OFDM is a multicarrier modulation technique in which a high rate bitstream is split into N parallel bitstreams of lower rate and each of these are modulated using one of N orthogonal sub-carriers. In a basic communication system, the date is modulated onto a single carrier frequency. The available bandwidth is then totally occupied by each symbol. This kind of system can lead to intersymbol-int...

Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motiv...

Let the orthogonal polynomials Pn(x) be defined by Pn(x) = (x− cn)Pn−1(x)− λnPn−2(x), P−1(x) = 0, P0(x) = 1, where λn+1 > 0, cn real, limn→∞ cn = c and limn→∞ λn = λ, (n ≥ 1). Blumenthal has proved that the true interval of orthogonality [σ, τ ] of the above polynomials is given by σ = c − 2 √ λ, τ = c + 2 √ λ and the zeros of Pn(x) are dense in [σ, τ ]. Blumenthal also asserted that the spectr...

A possible method to investigate non-Hermitian Hamiltonians is suggested through finding a Hermitian operator η+ and defining the annihilation and creation operators to be η+ -pseudo-Hermitian adjoint to each other. The operator η+ represents the η+ -pseudo-Hermiticity of Hamiltonians. As an example, a non-Hermitian and non-PT-symmetric Hamiltonian with imaginary linear coordinate and linear mo...

An orthogonality space is a set equipped with symmetric, irreflexive relation called orthogonality. Every has an associated complete ortholattice, the logic of space. To every poset, we associate consisting proper quotients (that means, nonsingleton closed intervals), certain relation. We prove that finite bounded poset lattice if and only its orthomodular lattice. chain Boolean algebra.