In this paper, the performance of frequency-hopping spread-spectrum wireless sensor network systems based on the generalized approach to signal processing in the presence of noise [1–5], which employ noncoherent reception and transmission diversity, is analyzed for frequency-selective Rayleigh fading channels. Two different types of transmission diversity systems, a fast frequency-hopping (FFH)...

Frequency-domain equalization (FDE) can take advantage of the frequency-selectivity of the channel to improve the transmission performance in a frequency selective fading channel. To further improve the transmission performance, the transmit diversity technique can be used. Cyclic delay transmit diversity (CDTD) can strengthen the frequencyselectivity while space-time transmit diversity (STTD) ...

Moreover, the two-dimensional (2-D) spreading codes, spreading on both time and frequency domain, has been applied to OFDM system [5-6]. Using the orthogonality property between the 2-D codes, the orthogonal frequency coded division multiplexing (OFCDM) is performed in the downlink for mobile communication systems [7-8]. The diversity gain can be obtained from frequency domain or time domain, r...

according to high costs of phase shifters in antenna arrays, new methods for beam steering without phase shifter were introduced. frequency diverse array (fda) concept is another approach to beam steering problem. in this structure, the subsequent antenna elements are fed with stepped discrete frequencies causing continuous scanning of space in time. so a range-angle dependent scanning is made ...

In this paper we derive the optimal diversity versus multiplexing tradeoff for a frequency selective i.i.d. Rayleigh MIMO channel. This tradeoff is shown to be better than the one of the frequency flat MIMO channel. Traditional approaches for frequency selective channels use OFDM techniques in order to exploit the diversity gain due to frequency selectivity. We show that although coding in OFDM...

Space-frequency coded Orthogonal Frequency Division Multiplexing (OFDM) is capable of realizing both spatial and frequency-diversity gains in multipath multiple-input multipleoutput (MIMO) fading channels. This naturally leads to the question of variable allocation of the channel’s degrees of freedom to multiplexing and diversity transmission modes. In this paper, we provide a systematic method...

Frequency-domain equalization used in MC-CDMA can be applied to the reception of DS-CDMA signals. Further performance improvement can be attained by the additional use of multiple transmit/receive antenna diversity. The BER performance improvement attainable by the joint use of frequency-domain equalization and multiple transmit/receive antenna diversity in a frequency-selective fading channel ...

Plant Diversity conservation is a main objective in rangelandmanagement. Plant diversity is a suitable index for showing the changes ofvegetation in rangelands and has a high correlation with ecosystem parameters.Therefore, using this index it is possible to find the changes and manage theecosystem correctly. The current research was performed to determine the speciesdiversity in Fashandak rang...