Now showing items 1-4 of 4

  • Artificial neural network based sparse channel estimation for OFDM systems 

    Authors:Tahir, Abdur Rehman Bin
    Publisher and Date:(Kadir Has University, 2017)
    In order to increase the communication quality in frequency selective fading channel environment, orthogonal frequency division multiplexing (OFDM) systems are used to combat inter-symbol-interference (ISI). In this thesis, a channel estimation scheme for the OFDM system in the presence of sparse multipath channel is studied. The channel estimation is done by using the artificial neural networks (ANNs) with Resilient Backpropagation training algorithm. This technique uses the learning capability ...

  • Power and rate adaptation for MQAM/OFDM systems under fast fading channels 

    Authors:Dong, Zhicheng; Fan, Pingzhi; Zhou, Weixi; Panayirci, Erdal
    Publisher and Date:(IEEE, 2012)
    In this paper the effect of power and rate adaptation on the spectral efficiency of orthogonal frequency division multiplexing (OFDM) systems using M-ary quadrature amplitude modulation (MQAM) is investigated in the presence of the fast fading channels under power and instantaneous bit error rate (BER) constraints. A lower bound on the maximum spectral efficiency of adaptive OFDM/MQAM systems is obtained together with a closed-form expression for the average spectral efficiency of adaptive OFDM ...

  • Power and rate adaptation for MQAM/OFDM systems under fast fading channels 

    Authors:Dong, Zhicheng; Fan, Pingzhi; Zhou, Weixi; Panayirci, Erdal
    Publisher and Date:(IEEE, 2012)
    In this paper the effect of power and rate adaptation on the spectral efficiency of orthogonal frequency division multiplexing (OFDM) systems using M-ary quadrature amplitude modulation (MQAM) is investigated in the presence of the fast fading channels under power and instantaneous bit error rate (BER) constraints. A lower bound on the maximum spectral efficiency of adaptive OFDM/MQAM systems is obtained together with a closed-form expression for the average spectral efficiency of adaptive OFDM ...

  • SISO - MIMO applications and analysis of visible light communications systems 

    Authors:Yeşilkaya, Anıl
    Publisher and Date:(Kadir Has University, 2016)
    Rapid development in technology and increasing necessity to reach information instantaneously saturates RF bands rapidly. Because of that, it can be seen that we are gradually approaching upper limits of the band. It can said that, operating beyond that upper limit would be hard and unfeasible for 5th generation mobile systems (5G). At this point, it is needed to develop alternative telecommunication systems to RF technology. VLC could be the most appropriate and appealing solution for researchers ...