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195 results on '"Koca, Mutlu"'

2. Stochastic Geometry Analysis of Interference Coordination in NOMA-based Heterogeneous Networks

Author

Altay, Can and Koca, Mutlu

Subjects
Computer Science - Networking and Internet Architecture
Abstract

In this paper, we present a stochastic geometry-based analysis for the coverage probability of multi-tier heterogeneous networks employing interference coordination for non-orthogonal multiple access (NOMA). Two basic and conventional interference coordination alternatives; strict fractional frequency reuse (FFR) and soft frequency reuse (SFR) are analyzed, and their performance gains on different instances are illustrated. Coverage probability analysis has been extended to that of spectral efficiency for a fair performance evaluation between different FFR methods. The analysis covers both open-access networks with micro- and pico-cells, and closed-access networks with femto-cells. For heterogeneous networks, NOMA is observed to achieve better spectral efficiency than OFDMA, while OFDMA provides better coverage. Both analysis and numerical results reveal that strict FFR provides better coverage while SFR provides spectral efficiency advantage in open-access. However, strict FFR outperforms SFR for both measures in closed-access networks., Comment: There are mistakes on statistical derivarions with the number of users

Published
2018

3. On the Foundation of NOMA and its Application to 5G Cellular Networks

Author

Sari, Hikmet, Maatouk, Ali, Caliskan, Ersoy, Assaad, Mohamad, Koca, Mutlu, and Gui, Guan

Subjects
Computer Science - Information Theory
Abstract

Non-Orthogonal Multiple Access (NOMA) is recognized today as a most promising technology for future 5G cellular networks and a large number of papers have been published on the subject over the past few years. Interestingly, none of these authors seems to be aware that the foundation of NOMA actually dates back to the year 2000, when a series of papers introduced and investigated multiple access schemes using two sets of orthogonal signal waveforms and iterative interference cancellation at the receiver. The purpose of this paper is to shed light on that early literature and to describe a practical scheme based on that concept, which is particularly attractive for Machine-Type Communications (MTC) in future 5G cellular networks. Using this approach, NOMA appears as a convenient extension of orthogonal multiple access rather than a strictly competing technology, and most important of all, the power imbalance between the transmitted user signals that is required to make the receiver work in other NOMA schemes is not required here., Comment: 6 pages, 8 figures, submitted to IEEE WCNC 2018

Published
2017

8. A General Framework for Performance Analysis of Spatial Modulation over Correlated Fading Channels

Author

Koca, Mutlu and Sari, Hikmet

Subjects
Computer Science - Information Theory
Abstract

We present a general method for the error analysis of spatial modulation (SM) systems over correlated and uncorrelated Rayleigh and Rician fading channels. The proposed method, making use of the properties of proper complex random variables and vectors, provides an exact upper bound for the class of fading channels considered for any number of transmit and receive antennas and for a wide family of linear modulation alphabets. Theoretical derivations are validated via simulation results., Comment: 6 pages, 3 figures. Submitted to IEEE International Conference on Communications (ICC) 2012, Ottawa, Canada

Published
2011

14. A Novel Scheduling Strategy in Priority-Aware IoT Networks for Age of Information Optimization

Author

Sayinbas, Oguzhan, Kose, Alper, Koca, Mutlu, and Anarim, Emin

Abstract

We propose a novel scheduling strategy for prioritization-critical time-sensitive Internet of things (IoT) networks. The goal is to decrease the number of sensors with outdated information and minimize the difference between their age of information (AoI) and the specified limit, within a resource-constrained environment. The proposed approach relies on reformulating the original problem as a knapsack problem. This novel method is shown to outperform benchmarks to satisfy the needs of priority-aware IoT networks.

Published
2024
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30. Double turbo equalization of continuous phase modulation with frequency domain processing

Author

Ozgul, Baris, Koca, Mutlu, and Delia, Hakan

Subjects
Digital communication, Digital communications -- Analysis, Phase modulation -- Usage, Decoders -- Usage
Abstract

In this paper, a doubly-iterative linear receiver, equipped with a soft-information aided frequency domain minimum mean-squared error (MMSE) equalizer, is proposed for the combined equalization and decoding of coded continuous phase modulation (CPM) signals over long multipath fading channels. In the proposed receiver architecture, the front-end frequency domain equalizer (FDE) is followed by the soft-input, soft-output (SISO) CPM demodulator and channel decoder modules. The receiver employs double turbo processing by performing back-end demodulation/decoding iterations per each equalization iteration to improve the a priori information for the front-end FDE. As presented by the computational complexity analysis and simulations, this process provides not only a significant reduction in the overall computational complexity, but also a performance improvement over the previously proposed iterative and noniterative MMSE receivers. Index Terms--Continuous phase modulation, double turbo processing, frequency domain equalization, intersymbol interference.

Published
2009

34. Iterative joint tone-interference cancellation and decoding for MIMO-OFDM

Author

Esli, Celal, Koca, Mutlu, and Delca, Hakan

Subjects
MIMO communications -- Research, Electromagnetic interference -- Control, Coding theory -- Research, Business, Electronics, Electronics and electrical industries, Transportation industry
Abstract

In this paper, multi-input-multi-output orthogonal frequency-division multiplexing (MIMO-OFDM) is considered in the presence of multipath fading and multitone interference (MTI). The MIMO-OFDM system makes joint use of channel coding and orthogonal space--frequency block coding (OSFBC) on the transmit side and iterative processing on the receiver side for robustness and improved performance against the fading and MTI effects of the channel. The new iterative receiver is implemented by either an optimal a posteriori probability (APP) space-frequency detector or a soft-information-aided minimum-mean-squared-error (MMSE) combiner at its front end and a soft-input--soft-output channel decoder at its back end. An approximate error performance analysis is provided for the OSFBC-OFDM system under maximum-likelihood decoding to illustrate the interference mitigation efficiency of the system. Then, the two iterative receivers are compared in terms of their computational complexities and bit error rate (BER) performances. As depicted in the BER graphs, both iterative receivers provide an improvement in performance after only a few detection/decoding iterations. It is also shown that despite its suboptimality, the MMSE receiver has the potential to achieve a BER performance close to that of the APP detector at a significantly lower cost. Index Terms--A posteriori probability (APP), minimum mean-squared error (MMSE), multi-input-multi-output orthogonal frequency-division multiplexing (MIMO-OFDM), multitone interference (MTI), orthogonal space--frequency block coding (OSFBC), turbo processing.

Published
2008

35. Doubly iterative equalization of continuous-phase modulation

Author

Ozgul, Baris, Koca, Mutlu, and Delic, Hakan

Subjects
Algorithm, Algorithms -- Usage, Phase modulation -- Methods, Electromagnetic interference -- Control
Abstract

In this paper, a doubly iterative receiver is proposed for joint turbo equalization, demodulation, and decoding of coded binary continuous-phase modulation (CPM) in multipath fading channels. The proposed receiver consists of three soft-input soft-output (SISO) blocks: a front-end soft-information-aided minimum mean square error (MMSE) equalizer followed by a CPM demodulator and a back-end channel decoder. The MMSE equalizer, combined with an a priori soft-interference canceler (SIC) and an a posteriori probability mapper, forms a SISO processor suitable for iterative processing that considers discrete-time CPM symbols which belong to a finite alphabet. The SISO CPM demodulator and the SISO channel decoder are both implemented by the a posteriori probability algorithm. The proposed doubly iterative receiver has a central demodulator coupled with both the front-end equalizer and the back-end channel decoder. A few back-end demodulation/decoding iterations are performed for each equalization iteration so as to improve the a priori information for the equalizer. As presented in the extrinsic information transfer (EXIT) chart analysis and simulation results for different multipath fading channels, this provides not only faster convergence to low bit error rates, but also lower computational complexity. Index Terms--Continuous-phase modulation (CPM), double turbo processing, extrinsic information transfer (EXIT) chart, intersymbol interference, minimum mean square error (MMSE) equalization.

Published
2007

36. Broadband beamforming with power complementary filters

Author

Koca, Mutlu and Levy, Bernard C.

Subjects
Signal processing -- Research, Filtering (Electronics) -- Research, Beam optics -- Research, Telecommunications equipment industry -- Research, Multichannel communication -- Research, Communications technology, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Design of space-time receivers is discussed. The receivers preserve the whiteness of channel noise while reducing the intersymbol interference (ISI) so that optimum maximum a posteriori (MAP) equalization can be performed on the receiver output.

Published
2002

37. Synchronisation Free Non-Coherent On-Off Keying Demodulation Techniques

Author

Batur, Okan Zafer, Pekcokguler, Naci, Dundar, Gunhan, and Koca, Mutlu

Subjects
Hardware_INTEGRATEDCIRCUITS
Abstract

Digital envelope detection, self-correlation and high frequency sampling techniques are proposed for high data rate demodulation of on-off keying signals that are widely used in impulse radio ultra-wideband receivers. The proposed designs eliminate the requirement of complex synchronisation circuit architectures and algorithms. The presented circuits are all digital and can be utilised in the baseband synchronisation. The digital envelope detection and self-correlation methods are implemented in 130 nm complementary metal oxide semiconductor (CMOS) technology and concepts are verified with measurement results. Post-layout simulation results are given for the high frequency sampling technique. Measurements show that the digital envelope detector demonstrates successful operation up to 600 Mbps data rate with 2.1 mW power consumption. The self-correlator consumes 10 mW with 100 Mbps data rate in the measurements. The post-layout simulations results show that the high frequency sampler can operate at 2 mW with 500 Mbps data rate.

Published
2019

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