Recently, high frequency bands (above 6 GHz) have attracted more attention for the next generation communication systems due to the limited frequency resources below 6 GHz. To reveal the influence of frequency on propagation channels, channel characterization results at 14.6 and 3.6 GHz bands based on measurements in an indoor scenario and in a reverberation chamber are presented. The measureme...

Since global availability of vaccine and antiviral agents against influenza caused by novel human subtypes is insufficient, the World Health Organization (WHO) recommends non-pharmaceutical public health interventions to contain infection, delay spread, and reduce the impact of pandemic disease. Virus transmission characteristics will not be completely known in advance, but difficulties in infl...

Free Space Optical Communications through cloud-obscured channels suffer from severe degradations due to multiscattering, which induces delay spread in the received signal. The delay spread of FSO channel can vary considerably according to channel conditions, varying from nanoseconds to microseconds for clear and cloudy channel, respectively. In this paper, we present the use of return-to-zero ...

In orthogonal frequency division multiplexing (OFDM) systems with differential phase shift keying (DPSK), it is possible to apply differential modulation either in the time or frequency domain depending on the condition of fading channels, such as the Doppler frequency shift and the delay spread. This paper proposes a simple calculation method, that is, an approximate closed-form equation of th...

The results of statistical analysis of the 60GHz indoor radio propagation channel data collected in 13 different indoor environments are presented. Major outcomes of the analysis are as follows: i) The Root Mean Square (RMS) delay spread values observed range between 3 and 23ns and show a good normal fit. A clear dependence between the rms delay spread values and the transmitter–receiver separa...

It is well-known that mobile communication systems are usually limited in their performance and capacity by three major impairments, which are multi-path fading, delay spread and co-channel interference (CCI). OFDMA (OFDM-FDMA) system can cope with the multi-path fading and delay spread easily due to the beneficial properties of OFDM technology. Though OFDMA scheme avoids intra-cell interferenc...

Results from propagation measurements, conducted in an indoor office environment at 2.4, 4.75, and 11.5 GHz, are presented. The data were obtained in small clusters of six measurements, using a coherent wideband measurement system. The channel characteristics for the three frequencies are compared by evaluating path loss, rms delay spread, and coherence bandwidth. An analytical model for evalua...

In this paper, a novel maximum Doppler spread estimation algorithm is presented for OFDM systems with the comb-type pilot pattern in doubly selective fading channels. First, the least-squared estimated channel frequency responses on pilot tones are used to generate two auto-correlation matrices with different lags. Then, according to these two matrices, a Doppler dependent parameter is measured...

Heating, ventilation, and air conditioning (HVAC) ducts in buildings behave as multimode waveguides when excited at radio frequencies and thus, can be used to distribute radio signals. The channel properties of the ducts are different from the properties of a usual indoor propagation channel. In this paper, we describe physical mechanisms which affect the HVAC channel impulse response and analy...

In this work, the delay limited capacity (DLC) of orthogonal frequency division multiplexing (OFDM) systems is investigated. The analysis is organized into two parts. In the first part, the impact of system parameters on the OFDM DLC is analyzed in a general setting. The main results are that under weak assumptions the maximum achievable single user DLC is almost independent of the distribution...