http://hdl.handle.net/10150/595560 Sun, 09 Jul 2017 18:03:35 GMT 2017-07-09T18:03:35Z http://hdl.handle.net/10150/624220 Title: ENERGY EFFICIENT ADAPTIVE SECTOR-BASED USER CLUSTERING ALGORITHM FOR CELLULAR NETWORK Author: Kassa, Hailu Belay; Aredo, Shenko Chura; Menta, Estifanos Yohannes Abstract: In this paper, we propose an adaptive and multi-sector-based user clustering algorithm which increases energy efficiency in a cellular network. Adaptive sectoring with dynamically changing sector angles is illustrated with a number of randomly distributed mobile stations. Transmitted power is equally shared by sectors before adaptive user clustering. The sector angles vary from 30 to 360 degrees by merging neighboring sectors and a sector is switched off till the user density exceeds a threshold (Td). The Td value is computed from the total number of users that the cell can accommodate over the area of the cell. The sectors with less than Td density exhibits transmit power which approaches to zero or sleeping state and so that the cumulative power is saved. Simulation results show that an average of 45% to 50% energy can be saved in 10 iterations. Tue, 01 Nov 2016 00:00:00 GMT http://hdl.handle.net/10150/624220 2016-11-01T00:00:00Z http://hdl.handle.net/10150/624224 Title: EVALUATION OF SPECTRAL Vs ENERGY EFFICIENCY TRADEOFF CONSIDERING TRANSMISSION RELIABILITY IN CELLULAR NETWORKS Author: Kassa, Hailu Belay; Engda, Tewelgn Kebede; Menta, Estifanos Yohannes Abstract: Spectral efficiency (SE), energy efficiency (EE), and transmission reliability are basic parameters to measure the performance of a cellular network. In this paper, spectral efficiency and energy efficiency tradeoff is considered keeping in mind the transmission reliability, where all the three are function of signal to noise ratio (SNR). SNR, in turn is a function of constellation size (or the number of bits per symbol) and data rate. Then, we propose a new power model which is as function of this SNR. Based on the power model, SE-EE trade-off function is evaluated taking transmission reliability in to consideration. Results confirmed that increasing constellation size results an increase in SNR and leads to a significant increase in energy efficiency without changing the transmit power. To demonstrate the validity of our analysis, channel gain and constellation size are varied keeping transmit power constant. The results also indicate that securing transmission reliability, the EE-SE trade-off is optimized by increasing the constellation size. Tue, 01 Nov 2016 00:00:00 GMT http://hdl.handle.net/10150/624224 2016-11-01T00:00:00Z http://hdl.handle.net/10150/624221 Title: SYMBOL SET SELECTION IN GSSK MIMO SYSTEMS WITH CORRELATED ANTENNAS Author: Shrestha, Mandip Abstract: Generalized space shift keying (GSSK) is a transmission scheme where only antenna indices are used to send information from the transmitter to a receiver. This paper investigates the best symbol set selection problem in GSSK multiple-input-multiple-output (MIMO) systems when the transmit antennas are correlated. Although multiple antennas can increase data rate and signal quality without increasing the bandwidth, spatial correlations among the antennas highly affect the performance of the system. The idea here is to maximize the inter-symbol Euclidean distance to obtain the best symbol set. Recently such an algorithm has been proposed for the visible light communication (VLC) systems. This paper adopts this VLC algorithm for radio frequency (RF) communication systems. The results show that the proposed symbol set design can provide several dBs of gain in the symbol error rate (SER) performance over randomly selected symbol sets in GSSK systems. Tue, 01 Nov 2016 00:00:00 GMT http://hdl.handle.net/10150/624221 2016-11-01T00:00:00Z http://hdl.handle.net/10150/624230 Title: OPTIMIZATION OF SYMBOL DISTANCE METRIC IN DIRECTIONAL MODULATION SYSTEMS Author: Christopher, Ryan M. Abstract: This paper investigates a directional modulation (DM) method that distorts the received symbol constellations along a set of undesired directions while maintaining an undistorted constellation in the direction of intended communications. The problem is formulated in terms of minimization of the symbol distance metrics along the undesired directions. An algorithm assigns a symbol pair to each undesired direction for symbol distance minimization. Constraints for good reception in the desired direction are also included. The method involves iterations between a quadratic minimization problem and an unbalanced transportation problem. Numerical results are presented to show the bit error rate (BER) benefits of the proposed method. Tue, 01 Nov 2016 00:00:00 GMT http://hdl.handle.net/10150/624230 2016-11-01T00:00:00Z