Articles written in Sadhana

    • Analysis of sum spectrum efficiency in multiple antennas multi-user MIMO cellular system for millimeter wave communications


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      In this paper, sum spectrum efficiency of two cell multiple-input multiple-output (MIMO) system having multiple antennas at base station (BS) and multiple user equipments (UEs) is analysed. The maximum ratio (MR) and multi-cell minimum mean squared error (M-MMSE) techniques are utilized for detection/precoding in the uplink/downlink scenario. In this paper, two boundary cases of propagation channel model: line of sight (LoS) and non-line of sight (NLoS), and generalized propagation channel model of millimeter wave (mmWave) are compared using MR and MMSE detection techniques. The closed bound expressions of sum spectrum efficiency of MR are expressed and simulated, whereas for M-MMSE, Monte-Carlo simulations are performed on the basis of its weighting vector. The fundamental limits on the system performance, using largeantenna arrays and many UEs satisfying practical constraints like desired signal to noise ratio (SNR), low complexity in signal processing, gain of inter cell interference and finite-dimensional channels are analysed.

    • Performance characterization of modified random direction mobility model in UAVs cellular network


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      This paper deals with the characterization of proposed modified random direction (M-RD) mobility model in unmanned aerial vehicles (UAVs) deployed as base stations for serving terrestrial users within finite cellular network. This mobility model is the upgradation to classical random direction (RD) mobility model with inclusion of several stops within the path to improve the probability of serving users. The simulation results of proposed M-RD mobility model in terms of distribution, density and average rate are compared with prevalent mobility models, i.e., random walk (RW) and random waypoint (RWP). Distribution plots showing positive skewness for RW/RWP and negative skewness for M-RD, reveal a framework for obtaining uniformity in the distribution with an adjustment of proportion of UBSs following RWP and M-RD. The density of the network ofinterfering UBSs for M-RD exhibits better homogeneity at large time intervals. Also, the average rate achieved by a typical user located at different locations in the environment has shown remarkable improvement in M-RD as compared to RW and RWP, especially at large time intervals.

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