1,720,970 research outputs found
Noncoherent detector for interleaved trellis-coded CPFSK signals transmitted over frequency-flat fading channels
No full textWe propose a novel two-stage noncoherent receiver for interleaved trellis-coded CPFSK signals transmitted over time-selective channels. The first stage of the receiver computes reliability information about the transmitted symbols and delivers it to the second stage which operates as a trellis decoder. Simulation results show that the proposed detection strategy outperforms previous noncoherent receivers with a moderate increase in complexity
Differential detection algorithms for MSK signals over AWGN and frequency-flat rayleigh fading channels
No full textNovel symbol-by-symbol differential detection algorithms are proposed for MSK signals transmitted over additive white Gaussian noise and frequency-flat Rayleigh fading channels. They are derived as approximations to the maximum-likelihood noncoherent detection strategy. Their error performance is assessed by computer simulation and is compared with that of other noncoherent detectors. It is shown that, with fading channels, the new algorithms outperform the traditional methods. © 1999 IEEE
Joint DOA and Channel Parameter Estimation for Code-Division Multiple-Access Systems
No full textWe consider the uplink of a DS-CDMA system and we assume that the base station is endowed with a linear antenna array. Transmission takes place over a multipath channel and the goal is to estimate the channel parameters and the directions of arrival of the signals from a user entering the network. Maximum likelihood estimation of all these parameters is not feasible as it involves a search over a multidimensional domain. Through suitable approximations we replace the above search by a sequence of mono-dimensional searches. This results in an estimation algorithm of reasonable complexity for third-generation cellular applications. The performance of the algorithm is assessed by simulation in a scenario inspired by the specifications of the FDD component of the UMTS standard. It is found that the channel parameters and the directions of arrival can be estimated with accuracy close to the Cramer-Rao bound
A Low Complexity Receiver with Interference Cancellation for Power-Controlled MC-CDMA Downlink Transmissions
No full textWe consider the downlink of a power-controlled MC-CDMA system in which the near-far effect limits
the performance of single-user receivers and calls for interference cancellation (IC)-based schemes. The
latter provide enhanced error rate performance but are not suited for downlink applications due to
their relatively large complexity. To overcome this problem, we present a novel reduced-complexity IC-
based detector in which interfering signals are canceled provided that their estimated power exceeds a
given threshold. In addition to the channel response, the proposed scheme requires knowledge of the
amplitudes of the users’ signals. The latter are estimated using two different methods that exploit some
pilot blocks placed at the beginning of the downlink frame. Numerical results are given to highlight the
effectiveness of the proposed scheme and to make comparisons with other existing IC-based solutions
Multipath channel estimation for the uplink of a DS-CDMA system
No full textThis paper investigates channel estimation in the uplink of a DS-CDMA system. The transmission medium is characterized by the presence of multipath components and the parameters of interest are the delays and complex gains of the propagation paths. We propose a new method for estimating the channel parameters of a user entering the system. The method is based on the maximum likelihood criterion and exploits a training sequence. In comparison with other estimation algorithms it has two advantages. First, it reduces a complicated multidimensional optimization problem to a sequence of one-dimensional problems. Secondly, it has better capability to resolve closely-spaced multipath components. Computer simulations are used to assess its performance. It is found that it is resistant to multiuser interference and can be effectively used in third generation mobile cellular networks
A blind detection technique for CPM signals transmitted over frequency-flat fading channels
No full textWe propose a novel detection technique for CPM signals transmitted over frequency-flat fading channels. Its most significant feature is that it operates without statistical information on the fading channel and, for this reason, it is nicknamed “blind detector”. Its error rate performance is assessed with CPFSK schemes and is compared with the performance of other decoder
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