ICTACT Journal on Communication Technology

Taskeen Nadkar ¹, Vinay Thumar ¹, G. P. S. Tej ¹, S. N. Merchant ¹, U. B. Desai ²

Affiliations
1 Department of Electrical Engineering, Indian Institute of Technology Bombay, IN
2 Department of Electrical Engineering, Indian Institute of Technology Hyderabad, IN

Abstract

The function of the Radio Resource Management module of a CR system is to evaluate the available resources and assign them to meet the Quality of Service (QoS) objectives of the Secondary User (SU), within some constraints on factors which limit the performance of the Primary User (PU). While interference mitigation to the PU spectral band from the SU's transmission, has received a lot of attention in recent literature, the novelty of our work is in considering a more realistic and effective approach of dividing the PU into sub-bands, and ensuring that the interference to each of them is below a specified threshold. The objective of this paper is joint determination of the channel adaptive guard interval, along with sub-carrier power allocation for an orthogonal frequency division multiplexing (OFDM)-based SU, to maximize the SU's throughput, within a power budget and with the aforementioned PU interference constraint. A multiple SU scenario is also considered, which entails assigning sub-carriers to users, besides determining the guard interval and power allocation. Simulation results are provided, which indicate the effectiveness of the proposed algorithms in a CR environment.

Keywords

Cognitive Radio, OFDM, Interference Mitigation, Guard Interval, Power Allocation.

Full Text

     

Y. Raja Vara Prasad ¹, Mirza Sami Baig ¹, Rahul K. Mishra ², P. Rajalakshmi ¹, U. B. Desai ¹, S. N. Merchant ²

Affiliations
1 Department of Electrical Engineering, Indian Institute of Technology Hyderabad, IN
2 Department of Electrical Engineering, Indian Institute of Technology Bombay, IN

Abstract

Air pollution has significant influence on the concentration of constituents in the atmosphere leading to effects like global warming and acid rains. To avoid such adverse imbalances in the nature, an air pollution monitoring system is utmost important. This paper attempts to develop an effective solution for pollution monitoring using wireless sensor networks (WSN) on a real time basis namely real time wireless air pollution monitoring system. Commercially available discrete gas sensors for sensing concentration of gases like CO2, NO2, CO and O2 are calibrated using appropriate calibration technologies. These pre-calibrated gas sensors are then integrated with the wireless sensor motes for field deployment at the campus and the Hyderabad city using multi hop data aggregation algorithm. A light weight middleware and a web interface to view the live pollution data in the form of numbers and charts from the test beds was developed and made available from anywhere on the internet. Other parameters like temperature and humidity were also sensed along with gas concentrations to enable data analysis through data fusion techniques. Experimentation carried out using the developed wireless air pollution monitoring system under different physical conditions show that the system collects reliable source of real time fine-grain pollution data.

Keywords

Wireless Sensor Networks (WSN), Gas Sensor Calibration, Light Weight Middleware, Multihop Data Aggregation, Web Interface.

Full Text