Neetu Sood

A Mobility Improvement Handover Scheme for Mobile-WiMAX

This paper presents a mobility improvement handover algorithm with less scan time implementation for Mobile WiMAX. Mobile WiMAX is a wireless technology based on IEEE802.16e for broadband wireless access. Mobile WiMAX introduces the most significant new feature, mobility to support for handovers, which can be considered as a basic requirement for mobile communication system. The mandatory handoff method is Hard Handoff for Mobile WiMAX and other two optional soft handoff methods are Macro Diversity Handoff and Fast Base Station Switching Handoff method. Handover delay generates during data transmission but handover delay should be less than 50milli second for real time applications such as VoIP. The existing draft standard considers only the received signal strength (RSS) when deciding handover. The mobility improvement handover scheme that depends upon the velocity factor has been taken into consideration in this paper. The proposed scheme skips some unnecessary handover stages, reduces handover delay by adjusting the handover parameters viz. handover RSS trigger and threshold handover RSS trigger value to improve the velocity of the mobile station. The proposed scenario has been implemented using QualNet network simulator which has lead to less handover time.

BER Performance of OFDM-BPSK and -QPSK Over Generalized Gamma Fading Channel

In this paper, the BER performance of OFDM-BPSK and -QPSK system over generalized gamma fading channel has been reported. This model is versatile enough to represent short-term fading such as Weibull, Nakagami-m, or Rayleigh as well as shadowing. The flexibility of this model is because of two fading parameters compared to only one in Nakagami-m fading model, which helps to analyze the severity of fading more deeply. Here, simulations of OFDM signals are carried with generalized gamma faded signal to understand the effect of channel fading.

BER performance of OFDM-BPSK and-QPSK over Nakagami-m fading channels

In this paper, the performance of OFDM-BPSK and-QPSK system in Nakagami-m channel has been reported. Here our approach is based on decomposition of Nakagami random variable into orthogonal random variables with Gaussian distribution envelopes. Results have been presented to obtain optimum value of m based on BER and SNR.

A joint application of optimal threshold based discrete cosine transform and ASCII encoding for ECG data compression with its inherent encryption.

In this paper, a joint use of the discrete cosine transform (DCT), and differential pulse code modulation (DPCM) based quantization is presented for predefined quality controlled electrocardiogram (ECG) data compression. The formulated approach exploits the energy compaction property in transformed domain. The DPCM quantization has been applied to zero-sequence grouped DCT coefficients that were optimally thresholded via Regula-Falsi method. The generated sequence is encoded using Huffman coding. This encoded series is further converted to a valid ASCII code using the standard codebook for transmission purpose. Such a coded series possesses inherent encryption capability. The proposed technique is validated on all 48 records of standard MIT-BIH database using different measures for compression and encryption. The acquisition time has been taken in accordance to that existed in literature for the fair comparison with contemporary state-of-art approaches. The chosen measures are (1) compression ratio (CR), (2) percent root mean square difference (PRD), (3) percent root mean square difference without base (PRD1), (4) percent root mean square difference normalized (PRDN), (5) root mean square (RMS) error, (6) signal to noise ratio (SNR), (7) quality score (QS), (8) entropy, (9) Entropy score (ES) and (10) correlation coefficient (rx,y). Prominently the average values of CR, PRD and QS were equal to 18.03, 1.06, and 17.57 respectively. Similarly, the mean encryption metrics i.e. entropy, ES and rx,y were 7.9692, 0.9962 and 0.0113 respectively. The novelty in combining the approaches is well justified by the values of these metrics that are significantly higher than the comparison counterparts.

Image reconstruction using cubic B-Spline interpolation

As the development and use of multimedia technology in different and varied fields has led to an explosion in its use in all environments, in medical, military, environmental, surveillance as well as industrial and quality control applications. In many of these applications a compression step is necessary with the inevitable loss of quality information, for the sake of saving a little more bandwidth or storage space. While doing compression, we generally discard some pixels or frame during encoding and even upon decoding/decompression the exact data is not regenerated therefore the final image is not exactly the same as the original image. Thus to incorporate the compression losses, reconstruction using interpolation technique have been applied on the compressed image such that this can predict the discarded pixels or the missing pixels from the image. The proposed algorithm uses cubic B-Spline interpolation technique for reconstruction, exhibits significant improvement in reconstructed image quality.

A 2D electrocardiogram data compression method using a sample entropy-based complexity sorting approach

Exploitation of inter and intra beat correlation for 2D ECG data compression. A progressive pre-processing techniques to foster the uniformity in 2D ECG array. Quasi-periodic ECG compression using entropy based nonlinear complexity sorting. Proposed method outperforms the variance based linear complexity sorting approach. This paper proposes an effectual sample entropy (SampEn) based complexity sorting pre-processing technique for two dimensional electrocardiogram (ECG) data compression. The novelty of the approach lies in its ability to compress the quasi-periodic ECG signal by exploiting the intra and inter-beat correlations. The proposed method comprises the following steps: (1) QRS detection, (2) Length normalization, (3) Dc equalization, (4) SampEn based nonlinear complexity sorting and (5) Compression using JPEG2000 Codec. The performance has been evaluated over 48 records from the MIT-BIH arrhythmia database. The average quality score (QS) measurements at different residual errors were 42.25, 4.73, and 2.75 for percentage root mean square difference (PRD), PRD1024, and PRD Normalized respectively. The work also reports extensive experimentations on the compressor for various durations of the ECG records (5-30 min, with 5-min increment). The proposed algorithm demonstrates significantly better performance in comparison to the contemporary state-of-the-art works present in the literature. Display Omitted

Semianalytic BER Estimation of SC-QPSK under Nakagami-m Frequency Selective Fading Channel with Diversity Reception

Semianalytic estimation of bit-error-rate (BER) is one of the efficient procedures for evaluating BER for modulation formats having circular constellation with noise component of the decision variable is circularly symmetric with Gaussian distribution. To ensure very rapid simulation run time analytical and simulation techniques are used together unlike conventional Monte Carlo simulation. This technique is demonstrated to estimate BER of SC-QPSK system under Nakagami-m frequency selective fading channel. Finally error rate estimation is extended to system having multiple channel reception using spatial diversity combiners. Our result shows that system performance degrades with increasing value of system parameter.

SER Analysis of OFDM System over Rayleigh Fading Channel

this paper, we present an efficient technique for the SER of OFDM system over Rayleigh fading channels, using well known characteristics function (CHF) based analysis approach. The exact probability density function of a sum of Rayleigh random vectors are used to derive the expression for the error rates of OFDM system. The average SER expressed in terms of the exponential and Bessel functions. Further to improve the system performance error-rate analysis is extended to a system using multichannel reception with maximal ratio combining. KeywordsDigital Communication, Rayleigh Fading channel, MRC diversity.

BER Performance of OFDM-BPSK and -QPSK over Generalized Alpha-Mu Fading Distribution

This paper evaluates the performance of OFDM-BPSK and -QPSK system in ¿-¿ distribution. A fading model which is based on the non-linearity present in the propagation medium is utilized here for generation of ¿-¿ variants. Different combinations of ¿ and ¿ provides various fading distributions, one of which isWeibll fading. Here, siulations of OFDM signals are carried with this Weibull faded signal to understand the effect of channel fading.

PAPR reduction in wavelet packet-based OFDM using PSO-based PTS technique

In multicarrier modulation scheme, PAPR reduction is the main problem. Techniques mentioned in literature are either too complex or not optimal. In this paper, an attempt has been made to reduce the PAPR of multi carrier modulation with the much less complexity. Wavelet packet-based orthogonal frequency division multiplexing has been employed with orthogonal subcarriers and similarly to OFDM high spectral efficiency is achieved in WP-OFDM by the overlapping subcarriers spectra. Further, PSO-based PTS techniques have been used to reduce the PAPR with much less complexity as compared to conventional optimal PTS technique in which search complexity increases exponentially. The performance of WP-OFDM for PTS technique and PSO-based PTS techniques have been implemented in this paper. Also, the simulation results are obtained shows that the PAPR is reduced significantly with much less search complexity.