Programming Abstractions for Software–Defined Wireless Networks

Software-Defined Networking (SDN) has received, in the last years, significant interest from the academic and the industrial communities alike. The decoupled control and data planes found in an SDN allows for logically centralized intelligence in the control plane and generalized network hardware in the data plane. Although the current SDN ecosystem provides a rich support for wired packet-switched networks, the same cannot be said for wireless networks where specific radio data-plane abstractions, controllers, and programming primitives are still yet to be established. In this work, we present a set of programming abstractions modeling the fundamental aspects of a wireless network, namely state management, resource provisioning, network monitoring, and network reconfiguration. The proposed abstractions hide away the implementation details of the underlying wireless technology providing programmers with expressive tools to control the state of the network. We also present a Software-Defined Radio Access Network Controller for Enterprise WLANs and a Python--based Software Development Kit implementing the proposed abstractions. Finally, we experimentally evaluate the usefulness, efficiency and flexibility of the platform over a real 802.11-based WLAN

Tidewater glaciers as “climate refugia” for zooplankton-dependent food web in Kongsfjorden, Svalbard

With climate warming, many tidewater glaciers are retreating. Fresh, sediment-rich sub-glacial meltwater is discharged at the glacier grounding line, where it mixes with deep marine water resulting in an upwelling of a plume visible in front of the glacial wall. Zooplankton may suffer increased mortality within the plume due to osmotic shock when brought in contact with the rising meltwater. The constant replenishment of zooplankton and juvenile fish to the surface areas attracts surface-foraging seabirds. Because access to other feeding areas, such as the marginal ice zone, has become energetically costly due to reduced sea-ice extent, glacial plumes may become increasingly important as “climate refugia” providing enhanced prey availability. Here, we investigated zooplankton concentrations within the plume and adjacent waters of four tidewater glaciers in Kongsfjorden, Svalbard, in early August 2016 and late July 2017. Our aim was to compare the zooplankton composition, abundance, and isotopic signatures within the plumes to those in adjacent fjord and shelf waters. Our hypothesis was that the plumes resulted in increased zooplankton mortality through osmotic shock and increased prey availability to predators. The mortality due to osmotic shock in the glacial plume was low (<5% dead organisms in samples), although slightly higher than in surrounding waters. This indicates that plumes are inefficient “death traps” for zooplankton. However, the high abundance and biomass of zooplankton within plume areas suggest that the “elevator effect” of rising glacial water supplies zooplankton to the sea surface, thereby enhancing prey availability for surface-feeding seabirds. Thus, our study provides evidence that glacial plumes are important as “climate refugia” for foraging seabirds. Stable isotope signatures showed that the glacial bay zooplankton and fish community represent a distinct isotopic niche. Additionally, zooplankton mortality associated with the plume estimated over 100-days of melt season supports a flux of 12.8 tonnes of organic carbon to benthic communities in the glacial bays. Benthic scavengers, such as Onisimus caricus and Anonyx nugax, were abundant in the glacial bay, where they feed on sinking organic matter.publishedVersio

CU Placement over a Reconfigurable Wireless Fronthaul in 5G Networks with Functional Splits

Mobile network operators are currently facing a tremendous increase in the level of data traffic. Although cell size reduction is one of the most common ways used to accommodate such traffic demand, densely deployed small cells also dramatically increase the level of intercell interference. By centralizing baseband signal processing at powerful computing infrastructures, called centralized unit (CU) pools, cloud radio access network (C‐RAN) enables advanced coordination algorithms to be employed in dense small cell networks. In C‐RAN, due to stringent bandwidth and latency requirements at the fronthaul links, the optical fiber, thanks to its bandwidth and latency characteristics, continues to be the most prevalent fronthaul medium option. Nevertheless, the optical fiber is one of the fronthaul options, while C‐RAN (physical layer radio frequency [PHY‐RF] split) is one of the functional splits that can be defined each coming with different fronthaul requirements. In this paper, we formulate and solve a dynamic CU placement problem for mobile networks as an integer linear programming (ILP) problem. In the considered network, CU pools are placed at the edges of the network, and a reconfigurable millimeter wave (MMW) wireless fronthaul links are used in order to provide decentralized units (DUs) with connectivity. We study the impact of different functional splits on the placement cost and on the acceptance ratio using different substrate networks. Lastly, we propose and evaluate a CU placement heuristic algorithm using a numerical simulator. The results reveal that the optimal functional split selection can lead to significant resource utilization benefits in the RAN

6G-LEGO: A framework for 6G network slices

International audienceNetwork slicing is a relatively recent paradigm that has become a subject of intensive research. Most of the existing approaches follow the ETSI NFV MANO model with some extensions related to multi-domain slicing, slice selection, etc. The framework is a part of the standalone variant of the 5G network standardized by 3GPP. However, the current implementation of network slicing in 5G has several limitations, especially regarding management and orchestration: The isolation of slice management is not appropriately addressed, the slice tenant management capabilities are limited, and the management and orchestration centralization raises serious scalability and reliability issues. Moreover, the slice-level operations are not well-separated from other processes due to a lack of proper separation of concerns. As a result, the overall network slicing architecture has complex interactions with many components of the 5G network. In this paper, we describe a new framework that uses an approach to sustain self-managed and self-orchestrated slices. To that end, we propose a modular architecture in which slices have embedded (in-slice) management and orchestration support, and multi-domain slices rely on multiple slice-agnostic orchestrators. The framework enables the composition of new slices as a combination of single domain-slices in a relatively easy, technology-independent manner

Up in the clouds: A taxonomical analysis of network management functionalities from a network as a service perspective

The externalization of network control and maintenance tasks, enabled by the emerging Networking as a Service (NaaS) paradigm, is an appealing opportunity for large Telcos to expand their network management offering to SMEs. In this paper we propose an architecture for network control and management capable of efficiently supporting the NaaS paradigm. Our methodology is based on a set of orthogonal requirements that forms the platform to assess the admissibility of different network management functions in the remote management plane. Such assessments are realized based on the taxonomical evaluation of the management functions classified according to the requirements they impose on the remote management plane in terms of security and robustness. Experimental results obtained from a proof-of-concept implementation deployed over a large scale testbed composed of about 500 WiFi Access Points shows that the signaling traffic for a practical implementation supporting not trivial autonomic control loops is lower that 20 bytes/s for each node. Moreover, the latency to execute administrative actions is in most cases in the order of 70 ms

SWAN: Base-band units placement over reconfigurable wireless front-hauls

International audienc