for an indoor non-directed line of sight optical wireless communication (nlos-owc) system we investigate the optimized lambertian order (olo) of light-emitting diodes (leds). we firstly derive an expression for the olo from a conventional lambertian led model. then, we analyze the indoor multi-cell nlos-owc channel characteristics including the optical power distribution and the multipath time ...

Previous models of disease spread involving delay have used basic SIR (susceptible--infectious--recovery) formulae and approaches. This paper demonstrates how time-varying SEIRS (S--exposed--I - R - S) models can be extended with delay to produce wave propagations that simulate periodic wave fronts of disease spread in the context of population movements. The model also takes into account the n...

This paper presents spatio-temporal measurements for the peer-to-peer radio channel at a center frequency of 1920 MHz with 140 MHz of radio-frequency bandwidth. The measurements were taken using a spread-spectrum channel sounder and an automated spatial probing system that uses precise computer-controlled positioning and orientation of omnidirectional and directional (30 beamwidth) antennas to ...

In the mobile radio environment, signals are usually impaired by fading and multipath delay phenomenon. In such channels, severe fading of the signal amplitude and inter-symbol-interference (ISI) due to the frequency selectivity of the channel cause an unacceptable degradation of error performance. Orthogonal frequency division multiplexing (OFDM) is an efficient scheme to mitigate the effect o...

In this paper, average frequency correlation and rootmean-squared (rms) delay spread estimation for wireless communication systems are described. A practical algorithm for averaged channel frequency correlation estimation, which can be used for measuring frequency selectivity, is given. Average rms delay spread of the channel is obtained directly from the channel frequency correlation estimate ...

This work analyzes the impact of delay spread on IEEE 802.15.4a networks using energy detection (ED) receivers. Specifically, we review the typical values for delay spread in Ultra Wide Band (UWB) systems reported to date for indoor, outdoor and industrial environments, and study how the delay spread impacts the bit-error rate with and without Multiuser Interference (MUI).

A novel cyclic-prefix based delay-spread estimation technique for wireless OFDM systems is proposed. In particular, the authors propose a technique for estimating the delays and powers of multipath components when the channel is sparse, i.e. a few strong multipaths distantly spaced in time, and a technique for estimating the RMS delay-spread when the channel has a large number of sample-spaced ...