Informatics Publishing Limited

C. Geetha Priya ¹, M. Suganthi ²

Affiliations
1 Mepco Schlenk Engineering College, Sivakasi - 626 005, IN
2 Thiagarajar College of Engineering, Madurai – 626 015, IN

Abstract

In this paper, a joint symbol timing estimation and carrier phase synchronization method for Orthogonal Frequency Division Multiplexing (OFDM) system is implemented for a Wireless Local Area Network (WLAN). Earlier approaches for symbol timing estimation make use of correlation of samples within the preamble. So preamble should be chosen with good autocorrelation property. Thus estimation method directly depends on the preamble. The implemented method for timing estimation in this paper is preamble independent. This method can be applied for any preamble structure and this scheme gives more accurate estimate of symbol timing. Also a method for carrier phase recovery is implemented in OFDM WLAN system. This algorithm for carrier phase compensation can effectively recover Residual Frequency Offset (RFO) and phase in the presence of Inter Carrier Interference (ICI). This scheme for symbol timing and carrier phase recovery is analyzed for WLAN environment and simulation results are shown.

Keywords

Carrier Frequency Offset (CFO), Correlation Sequence of Preamble (CSP), Decision-Directed (DD), Inter Carrier Interference (ICI), Orthogonal Frequency Division Multiplexing (OFDM), Quadrant Decision (QD), Residual Frequency Offset (RFO).

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D. David Neels Pon Kumar ¹, K. Murugesan ², S. Raghavan ³, M. Suganthi ⁴

Affiliations
1 ECE Department, at SRCE, Alangulam, Tirunelveli, IN
2 Bharathiar Institute of Engg. For women, Attur, Chinna Salem, IN
3 IIT, Delhi, IN
4 ECE Dept. at TCE, Madurai, IN

Abstract

Wireless Interoperability for Microwave Access (WiMAX) is one of the most familiar broadband wireless access technologies that support multimedia transmission. IEEE802.16 Medium Access Control (MAC) covers a large area for bandwidth allocation and QoS mechanisms for various types of applications. Nevertheless, the standard lacks a MAC scheduling algorithm that has a multi-dimensional objective of satisfying QoS requirements of the users, maximizing channel utilization while ensuring fairness among users. So we are proposing a novel Priority based Scheduling Algorithm using Fuzzy logic and Artificial neural networks (ANN) that addresses these aspects simultaneously. The initial results show that a fair amount of fairness is attained while keeping the priority intact. Results also show that maximum channel utilization is achieved with a negligible increment in processing time.

Keywords

Artificial Neural Networks, Fuzzy Logic, Fairness, QoS, Scheduling Algorithms.

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T. Loganayagi ¹, Inooni Sharahabeel ¹, M. Suganthi ²

Affiliations
1 Mahendra Engineering College, Mallasamudram, Namakkal, IN
2 Kumaraguru College of Technology, Coimbatore, IN

Abstract

Face recognition has made significant improvement in the last decade, but robust commercial applications are still lacking. Current authentication/ identification applications are limited to controlled settings, e.g., limited pose and illumination changes. This paper proposes a novel framework for real-world face recognition in uncontrolled settings named Face Analysis for Commercial Entities (FACE). Its robustness comes from normalization (“correction”) strategies to address pose and illumination variations. FACE adopts reliability indices, which estimate the “acceptability” of the final identification decision made by the classifier.    The rewards of FACE are: data fusion; online identity management; and interoperability. The results obtained by FACE witness a significant increase in accuracy when compared with the results produced by the other algorithmic rule considered.

Keywords

Face Recognition, Identity Management, Inter Operability, Pose and Illumination Changes, Reliability Indices.

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R. Suresh Babu ¹, M. Suganthi ², K. Ramasamy ³

Affiliations
1 Department of Electronics and Communication Engineering, Kamaraj College of Engineering and Technology, Tamil Nadu, IN
2 Department of Electronics and Communication Engineering, Thiagarajar College of Engineering, Tamil Nadu, IN
3 Department of Electronics and Communication Engineering, P.S.R.R.College of Engineering for Women, Tamil Nadu, IN

Abstract

Present wireless communication systems uses FDMA, TDMA and CDMA techniques and are facing various issues like multipath fading, time dispersion which leads to inter symbol interference (ISI), lower bit rate capacity and less spectral efficiency. In a conventional terrestrial broadcasting, the transmitted signal arrives at the receiver through various paths of different lengths. Hence multiple versions of the signal interfere with each other and it becomes difficult to extract the original information. The use of Space Time Block Coded (STBC) Orthogonal Frequency Division Multiplexing (OFDM) technique provides better solution for the above issues. In this paper, we study the Bit Error Rate (BER) performance of STBC OFDM system employing BPSK, QPSK and QAM modulations. As STBCs have been derived from Generalized Complex Orthogonal Designs (GCOD), the norms of the column vectors are the same (e.g., Alamouti Code). We present an analysis of how multiple transmitting antennas and one receiving antenna produces reduced BER at lower value of SNR. From the simulation results, we observed that the BPSK allows improved BER performance over a noisy channel at the cost of maximum data transmission capacity. But the use of QPSK and QAM allows higher transmission capacity at the cost of slight increase in the probability of error.

Keywords

Generalized Complex Orthogonal Design, Space Time Block Code, Alamouti Code, OFDM, Antenna Diversity.

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