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This paper describes a channel estimation and tracking scheme for OFDM MIMO systems based on pilot tones. The mean square error of the proposed scheme is derived, and through this we derive optimal training sequences and placement of the pilot tones. It is shown in this paper that minimum mean square (MMSE) channel estimation is obtained with equipowered,(More)
Orthogonal frequency-division multiplexing (OFDM) modulation is a promising technique for achieving the high bit rates required for a wireless multimedia service. Without channel estimation and tracking, OFDM systems have to use differential phase-shift keying (DPSK), which has a 3-dB signalto-noise ratio (SNR) loss compared with coherent phase-shift keying(More)
  • Ye Li
  • IEEE Trans. Vehicular Technology
  • 2000
In this paper, we investigate pilot-symbol-aided parameter estimation for orthogonal frequency division multiplexing (OFDM) systems. We first derive a minimum mean-square error (MMSE) pilot-symbol-aided parameter estimator. Then, we discuss a robust implementation of the pilot-symbol-aided estimator that is insensitive to channel statistics. From the(More)
We consider the design of iterative receivers for space-time block coded orthogonal frequency-division multiplexing (STBC-OFDM) systems in unknown wireless dispersive fading channels, with or without outer channel coding. First, we propose a maximum-likelihood (ML) receiver for STBC-OFDM systems based on the expectation-maximization (EM) algorithm. By(More)
OBJECTIVE To assess the degree to which the Chinese people are protected from catastrophic household expenditure and impoverishment from medical expenses and to explore the health system and structural factors influencing the first of these outcomes. METHODS Data were derived from the Fourth National Health Service Survey. An analysis of catastrophic(More)
Orthogonal frequency-division multiplexing (OFDM) is one of the promising techniques for future mobile wireless data systems. For OFDM systems with cochannel interference, adaptive antenna arrays can be used for interference suppression. This paper focuses on a key issue for adaptive antenna arrays, that is, parameter estimation for the minimum mean square(More)
This paper investigates multiuser downlink data scheduling with quality-of-service (QoS) provisioning over multiple shared fading channels, which, for a network point of view, provides line flexibility and granularity for resource allocation. A user-centric metric-a utility function with respect to mean waiting time-which is able to maintain fairness among(More)
Transmitter diversity and down-link beamforming can be used in high-rate data wireless networks with orthogonal frequency division multiplexing (OFDM) for capacity improvement. In this paper, we compare the performance of delay, permutation and space–time coding transmitter diversity for high-rate packet data wireless networks using OFDM modulation. For(More)