Thumbnail Image

Theses

Browse

2016 - 20193
Reset filters
Subject: Electronics and Communication Engineering × End date: 2019 × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    ThesisItemOpen Access
    Channel prediction in cognitive radio network using hierarchical neural system for throughput maximization
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-09) Goyal, Neetu; Mathur, Sanjay
    Wireless Communication has shown exponential upsurge in demand of wireless devices. Due to ever increasing demand of wireless communication, there is spectrum scarcity which is caused by a fixed spectrum allocation policy. Studies on usage pattern reveal that most of the allocated spectrum experiences low utilization under fixed spectrum allocation regime and spectrum occupancy varies from milliseconds to hours. This motivated the concept of frequency reuse that would allow secondary networks to borrow unused radio spectrum from primary licensed networks (users). The core technology behind frequency reuse is Cognitive Radio for which one of the essential components is channel sensing, i.e., the wireless devices can sense the radio spectrum environment within their operating range to detect frequency bands that are not occupied by primary users. This thesis presents a study on maximizing the throughput for secondary user by predicting the primary free channel in advance to save time in sensing and maximizing transmission time in a frame. The study involves exhaustive exploration of various classifiers for predictive decision making and later development of hierarchal neural network model for predicting best possible channel for transmission in following frame. It starts with performance analysis of spectrum sensing techniques, energy detector and matched filter are discussed with simulation results. On the basis of these results, energy detector is found best technique which is further analysed in fading scenario and with mobile SU. There exists a sensing-throughput trade off, hence proposed model focuses on parallel processing for predicting the next channel while primary user continues to transmit in current frame. The model considers three type of radio channel condition scenario namely, constant fading, cyclostationary fading and fast fading. The performance of the system is found to be closer to upper bound for best channel throughput and results are discussed in comparison to lower bound statistics.
  • Thumbnail Image
    ThesisItemOpen Access
    A novel compact wide band notched slot antenna with enhanced bandwidth for wireless applications
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2016-08) Saxena, Ankur; Gangwar, R.P.S.
    In recent years, there has been a substantial amount of research in the ultra wide band technology for innovation in wireless applications. The electronic gadgets enabled with this technology may be enforced in wearable/handy products. Such type of specific applications excites the challenges to researchers and industries to make this technology different from other conventional antennas of limited bandwidth. Compact size and volume are critical constraints for wearable and portable device applications. A reliable performance for the entire bandwidth along with radiation pattern is required for high data rate applications. Therefore, it has become necessary to develop an antenna with compact size, enhanced bandwidth and notched characteristics. In view of the above, an attempt has been made to develop a novel compact wide band notched slot antenna with enhanced bandwidth for wireless applications. In this dissertation, ultra wide band antennas with an objective to reduce antenna size with increased bandwidth are studied. Further, to minimize the interference problem, the implementable band notching techniques are explored. Initially, UWB antenna is developed using FR-4 substrate of thickness 1.6 mm. A modified rectangular patch in a rectangular slot in ground plane is designed to achieve large bandwidth. Two symmetrical semi-circular slots are implemented to enhance the impedance matching from 15 GHz and above frequency range. A T-stub inside an elliptical slot within the patch is created to achieve band-notching characteristics. The proposed design is simulated using HFSS. The design is fabricated and measured. The simulated and measured results in terms of reflection coefficient, radiation pattern and peak gain is compared. The novelty of this research work is the development of compact antenna with overall dimensions of 14x14 mm2 and antenna bandwidth of 161%. The size and bandwidth are compared with previously designed antennas.
  • Thumbnail Image
    ThesisItemOpen Access
    Metaheuristic approaches for adaptive array signal processing in smart antenna
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2016-07) Sharma, Abhinav; Mathur, Sanjay