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— In this letter, we propose two simple OFDM mean delay estimation schemes, channel impulse response (CIR)-based and differential schemes, which are applicable for adaptive algorithms including improved channel estimation and fast handover. Instead of time-domain processing requiring additional inverse fast Fourier transform (IFFT), the mean delay can be(More)
— This paper presents an exact analysis of the effect of the carrier frequency offset on orthogonal frequency division multiplexing (OFDM) systems for a general multipath fading channel. As is well known, the carrier frequency offset attenuates the desired signal and causes inter-carrier interference, thus reducing the signal-to-noise ratio (SNR). The SNR(More)
— This letter analyzes the effect of the carrier frequency offset on orthogonal frequency division multiplexing (OFDM) systems for multipath fading channels. A simple approximate expression for the average signal-to-noise ratio (SNR) is derived. This approximate expression is shown to be an upper bound of the average SNR for flat fading channels and an(More)
— This paper analyzes the effect of phase noise on orthogonal frequency division multiplexing (OFDM) systems with a focus on time-direction (TD) differential receivers. Both Wiener phase noise and wide-sense stationary (WSS) phase noise are considered. A signal-to-noise ratio (SNR) expression for TD differential receivers is derived in the presence of phase(More)
—Hybrid Automatic Repeat reQuest (HARQ) schemes are becoming common in wireless systems. In addition to the channel characteristics, several system design considerations need to be taken into account when choosing the particular HARQ scheme to be used. For SISO systems, it has been shown that the coding gain of Incremental Redundancy (IR-) HARQ over Chase(More)
—This paper examines the detection problem of the preamble sequence index in the WiMAX system. The mobile station receiver knows all the possible preamble sequences and should estimate which preamble sequence has been transmitted from the base station. Since the preamble in the orthogonal frequency division multiplexing (OFDM) transmission is usually the(More)
—When a preamble signal is repeated multiple times in OFDM systems, we derive joint maximum likelihood (ML) estimation of the frame timing (FT) and carrier frequency offset (CFO). Unlike conventional estimators which use correlation of adjacent repetition patterns only or some specific sets of patterns, the joint ML estimation exploits correlation of any(More)