15 research outputs found
Fundamental Limits on Latency in Transceiver Cache-Aided HetNets
Stringent mobile usage characteristics force wire- less networks to undergo a
paradigm shift from conventional connection-centric to content-centric
deployment. With respect to 5G, caching and heterogeneous networks (HetNet) are
key technologies that will facilitate the evolution of highly content- centric
networks by facilitating unified quality of service in terms of low-latency
communication. In this paper, we study the impact of transceiver caching on the
latency for a HetNet consisting of a single user, a receiver and one
cache-assisted transceiver. We define an information-theoretic metric, the
delivery time per bit (DTB), that captures the delivery latency. We establish
coinciding lower and upper bounds on the DTB as a function of cache size and
wireless channel parameters; thus, enabling a complete characterization of the
DTB optimality of the network under study. As a result, we identify cache
beneficial and non-beneficial channel regimes.Comment: 5 pages, ISIT 201
Delivery Time Minimization in Edge Caching: Synergistic Benefits of Subspace Alignment and Zero Forcing
An emerging trend of next generation communication systems is to provide
network edges with additional capabilities such as additional storage resources
in the form of caches to reduce file delivery latency. To investigate this
aspect, we study the fundamental limits of a cache-aided wireless network
consisting of one central base station, transceivers and receivers from
a latency-centric perspective. We use the normalized delivery time (NDT) to
capture the per-bit latency for the worst-case file request pattern at high
signal-to-noise ratios (SNR), normalized with respect to a reference
interference-free system with unlimited transceiver cache capabilities. For
various special cases with and that satisfy , we establish the optimal tradeoff between cache storage and latency. This
is facilitated through establishing a novel converse (for arbitrary and
) and an achievability scheme on the NDT. Our achievability scheme is a
synergistic combination of multicasting, zero-forcing beamforming and
interference alignment.Comment: submitted to ICC 2018; fixed some typo
A Survey on Robust Interference Management in Wireless Networks
Recent advances in the characterization of fundamental limits on interference management in wireless networks and the discovery of new communication schemes on how to handle interference led to a better understanding towards the capacity of such networks. The benefits in terms of achievable rates of powerful schemes handling interference, such as interference alignment, are substantial. However, the main issue behind most of these results is the assumption of perfect channel state information at the transmitters (CSIT). In the absence of channel knowledge the performance of various interference networks collapses to what is achievable by time division multiple access (TDMA). Robustinterference management techniques are promising solutions to maintain high achievable rates at various levels of CSIT, ranging from delayed to imperfect CSIT. In this survey, we outline and study two main research perspectives of how to robustly handle interference for cases where CSIT is imprecise on examples for non-distributed and distributed networks, namely broadcast and X-channel. To quantify the performance of these schemes, we use the well-known (generalized) degrees of freedom (GDoF) metric as the pre-log factor of achievable rates. These perspectives maintain the capacity benefits at similar levels as for perfect channel knowledge. These two perspectives are: First,scheme-adaptationthat explicitly accounts for the level of channel knowledge and, second,relay-aided infrastructure enlargementto decrease channel knowledge dependency. The relaxation on CSIT requirements through these perspectives will ultimately lead to practical realizations of robust interference management techniques. The survey concludes with a discussion of open problems
Interference management in wireless caching and distributed computing
Interferenzhandhabung ist ein wichtiges Instrument zur Optimierung von zukünftigen Kommunikationssystemen. Statt jedem Nutzer einen individuellen Zugang zu Funkressourcen zu gewähren, müssen zukünftige Systeme aufgrund der Knappheit der Frequenzzuteilungen, Interferenz in Kauf nehmen. Dies führt zu dem Irrglauben das Interferenz grundsätzlich schädlich ist. In bestimmten Applikationen kann Interferenz jedoch als etwas Nützliches betrachtet werden. Beispiele sind Situationen, in denen Interferenzen für die Enkodierung und Dekodierung als Zusatzinformationen dienen, oder wenn Interferenzen als Rauschquellen für sicherheitsrelevante Applikationen genutzt werden. In dieser Dissertation greifen wir auf diese Situationen zurück und betrachten zu diesem Zweck die Problemstellungen des Cachings und der sicheren, verteilten Matrixmultiplikation. Dazu nutzen wir informationstheoretische Methoden, um optimale Kodierungsstrategien im Hinblick auf Ressourcenausnutzung zu entwickeln
A survey on robust interference management in wireless networks
Recent advances in the characterization of fundamental limits on interference management in wireless networks and the discovery of new communication schemes on how to handle interference led to a better understanding towards the capacity of such networks. The benefits in terms of achievable rates of powerful schemes handling interference, such as interference alignment, are substantial. However, the main issue behind most of these results is the assumption of perfect channel state information at the transmitters (CSIT). In the absence of channel knowledge the performance of various interference networks collapses to what is achievable by time division multiple access (TDMA). Robustinterference management techniques are promising solutions to maintain high achievable rates at various levels of CSIT, ranging from delayed to imperfect CSIT. In this survey, we outline and study two main research perspectives of how to robustly handle interference for cases where CSIT is imprecise on examples for non-distributed and distributed networks, namely broadcast and X-channel. To quantify the performance of these schemes, we use the well-known (generalized) degrees of freedom (GDoF) metric as the pre-log factor of achievable rates. These perspectives maintain the capacity benefits at similar levels as for perfect channel knowledge. These two perspectives are: First,scheme-adaptationthat explicitly accounts for the level of channel knowledge and, second,relay-aided infrastructure enlargementto decrease channel knowledge dependency. The relaxation on CSIT requirements through these perspectives will ultimately lead to practical realizations of robust interference management techniques. The survey concludes with a discussion of open problems