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Quasicoherent Signal Reception with Interrupted Pilot Signal
in Fast Fading Channel for Mobile Communication Systems


One of the requirements imposed on mobile communication systems of the present and future generations is to support the communication with users moving at a high rate. Consequently, a mobile communication system must effectively operate under fast (high frequency) fading conditions. Here while using an interrupted pilot signal many known carrier recovery methods become non-operable or non-efficient. There have been developed different algorithms with an interrupted pilot signal under fast fad-ing conditions that differ by an application complexity.

Some algorithms do not require the knowledge of the channel autocorrelation function. They are based on the parameterization of a complex signal enve-lope changing in time by decomposing it in a sequence by some function system and estimating these parameters. There have been also developed a quasicoherent reception algorithm adaptive to the fading frequency that is based on the filtration of pilot symbols, adaptive interpolating complex envelope of path signals, and iterative procedure using information symbols. The proposed algorithms are analyzed by a computer simulation method, their parameters are optimized, and the accuracy characteristics of the al-gorithms are compared. The high efficiency of the algorithm as compared with alternative algorithms is demonstrated.

The utilization of information symbols in order to estimate the complex envelope allows substantially increasing the accuracy of its estimation under fast fading conditions, and consequently, notably reducing the error probability of information parameter estimation. Fig. 1 demonstrates, as an example, curves of a dependence of probability of erroneous binary symbols reception of the developed algorithms versus a signal-noise ratio, obtained while multiplying F fading frequency by t, F t =0.055 symbol duration. Curves, shown in Fig. 2, are obtained for the adaptive algorithm at different F t product values. It is evident that the adaptive algorithm characteristics are close to the coherent reception char-acteristics at 1.8 GHz carrier frequency and at user movement speed less than 300 km/h.

The obtained results enable us to select the quasicoherent signal reception algorithm under fast fading conditions depending on the requirements imposed on the algorithm’s accuracy and implementa-tion simplicity.





 

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| Multipath Reception | Smart Antenna Forward Link |
| Smart Antenna Reverse Link | Multi Antenna Reception and Transmission |
| Optimal balance of info & pilot signal components |
| Power and Data Rate Transmission Control | Multi-User Detection | Contact |