We analyze the error floor of unequalized personal communications systems using minimum-shift keying (MSK) with training-sequence-based adaptive sampling in a two-delay fading channel. We include Gaussian filtering of the input, finite accuracy in determining the optimum sampling time, and filtering at the receiver. We prove that for pure MSK and low time dispersion, training-sequence-based adaptive sampling can completely avoid errors caused by intersymbol interference. The actual errors are caused by "secondary" effects (filtering and finite-resolution sampling) in conjunction with the channel time dispersion. Errors occur if the normalized phasor of the channel impulse response falls into certain error regions; the computation of these regions gives physical insights into the error mechanism and allows a highly efficient computation of the average bit-error rate (BER). The average BER varies as K/spl middot/(S/T)/sup 2/, where S is the RMS delay spread and T is the bit length. The proportionality constant K depends on the Gaussian filtering in the transmitter, the receiver filtering, and the amount of oversampling. The BER can be orders of magnitude lower than for the (quasi-) fixed sampling case, in which timing is derived solely based on the channel delay power profile. For two-branch diversity reception, we show that the BER is proportional to (S/T)/sup 4/.

This paper presents a new concept for direction of arrival (DOA) estimation and signal reconstruction from the output signals of an equispaced array. The proposed single snapshot algorithm, which is based on a direct data matrix only, utilizes the concept of virtual imaged arrays to reach the theoretical limit of antenna elements for resolution of a given number of coherent paths. Extensive simulations of our new and some well known algorithms show equal performance of these types whereas our new algorithm excels by reducing computational and hardware complexity.

DECT (Digital European Cordless Telecommunication) is the current standard for digital cordless indoor communication in Europe. We investigate the use of channel equalization to increase the coverage area of DECT in large delays spread environments. We show that it is possible to use all equalizer and still stay within the DECT-common air interface. The equalizer structure is a decision feedback equalizer (DFE). The packet synchronizing word, which is used for slot synchronization, is used as trailing sequence for tap gain adjustment. For adaptation a recursive least squares (RLS) algorithm is used. The results show that the tolerable delay spread for receivers with an adaptive equalizer can be significantly increased depending on the length of the equalizer.>