Maximum Likelihood (ML) algorithms, for the joint estimation of synchronization impairments and channel in Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system, are investigated in this work. A system model that takes into account the effects of carrier frequency offset, sampling frequency offset, symbol timing error, and channel impulse response is formu...

Sensitivity to carrier frequency offset (CFO) is one of the biggest drawbacks of orthogonal frequency division multiplexing (OFDM) system. A lot of CFO estimation algorithms had been studied for compensation of CFO in OFDM system. However, with the adoption of direct-conversion architecture (DCA), which introduces additional impairments such as dc offset (DCO) and in-phase/quadrature (I/Q) imba...

We present a novel algorithm for estimating the Carrier Frequency Offset (CFO) in an OFDM receiver. The algorithm is based on locating the spectral minimas within null subcarriers embedded in the spectrum. This is done by using a scaled DFT algorithm to calculate the spectrum of the OFDM symbol around the null subcarrier, followed by averaging the absolute square of the amplitude. The method is...

In this paper, we address the problem of carrier frequency offset (CFO) estimation for Orthogonal Frequency Division Multiplexing (OFDM) communications systems with multiple antennas. We reconstruct the received signal to form data model with multiinvariance property, and subsequently derive a multiple-invariance ESPRIT algorithm for CFO estimation. This algorithm has improved CFO estimation co...

A carrier separated OFDM system is proposed to support high data rates in mobile multiple access environments. OFDM is considered to support high data rates and carrier separation is introduced to combat multipath fading. The performance is comparable to that of a frequency hopped OFDM system. While promising robustness against multipath fading, the computational complexity of a carrier separat...

RF-ID systems are susceptible to frequency interference from other communciation systems particularly when the RF-ID tags transmit on a fixed carrier frequency. The RF-ID systems are less vunerable to frequency interference when frequency diversity is used by the RF-ID system. This paper proposes an architecture for an RF-ID receiver which allows a number of active RF-ID tags with oscillators o...

Cyclic delay diversity (CDD) is a simple technique to intentionally increase frequency selectivity of channels for orthogonal frequency division multiplexing (OFDM).This paper proposes a residual carrier frequency offset (RFO) estimation scheme for OFDMbased broadcasting system using CDD. In order to improve the RFO estimation, this paper addresses a decision scheme of the amount of cyclic dela...

We bound the number of electromagnetic signals which may be observed over a frequency range 2W for a time T within a region of space enclosed by a radius R. Our result implies that broadband fields in space cannot be arbitrarily complex: there is a finite amount of information which may be extracted from a region of space via electromagnetic radiation. Three-dimensional space allows a trade-off...