Bahattin Karakaya | Istanbul University (original) (raw)
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In this article, we focus on the hybrid of orthogonal and non-orthogonal broadcasting. The hybrid... more In this article, we focus on the hybrid of orthogonal and non-orthogonal broadcasting. The hybrid configuration is raised and proposed for improving cellular digital television broadcasting (CDTB) technology. The hybrid scheme is configured as layered division multiplexing (LDM) multiplexed with an evolved multimedia broadcast multicast service (eMBMS) standalone layer is superimposed. The LDM and eMBMS are subsections of power division-non orthogonal multiple access (PD-NOMA) and long-term evolution (LTE) respectively. We assume perfect knowledge of the channel state information (CSI) over the Rayleigh fading multipath channel. The bit error rate (BER) and outage probability performance criteria are investigated. The impact of injection level using the fractional transmit power allocation (FTPA) algorithm is discussed. The proposed hybrid can operate in conditions without a subscriber identity module (SIM) card for uplink beamforming and internet protocol (IP). The broadcast network provider selection is feasible by the user equipment (UE) device. Performance analysis is derived based on the exact closed-form expressions, which allows the theory of hybrid proposed LDM/eMBMS consistent with results. Evaluations and performance will be done based on the Monte Carlo iterative methodology. The results show that the performance and efficiency will be increased when a proposed hybrid LDM/ eMBMS configuration is compared with LDM and eMBMS services individually.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
This paper represents efficient expectation-maximization (EM) and space-alternating generalized e... more This paper represents efficient expectation-maximization (EM) and space-alternating generalized expectation-maximization (SAGE) algorithm based iterative channel estimation methods for multi-cell massive multiple input multiple output (MIMO) systems. The proposed iterative channel estimation methods converge to the same mean square error (MSE) performance of the least squares (LS) estimator with the increasing number of iterations. LS channel estimation method requires conjugate transpose of a large-size pilot matrix. Conjugate transpose of the large-size matrix increases computational complexity. The size of the pilot matrix depends on the number of users. As the number of users increases, computational complexity increases too. In the proposed iterative channel estimation methods, the size of the pilot matrix is reduced to the vector size and the computational complexity is significantly reduced. The SAGE algorithm can estimate the channel by performing fewer iterations than EM, so it is a preferable method in terms of convergence speed.
2018 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2018
This paper represents an efficient expectation-maximization (EM) algorithm based maximum a poster... more This paper represents an efficient expectation-maximization (EM) algorithm based maximum a posteriori (MAP) channel estimation method for multi-cell massive multiple input multiple output (MIMO) systems. MAP channel estimation method requires conjugate transpose of a τ x K pilot matrix where is the number of pilot symbols per user and K is the number of single antenna users. Conjugate transpose of large-size matrix increases computational complexity. The proposed method estimates the channel iteratively and converges to the same mean square error (MSE) performance of the MAP estimator with the increasing number of iterations. Consequently, the proposed method with low-rank approximation avoids conjugate transpose of large-size matrix and hence reduces the computational complexity significantly,
2018 Wireless Telecommunications Symposium (WTS), 2018
This paper represents an efficient space-alternating generalized expectation-maximization (SAGE) ... more This paper represents an efficient space-alternating generalized expectation-maximization (SAGE) algorithm based maximum a posteriori (MAP) channel estimation method for multi-cell massive multiple input multiple output (MIMO) systems. MAP channel estimation method requires conjugate transpose of a t × k pilot matrix where t is the number of pilot symbols per user and k is the number of single antenna users. Conjugate transpose of the large-size matrix increases computational complexity. The proposed method estimates the channel iteratively and converges to the same mean square error (MSE) performance of the MAP estimator with the increasing number of iterations. Consequently, the proposed method with low-rank approximation avoids conjugate transpose of the large-size matrix and hence reduces the computational complexity significantly.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
In this work, a DVB-T (Digital Video Broadcasting Terrestrial) receiver model presented. Performa... more In this work, a DVB-T (Digital Video Broadcasting Terrestrial) receiver model presented. Performance results between real-time conditions and simulations are compared for DVB-T. The effects of various channel estimation methods and viterbi decoding methods on the system have been examined.
This paper analyzes the effects of channel estimation errors on the error performance of the rece... more This paper analyzes the effects of channel estimation errors on the error performance of the recently proposed quadrature channel modulation (QCM) over flat Rayleigh fading channels. A closed-form expression for the pairwise error probability (PEP) of the QCM scheme is derived in the presence of channel estimation errors, and used to calculate upper bound of the average bit error probability (ABEP) for M -QAM signalling. Computer simulation results are provided to corroborate the accuracy of the derived analysis with increasing signal-to-noise ratio (SNR). It has been shown by the computer simulation that the QCM scheme is considerably robust to channel estimation errors.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
Software-defined radio (SDR) is a radio communication system where components such as frequency o... more Software-defined radio (SDR) is a radio communication system where components such as frequency offset compensator, timing recovery, modulator, demodulator and other blocks that have been implemented by means of software on embedded systems. It supplies flexibility and cost efficiency to develop new communication systems. In this paper, a SDR testbed has been done to evaluate the performance of OFDM system practically for different system parameters over wireless channels. OFDM is extremely sensitive to synchronization errors such as time and frequency offsets. Especially the carrier frequency offset (CFO) which is induced by oscillator discrepancies between the transmitter and receiver is very destructive if it is not compensated correctly at the receiver. Therefore, we applied the Schmidl and Cox (S&C) algorithm to solve synchronization problems in SDR based OFDM system. We showed that proposed receiver has sufficient skills for reliable communication.
Qatar Foundation Annual Research Forum Proceedings
Abstract Qatar is a leading natural gas producer and exporter in the world. Most of the natural g... more Abstract Qatar is a leading natural gas producer and exporter in the world. Most of the natural gas (and oil) of Qatar is extracted from offshore wells, and then it is transferred to onshore for processing. In addition, Qatar is connected to UAE by one of the world's longest underwater pipelines (managed by Dolphin Energy), to transfer processed gas from the offshore north field to the UAE. Security of such critical offshore infrastucture against threats along with the environmental and preventive maintenance monitoring (eg, pollution, ...
Wireless Personal Communications
2016 24th Signal Processing and Communication Application Conference (SIU), 2016
2015 9th International Conference on Application of Information and Communication Technologies (AICT), 2015
2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), 2014
2007 9th International Symposium on Signal Processing and Its Applications, 2007
Systems employing multiple transmit and receive antennas, known as multiple input multiple output... more Systems employing multiple transmit and receive antennas, known as multiple input multiple output (MIMO) systems can be used with OFDM to improve the resistance to channel im-pairments. Thus the technologies of OFDM and MIMO are equipped in fixed wireless ...
EURASIP Journal on Wireless Communications and Networking, 2009
Long-Term Evolution (LTE) systems will employ single carrier frequency division multiple access (... more Long-Term Evolution (LTE) systems will employ single carrier frequency division multiple access (SC-FDMA) for the uplink. Similar to the Orthogonal frequency-division multiple access (OFDMA) technology, SC-FDMA is sensitive to frequency offsets leading to intercarrier interference (ICI). In this paper, we propose a Kalman filter-based approach in order to mitigate ICI under high Doppler spread scenarios by tracking the variation of channel taps jointly in time domain for LTE uplink systems. Upon acquiring the estimates of channel taps from the Kalman tracker, we employ an interpolation algorithm based on polynomial fitting whose order is changed adaptively. The proposed method is evaluated under four different scenarios with different settings in order to reflect the impact of various critical parameters on the performance such as propagation environment, speed, and size of resource block (RB) assignments. Results are given along with discussions.
2006 IEEE 14th Signal Processing and Communications Applications, 2006
... kestirimi yaklasimi 6nerilmistir. Kanal kestirim gorevini estimation approach for MIMO-OFDM s... more ... kestirimi yaklasimi 6nerilmistir. Kanal kestirim gorevini estimation approach for MIMO-OFDM systems. The proposed ... den iletilen egitim sembolleri arasinda,iletisim ortami cokyollu stirim problemi bagimsiz .zde§e dagilmi karma ik Gauss KL oldugu i*insadece diklik yetmez. ...
2012 20th Signal Processing and Communications Applications Conference (SIU), 2012
Abstract In this paper, we investigate a multi-carrier multi-relay cooperative system with amplif... more Abstract In this paper, we investigate a multi-carrier multi-relay cooperative system with amplify-and-forward relaying over frequency-selective underwater acoustic channels. Relay selection rules rely on the maximization of signal-to-noise ratio (SNR). We basically use two distinct relay selection schemes; one bases on SNR-summation and the other bases on selecting the relay which gives the best SNR among chosen the worst SNRs of all subcarriers in each relay (best of worst). These are used in conjunction with so-called per- ...
Array
In this article, we focus on the hybrid of orthogonal and non-orthogonal broadcasting. The hybrid... more In this article, we focus on the hybrid of orthogonal and non-orthogonal broadcasting. The hybrid configuration is raised and proposed for improving cellular digital television broadcasting (CDTB) technology. The hybrid scheme is configured as layered division multiplexing (LDM) multiplexed with an evolved multimedia broadcast multicast service (eMBMS) standalone layer is superimposed. The LDM and eMBMS are subsections of power division-non orthogonal multiple access (PD-NOMA) and long-term evolution (LTE) respectively. We assume perfect knowledge of the channel state information (CSI) over the Rayleigh fading multipath channel. The bit error rate (BER) and outage probability performance criteria are investigated. The impact of injection level using the fractional transmit power allocation (FTPA) algorithm is discussed. The proposed hybrid can operate in conditions without a subscriber identity module (SIM) card for uplink beamforming and internet protocol (IP). The broadcast network provider selection is feasible by the user equipment (UE) device. Performance analysis is derived based on the exact closed-form expressions, which allows the theory of hybrid proposed LDM/eMBMS consistent with results. Evaluations and performance will be done based on the Monte Carlo iterative methodology. The results show that the performance and efficiency will be increased when a proposed hybrid LDM/ eMBMS configuration is compared with LDM and eMBMS services individually.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
This paper represents efficient expectation-maximization (EM) and space-alternating generalized e... more This paper represents efficient expectation-maximization (EM) and space-alternating generalized expectation-maximization (SAGE) algorithm based iterative channel estimation methods for multi-cell massive multiple input multiple output (MIMO) systems. The proposed iterative channel estimation methods converge to the same mean square error (MSE) performance of the least squares (LS) estimator with the increasing number of iterations. LS channel estimation method requires conjugate transpose of a large-size pilot matrix. Conjugate transpose of the large-size matrix increases computational complexity. The size of the pilot matrix depends on the number of users. As the number of users increases, computational complexity increases too. In the proposed iterative channel estimation methods, the size of the pilot matrix is reduced to the vector size and the computational complexity is significantly reduced. The SAGE algorithm can estimate the channel by performing fewer iterations than EM, so it is a preferable method in terms of convergence speed.
2018 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2018
This paper represents an efficient expectation-maximization (EM) algorithm based maximum a poster... more This paper represents an efficient expectation-maximization (EM) algorithm based maximum a posteriori (MAP) channel estimation method for multi-cell massive multiple input multiple output (MIMO) systems. MAP channel estimation method requires conjugate transpose of a τ x K pilot matrix where is the number of pilot symbols per user and K is the number of single antenna users. Conjugate transpose of large-size matrix increases computational complexity. The proposed method estimates the channel iteratively and converges to the same mean square error (MSE) performance of the MAP estimator with the increasing number of iterations. Consequently, the proposed method with low-rank approximation avoids conjugate transpose of large-size matrix and hence reduces the computational complexity significantly,
2018 Wireless Telecommunications Symposium (WTS), 2018
This paper represents an efficient space-alternating generalized expectation-maximization (SAGE) ... more This paper represents an efficient space-alternating generalized expectation-maximization (SAGE) algorithm based maximum a posteriori (MAP) channel estimation method for multi-cell massive multiple input multiple output (MIMO) systems. MAP channel estimation method requires conjugate transpose of a t × k pilot matrix where t is the number of pilot symbols per user and k is the number of single antenna users. Conjugate transpose of the large-size matrix increases computational complexity. The proposed method estimates the channel iteratively and converges to the same mean square error (MSE) performance of the MAP estimator with the increasing number of iterations. Consequently, the proposed method with low-rank approximation avoids conjugate transpose of the large-size matrix and hence reduces the computational complexity significantly.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
In this work, a DVB-T (Digital Video Broadcasting Terrestrial) receiver model presented. Performa... more In this work, a DVB-T (Digital Video Broadcasting Terrestrial) receiver model presented. Performance results between real-time conditions and simulations are compared for DVB-T. The effects of various channel estimation methods and viterbi decoding methods on the system have been examined.
This paper analyzes the effects of channel estimation errors on the error performance of the rece... more This paper analyzes the effects of channel estimation errors on the error performance of the recently proposed quadrature channel modulation (QCM) over flat Rayleigh fading channels. A closed-form expression for the pairwise error probability (PEP) of the QCM scheme is derived in the presence of channel estimation errors, and used to calculate upper bound of the average bit error probability (ABEP) for M -QAM signalling. Computer simulation results are provided to corroborate the accuracy of the derived analysis with increasing signal-to-noise ratio (SNR). It has been shown by the computer simulation that the QCM scheme is considerably robust to channel estimation errors.
2018 26th Signal Processing and Communications Applications Conference (SIU), 2018
Software-defined radio (SDR) is a radio communication system where components such as frequency o... more Software-defined radio (SDR) is a radio communication system where components such as frequency offset compensator, timing recovery, modulator, demodulator and other blocks that have been implemented by means of software on embedded systems. It supplies flexibility and cost efficiency to develop new communication systems. In this paper, a SDR testbed has been done to evaluate the performance of OFDM system practically for different system parameters over wireless channels. OFDM is extremely sensitive to synchronization errors such as time and frequency offsets. Especially the carrier frequency offset (CFO) which is induced by oscillator discrepancies between the transmitter and receiver is very destructive if it is not compensated correctly at the receiver. Therefore, we applied the Schmidl and Cox (S&C) algorithm to solve synchronization problems in SDR based OFDM system. We showed that proposed receiver has sufficient skills for reliable communication.
Qatar Foundation Annual Research Forum Proceedings
Abstract Qatar is a leading natural gas producer and exporter in the world. Most of the natural g... more Abstract Qatar is a leading natural gas producer and exporter in the world. Most of the natural gas (and oil) of Qatar is extracted from offshore wells, and then it is transferred to onshore for processing. In addition, Qatar is connected to UAE by one of the world's longest underwater pipelines (managed by Dolphin Energy), to transfer processed gas from the offshore north field to the UAE. Security of such critical offshore infrastucture against threats along with the environmental and preventive maintenance monitoring (eg, pollution, ...
Wireless Personal Communications
2016 24th Signal Processing and Communication Application Conference (SIU), 2016
2015 9th International Conference on Application of Information and Communication Technologies (AICT), 2015
2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), 2014
2007 9th International Symposium on Signal Processing and Its Applications, 2007
Systems employing multiple transmit and receive antennas, known as multiple input multiple output... more Systems employing multiple transmit and receive antennas, known as multiple input multiple output (MIMO) systems can be used with OFDM to improve the resistance to channel im-pairments. Thus the technologies of OFDM and MIMO are equipped in fixed wireless ...
EURASIP Journal on Wireless Communications and Networking, 2009
Long-Term Evolution (LTE) systems will employ single carrier frequency division multiple access (... more Long-Term Evolution (LTE) systems will employ single carrier frequency division multiple access (SC-FDMA) for the uplink. Similar to the Orthogonal frequency-division multiple access (OFDMA) technology, SC-FDMA is sensitive to frequency offsets leading to intercarrier interference (ICI). In this paper, we propose a Kalman filter-based approach in order to mitigate ICI under high Doppler spread scenarios by tracking the variation of channel taps jointly in time domain for LTE uplink systems. Upon acquiring the estimates of channel taps from the Kalman tracker, we employ an interpolation algorithm based on polynomial fitting whose order is changed adaptively. The proposed method is evaluated under four different scenarios with different settings in order to reflect the impact of various critical parameters on the performance such as propagation environment, speed, and size of resource block (RB) assignments. Results are given along with discussions.
2006 IEEE 14th Signal Processing and Communications Applications, 2006
... kestirimi yaklasimi 6nerilmistir. Kanal kestirim gorevini estimation approach for MIMO-OFDM s... more ... kestirimi yaklasimi 6nerilmistir. Kanal kestirim gorevini estimation approach for MIMO-OFDM systems. The proposed ... den iletilen egitim sembolleri arasinda,iletisim ortami cokyollu stirim problemi bagimsiz .zde§e dagilmi karma ik Gauss KL oldugu i*insadece diklik yetmez. ...
2012 20th Signal Processing and Communications Applications Conference (SIU), 2012
Abstract In this paper, we investigate a multi-carrier multi-relay cooperative system with amplif... more Abstract In this paper, we investigate a multi-carrier multi-relay cooperative system with amplify-and-forward relaying over frequency-selective underwater acoustic channels. Relay selection rules rely on the maximization of signal-to-noise ratio (SNR). We basically use two distinct relay selection schemes; one bases on SNR-summation and the other bases on selecting the relay which gives the best SNR among chosen the worst SNRs of all subcarriers in each relay (best of worst). These are used in conjunction with so-called per- ...