Araştırma Çıktıları | WoS | Scopus | TR-Dizin | PubMed
Permanent URI for this communityhttps://hdl.handle.net/20.500.14719/1741
Browse
8 results
Search Results
Publication Metadata only MIMO systems with non-exact CSI, Eksik kanal bilgisi Altinda MIMO sistemler(2010) Soysal, Alkan; Soysal, Alkan, Bahçeşehir Üniversitesi, Istanbul, TurkeyMultiple antenna systems are known to provide very large data rates, when the perfect channel state information is available at the receiver. However, this requires the receiver to perform a noise-free, multi-dimensional channel estimation, without using communication resources. In practice, any channel estimation is noisy and uses system resources. We shall examine the trade-off between improving channel estimation and increasing the achievable data rate. Lower and upper bounds for the capacity of the system will be derived. ©2010 IEEE. © 2011 Elsevier B.V., All rights reserved.Publication Metadata only Comparison of LTE 800 MHz and LTE 2600 MHz frequency bands in terms of cell coverage, LTE 800 MHz ve LTE 2600 MHz frekans bantlarinin hücre kapsama bakimindan karşilaştirilmasi(2011) Tura, Ömer; Yüksel, Güray; Soysal, Alkan; Tura, Ömer, Bahçeşehir Üniversitesi, Istanbul, Turkey; Yüksel, Güray,; Soysal, Alkan, Bahçeşehir Üniversitesi, Istanbul, TurkeyIn this study, we compared 800 MHz and 2600 MHz bands in terms of cell coverage which will be used in 3GPP (Third generation Partnership Project) LTE (Long term Evolution) release 8. In RF planning, 800 MHz frequency band is used in the rural areas since coverage is crucial in such areas, and 2600 MHz frequency band is used in the urban areas in which capacity is more necessary than coverage. We used Atoll as an RF planning tool to simulate the two frequency bands for comparison in terms of coverage. The results are evaluated with respect to the furthest distance from the base station where the signal level threshold is obtained. © 2011 IEEE. © 2011 Elsevier B.V., All rights reserved.Publication Metadata only Energy efficiency in DF relay networks, Çöz-Ilet Aktarma Aǧlarinda Enerji Verimlilig ̌i(2013) Saimler, Merve; Soysal, Alkan; Saimler, Merve, Bahçeşehir Üniversitesi, Istanbul, Turkey; Soysal, Alkan, Bahçeşehir Üniversitesi, Istanbul, TurkeyEnergy efficiency in wireless networks has taken an important role in recent years due to the global climate change and growing demand for higher data rates. Cooperative communications might be efficient in improving coverage of a cell whereas it can also contribute to the energy efficiency of wireless systems with the help of its distributed structure. Improving the energy efficiency of a wireless system by using cooperative communications is the main objective of this paper. We analyze deployment strategies for decode-And-forward (DF) networks in order to minimize the power consumption of a cell. Deployment strategies include choosing relay locations and finding the optimum number of relays. We conclude by showing the effect of using a relay in a cellular system as opposed to direct transmission in terms of energy efficiency. © 2013 IEEE. © 2013 Elsevier B.V., All rights reserved.Publication Metadata only Energy efficiency in DF and AF relay networks, Çöz-ilet ve yükselt-ilet aktarma aǧlarinda enerji verimliliǧi(IEEE Computer Society [email protected], 2014) Saimler, Merve; Soysal, Alkan; Saimler, Merve, Bahçeşehir Üniversitesi, Istanbul, Turkey; Soysal, Alkan, Bahçeşehir Üniversitesi, Istanbul, TurkeyEnergy efficiency in wireless networks has taken an important role in recent years due to the global climate change and growing demand for higher data rates. Cooperative communications might be efficient in improving coverage of a cell whereas it can also contribute to the energy efficiency of wireless systems with the help of its distributed structure. Improving the energy efficiency of a wireless system by using cooperative communications is the main objective of this paper. We analyze deployment strategies for decode-and-forward (DF) and amplify-and-forward (AF) networks in order to minimize the power consumption of a cell. Deployment strategies include choosing relay locations and finding the optimum number of relays. We conclude by showing the effect of using a relay in a cellular system as opposed to direct transmission in terms of energy efficiency. © 2014 IEEE. © 2014 Elsevier B.V., All rights reserved.Publication Metadata only Energy efficient microcell deployment for HetNets, HetNet'lerde Enerji Verimli Mikro Hücre Yerleşimi(Institute of Electrical and Electronics Engineers Inc., 2015) Demirtaş, Mahmut; Soysal, Alkan; Demirtaş, Mahmut, Elektrik Ve Elektronik Mühendisliʇi Bölümü, Bahçeşehir Üniversitesi, Istanbul, Turkey; Soysal, Alkan, Elektrik Ve Elektronik Mühendisliʇi Bölümü, Bahçeşehir Üniversitesi, Istanbul, TurkeyDue to growing power consumption and data-rate demand in cellular networks, it is crucial to design the future networks with energy and spectral efficient strategies. Using heterogeneous networks (HetNets) is one possible way of improving energy and spectral efficiency in cellular networks. In this paper, under a coverage constraint, we consider deploying strategies of low power microcells in order to improve the energy and area spectral efficiencies of the conventional macrocell only cellular network. We observe that deploying microcells while keeping the coverage area the same, increases both energy and spectral efficiencies. Finally, we conclude that it is possible to determine a range of inter site distance (ISD) that maximizes the energy efficiency while providing the required traffic demand. © 2021 Elsevier B.V., All rights reserved.Publication Metadata only Energy and spectral efficient microcell deployment in heterogeneous cellular networks, Heterojen Hücresel Aǧlarda Enerji ve Spektral Verimli Mikro Hücre Yerleşimi(Institute of Electrical and Electronics Engineers Inc., 2016) Demirtaş, Mahmut; Soysal, Alkan; Demirtaş, Mahmut, Bahçeşehir Üniversitesi, Istanbul, Turkey; Soysal, Alkan, Bahçeşehir Üniversitesi, Istanbul, TurkeyWith the ubiquitous data-rate demand in cellular networks, total power consumption is growing rapidly. Thus, it is essential to design the future networks with energy and spectral efficient strategies. Using heterogeneous networks (HetNets) is one possible way of improving spectral and energy efficiencies in cellular networks. In this paper, under coverage ratio and area spectral efficiency constraints, we consider deploying strategies with low power small cells in order to improve the spectral and energy efficiencies of the conventional macrocell only cellular network. To compare the efficiencies of different scenarios, we employ area spectral efficiency and power consumption per bit criterion. As a result, we observe that deploying microcells increases both energy and spectral efficiencies. © 2017 Elsevier B.V., All rights reserved.Publication Metadata only Energy and spectral efficiency for heterogeneous cellular networks with stochastic deployment, Hücreleri Stokastik Yerleştirilmiş Heterojen Mobil Şebekeler için Enerji ve Spektral Verimlilik(Institute of Electrical and Electronics Engineers Inc., 2017) Demirtaş, Mahmut; Sagginda, Caggatay; Soysal, Alkan; Demirtaş, Mahmut, Bahçeşehir Üniversitesi, Istanbul, Turkey; Sagginda, Caggatay, Telefonaktiebolaget LM Ericsson, Stockholm, Sweden; Soysal, Alkan, Bahçeşehir Üniversitesi, Istanbul, TurkeyIn this paper, we investigate the energy efficiency and spectral efficiency of heterogeneous networks, where macro-cell and microcell base stations are deployed according to two separate stochastic geometry based processes. Here, micro base stations are placed over the regions for which the received signal strength is below a certain limit. By employing the deployment model we propose, we investigate the effects of certain parameters like macro and micro base station densities, and user density on energy efficiency of heterogeneous networks. The results show that deploying micro base stations considerably improves both energy efficiency and spectral efficiency in a dense user scenario. © 2017 Elsevier B.V., All rights reserved.Publication Metadata only Energy efficiency optimization of heterogeneous networks, Heterojen aǧlarda enerji verimliliǧi eniyilemesi(Institute of Electrical and Electronics Engineers Inc., 2018) Demirtaş, Mahmut; Soysal, Alkan; Demirtaş, Mahmut, Bahçeşehir Üniversitesi, Istanbul, Turkey; Soysal, Alkan, Bahçeşehir Üniversitesi, Istanbul, TurkeyIn this study, we aim to optimize the energy efficiency of a 2-tier heterogeneous cellular network that consists of macro and micro cells. We model macro and micro cell tiers by employing two separate stochastic processes. Then, we propose a constrained optimization problem, and show that the energy efficiency is a monotone increasing and a concave function of micro cell density. By using these characteristics, we offer a parametric solution for the energy efficiency problem. In addition, we simulate certain scenarios to verify our theoretical findings, and investigate the effects of macro cell density and area power consumption constraint on the optimum energy efficiency and the optimum micro cell density. © 2018 Elsevier B.V., All rights reserved.