Topology control for wireless networks with highly-directional antennas

In order to steer antenna beams towards one another for communication, wireless nodes with highly-directional antennas must track the channel state of their neighbors. To keep this overhead manageable, each node must limit the number of neighbors that it tracks. The subset of neighbors that each node chooses to track constitutes a network topology over which traffic can be routed. We consider this topology design problem, taking into account channel modeling, transmission scheduling, and traffic demand. We formulate the optimal topology design problem, with the objective of maximizing the scaling of traffic demand, and propose a distributed method, where each node rapidly builds a segment of the topology around itself by forming connections with its nearest neighbors in discretized angular regions. The method has low complexity and message passing overhead. The resulting topologies are shown to have desirable structural properties and approach the optimal solution in high path loss environments.National Science Foundation (U.S.) (Grant CNS-1524317)National Science Foundation (U.S.) (Grant CNS-1116209)National Science Foundation (U.S.) (Grant AST-1547331)United States. Air Force (Contract FA8721-05-C-0002

Whether and Where to Code in the Wireless Relay Channel

The throughput benefits of random linear network codes have been studied extensively for wirelined and wireless erasure networks. It is often assumed that all nodes within a network perform coding operations. In energy-constrained systems, however, coding subgraphs should be chosen to control the number of coding nodes while maintaining throughput. In this paper, we explore the strategic use of network coding in the wireless packet erasure relay channel according to both throughput and energy metrics. In the relay channel, a single source communicates to a single sink through the aid of a half-duplex relay. The fluid flow model is used to describe the case where both the source and the relay are coding, and Markov chain models are proposed to describe packet evolution if only the source or only the relay is coding. In addition to transmission energy, we take into account coding and reception energies. We show that coding at the relay alone while operating in a rateless fashion is neither throughput nor energy efficient. Given a set of system parameters, our analysis determines the optimal amount of time the relay should participate in the transmission, and where coding should be performed.Comment: 11 pages, 12 figures, to be published in the IEEE JSAC Special Issue on Theories and Methods for Advanced Wireless Relay

An overview of the CPRI specification and its application to C-RAN-based LTE scenarios

The CPRI specification has been introduced to enable the communication between radio equipment and radio equipment controllers, and is of particular interest for mobile operators willing to deploy their networks following the novel cloud radio access network approach. In such a case, CPRI provides an interface for the interconnection of remote radio heads with a baseband unit by means of the so-called fronthaul network. This article presents the CPRI specification, its concept, design, and interfaces, provides a use case for fronthaul dimensioning in a realistic LTE scenario, and proposes some interesting open research challenges in the next-generation 5G mobile network.The authors would like to acknowledge the support of projects CRAMnet (grant no. TEC2012-38362-C03-01) and EU H2020 5G-Crosshaul Project (grant no. 671598) to the development of this work.European Commissio