Interference management for self-organized femtocells towards green networks
ABSTRACT The femtocell concept is an emerging technology for deploying the next generation of the wireless networks, aiming at indoor coverage enhancement, increasing capacity and offloading the overlay macrocell traffic. One of the main challenges in short range femtocell networks is how to (re)configure the Home Node Bs (HNBs) in an autonomous manner so as to manage interference and diminish the energy consumption among nearby femtocells efficiently. In this paper, we investigate the indoor femtocell deployment making use of both the Frequency Division Duplexing (FDD) and the Time Division Duplexing (TDD) methods. In the FDD case, the HNBs share both the Uplink (UL) and Downlink (DL) channels with the macrocell without any cooperation to coordinate their access to the air interface. Conversely, in the TDD underlay case, femtocells only reuse the macrocell UL spectrum and cooperate with each other in order to minimize the interference among themselves, either with or without further coordination with the Macro User Equipment (MUE). The proposed solution is evaluated by means of system-level simulations using the Monte Carlo approach. Investigations have shown that the TDD underlay approach not only reduces the perceived interference levels, but also diminishes the outage probability.
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Article: Femtocell networks: a survey[show abstract] [hide abstract]
ABSTRACT: The surest way to increase the system capacity of a wireless link is by getting the transmitter and receiver closer to each other, which creates the dual benefits of higher-quality links and more spatial reuse. In a network with nomadic users, this inevitably involves deploying more infrastructure, typically in the form of microcells, hot spots, distributed antennas, or relays. A less expensive alternative is the recent concept of femtocells - also called home base stations - which are data access points installed by home users to get better indoor voice and data coverage. In this article we overview the technical and business arguments for femtocells and describe the state of the art on each front. We also describe the technical challenges facing femtocell networks and give some preliminary ideas for how to overcome them.IEEE Communications Magazine 10/2008; · 3.66 Impact Factor
- Bell Labs Technical Journal. 01/2008; 13:221-245.
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ABSTRACT: In cognitive radio (CR) networks, a secondary CR network borrows spectrum bands from primary networks for the purpose of improving spectrum efficiency. In this paper, we present a model in which a secondary network uses uplink sub-carriers by borrowing from a primary network in OFDM-based systems. We show optimization formulation and propose allocation algorithms for the model. Performance of proposed algorithms is evaluated by simulations. We can conclude that our CR network can be used to improve the utilization of precious bandwidth resource.Innovations in Information Technology, 2007. IIT '07. 4th International Conference on; 12/2007