M. Arthi

Because of expensive placement and degradation in spectrum allocation, deployment of serving nodes has become an important issue in the cellular communication. One of the potential remedy to improve the spectral efficiency per unit area is the densification of serving nodes. Long term evolution-advanced (LTE-A) introduced the idea of heterogeneous network (HetNet), containing different eNB of different coverage ranges. But placing the eNBs of different coverage ranges are very difficult. In order to provide a good quality of transmission to the users in the coverage holes, LTE-A also defines multi-hop relay (MHR) networks, where the relay stations (RS) are placed along with the eNBs. But both HetNet and MHR placement approaches are not standardized. In this work, we have proposed a fuzzy logic based coverage and cost effective serving nodes placement scheme. Our placement scheme chooses the optimal eNB sites from the candidate sites in the service area in order to minimize the placement cost while maintaining the coverage more than the expected coverage. Also according to the power constraint on each eNB, it will adjust the range of the cell to get the proper coverage while satisfying the requirements of user. From the simulation results, we can see that our fuzzy logic based placement scheme minimizes the cost of the system and also provides better coverage ratio (CR) under the power constraints.

The recent development of mobile communications, has led to the increment of number of users that network operators need to serve. To cope with the increasing demand of users, the deployment of evolved node base stations (eNB) is an open issue in the present scenario. In our work, focus is on developing a cost-effective and power-efficient eNB deployment framework for Heterogeneous Cellular Networks (HCNs). HCNs are look upon as an integral part of the mobile communication systems. Conventional systems considered eNBs having identical coverage area for deployment while in our paper, for beyond 4G standard HCNs considers distinct size of coverage area. In this paper, an uniform clustering algorithm is proposed for eNB deployment scheme where small low power cells like microcells and picocells are deployed along with the high power macro cells to improve the throughput and spectral efficiency with least cost.

In 4G and beyond 4G cellular communication systems, multi-hop relay network (MHR) plays a vital role. Improper deployment of relay station (RS) in MHR network creates some severe issues. The conventional studies on RS deployment have not considered the practical issue of link overloading. In this paper, a two-phase, fuzzy based selection and deployment scheme for RSs is proposed by considering link overloading issue. The study also analyses the trade-off between deployment budget, network throughput and overall service coverage. Simulation results show that the proposed scheme performs better than the conventional scheme.

Femto cell networks are becoming very popular in indoor home and small business environments. Femto cells will introduce more interference since all of them work on same frequency band. This limits the capacity of femto cell users. Femto cells may also introduce interference to macro cell users, this again reduces the capacity of Macro cell users. The interference has to be mitigated to improve the capacity of the users. In this work, Sleep mode activation based algorithm is proposed to mitigate the effect of co-tier and cross-tier interference. The simulation results prove that the proposed algorithm improves the Signal to Interference plus Noise Ratio (SINR) when compared no sleep mode based algorithms.

Purpose: To compare the intermediate-term refractive outcomes of a single-step and a two-step approach for silicone oil removal (SOR) and cataract surgery. Methods: Case records of patients who had SOR and phacoemulsification (PE) from 2011 to 2013 at a tertiary center in South India were retrospectively analyzed. A total of 135 eyes that underwent ultrasound biometry (UB) were studied. Eighty-seven eyes had SOR and PE at a single surgery (Group A), where as UB was done in a silicone oil (SO) filled eye. Forty-eight eyes had SOR followed by PE later (Group B), where UB was done in a fluid-filled eye. The refractive error (RE) and best-corrected visual acuity (BCVA) at postoperative day 45 (D45) and postoperative month 3 (M3) were compared. Results: Baseline axial length, intraocular lens (IOL) power, and RE in both groups were comparable. A myopic shift (4.18 ± 5.47 diopters [D]) was noted in 92% eyes at M3. Forty-nine percent eyes had a RE of ≤±1.5D at M3. RE at D45 and at M3 was significantly lesser in Group B (−1.73 ± 2.04 vs. −0.64 ± 1.75; P, 0.002). BCVA was significantly lesser in Group A at baseline, at D45, and at M3 (P < 0.01 for all). There was no difference in other baseline characteristics of eyes that had RE ≤±1.5D and those that had RE >±1.5D at M3. Conclusion: SO-filled eyes had a myopic shift in refraction after SOR and PE. When UB is used for IOL power calculation, better refractive outcomes are obtained when SOR and PE are performed in a two-step approach.