Focusing on transmit diversity orthogonal frequency-division multiplexing (OFDM) transmission through frequency-selective channels this paper pursues a channel estimation approach in time domain for both space-frequency OFDM (SF-OFDM) and space-time OFDM (ST-OFDM) systems based on AR channel modelling. The paper proposes a computationally efficient pilot-aided linear minimum mean-square-error (MMSE) time-domain channel estimation algorithm for OFDM systems with transmitter diversity in unknown ...

This paper presents an iterative scheme for joint timing acquisition multi-channel parameter estimation and multiuser soft-data decoding. As an example an asynchronous convolutionally coded direct-sequence code-division multiple-access system is considered. The proposed receiver is derived within the space-alternating generalized expectation-maximization framework implying that convergence in likelihood is guaranteed under appropriate conditions in contrast to many other iterative receiver ...

Amplitude and frequency modulations are still the most popular modulation techniques in data transmission at telecommunication systems such as radio and television broadcasting gsm etc. However the architectures of these individual systems are totally different. In this paper it is shown that a cellular neural network with an opposite-sign template can behave either as an amplitude or a frequency modulator. Firstly a brief information about these networks is given and then the amplitude and frequency ...

The challenging problem in the design of digital receivers of today's and future high-speed high data-rate wireless communication systems is to implement the optimal decoding and channel estimation processes jointly in a computationally feasible way. Without realising such a critical function perfectly at receiver the whole system will not work properly within the desired performance limits. Unfortunately direct implementation of such optimal algorithms is not possible mainly due to their ...

In every reflectance-based application like broadband matching circuit modeling etc. a nonlinear equation following from energy conservation the Feldtkeller equation must be solved in order to obtain real networks. In the literature however there is no analytic solution available but only numerical solutions. Consequently the resulting error depends on the accuracy of the numerical tools. In this paper an analytic solution is proposed which is based on the modified ABCD-parameters of a lossless ...

Due to the sparse structure of ultra-wideband (UWB) channels compressive sensing (CS) is suitable for UWB channel estimation. Among various implementations of CS the inclusion of Bayesian framework has shown potential to improve signal recovery as statistical information related to signal parameters is considered. In this paper we study the channel estimation performance of Bayesian CS (BCS) for various UWB channel models and noise conditions. Specifically we investigate the effects of (i) sparse ...

At the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) for example virtual photons produce many particles. At small impact parameters where the colliding nuclei make peripheral collisions photon fluxes are very large and these are responsible for the multiple photonuclear interactions. Free pair productions bound free pair productions and nuclear Coulomb excitations are important examples of such interactions and these processes play important roles in the beam luminosity ...

Decoupling and matching networks may be used to improve the performance of compact antenna arrays where mutual radiator coupling has caused a degradation of the diversity capabilities. A popular network consists of a 180 degrees rat-race directional coupler which decouples the antenna ports followed by impedance matching networks at each port. Researchers however usually neglect the presence of losses both within the antenna array and the decoupling and matching network. For this reason we have ...

In this paper an alternative approach is presented to design equalizers (or matching networks) with commensurate (or equal length) transmission lines. The new method automatically yields the matching network topology with characteristic impedances of the commensurate lines. In the implementation process of the new technique first the driving point impedance data of the matching network is generated by tracing a pre-selected transducer power gain shape without optimization. Then it is modelled its ...

In this paper a practical method is presented to design broadband matching networks via reflection coefficient modeling. In the proposed algorithm reflection function values (rho(2)) at sample frequencies are optimized to get the desired gain level. At the same time the corresponding reflection coefficient values (S-2) are calculated and modeled. Then matching network topology and element values are obtained via the formed reflection coefficient expression. An example is presented to explain the ...