and blind steganalysis algorithms

· Developed a soft decoding algorithm for Reed-Solomon codes of Gilbert-Elliott channels

• 2006-2008

• 2005-2005

· Developed a digital audio fingerprinting algorithm for digital recording system identification from digital audio files alone, for forensic purposes

• 2000-2005

· Awarded during my five years of education at the American University in Cairo for maintaining high GPA from Fall 2000 till Spring 2005

## News

• ### Uniquely Decodable Code-Division via Augmented Sylvester-Hadamard Matrices

My PhD thesis on overloaded code-division multiplexing code sets.

In this work I investigate the overloaded code-division multiplexing where the number of multiplexed signals exceeds the code (signature) length $L$. I developed overloaded code design framework where code set satisfy “errorless” (uniquely decodability) property in noiseless multiplexed transmission. In this work my goal is to identify the maximum number of codes/signatures that can be potentially appended to a Sylvester-Hadamard matrix of order $L$, while maintaining the errorless code property.

• ### Hierarchical Criteria for the Design of Super Signature Sets for Code-Division Multiplexing

Code sequences (signatures) for overloaded code-division multiplexing applications.

I consider the problem of designing sets of code sequences (signatures) for overloaded CDM applications from binary alphabet. I first introduce a method for constructing a large code set by operating Kronecker product on two smaller codes. In particular, I developed conditional hierarchical criteria for the code (signature) design framework where a simplified maximum-likelihood (SML) detection scheme can be utilized to make CDM systems practically implementable.

• ### Improved Soft Decoding of Reed-Solomon Codes on Gilbert-Elliott Channels

New soft decoding of RS codes.

In order to improve and control errors in data transmission over the unreliable or noisy communication channels we may leverage channel coding theory. One of such codes are Reed-Solomon (RS) codes, which is perhaps the most widely used and studied codes. The problem of list decoding of RS codes over the phased burst channels is investigated. I present evidence that the algorithm development by Guruswami and Rudra can also give improvement for more “irregular” burst errors.

Specifically, I present simulation results where such soft decoding of RS codes outperforms existing soft decoding algorithms proposed by Koetter and Vardy and, more recently, Das and Vardy on Gilbert-Elliott channels. I also present a theoretical result that for certain Gilbert-Elliott channels, with high probability over the errors, the output list size for list decoding RS codes is one.

Unsupervised (blind) low-complexity algorithm based on generalized least-squares principle.

Steganography, which literately means “covered writing” in Greek, refers to a broad class of problems where secure data transmission is achieved by hiding a message in a host object. Steganalysis, which is the countermeasure of steganography. I proposed a passive spread-spectrum steganalysis algorithm to decide the presence or absence of spread-spectrum hidden data in a given image (a binary hypothesis testing problem). Unlike conventional feature-based approaches, I developed an unsupervised (blind) low-complexity approach based on generalized least-squares principles that may enable rapid high volume image processing.

• ### On the Extraction of Spread-Spectrum Hidden Data in Digital Media

Blindly extracting embedded data based on M-IGLS algorithm.

I also considered the problem of blindly extracting data embedded over a wideband in a spectrum (transform) domain of a digital medium (e.g., image, audio, and video). I first developed a multisignature iterative generalized least-squares (MIGLS) core procedure to seek unknown data hidden in hosts via multi-signature direct-sequence spread-spectrum embedding. Neither the original host nor the embedding signatures are assumed available. Then, cross-correlation enhanced M-IGLS (CCMIGLS), a procedure based on statistical analysis of repeated independent M-IGLS processing of the host, is seen to offer most effective hidden message recovery.

• ### A Simplified Near Maximum Likelihood Decoding Algorithm for Overloaded CDMA

New decoding algorithm for my overloaded CDMA over AWGN.

This work is the continuation of my uniquely decodable code design. Here I focus on developing a decoder for overloaded CDMA system under Additive White Gaussian Noise (AWGN) having almost like Maximum Likelihood (ML) performance with very low computation complexity. Advantage of this decoder over the well known algorithms is that it takes into consideration the specific structure of such codes.

It should outperform quasi-optimal solution of probabilistic association algorithm (PDA) or Soft Interference Cancelation (SIC) algorithm, well know sphere decoding algorithm, slab decoding or Semi-Definite Programming (SDP) algorithms.

• ### Deterministic Construction of Compressed Sensing Matrices

Compressed sensing matrices based on overloaded code sets.

I investigate the connection between uniquely decodable code set and antipodal compressed sensing matrices. The field of compressed sensing deals with reliable reconstruction of $k$-sparse vector $\mathbf{x}_{n \times 1}$ from $\mathbf{y}_{m \times 1} = \mathbf{\Phi}_{m \times n} \mathbf{x}_{n\times 1}$ where $m \ll n$. One aspect of the problem is to select the good sampling matrix $\mathbf{\Phi}_{m \times n}$ and another aspect is to reconstruct $\mathbf{x}_{n \times 1}$ from the measurements $\mathbf{y}_{m \times 1}$ by exploiting the sparsity constraint. My goal is to develop sampling matrix $\mathbf{\Phi}_{m \times n}$ with good compression ratio. Since the ratio between $m$ and $n$ of uniquely decodable codes is $\frac{n}{m} = \frac{p 2^{p-1} +1 }{2^p}\simeq \frac{p 2^{p-1} }{2^p} \simeq \frac{p}{2}$ where $p$ is the exponent of powers of $2$.

For larger sizes it satisfies $m \ll n$. The matrices should also satisfy one of the well-studied conditions on the sensing matrix which guarantees stable recovery for a number of reconstruction methods, which is called Restricted Isometry Property (RIP). The asymptotic analysis comparing different deterministic construction of sensing matrices such as based on classical finite-geometry generalized polygons or other well known sampling matrices.

• ### New Simplified Multiuser Detection for SCMA

Low-complexity decoding scheme for SCMA.

In order to meet the requirements of massive connectivity, higher throughput, lower latency, better quality of service, new waveform and multiple access technology should be designed. Sparse code multiple access (SCMA) is a multi-dimensional codebook-based non-orthogonal spreading technique with near optimal spectral efficiency, which can potentially address the above requirement. Sparsity of SCMA codewords makes the near-optimal detection of over-laid SCMA layers practically feasible. I am going to analyze SCMA scheme in theory as well as looking into the construction of sparse code sets to identify room for possible improvements

In SCMA, incoming bits are directly mapped to multi-dimensional complex codewords selected from predefined codebook sets. I am particularly interested in looking at different effective mapping schemes that can maximize the system sum rate and minimize the interference among the users. Work on developing a simplified SCMA detection algorithm whose performance is comparable to Sum-Product algorithm but has lower complexity.

• ### Quasi-Orthogonal Space-Time Block Code Design for Massive-MIMO

Hadamard matrix based multi-dimensional constellations design.

Massive multiple-input multiple-output (MIMO) technology has become an attractive field of re- search, which can be built with inexpensive, low-power components. Massive MIMO systems, or large-scale antenna systems, have been investigated as new cellular network architecture for the next generation high-speed wireless communications. Massive MIMO can improve spectrum efficiency, energy efficiency and performance reliability. The transmit diversity scheme proposed by Alamouti is a simple and effective orthogonal space-time block codes (OSTBC) of full rate with two transmit antennas for the system. Unfortunately, for more than two transmit antennas, the rate of the OST- BC, defined by the number of symbols transmitted divided by the number of time slots used by the OSTBC, cannot be larger than 3/4. Since this field of research is still in its infancy, much work still needs to be done.

I believe Quasi-Orthogonal STBC (QOSTBC) might be a potential candidate to address that problem. I would like to conduct more thorough investigations in a massive MIMO configuration with a larger number of antennas. I am also interested in extending the traditional OSTBC design to include Hadamard matrix, or raptor codes. I am going to exploit the multi-dimensional constellations design for massive-MIMO.

• ### High-Rate Space-Time-Frequency Codes For Multiuser MIMO-OFDM System

Codes that achieve maximum diversity with efficient decoding algorithms.

Over MIMO frequency-selective fading channels, space time coding (STC) scheme cannot achieve multipath diversity. To overcome the inter-symbol interference (ISI) induced by multipath, orthogonal frequency-division multiplexing (OFDM) was applied to MIMO system, referred to as MIMO- OFDM. It provides the opportunity to code the transmitted symbols over three dimensional coding; different antennas (space), time and sub-carriers (frequency). This coding scheme is known as space- time-frequency block coding, and it can exploit the multipath diversity. However, the complexity. of such system is considerably high.

My objective is to introduce new space-time-frequency codes that can achieve maximum diversity as well as highly efficient decoding algorithms for such codes with a reasonable complexity for MIMO-OFDM communication system. It will be also interesting to investigate the MIMO-OFDM code-division multiplexing (CDM) by carefully selecting overloaded code-division multiplexing scheme.

• ### Energy Efficiency Optimization For MIMO-OFDM Cognitive Radio Network

Joint optimal power allocation and beamforming strategy.

Cognitive radio (CR) is a promising approach to enhance the radio spectrum utilization, in which secondary user (SU) can opportunistically access the licensed spectrum of primary user (PU). In particular, CR allows multiple SUs to simultaneously share the PU's spectrum as long as the interference from SUs to PU is under certain threshold. MIMO-OFDM is considered as a good physical layer candidate in cognitive radios because of its high efficiency and flexibility in dynamic spectrum usage, as well as higher system capacity and reliability due the use of multiple antennas. Since the formulated energy-efficient problem is non-convex in general it is difficult to solve directly.

My intention is to study the joint optimal power allocation and beamforming strategy to optimize the energy efficiency MIMO cognitive radio under spatial interference constraints, considering both the availability and absence of the PU channel state information (CSI). I will be working on developing an efficient receive architectural design for MIMO-OFDM based CR communications, with the intention to reduce the cost of sampling signals from multiple channels that utilizes compressive sensing (CS) technique.

## Miselenous

### Abstract Algebra

Youtube videos on Abstract Algebra. Groups, Rings, Field, Vector spaces, Modules and much more!

### Coursera

Online courses of variety of subjects. Profeesors from well known universities, Stanford, Princton, etc.

### Puzzles

Lots of mathematical challenging questions.

### Graphing Tools

Nice tools for equation graphing

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#### Improved Soft Decoding of Reed-Solomon Codes on Gilbert-Elliott Channels

M. Kulhandjian, H. Kulhandjian and Claude D'Amours,
Conference Papers Proc. IEEE Int. Symp. Inf. Theory (ISIT), Paris, France, Jul. 07-12, 2019, pp. 1072-1076.

#### Abstract

It was shown by Guruswami and Rudra that Reed-Solomon codes can be list decoded to recover from phased burst errors (i.e. errors occurring within fixed regular intervals) up to the information-theoretic limit and, in particular, beyond the Guruswami-Sudan bound. In this paper, we present evidence that the algorithm developed by Guruswami and Rudra can also give improvement for more "irregular" burst errors. We develop a low-complexity multiplicity assignment scheme for soft decoding of Reed-Solomon (RS) codes. Specifically, we present simulation results where such soft decoding of RS codes outperforms the existing soft decision decoding algorithms of Koetter and Vardy as well as the algorithm of Das and Vardy on Gilbert-Elliott channels (under QAM and BPSK modulations) for channels that are more bursty. We also present a theoretical result that shows that for certain Gilbert-Elliott channels, with high probability of errors, the output list size for list decoding RS codes is one.

#### Fast Decoder for Overloaded Uniquely Decodable Synchronous Optical CDMA

M. Kulhandjian, C. D'Amours, H. Kulhandjian, H. Yanikomeroglu and G. Khachatrian,
Conference Papers Proc. IEEE Wireless Commun. and Network. Conf. (WCNC), Marrakech, Morocco, Apr. 15-19, 2019, pp. 1-7.

#### Abstract

In this paper, we propose a fast decoder algorithm for uniquely decodable (errorless) code sets for overloaded synchronous optical code-division multiple-access (O-CDMA) systems. The proposed decoder is designed in a such a way that the users can uniquely recover the information bits with a very simple decoder, which uses only a few comparisons. Compared to maximum-likelihood (ML) decoder, which has a high computational complexity for even moderate code lengths, the proposed decoder has much lower computational complexity. Simulation results in terms of bit error rate (BER) demonstrate that the performance of the proposed decoder for a given BER requires only 1 - 2 dB higher signal-to-noise ratio (SNR) than the ML decoder.

#### Design of Permutation-Based Sparse Code Multiple Access System

M. Kulhandjian and Claude D'Amours,
Conference Papers Proc. IEEE Pers., Indoor, Mobile Radio Conf. (PIMRC) 2017, Montreal, Canada, Oct. 08-13, 2017, pp. 1031-1035.

#### Abstract

We consider the problem of designing a sparse code multiple access (SCMA) codebook that is based on permutation. Conventional SCMA is a multidimensional codebook-based non-orthogonal spreading technique, in which each layer of incoming bits are directly mapped to multidimensional codewords which have nonzero entries on the same resources. In this paper, unlike the traditional SCMA scheme, the data bits to be transmitted determine the nonzero entry locations based on the permutation. The proposed SCMA codebooks are converted to a multiuser code-division multiple-access (CDMA) detection system before applying an iterative decoder. The complexity of the proposed iterative decoder is lower in comparison to exponential message passing algorithm (MPA) and outperforms in terms of bit-error-rate (BER).

#### On the extraction of spread-spectrum hidden data in digital media

M. Li, M. Kulhandjian, D. A. Pados, S.N. Batalama, M. J. Medley, and J. D. Matyjas,
Conference Papers Proc. IEEE Int. Conf. Commun.(ICC), Ottawa, Canada, June 10-15, 2012, pp. 1031-1035.

#### Abstract

This paper considers the problem of blindly extracting data embedded over a wide band in a spectrum (transform) domain of a digital medium (image, audio, video). We first develop a multi-signature iterative generalized least-squares (M-IGLS) core procedure to seek unknown data hidden in hosts via multi-signature direct-sequence spread-spectrum embedding. Neither the original host nor the embedding signatures are assumed available. Then, cross-correlation enhanced M-IGLS (CC-M-IGLS), a procedure described herein in detail that is based on statistical analysis of repeated independent M-IGLS processing of the host, is seen to offer most effective hidden message recovery. Experimental studies on images show that the proposed CC-M-IGLS algorithm can achieve recovery probability of error close to what may be attained with known embedding signatures and host autocorrelation matrix.

#### Low-Complexity Detection for Faster-than-Nyquist Signaling based on Probabilistic Data Association

M. Kulhandjian, E. Bedeer, H. Kulhandjian, C. D'Amours and H. Yanikomeroglu,
Journal Paper IEEE Commun. Lett., vol.8, no.7, pp.1-6, Dec. 2019.

#### Abstract

In this paper, we investigate the sequence estimation problem of faster-than-Nyquist (FTN) signaling as a promising approach for increasing spectral efficiency (SE) in future communication systems. In doing so, we exploit the concept of Gaussian separability and propose two probabilistic data association (PDA) algorithms with polynomial time complexity to detect binary phase-shift keying (BPSK) FTN signaling. Simulation results show that the proposed PDA algorithm outperforms the and SSSgb$K$SE algorithms for all SE values with a modest increase in complexity. The PDA algorithm approaches the performance of the semidefinite relaxation (SDRSE) algorithm for SE values of $0.96$ bits/sec/Hz, and it is within the $0.5$ dB signal-to-noise ratio (SNR) penalty at SE values of $1.10$ bits/sec/Hz for the fixed values of $\beta = 0.3$.

#### Extracting Spread-Spectrum Hidden Data From Digital Media

M. Li, M. Kulhandjian, D. A. Pados, S.N. Batalama, and M. J. Medley,
Journal Paper Trans. Inf. Forens. Security, vol.8, no.7, pp.1201-1210, July 2013.

#### Abstract

We consider the problem of extracting blindly data embedded over a wide band in a spectrum (transform) domain of a digital medium (image, audio, video). We develop a novel multicarrier/signature iterative generalized least-squares (M-IGLS) core procedure to seek unknown data hidden in hosts via multicarrier spread-spectrum embedding. Neither the original host nor the embedding carriers are assumed available. Experimental studies on images show that the developed algorithm can achieve recovery probability of error close to what may be attained with known embedding carriers and host autocorrelation matrix.

#### Uniquely decodable code-division via augmented Sylvester-Hadamard matrices

M. Kulhandjian, and D. A. Pados,
Conference Papers Proc. IEEE Wireless Comm. and Networking Conf. (WCNC), Paris, France, Apr. 1-4, 2012, pp.359-363.

#### Abstract

We consider the problem of designing binary antipodal uniquely decodable (errorless) code sets for overloaded code-division multiplexing applications where the number of signals K is larger than the code length $L$. Our proposed errorless code set design aims at identifying the maximum number of columns that can be potentially appended to a Sylvester-Hadamard matrix of order $L$, while maintaining the errorless code property. In particular, we derive formally the maximum number of columns that may be appended to the Sylvester-Hadamard matrix of order $L = 8$ and use this result as a seed to produce an infinite sequence of designs in increasing $L$. In the noiseless transmission case, a simple algorithm is developed to uniquely decode all signals. In additive white Gaussian noise (AWGN), a slab-sphere decoding scheme can be utilized for efficient and effective decoding.

M. Li, M. Kulhandjian, D. A. Pados, S.N. Batalama, and M. J. Medley,
Conference Papers Proc. IEEE Int. Image Process. (ICIP), Brussels, Belgium, Sept.11-14, 2011, pp. 1957-1960

#### Abstract

We consider the problem of passive spread-spectrum steganalysis where the objective is to decide the presence or absence of spread-spectrum hidden data in a given image (a binary hypothesis testing problem). Unlike conventional feature-based approaches, we describe an unsupervised (blind) low-complexity approach based on generalized least-squares principles that may enable rapid high-volume image processing. Extensive experiments on image sets and comparisons with existing steganalysis techniques demonstrate most satisfactory classification performance measured in probability of correct detection versus induced false alarm rate.

### Currrent Teaching

• 2016 2016

#### SYSC 5606 Introduction to Mobile Communications

Prepared class lectures, assignments, midterms and finals for about thirty students

• 2015 2015

#### SYSC 5606 Introduction to Mobile Communications

Prepared class lectures, assignments, midterms and finals for about thirty students

• 2008 2008

• 2008 2008

• 2008 2008

• 2007 2007

• 2007 2007

### Technical Program Committee (TPC) Session Chair

• IEEE Pers., Indoor, Mobile Radio Conf. (PIMRC) 2017
• IEEE Vehicular Technology Conference (VTC-Spring) 2016

### TPC Member

• IEEE (WiMob) 2017
• IEEE (Globcom) 2017
• IEEE Int. Conference on Communications (ICC-CQRM) 2016-2018
• IEEE Vehicular Technology Conference (VTC-Spring) 2016
• IEEE Vehicular Technology Conference (VTC-Fall) 2012-2015

### Referee Service

• SPRINGER Anals of Telecommunications
• IEEE Transactions on Image Processing
• ELSEVIER Transactions on Journal of Information Security and Applications
• IEEE Transactions on Information Theory

## Contact Me

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