In this paper, a hybrid method of support vector machine and genetic algorithm (GA) is proposed and its implementation in intrusion detection problem is explained. The proposed hybrid algorithm is employed in reducing the number of features from 45 to 10. The features are categorized into three priorities using GA algorithm as the highest important is the first priority and the lowest important is placed in the third priority. The feature distribution is done in a way that 4 features are placed in the first priority, 4 features in the second, and 2 features in the third priority. The results reveal that the proposed hybrid algorithm is capable of achieving a true-positive value of 0.973, while the false-positive value is 0.017.

A hybrid method consisting of GA and SVM for intrusion detection system

To take maximum advantage of the increasing Global Navigation Satellite Systems (GNSS) data to improve the accuracy and resolution of global ionospheric TEC map (GIM), an approach, named Spherical Harmonic plus generalized Trigonometric Series functions (SHPTS), is proposed by integrating the spherical harmonic and the generalized trigonometric series functions on global and local scales, respectively. The SHPTS-based GIM from January 1st, 2001 to December 31st, 2011 (about one solar cycle) is validated by the ionospheric TEC from raw global GPS data, the GIM released by the current Ionospheric Associate Analysis Center (IAAC), the TOPEX/Poseidon satellite and the DORIS. The present results show that the SHPTS-based GIM over the area where no real data are available has the same accuracy level (approximately 2–6 TECu) to that released by the current IAAC. However, the ionospheric TEC in the SHPTS-based GIM over the area covered by real data is more accurate (approximately 1.5 TECu) than that of the GIM (approximately 3.0 TECu) released by the current IAAC. The external accuracy of the SHPTS-based GIM validated by the TOPEX/Poseidon and DORIS is approximately 2.5–5.5 and 1.5–4.5 TECu, respectively. In particular, the SHPTS-based GIM is the best or almost the best ranked, along with those of JPL and UPC, when they are compared with TOPEX/Poseidon measurements, and the best (in addition to UPC) when they are validated with DORIS data. With the increase in the number of GNSS satellites and contributing stations, the performance of the SHPTS-based GIM can be further improved. The SHPTS-based GIM routinely calculated using global GPS, GLONASS and BDS data will be found at the website http://www.gipp.org.cn.

SHPTS: towards a new method for generating precise global ionospheric TEC map based on spherical harmonic and generalized trigonometric series functions

To take maximum advantage of the increasing Global Navigation Satellite Systems (GNSS) data to improve the accuracy and resolution of global ionospheric TEC map (GIM), an approach, named Spherical Harmonic plus generalized Trigonometric Series functions (SHPTS), is proposed by integrating the spherical harmonic and the generalized trigonometric series functions on global and local scales, respectively. The SHPTS-based GIM from January 1st, 2001 to December 31st, 2011 (about one solar cycle) is validated by the ionospheric TEC from raw global GPS data, the GIM released by the current Ionospheric Associate Analysis Center (IAAC), the TOPEX/Poseidon satellite and the DORIS. The present results show that the SHPTS-based GIM over the area where no real data are available has the same accuracy level (approximately 2–6 TECu) to that released by the current IAAC. However, the ionospheric TEC in the SHPTS-based GIM over the area covered by real data is more accurate (approximately 1.5 TECu) than that of the GIM (approximately 3.0 TECu) released by the current IAAC. The external accuracy of the SHPTS-based GIM validated by the TOPEX/Poseidon and DORIS is approximately 2.5–5.5 and 1.5–4.5 TECu, respectively. In particular, the SHPTS-based GIM is the best or almost the best ranked, along with those of JPL and UPC, when they are compared with TOPEX/Poseidon measurements, and the best (in addition to UPC) when they are validated with DORIS data. With the increase in the number of GNSS satellites and contributing stations, the performance of the SHPTS-based GIM can be further improved. The SHPTS-based GIM routinely calculated using global GPS, GLONASS and BDS data will be found at the website http://www.gipp.org.cn.

SHPTS: Towards a new method for generating precise global ionospheric TEC maps based on spherical harmonic and generalized trigonometric series functions

An Algebraic Solution of the GPS Equations

It is known that satellite radiolocalization was born in the military environment and was originally conceived for defense purposes. Nevertheless, the commercial explosion (dated to 20 years ago) of global positioning system (GPS) in the civil market (automotive, tourism, etc.) significantly changed the original perspectives of this technology. Another big change is expected when other global navigation satellite systems (GNSSs) such as the European Galileo or the Chinese COMPASS become operational and commercial. In fact, modern GNSSs are conceived principally for the civil market (at the opposite of GPS, whose civil employment is given as a sort of “kind gift,” with lower performance than that one granted to military users). The scope of this paper is to provide readers with a clear focus about the potentialities of current and forthcoming GNSSs and associated technologies in a renewed mass-market perspective. The paper also opens a window to the future of radiolocalization technology beyond GPS and GNSS, dealing with the role of digital signal processing and software-defined radio (SDR) in next-generation navigation systems and with the seamless integration of satellite-based navigation with other technologies in order to provide reliable position information also in hostile environments.

Satellite Radiolocalization From GPS to GNSS and Beyond: Novel Technologies and Applications for Civil Mass Market

Several countries have been developing satellite-based augmentation systems (SBAS) for improving positional accuracy of global positioning system (GPS). India is also developing one such system popularly known as GPS aided geo augmented navigation (GAGAN) system. Modelling of ionospheric effects is one of the major challenges in developing precise and reliable GAGAN. The high values of total electron content (TEC), the large diurnal and seasonal variability and intense irregularities present in the low-latitude ionosphere, lead to unacceptable positional errors in GAGAN service region. Todd Walter et al. of Stanford University, USA have made significant contribution in the area of SBAS ionospheric grid modelling by developing the popularly known planar fit model. It is reported by Walter et al. (2000) that a constant decorrelation value of 35 cm was proposed over the wide area augmentation system (WAAS) service region. To provide accurate estimation of ionospheric delays at user ionospheric pierce points (IPP) during a storm or intense irregularities, an irregularity detector and a decorrelation adaptor are incorporated in the modelling. As planar fit model is not adequate to model intense irregularities of Indian ionosphere, a modified planar fit model is applied for GAGAN data on similar lines as was done for WAAS and the results are encouraging.

Modelling of low-latitude ionosphere using modified planar fit method for GAGAN

Intrusion in Wireless network differs from IP network in a sense that wireless intrusion is both of packet level as well as signal level. Hence a wireless intrusion signature may be as simple as say a changed MAC address or jamming signal to as complicated as session hijacking. Therefore merely managing and cross verifying the patterns from an intrusion source are difficult in such a network. Beside the difficulty of detecting the intrusion at different layers, the network credential varies from node to node due to factors like mobility, congestion, node failure and so on. Hence conventional techniques for intrusion detection fail to prevail in wireless networks. Therefore in this work we device a unique agent based technique to gather information from various nodes and use this information with an evolutionary artificial immune system to detect the intrusion and prevent the same via bypassing or delaying the transmission over the intrusive paths. Simulation results show that the overhead of running AIS system does not vary and is consistent for topological changes. The system also proves that the proposed system is well suited for intrusion detection and prevention in wireless network.

An Agent Based Intrusion Detection System for Wireless Network with Artificial Immune System (AIS) and Negative Clone Selection

The positional accuracy of navigation receiver is an important factor for various applications Based on the application, the achieved positional accuracy levels vary from meters to millimeters IRNSS-GPS-SBAS (IGS) receiver is capable of receiving all the seven IRNSS satellite signals in L5 (117645MHz) and S1 (2492028MHz) band in addition to twelve GPS satellite signals and two SBAS (GAGAN) satellite signals in L1 (157542 MHz) frequency band In this paper the position accuracy is evaluated in terms of 2DRMS, 3DRMS CEP, SEP, Geometric Dilution of Precision (GDOP) and Doppler shift in various modes namely Hybrid (IRNSS L5 and GPS L1), IRNSS dual frequency (L5 and S1), IRNSS L5 only and IRNSS S1 only mode In Hybrid mode, it is found that all the positional accuracy values are better than the corresponding other mode values

Preliminary performance evaluation of IRNSS-GPS-SBAS receiver in terms of position accuracy and velocity

This paper mainly deals with the performance comparison of several video coding standards by means of peak signal-to-noise ratio and subjective testing like Rate Distortion (RD) curves and average bit-rate savings. A particular procedure is applied for the video coding standards H.265/High Efficiency Video Coding (HEVC), H.264/MPEG4- Advance Video Coding (AVC), MPEG4V2, MPEG4 and the Google video codec's such as VP8, VP9 at different bit-rates and Peak Signal-to-Noise Ratios (PSNR) are estimated. The bit-rate reduction on an average is achieved about 50% for comparable to earlier video coding standards. The results obtained illustrate the H.265/HEVC achieving high peak signal-to-noise at low bit rates. This resembles high coding efficiency, comparing with lower versions of video coding standards.

Analysis of video coding standards using PSNR and bit rate saving

Accurate position estimation is the vital issue in Location Based Services (LBS) of 3G communications. The quality of LBS depends on the positioning technologies used and the network topology. In this paper, the performance of four prominent self-position fixing methods namely i) RSS Statistics, ii) Least squares (LS) iii) Weighted LS (WLS) and iv) Constrained WLS (CWLS) are compared. The estimations are based on RSS measurements from surrounding base stations (BS) in GSM network. In statistics of Received Signal Strength (RSS) method, 2-D location of MS is estimated based on PDF of propagation distances derived from RSS data using Minimum Mean Square Error criterion. In LS estimation techniques, correlation that exists between propagation distances and RSS measurements is exploited. The performance of WLS method is better than LS method with the inclusion of weight matrix. In CWLS, Lagrangian multiplier is introduced to include the radial distance constraint to improve reliability and integrity of estimates. Experiments are conducted to acquire RSS data by using Test Equipment for Mobile Systems (TEMS) investigation tool and GSM/GPRS 900/1800MHz dual frequency modem for both stationary and kinematic modes of mobile. RSS data acquired in the coverage area of Tirumalgiri BS (17° 28' 11", 78° 30' 55", 560m) Hyderabad city, India. BS antenna is at the height of 33m. It transmits power at an effective isotropic radiated power (EIRP) of 43 dBm on 950.6 MHz frequency. The acquired field strength values at various points are ranging from −80dBm to −35dBm. For a typical urban GSM cell structure (σ shadowing = 6 to 8dB) simulated position estimates are obtained. Experimentally observed results are verified with GPS measurements and found that accuracy is limited by number of hearable BSs involved in the estimation. Comparative error analysis indicates that the accuracy of the location estimation greatly depends on the cell size. Error is least when the BSs involved are well distributed in all the directions around and nearer to the MS which has least Geometric Dilution of Precision (GDOP). It is found that, CWLS method performs well in a densely populated urban city with Multiple Multi-storied structures. Experimental results indicate that CWLS offer less Circular Error Probability (86.7m), RMSE (2.58m), least GDOP (2.0) and error a (1.54m) with 7 BSs. The result will be an important input for designing location assisted handoffs required for reliable mobile links and in deployment of BSs at proper locations to achieve uninterrupted coverage.

D. Krishna Reddy

Papers

Modelling of low-latitude ionosphere using modified planar fit method for GAGAN

An Agent Based Intrusion Detection System for Wireless Network with Artificial Immune System (AIS) and Negative Clone Selection

Preliminary performance evaluation of IRNSS-GPS-SBAS receiver in terms of position accuracy and velocity

Analysis of video coding standards using PSNR and bit rate saving

Mobile position estimation with RSS Based techniques in an urban city with multiple multi-storied structures