Joint Time Offset and Fading Channel Coefficient Estimation for Cooperative Communication Systems

In this paper, we investigate joint channel gain and time offset estimation for two different data aided methods in cooperative communication with amplify-and-forward (AF) relaying. First one is the Cascaded Estimation (CE) method which channel gain, and time offset consisting of both source-to-relay, and relay-to-destination links are estimated at the destination terminal, second one is Disintegrated Estimation (DE) method which channel gain, and time offset are estimated seperately at the relay for source-to-relay link, and at the destination for relay-to-destination link. Both of the proposed joint estimators are based on Expectation-Maximization (EM) algorithm and, produce a low-complexity solution of itaretive maximum likelihood (ML) estimation. It was observed by the bit error rate (BER) curves, the proposed methods provide good performances with low-complexity

Adaptive relay selection method for asynchronous amplify and forward cooperative communications

23rd International Conference on Telecommunications (ICT) -- MAY 16-18, 2016 -- Thessaloniki, GREECEWOS: 000386851600031In this paper, we propose a new adaptive relay selection method named as Adaptive Best Relay Assessment (ABRA) for cooperative communication with amplify and forward (AF) relaying. ABRA is based on two relay selection criteria which are cascaded channel gain coefficient and cascaded time offset in source-relay-destination (S-R-D) channel. Our simulation results demonstrate that the channel gain coefficient is the best criteria at low signal-to-noise ratio (SNR) regimes and time offset at high SNR regimes. Therefore, we combine these two criteria to select best relay for all SNR values. Finally, ABRA achieves the best bit error rate (BER) performance in asynchronous AF cooperative communications for three different path gain ratios 30 dB, 0 dB, and -30 dB

İşbirlikli haberleşmede birleştirilmiş zaman kayması ve sönümlemeli kanal katsayısı kestirimi

2013 21st Signal Processing and Communications Applications Conference, SIU 2013 -- 24 April 2013 through 26 April 2013 -- Haspolat -- 98109In this paper, we investigate joint channel gain and time offset estimation for two different data aided methods in cooperative communication with amplify-And-forward (AF) relaying. First one is the Cascaded Estimation (CE) method which channel gain, and time offset consisting of both source-to-relay, and relay-to-destination links are estimated at the destination terminal, second one is Disintegrated Estimation (DE) method which channel gain, and time offset are estimated seperately at the relay for source-to-relay link, and at the destination for relayto- destination link. Both of the proposed joint estimators are based on Expectation-Maximization (EM) algorithm and, produce a low-complexity solution of itaretive maximum likelihood (ML) estimation. It was observed by the bit error rate (BER) curves, the proposed methods provide good performances with lowcomplexity. © 2013 IEEE

Adaptive Relay Selection Method for Asynchronous Amplify and Forward Cooperative Communications

In this paper, we propose a new adaptive relay selection method named as Adaptive Best Relay Assessment (ABRA) for cooperative communication with amplify and forward (AF) relaying. ABRA is based on two relay selection criteria which are cascaded channel gain coefficient and cascaded time offset in source-relay-destination (S-R-D) channel. Our simulation results demonstrate that the channel gain coefficient is the best criteria at low signal-to-noise ratio (SNR) regimes and time offset at high SNR regimes. Therefore, we combine these two criteria to select best relay for all SNR values. Finally, ABRA achieves the best bit error rate (BER) performance in asynchronous AF cooperative communications for three different path gain ratios 30 dB, 0 dB, and -30 dB

An Adaptive Modulation Scheme for Coded Free-Space Optical Systems

For very slowly-varying fading channels as in the case of atmospheric turbulence-induced fading, it is possible to reliably estimate the channel state information and send it back to the transmitter. The transmitter can use this information to vary the transmission parameters such as power, modulation size, code rate etc according to the channel conditions. This is known as link adaptation. In this paper, we consider a turbo-coded free-space optical (FSO) system with M-ary pulse position modulation over log-normal turbulence channels and propose an adaptive modulation scheme under peak power constraints. Our simulation results demonstrate significant performance improvements of the proposed adaptive scheme over non-adaptive counterparts

On the performance of SC-FDE schemes with decision feedback equalizer for visible light communications

ADVA;Ericsson;Silicon Labs17th International Conference on Transparent Optical Networks, ICTON 2015 -- 5 July 2015 through 9 July 2015 -- -- 113894In this paper, we investigate the two single carrier frequency domain equalization (SC-FDE) techniques, namely on-off keying single carrier frequency domain equalization (OOK-SC-FDE) and decomposed quadrature optical (DQO)-SC-FDE, under realistic channel conditions with a practical LED model for visible light communications (VLC). We first compare their performances under dynamic range constraints of the LEDs and observe lower peak-to-average power ratio (PAPR) for SC-FDE schemes as compared to orthogonal division multiplexing (OFDM) techniques. We further introduce decision feedback equalizer (DFE) for SC-FDE schemes and demonstrate performance improvement in multi-tap indoor VLC channels. © 2015 IEEE

On the Performance of SC-FDE Schemes with Decision Feedback Equalizer for Visible Light Communications

In this paper, we investigate the two single carrier frequency domain equalization (SC-FDE) techniques, namely on-off keying single carrier frequency domain equalization (OOK-SC-FDE) and decomposed quadrature optical (DQO)-SC-FDE, under realistic channel conditions with a practical LED model for visible light communications (VLC). We first compare their performances under dynamic range constraints of the LEDs and observe lower peak-to-average power ratio (PAPR) for SC-FDE schemes as compared to orthogonal division multiplexing (OFDM) techniques. We further introduce decision feedback equalizer (DFE) for SC-FDE schemes and demonstrate performance improvement in multi-tap indoor VLC channels