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IEEE 802.11ad millimeter-wave (mm-wave) WLAN nodes achieve high throughput at the cost of the frequent re-steering requirement of highly directional antenna beams to establish and maintain links disrupted by beam misalignment, node mobility, or link blockage. Consequently, rapid and robust beamsteering algorithms are essential to enable seamless communication in mm-wave WLANs. In this paper we propose...
In this paper we study the performance of machine learning based signal classification approaches in realistic wireless environments. We focus in particular on impact of interference from modulated signals and influence of realistic wireless channel conditions on classification performance. For this we use both numerical simulations as well as software defined radio based implementations. We also...
Effective interference evaluation methods are crucial when making regulatory decisions about whether new wireless technologies should be allowed to operate. Such decisions are highly relevant for both DSA technologies in licensed bands and for technologies coexisting in unlicensed bands. In this paper we demonstrate the benefit of risk-informed interference assessment as an effective method that aids...
Designing distributed protocols with limited requirements for exchange of feedback information between the nodes is a key element in the development of cognitive and self-organizing ad hoc networks. We argue that the Minority Game (MG) and its variations can constitute useful tools towards this direction. In particular, the MG formulation is well suited for addressing a variety of resource allocation...
The millimeter-wave (mm-wave) bands are currently being explored for multi-Gbps wireless local area networks (WLANs). Directional antennas are required to overcome the high attenuation inherent at the mm-wave frequencies. However, directionality makes link maintenance and establishment tasks complex, especially under node mobility, as slight misalignment of antenna beams between nodes leads to link...
The abundance of unlicensed frequency resources in the mm-Wave frequency range, especially round 60 GHz bands, have a great potential to fulfill the increasing demands of high speed wireless applications. In mm-Wave wireless communication systems, directional transmission technologies become an inherent feature to compensate the high pathloss. The frame aggregation scheme is designed to maximize network...
The non-orthogonal multiple access (NOMA) has been investigated recently as a candidate radio access technology for the next generation mobile networks. It realizes powerdomain user multiplexing by employing the successive interference cancellation (SIC). This paper focuses on the power allocation and user set selection problems in multi-user downlink NOMA systems with the aim of providing proportional...
We present results from a detailed comparative study of the performance of three different frequency assignment schemes for interference management in heterogeneous LTE networks. Realistic indoor propagation models are used in order to obtain accurate results. We show that simple graph based frequency assignment schemes yield an excellent compromise between computational complexity and high performance...
Future 5G cellular networks are expected to exploit the abundant spectrum resources of the millimeter-wave (mm-wave) bands to satisfy demand for multi-Gbps mobile links anticipated by exponential data traffic growth. However, given the directional nature of mm-wave links, the feasibility of mm-wave mobile networks is critically dependent on efficient antenna beamsteering and a rich inventory of strong...
The non-orthogonal multiple access (NOMA) has been investigated recently as a candidate radio access technology in future mobile networks. It is able to implement power-domain user multiplexing based on successive interference cancellation (SIC). This paper focuses on the user pairing and power allocation problem in the 2-user NOMA system. The optimal solution in closed-form is derived with the proportional...
Accurate estimation of aggregate interference is crucial for understanding the potential capacity gains from densification of cells. In this paper we study the impact of three-dimensionality of femtocell deployments on both cross-tier and co-tier aggregate interference using realistic building data and accurate propagation models. Our results show that the three-dimensional character of urban femtocell...
Directional antennas in wireless networks can provide substantial performance gain and opportunities. In the case of high-frequency systems, such as emerging 60 GHz networks, they are inherent feature of the system design. In contrast to the traditional omni-directional antennas, directional antennas are capable of reducing the interference level, increasing the communication range, and improving...
Crosstalk between physically co-located lines is a pressing issue in VDSL2 access networks. In order to enhance the crosstalk mitigation capabilities of the latest extension to VDSL2, vectoring G.993.5, full control over all lines within the same cable binder is required. However, this is not always possible in practical deployments due to regulatory, structural, or late technology adoption constraints...
Due to the high expected increase in mobile data traffic and the scarcity of licensed spectrum for cellular networks, 3GPP has started preliminary work for standardizing LTE operation in the 5 GHz unlicensed band (LTE-U). However, LTE-U would interfere with other legacy technologies operating in the unlicensed band, the most important being contention-based Wi-Fi, which would be blocked by conventional...
To meet the rapidly growing requirement for universal coverage of high-speed mobile services, wireless cellular networks have been moving towards increasing density. Inter-cell cooperation in such densely deployed networks is becoming more significant than ever before. Among others, data rate estimation is a fundamental issue for inter-cell resource management and optimization. In this paper, we focus...
The large contiguous bandwidths available in the mm-wave frequency bands have recently started to gain significant attention due to the growing belief that it can alleviate the spectrum shortage at lower frequencies and meet the increasing high data rate demands. While some commercially available mm-wave transceivers in the 60 GHz and 70 GHz bands have been developed, only a few studies exist on the...
The estimation of IEEE 802.11 Wi-Fi access point (AP) densities is an important cornerstone in deriving accurate models for the deployment structure of opportunistic wireless networks. Such densities are usually derived through large-scale wardriving-like measurement campaigns with COTS devices. Due to shielding, limited receiver sensitivity, and sampling density constraints, in general only a subset...
Due to the significant increase in mobile data traffic volume during the last few years, offloading techniques have been considered for alleviating the traffic load from cellular networks. Two principal small cell offloading solutions are LTE femtocells and Wi-Fi. Femtocells are low power user-deployed LTE base stations that overlay the macro-cellular network and share its licensed spectrum, whereas...
In this paper we analyze the potential use of underutilized TV frequencies to enable high-speed hotspots and data offloading in trains. We propose a system where the hotspots connect via TV frequencies to base stations that are located at the train stations. Using data from the railway network of Germany and detailed spectrum availability information we carry out a performance analysis for various...
Femtocell networks have emerged as an important means of offloading traffic from today's LTE cellular networks. However, deploying LTE femtocells increases the interference in the network, as they share licensed spectrum with the macro-cellular network. Consequently, a wide range of interference mitigation techniques have been proposed to enable coexistence of femtocells and macrocells. Techniques...
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