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This paper presents a first order Takagi-Sugeno-Kang (TSK) type fuzzy equalizer to mitigate nonlinear power amplifier distortion effects from the received signal in orthogonal frequency division multiplexing (OFDM) systems. Here we propose a Comprehensive Learning Particle Swarm Optimizer (CLPSO) based structure identification of the TSK equalizer. CLPSO uses a new learning strategy that achieves...
Traditional OFDM based transmission system uses Cyclic Prefix (CP) in an OFDM symbol in order to maintain orthogonality of transmission. Present days' Ultra-Wideband (UWB) systems use Multi-Band OFDM (MB-OFDM) techniques for transmission in application like Wireless Personal Area Network (WPAN). UWB based systems are power limited by the regulation of FCC. CP introduces correlation in the transmitted...
Easy channel equalization for OFDM based UWB communications is considered to be one of its major advantages. Due to the format of transmission, the channel affects the signal only at discrete frequencies, and hence single-tap equalization is usually deemed sufficient. In this paper the selection of an efficient algorithm for equalization and its implementation is reported for indoor WPAN applications...
We present a fast converging scheme for estimating the coarse frequency offset in multi-band orthogonal frequency division multiplexing (MB-OFDM) based ultra-wideband (UWB) systems. Our estimator performs an averaging of initial estimate over multiple bands and shows an improved estimation of =3 times for band group 1 compared to our earlier proposed scheme. Cramer Rao lower bound (CRLB) on the estimation...
We present a fast converging scheme for estimating coarse frequency offset (FO) in multi-band orthogonal frequency division multiplexing (MB-OFDM) based ultra-wideband (UWB) systems for wireless personal area network (WPAN). Our estimator performs an averaging of initial estimate over multiple bands and shows an improved estimation of cong3 times in terms of estimation error variance for band group...
Selected Mapping (SLM) is a well known distortionless phase control Peak-to-Average-Power-Ratio (PAPR) reduction technique for Orthogonal Frequency Division Multiplexing (OFDM) systems. A major limitation of SLM-OFDM systems is that the receiver requires exact information of the phase set used at the transmitter. Usually side information (SI) is either transmitted explicitly at the loss of data rate...
In this paper we present a novel technique to reduce silicon area of 128 point, 1 GSPS FFT architecture called as Mixed Radix Multi-path Delay Feedback (MRMDF) architecture proposed in. The architecture has been targeted 180 nm CMOS technology for fabrication. The design is intended to comply with ECMA-368 standard, which is one of the leading MB-OFDM standards for UWB application. The major bottleneck...
An Ultra-Wideband (UWB) channel exhibits frequency dependent delay characteristics in different bands of transmission. In [6] we studied and quantified the differences of delay parameters over frequency bands 3.1-4.6 GHz in several UWB channel models (CM). Based on this observation, we proposed an adaptive timing synchronization scheme (ATS) which estimates and maintains the timing delays of each...
Fast Fourier transform (FFT) is the reduced complexity algorithm to implement highly computational complex discrete Fourier transform (DFT). Cooley-Tookey based decomposition method is the most popular technique for an N point DFT where N is an integral power of 2. There are 2 decomposition techniques, decimation in frequency (DIF) and decimation in time (DIT), which are widely popular. Both the techniques...
In this paper we propose a multiple access scheme using multi-symbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM) with reduced computational complexity. MSE-OFDM is a bandwidth efficient OFDM scheme, where a number of OFDM symbols are grouped together as a frame and protected by one single cyclic prefix (CP). This improves the bandwidth efficiency and robustness of the system...
This paper analyzes mathematically the crucial points of signal processing in a multi-band (MB) orthogonal frequency division multiplexing (OFDM) based system considering realistic ultra-wideband (UWB) channel environment. In the process of analysis, it emphasizes the significant aspects of UWB receiver design in comparison with a narrow-band system design. This is extended further with a frequency...
This work explores theoretically the unique aspects of different signal processing stages in a Multi-Band (MB) Orthogonal Frequency Division Multiplexing (OFDM) based system in realistic Ultra-Wideband (UWB) channel. In the process of analysis, it emphasizes the significant aspects of signal processing steps in UWB receiver design comparing a narrow-band system. The analysis preliminary considers...
An ultra-wideband channel is expected to exhibit different delay characteristics in different bands. In this paper, wideband channel delay characteristics are studied and delay parameters are found considerably different over frequency bands 3.1-4.6 GHz. Based on this observation, an adaptive timing synchronization scheme (ATS) which estimates and maintains the timing delays of each band separately...
A low-complexity correlation based symbol timing synchronization (CBTS) algorithm for UWB MB-OFDM systems is presented. The correlation based scheme attempts to locate the start of the FFT window during frame synchronization sequence (FS) of the received preamble by firstly correlating the received samples with known training samples and then identifying the first significant multi-path component...
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