Tanuja Satish Dhope

Cluster based cooperative sensing:-A survey

The complexity of wireless system requires a careful design, especially related to bandwidth and energy efficiency. The energy efficiency is getting more and more on importance, due to increasing penetration of various wireless systems in different battery-oriented applications, as well as due to the more conscious global view on the need for “greening the Earth”. Bandwidth efficiency is very important parameter, because it relates to frequency spectrum, which is naturally limited resource. The cognitive radio has been proposed as the future technology to meet the ever increasing demand of the radio spectrum by allocating the spectrum dynamically to allow unlicensed access on non-interfering basis. Cooperative spectrum sensing has been proposed to combat the multipath fading, shadowing and receiver uncertainty problem improving the detection performance by exploiting spatial diversity but at the cost of increase in cooperation overhead such as extra sensing time, delay, energy and operations devoted to cooperative sensing. Cluster based cooperative sensing can improve the performance and reduce the computational cost. In recent years, many methods of cooperative spectrum sensing have been proposed based on the clustering technique. In this paper, we provide an extensive review of cluster-based cooperative spectrum sensing.

Comparison of DoA Estimation Algorithms in SDMA System

With Space Division Multiple Access (SDMA) schemes employing digital signal processing algorithms in its smart antenna systems, it is possible to improve the system capacity of modern wireless communication systems by enabling users angular separation. Angular separation ability enhances reception in Signal-of-Interest direction and minimizes interference in Signal-of-Not-Interest direction. Direction of Arrival (DoA) algorithms are used for estimation of a number of incident plane waves on the antenna array and their incidence angles. This paper compares performance of three DoA algorithms: MUSIC, root-MUSIC and Capon applied on the uniform linear array in the presence of uncorrelated white noise. The simulation results show that MUSIC outperformed root-MUSIC and Capon in both required number of snapshots and number of array elements as well as in signal-to-noise ratio requirements.

What About Spectrum Opportunities in `Angle' Dimension for Dynamic Spectrum Access in Cognitive Radio Network context? A new Paradigm in Spectrum Sensing

The cognitive radio technology is the new paradigm to fulfill ever increasing need of bandwidth ultimately the radio spectrum by accommodating the radio spectrum dynamically to secondary users/unlicensed users without causing the interference. In cognitive radio, the spectrum opportunities have been checked for Space, Time and frequency dimensions but ‘Angle’ dimension has not been explored till now. In this paper we have investigated accuracy of various ‘Angle-of-Arrival (AoA)’ estimation algorithms: ESPRIT, MUSIC, Bartlett, and Capon for opportunistic secondary users’ network under AWGN and time varying fading channels. The improvement in performance of these algorithms has been observed as array elements, signal-to-noise ratio and samples increases. An ‘adaptive thresholding’ technique has been proposed to improve the performance of AoA algorithms. Thus by estimating an ‘Angle-of- Arrival’ of licensed users, the unlicensed users can be accommodated in the same geographical area into the same channel in the same frequency band at the same time by directing unlicensed users’ beam in different direction than the direction of licensed users. Thereby improving spectrum utilization.