Femtocell Networks Ismail Guvenc

Femtocells are small cellular base stations that may be deployed in residential, enterprise, or outdoor areas. They utilize the available broadband connections of the users (e.g., cable or DSL) and typically have a coverage radius on the order of ten meters or more. Due to their various advantages, recently there has been a growing interest in femtocell networks both in academia and in industry. Two of the main advantages of these networks include staggering capacity gains for next generation broadband wireless communication systems and the elimination of the dead-spots in a macrocellular network. Due to very short communication distances, femtocell networks offer significantly better signal qualities compared to the current cellular networks. This makes high-quality voice communications and high data rate multimedia type of applications possible in indoor environments. Small-size coverage also implies a reasonably accurate location capability without any sophisticated positioning protocol, which implies a wide range of promising applications within the domain of location-based services. Despite several benefits, this new type of technology also comes with its own challenges, and there are important technical problems that need to be addressed for successful deployment and operation of these networks. Standardization efforts related to femtocell networks in 3GPP and IEEE are ongoing with full speed. In the meanwhile, there is also a growing interest in the academia towards fully exploiting the benefits of this promising technology. The goal of this special issue was to solicit high-quality unpublished research papers on design, evaluation, and performance analysis of femtocell networks. Based on the submitted manuscripts, eight manuscripts have been accepted, which will be summarized briefly in this editorial letter. Probably the most important problem in femtocell networks is the presence of interference between neighboring femtocell networks and between the femtocell networks and the macrocell network. Our special issue opens with two papers that investigates the interference characteristics in femtocell networks. In " On uplink interference scenarios in two-tier networks " , the authors Z. Shi et al. investigate uplink interference characteristics in a two-tier UMTS networks where a large number of femtocells are randomly deployed in the coverage area of a macrocellular network sharing the same carrier. Two severe interference scenarios are analyzed using simulations and it is shown that under these conditions both the femtocell and macrocell throughput is significantly reduced if no interference mitigation techniques are employed. In addition different interference mitigation techniques are discussed that can help to reduce …