In orthogonal frequency-division multiplexing (OFDM) communications, carrier frequency offset must be estimated and compensated at the receiver to maintain orthogonality. In this paper, we examine the performance of a blind carrier frequency offset estimation algorithm for OFDM communications. Experiments were conducted on a system operating at close to 2 MBits/s. Insights obtained from these e...

This paper discusses the effects of frequency offset on the performance of orthogonal frequency division multiplexing (OFDM) digital communications. The main problem with frequency offset is that it introduces interference among the multiplicity of carriers in the OFDM signal. The aim of this survey is to investigate Carrier frequency offset estimation method in based OFDM systems. According to...

We develop and analyze timing and carrier frequency offset synchronization algorithms for generalized asynchronous and quasisynchronous orthogonal frequency division multiple access systems using null subcarriers and subcarrier hopping. We derive an approximate analytic expression for the variance of the frequency offset estimators as a function of the number of active users and the SNR and sho...

Single carrier frequency division multiple access (SCFDMA) is one well-known scheme, which has recently become a preferred choice for uplink channels. Due to the usage of single carrier, the performance of SC-FDMA systems degrades in deep frequency selective fading channels. In this paper, we propose a structure of equalizer based on frequency domain decision feedback which could be used for mu...

High Order Quadrature Amplitude Modulation (QAM) is a high-bandwidth-efficient modulation scheme employed in the wireless communications. For this type of modulation, one of the most important problems is carrier recovery to allow a coherent demodulation. To extract correctly the transmitted symbols as the carrier frequency offset between the transmitter and receiver is inevitable, the receiver...

In this paper, we propose to increase residual carrier frequency offset tolerance based on short perfect reconstruction pulse shaping for coherent optical-orthogonal frequency division multiplexing. The proposed method suppresses the residual carrier frequency offset induced penalty at the receiver, without requiring any additional overhead and exhaustive signal processing. The Q-factor improve...

In this paper, a new strategy of switchable CMOS phase-locked loop frequency synthesizer is proposed to increase its tuning range. The switchable PLL which integrates two phase-locked loops with different tuning frequencies are designed and fabricated in 0.5 μm n-well CMOS process. Cadence/Spectre simulations show that the frequency range of the switchable phased-locked loop is between 320 MHz ...

This paper discusses on the UWB carrier frequency generator that is capable of fast switching between different center frequencies. By using a switching network, the different frequencies from different local oscillators are switched within 4ns. A new topology of NMOS switch based on series-shunt configuration is proposed so that it is able to pass the signal from oscillators to output without ...