Jorge Baranda

Rapid prototyping of standard-compliant visible light communications system

This article describes the implementation of a prototype visible light communications system based on the IEEE 802.15.7 standard using low-cost commercial off-the-shelf analog devices. The aim of this article is to show that this standard provides a framework that could promote the introduction of applications into the market. Thus, these specifications could be further developed, reducing the gap between the industry and research communities. The implemented prototype makes use of software defined radio platforms to interface between the analog devices and the computer where the signal processing is performed. The use of this concept provides the system with enough flexibility and modularity to include new features in the prototype without requiring long development time.

An SDR implementation of a visible light communication system based on the IEEE 802.15.7 standard

The aim of this paper is to present an implementation of a functional IEEE 802.15.7 real-time testbed based on the Software Defined Radio (SDR) concept. This implementation is built with low cost commercial off-the-shelf (COTS) analog devices and the use of Universal Software Radio Peripheral version 2 (USRP2) equipment combined with a generic object-oriented framework that takes advantage of several open source software libraries. The prototype is validated in a controlled laboratory environment with an over-the-air measurement campaign.

Hierarchical SDN orchestration of wireless and optical networks with E2E provisioning and recovery for future 5G networks

This paper proposes the hierarchical SDN orchestration of heterogeneous wireless/optical networks. End-to-End connectivity services are provisioned through different network segments by means of a Transport API. The hierarchical approach allows scalability, modularity and more security.

A self-organized backpressure routing scheme for dynamic small cell deployments

The increase of demand for mobile data services requires a massive network densification. A cost-effective solution to this problem is to reduce cell size by deploying a low-cost all-wireless Network of Small Cells (NoS). These hyper-dense deployments create a wireless mesh backhaul among Small Cells (SCs) to transport control and data plane traffic. The semi-planned nature of SCs can often lead to dynamic wireless mesh backhaul topologies.This paper presents a self-organized backpressure routing scheme for dynamic SC deployments (BS) that combines queue backlog and geographic information to route traffic in dynamic NoS deployments. BS aims at relieving network congestion, while having a low routing stretch (i.e., the ratio of the hop count of the selected paths to that of the shortest path). Evaluation results show that, under uncongested conditions, BS shows similar performance to that of an Idealized Shortest PAth routing protocol (ISPA), while outperforming Greedy Perimeter Stateless Routing (GPSR), a state of the art geographic routing scheme. Under more severe traffic conditions, BS outperforms both GPSR and ISPA in terms of average latency by up to a 85% and 70%, respectively. We conducted ns-3 simulations in a wide range of sparse NoS deployments and workloads to support these performance claims.

A service-based model for the hybrid software defined wireless mesh backhaul of small cells

The backhaul of upcoming dense 5G Small Cell (SC) networks needs a full redesign, but there is no clear consensus on how to deploy such infrastructure. A low-cost backhaul solution is that provided by a wireless mesh network. Additionally, Software Defined Networking (SDN) is being considered as an alternative to distributed approaches to lower network infrastructure costs while enabling programmability and flexibility mostly for wired networks. This paper evolves the canonical SDN model by presenting a service-based hybrid SDN (hSDN) model that alleviates the problems caused by the unreliability of the in-band control channel formed by a wireless mesh backhaul between the SDN controller and the SCs. At the infrastructure level, we propose a wireless mesh backhaul combining sub-6GHz and millimeter wave links with long range microwave links. This architecture pursues the coexistence of network services located on top of a centralized SDN controller, with distributed network services, such as routing. To show the robustness of our proposed model, we compare a service-based hSDN model and a canonical SDN model under perfect control plane communication channel. In our service-based hSDN model, we further compare two distributed routing schemes used as fallback control plane mechanisms when the SDN controller is unreachable. Simulation results with ns-3 show improvements of up to 1.5x and 6x in terms of throughput and latency, respectively.

Prototyping with SDR: A quick way to play with next-gen communications systems

In this paper we present our approach regarding the implementation of new wireless radio receivers exploiting filterbank techniques, using a software-development driven approach. The fact that most of the common radio communication systems share a similar structure has been exploited to create a framework which provides a generic layout and tools to construct reconfigurable transmitters and/or receivers. By combining our own generic object-oriented framework built on top of the GNU Radio software framework with the use of the Universal Software Radio Peripheral version 2 (USRP2), we have been able to quickly implement a working proof of concept of an Uplink (UL) Filterbank Multicarrier (FBMC) receiver, both for Single-Input Single-Output (SISO) and Multiple-Input Multiple-Output (MIMO) scenario, within the 7th European framework project called PHYDYAS. As well, a description of the methodology we have applied from software engineering in order to build this demonstrator is herein included, which shows the suitability of using Software Defined Radio (SDR) technologies for fast prototyping of new wireless communication systems.

Experimental evaluation of self-organized backpressure routing in a wireless mesh backhaul of small cells

Small cells (SC) are low-power base stations designed to cope with the anticipated huge traffic growth of mobile communications. These increasing capacity requirements require the corresponding backhaul capacity to transport traffic from/to the core network. Since it is unlikely that fiber reaches every SC, a wireless mesh backhaul amongst SCs is expected to become popular. These low-cost deployments require to balance resource consumption amongst SCs, however, current routing protocols were not designed to fulfill this requirement. To tackle this challenge, we presented and developed with ns-3 a self-organized backpressure routing protocol (BP), designed to make the most out of the backhaul resources. This paper provides the evaluation of BP exploiting built in ns-3 emulation features to allow rapid prototyping under real-world conditions and through controlled ns-3 simulations. Through a novel evaluation methodology based on ns-3 emulation, we evaluate BP in a 12 SC indoor wireless mesh backhaul testbed under different wireless link rates and topologies, showing Packet Delivery Ratio (PDR) gains of up to 50% with respect to shortest path (SP). Through simulations, we show BP scalability properties with both the size of the backhaul and the number of backhaul radios per SC. Results in single- and multi-radio deployments show TCP traffic gains with BP of up to 79% and 95% compared to SP in terms of throughput and latency, respectively.

Efficiency improvement of human body detection with histograms of oriented gradients

In this paper we investigate improvements to the efficiency of human body detection using histograms of oriented gradients (HOG). We do this without compromising the performance significantly. This is especially relevant for embedded implementations in smart camera systems, where the on-board processing power and memory is limited. We focus on applications for indoor environments such as offices and living rooms. We present different experiments to reduce both the computational complexity as well as the memory requirements for the trained model. Since the HOG feature length is large, the total memory size needed for storing the model can become more than 50 MB. We use a feature selection based on Bayesian theory to reduce the feature length. Additionally we compare the performance of the full-body detector with an upper-body only detector. For computational complexity reduction we employ a ROI-based approach.

Towards a unified fronthaul-backhaul data plane for 5G The 5G-Crosshaul project approach

The paper presents a study of key aspects in the design of a flexible unified data plane capable of integrating both fronthaul and backhaul transport in future 5G systems. In this study, we first review candidate access and multiplexing technologies from the state of the art and assess their capability to support legacy and new fronthaul and backhaul traffic. We then propose a new design framework for the targeted flexible unified data plane, featuring a primary packet-switching path supported by an auxiliary circuit-switching for extreme low latency scenarios. This comprises a summary of the first results achieved in the 5G-Crosshaul EU project since its kick-off in July 2015.

BP-MR: Backpressure Routing for the Heterogeneous Multi-radio Backhaul of Small Cells

Dense small cell (SC) deployments are expected to help handling the explosive growth of mobile data usage. However, the backhaul of these deployments will face several challenges where point-to-point (PTP) and point-to-multipoint (PMP) wireless technologies will be combined forming multipoint-to-multipoint (MP2MP) wireless mesh backhauls. In this context, routing and load balancing solutions will be of key importance to maximize the use of wireless backhaul resources. This paper presents Backpressure for Multi-Radio (BP-MR), a distributed routing and load balancing protocol specifically designed for heterogeneous MP2MP wireless mesh backhauls. The backhaul is heterogeneous in the sense that each node may embed a different number of diverse wireless interfaces. BP-MR introduces a two-stage routing process to appropriately handle Head-of-Line blocking issues that appear in such multi-radio environments. We validate these improvements with ns-3 simulations under different network conditions. As a consequence of an improved wireless link usage efficiency, results show improvements in throughput of up to 34% and in latency of up to one order of magnitude with respect to state-of-the-art approaches.