Angle and delay estimation of space-time channels for TD-CDMA systems

BER Performance Improvement with Joint Angle-Delay-Polarization Estimation of Multipath Channel Parameters

“…The base-band signals received by the array of 2M antennas are low-pass filtered and oversampled by P with respect to the chip rate 1/T . Assuming that a training sequence is transmitted within each burst, similarly to the signal model in [5], the block of 2M received signals (one for each sensor) within the ℓ-th time-slot can be compactly written as:…”

“…The single-user model (1) can easily be extended to the multi-user case since the received signal at the base station is the sum of the contribution of each user. In the following, for sake of simplicity, only the single-user case will be considered since it has been shown (see [5] and references therein) that the orthogonality of the training sequences allows to reduce the multi-user channel estimation problem to several single-user problems.…”

“…The effects of the mobility of the user and the obstacles in the proximity of the user are that the channel is time-varying. If the user's velocity is not too great, anglesdelays-polarizations are invariant for L time-slots (see [5] [11] and references therein). The amplitudes are assumed constant within the training period (or within the burst) but vary from slot to slot.…”

“…However, angles of arrival, delays and polarization are not changing significantly between two slots (see [1], [2], [5] [11] and references therein). In the following, we will assume that these parameters remain constant over L time-slots (where L < 20 is reasonable for UTRA-TDD standard [5]). Consequently, several observations of the channel can be obtained by considering the bursts transmitted on L time-slots.…”

“…Different approaches to solve the Joint Angle and Delay Estimation (JADE) problem have been proposed in the literature (see e.g., [4], [5] and references therein) and it is shown that subspace based methods like ESPRIT (Estimation of Sinusoidal Parameters by Rotational Invariance Technique) approach provide good performance in a TD-CDMA system for a realistic channel estimation. On the other hand, preliminary experimental investigations in microcell environments [6] have empirically illustrated that polarization diversity is an attractive solution to achieve decorrelated antenna elements and an extensive model for vector-sensor array processing has been proposed by Nehorai in [7].…”