Abstract
Orthogonal Frequency Division Multiplexing (OFDM) is a promising research area in Wireless Communication for high data rates. The Multiple Inp ut-Multiple Output (MIMO) technology when incorporated with the OFDM system promise a significant boost in the performance. But, the MIMOOFDM systems are very sensitive to Carrier Frequency Offset (CFO) as it deteriorates the system performance with the rise of Inter-Carrier-Interfer ence (ICI). A theoretical analysis to evaluate the performance of Orthogonal Frequency Division Multiplexing (OFDM) systems is done here, under the combined influence of phase offset and frequency of fset over rayleigh, Weibull and Nakagami fading channels using Binary Phase Shift Keying (BPSK) Modulation. The analysis of increase in Bit Error Rate (BER) caused by the presence of phase offset and fr equency offset is evaluated assuming Gaussian probability density function. Hence the estimation and correction of CFO plays a vital role in MIMOOFDM systems. A method for CFO estimation and correction is analyzed in the MIMO-OFDM system with 16-QAM modulation. In non-pilot-aided systems the CFO acquisition is done using Maximum Likelihood Estimation (MLE) algorithm. The proposed scheme uses the same block for CFO correction of MIMOOFDM symbols. Since the same phase calculation block is used for the ML estimation along with the acquisition, the computational cost and the comple xity of implementation is reduced.
Highlights
Orthogonal Frequency Division Multiplexing at the transmitter and receiver in rich scattering environments and at sufficiently high Signal to Noise Ratios (SNR)
A theoretical analysis to evaluate the performance of Orthogonal Frequency Division Multiplexing (OFDM) systems is done here, under the combined influence of phase offset and frequency offset over rayleigh, Weibull and Nakagami fading channels using Binary Phase Shift Keying (BPSK) Modulation
The received signal Equation (14), along with its frequency offset is expressed in the presence of Additive White Gaussian Noise (AWGN) as: r where, wl(k) is the Additive White Gaussian Noise (AWGN) on the lth receive antenna with zero mean and variance σl2, hi,l is the channel gain between the ith transmit antenna and the lth receive antenna and ε denotes the Carrier Frequency Offset (CFO) normalized to the inter-carrier spacing
Summary
Orthogonal Frequency Division Multiplexing at the transmitter and receiver in rich scattering environments and at sufficiently high Signal to Noise Ratios (SNR) MLE algorithm is considered for the frequency correction scheme in the study as it is a highly efficient non-data-aided synchronization method. It shares a common block with the frequency tracking algorithm. The computational cost and implementation complexity is reduced to a great extent, by sharing the same phase calculation block with the acquisition step This scheme does not require any pilot symbol as it uses the information brought by OFDM symbols; high bandwidth efficiency can be achieved. Suresh et al (2012) proposed a novel method to estimate fine symbol timing error for MB-OFDM based UWB system which will be suitable for MB-OFDM receivers for UWB positioning and UWB communication
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