Sakuntala S. Pillai

Learn More
This paper describes the analysis of the audio and speech output of the 16 kb/s Low Delay CELP algorithm (LD-CELP). For various speech file conversions, the SoX (Sound eXchange) tool is used. Praat software is used to extract details regarding the quality of the sound synthesized by the coder. The C program of the coder was compiled using the GCC compiler(More)
Orthogonal frequency division multiplexing (OFDM) has attracted a lot of attention because of its high data rate, high spectrum efficiency and robustness against frequency-selective fading channels This paper addresses channel estimation based on time-domain channel statistics. Here the statistical characteristics of AWGN channel is estimated using(More)
Lasercom or laser communication is an optical wireless communication, envisioned to be the next generation wireless communication technology due to its inherent characteristics like increased bandwidth, high data rate, security, immunity to interference, unregulated spectrum etc. Lasercom is a better alternative to conventional communication schemes due to(More)
The design of high quality speech coders with low data rate is a very challenging task in speech processing. CELP provides good quality coded speech at a very low bit rate of 4.8kbps. Two types of codebooks namely Gaussian codebook and Fixed codebook are used in this analysis. The changes in the performance of the CELP codec is evaluated for theses two(More)
Cognitive Radio (CR) is a promising technology to alleviate spectrum scarcity problem. CR enables a technique called spectrum leasing where the secondary users able to access licensed spectrum bands opportunistically by making monetary payment. A three phase spectrum leasing scheme is considered where primary user allows users in a distributed secondary(More)
Traditional Orthogonal Frequency Division Multiplexing (OFDM) system is a multi carrier transmission technique that splits data stream into a number of data subcarriers in parallel. In this method, a 4-Weighted Fractional Fourier Transform (4-WFRFT) is proposed for modulation / demodulation of the subcarriers. The method uses Maximum Likelihood Estimation(More)
For last-mile networks the in-building electric power lines are considered an attractive medium for high-speed data transmission. In this paper we consider the channel response in the 1–30MHz band. The development of a Broadband PowerLine Communications (BPLC) network topology is analyzed so as to obtain better performance through channel modeling.(More)
Transmit precoding utilizes the channel state information (CSI) to precode the data so that the effect of fading is equalized. Three simple precoding schemes for Rayleigh fading multiple-input multiple-output (MIMO) system are explained. CSI is required only at the transmitter and not at the receiver. So the computational complexity is reduced at the(More)
A novel blind carrier frequency offset (CFO) estimation method for orthogonal frequency division multiplexing (OFDM) systems using constant modulus constellations is proposed in this study. CFO is estimated by minimizing a hybrid cost function which is formulated using properties of the covariance matrix and the magnitude of two nearby OFDM symbols. The(More)