PERFORMANCE OF DIGITAL DECT RADIO LINKS BASED ON SEMIANALYTICAL METHODS

In this paper, we report a very efficient semiana- lytical approach fo r the performance evaluation of differential detection schemes for GMS K signals of the DECT standard. Precisely, for a given channel, perfor mance is determined by means of an analytical procedure which includes the saddlepoint approximation. We consider both static channels (with impulse response generated by the simulation program SIRCIM) and two- ray Rayleigh and log-normal fading channels. As a departure from previ ous works, our receiver includes an all-digital part after the analog differential detection scheme. The digital part includes: 1) a block f or the estimation of both the optimum sampling phase and the nonlinear channel coefficients (by making use of the DECT training sequence), 2 ) a one-tap decision feedback (DF) equalizer, and 3) a block for the e valuation of the approximate optimum bias level (gamma(e)) in the thre shold detector. Both the DF equalizer coefficient and gamma(e) are bas ed on the nonlinear channel coefficients estimate. For channels with a normalized delay spread up to 0.2, the use of the optimum threshold t ogether with the DF equalizer permits a gain of about 2 dB at BER = 10 (-6) with respect to a receiver without equalization and a zero-level decision threshold. In addition, we discover that, in indoor environme nts, the 2-bit GMSK detector performs roughly the same as the 1-bit de tector. The threshold optimization is also effective in the presence o f channels affected by fading. To support this statement, we report th e performance of the 1-bit differential detection scheme combined with antenna selection diversity in the presence of a two-ray log-normal a nd Rayleigh fading channel.