In this letter we propose a realistic channel model for visible light communication (VLC) assuming a mobile user. Based on non-sequential ray tracing we first obtain channel impulse responses for each point over the user movement trajectories and then express path loss and delay spread as a function of distance through curve fitting. Our results demonstrate large variations in received power. In system design this necessitates the use of adaptive schemes where transmission parameters can be selected ...

A subspace tracking technique has drawn a lot of attentions due to its wide applications. The main objective of this approach is to estimate signal or noise subspace basis for the sample covariance matrix. In this paper we focus on providing a fast stable and adaptive subspace tracking algorithm that is implemented with low computational complexity. An alternative realization of the fast approximate power iteration (FAPI) method termed modified FAPI (MFAPI) is also presented. Rather than solving ...

In this paper the system performance of M-ary code shift keying (MCSK) impulse modulation is studied in detail and compared to M-ary pulse position modulation (MPPM) under single- and multi-user scenarios. For that bounds on the semi-analytic symbol-error rate (SER) expressions are derived and simulation studies are conducted. When practical implementations of MCSK and MPPM are considered it is shown that MCSK can provide about 2 dB performance gain over MPPM as it reduces the effects of multipath ...

In this work an algorithm to design lossless ladder networks with simple lumped elements connected via commensurate transmission lines is proposed. After giving the algorithm a lumped-element low-pass Chebyshev filter was transformed to its mixed-element counterpart to illustrate the utilization of the algorithm. The filter designed for a frequency band around 1 GHz was fabricated and experimentally characterized. We find very good agreement between measured and simulated transducer power gain ...

Analog techniques are desirable for hardware implementation of neural networks due to their numerous advantages such as small size low power and high speed. However these advantages are often offset by the difficulty in the training of analog neural network circuitry. In particular training of the circuitry by software based on hardware models is impaired by statistical variations in the integrated circuit production process resulting in performance degradation. In this paper a new paradigm of ...

Regulation in Europe and Japan requires the implementation of detect-and-avoid (DAA) techniques in some bands for the coexistence of licensed primary systems and secondary ultra wideband (UWB) systems. In a typical coexistence scenario a primary system may have potentially interdependent uplink-downlink communication channels (e. g. simultaneous uplink-downlink communications in a frequency division duplex system) overlapping with the frequency band of a UWB system. If such interdependencies of ...

This paper is concerned with the challenging and timely problem of data detection for coded orthogonal frequency-division multiplexing (OFDM) systems in the presence of frequency-selective and very rapidly time varying channels. New low-complexity maximum a posteriori probability (MAP) data detection algorithms are proposed based on sequential detection with optimal ordering (SDOO) and sequential detection with successive cancellation (SDSC). The received signal vector is optimally decomposed into ...

This paper is concerned with the challenging and timely problem of joint channel estimation and equalization for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and very rapidly time varying channels. The resulting algorithm is based on the space alternating generalized expectation maximization-maximum a posteriori probability (SAGE-MAP) technique which is particularly well suited to multicarrier signal formats. The algorithm is implemented in the ...

The paper considers two different antenna selection schemes for space-time coded systems over flat fading channels. First we explore antenna selection at the transmitter side based on the received signal to noise ratios. We then study the joint selection of receive and transmit antennas. Both schemes assume a slowly fading channel (i.e. quasi-static fading) and require some limited feedback from the receiver to the transmitter. By computing upper bounds on the pairwise error probabilities and ...

This letter considers the effect of channel estimation errors on the performance of space-time coded (STC) systems with transmit and receive antenna selection over quasi-static flat fading channels. By performing pairwise error probability analysis and presenting numerical examples we show that the diversity order achieved with perfect channel state information (CSI) is still achievable with imperfect CSI used both at the antenna selection and the space-time decoding processes. We note that our ...