MAC–Engine: a new architecture for executing MAC algorithms on commodity WiFi hardware

In this demo, we prove that the flexibility supported by off–the–shelf IEEE 802.11 hardware can be significantly ex- tended if we move the control of the MAC programming interface from the driver to the firmware, i.e. from the host CPU to the card CPU. To this purpose, we introduce the concept of MAC–Engine, that is an executor of Pro- grammable Finite State Machines (PFSM) implemented at the firmware level: we show how the card itself can support different protocol logics thanks to PFSM bytecode repre- sentations that can be dynamically injected inside the card memory at run-time without incurring in down time issues or network disconnect events. We provide different PFSM examples in order…

Learning from Errors: Detecting ZigBee Interference in WiFi Networks

In this work we show how to detect ZigBee interference on commodity WiFi cards by monitoring the reception errors, such as synchronization errors, invalid header formats, too long frames, etc., caused by ZigBee transmissions. Indeed, in presence of non-WiFi modulated signals, the occurrence of these types of errors follows statistics that can be easily recognized. Moreover, the duration of the error bursts depends on the transmission interval of the interference source, while the error spacing depends on the receiver implementation. On the basis of these considerations, we propose the adoption of hidden Markov chains for characterizing the behavior of WiFi receivers in presence of controlle…

Supporting code mobility and dynamic reconfigurations over Wireless MAC Processor Prototype

Mobile networks for Internet Access are a fundamental segment of Internet access net- works, where resource optimization are really critical because of the limited bandwidth availability. While traditionally resource optimizations have been focused on high effi- cient modulation and coding schemes, to be dynamically tuned according to the wireless channel and interference conditions, it has also been shown how medium access schemes can have a significant impact on the network performance according to the application and networking scenarios. This thesis work proposes an architectural solution for supporting Medium Access Con- trol (MAC) reconfigurations in terms of dynamic programming and c…

MAC design on real 802.11 devices: From exponential to Moderated Backoff

In this paper we describe how a novel backoff mechanism called Moderated Backoff (MB), recently proposed as a standard extension for 802.11 networks, has been prototyped and experimentally validated on a commercial 802.11 card before being ratified. Indeed, for performance reasons, the time critical operations of MAC protocols, such as the backoff mechanism, are implemented into the card hardware/firmware and cannot be arbitrarily changed by third parties or by manufacturers only for experimental reasons. Our validation has been possible thanks to the availability of the so called Wireless MAC Processor (WMP), a prototype of a novel wireless card architecture in which MAC protocols can be p…

Learning From Errors: Detecting Cross-Technology Interference in WiFi Networks

In this paper, we show that inter-technology interference can be recognized using commodity WiFi devices by monitoring the statistics of receiver errors. Indeed, while for WiFi standard frames the error probability varies during the frame reception in different frame fields (PHY, MAC headers, and payloads) protected with heterogeneous coding, errors may appear randomly at any point during the time the demodulator is trying to receive an exogenous interfering signal. We thus detect and identify cross-technology interference on off-the-shelf WiFi cards by monitoring the sequence of receiver errors (bad PLCP, bad FCS, invalid headers, etc.) and propose two methods to recognize the source of in…

Designing the 5G network infrastructure: a flexible and reconfigurable architecture based on context and content information

5G networks will have to offer extremely high volumes of content, compared to those of today’s. Moreover, they will have to support heterogeneous traffics, including machine-to-machine, generated by a massive volume of Internet-of-Things devices. Traffic demands will be variable in time and space. In this work, we argue that all this can be achieved in a cost-effective way if the network is flexible and reconfigurable. We present the Flex5Gware network architecture, designed to meet the above requirements. Moreover, we discuss the links between flexibility and reconfigurability, on the one side, and context awareness and content awareness, on the other; we show how two of the building…

MAC-Engine

In this demo, we prove that the flexibility supported by off-the-shelf IEEE 802.11 hardware can be significantly extended if we move the control of the MAC programming interface from the driver to the firmware, i.e. from the host CPU to the card CPU. To this purpose, we introduce the concept of MAC--Engine, that is an executor of Programmable Finite State Machines (PFSM) implemented at the firmware level: we show how the card itself can support different protocol logics thanks to PFSM bytecode representations that can be dynamically injected inside the card memory at run-time without incurring in down time issues or network disconnect events. We provide different PFSM examples in order to t…

Demo - MAC learning: Enabling automatic combination of elementary protocol components

Cognition as a way to deal with the challenges of future wireless networks has been largely considered by the recent literature, with a main focus on physical layer adaptability and dynamic spectrum access. In this demo, we show how a simple cognition mechanism can be also applied at the MAC layer, by exploiting the emerging paradigm of programmable wireless cards. The idea is using the formal definition of simple MAC protocol components and platform-independent representation of channel events gathered from the wireless node, for emulating the behavior of protocols which are not currently running on the network, learning about their expected performance, and dynamically reconfiguring the w…

Exploring Training Options for RF Sensing Using CSI

This work analyzes human behavior recognition approaches using WiFi channel state information from the perhaps less usual point of view of training and calibration needs. With the help of selected literature examples, as well as with more detailed experimental insights on our own Doppler spectrum-based approach for physical motion/presence/cardinality detection, we first classify the diverse forms of training so far employed into three main categories (trained, trained-once, and training-free). We further discuss under which conditions it is possible to move toward lighter forms of calibration or even succeed in devising fully untrained model-based solutions. Our take home messages are main…

Enabling a win-win coexistence mechanism for WiFi and LTE in unlicensed bands

The problem of WiFi and LTE coexistence has been significantly debated in the last years, with the emergence of LTE extensions enabling the utilization of unlicensed spectrum for carrier aggregation. Since the two technologies employ com-pletely different access protocols and frame transmission times, supporting coexistence with minimal modifications on existing protocols is not an easy task. Current solutions are often based on LTE unilateral adaptations, being LTE in unlicensed bands still under definition. In this paper, we demonstrate that it is possible to avoid a subordinated role for WiFi nodes, by simply equipping WiFi nodes with a sensing mechanism based on adaptive tunings of the …

Wireless MAC processors: programming MAC protocols on commodity hardware

Programmable wireless platforms aim at responding to the quest for wireless access flexibility and adaptability. This paper introduces the notion of wireless MAC processors. Instead of implementing a specific MAC protocol stack, Wireless MAC processors do support a set of Medium Access Control “commands” which can be run-time composed (programmed) through software-defined state machines, thus providing the desired MAC protocol operation. We clearly distinguish from related work in this area as, unlike other works which rely on dedicated DSPs or programmable hardware platforms, we experimentally prove the feasibility of the wireless MAC processor concept over ultra-cheap commodity WLAN hardw…

WMPS: A Positioning System for Localizing Legacy 802.11 Devices

The huge success of location-aware applications calls for the quick development of a positioning system alternative to GPS for indoor localization based on existing technologies such as 802.11 wireless networks. In this paper we propose WMPS, the Wireless MAC Processor Positioning System, that is a localization system running on off-the-shelf 802.11 Access Points and based on time-of-flight ranging of users’ standard terminals. We prove through extensive experiments that propagation delays can be measured with the accuracy required by indoor applications despite the different noise components that can affect the result, like latencies of the hardware transreceivers, multi- path, ACK jitters…

Enabling Cognitive-Radio Paradigm on Commercial Off-The-Shelf 802.11 Hardware

Cognitive Radio paradigm (CR) has been recognized as key enabler for next generation wireless networking: the pos- sibility to access the limited radio spectrum in an oppor- tunistic manner allows secondary users to boost their trans- mission performance without interfering with existing pri- mary networks. Full testing and experimenting with this paradigm, however, is still a tough task, given either the i) limited capabilities above the PHY layer of cheap SDR so- lutions, or the ii) heavy investment required for setting up multi-node testbeds powered by FPGAs. In this demo we show how we leveraged our Wireless MAC Processor archi- tecture to tackle the two issues at the same time, providi…

DEMO: Unconventional WiFi-ZigBee communications without gateways

Nowadays, the overcrowding of ISM bands is becoming an evident limitation for the performance and widespread usage of 802.11 and 802.15.4 technologies. In this demo, we prove that it is possible to opportunistically exploit the inter-technology interference between 802.11 and 802.15.4 to build an unconventional low-rate communication channel and signalling protocol, devised to improve the performance of each contending technology. Differently from previous solutions, inter-technology communications do not require the deployment of a gateway with two network interfaces, but can be activated (when needed) directly between two heterogeneous nodes, e.g. a WiFi node and a ZigBee node. This capab…

A Navigation and Augmented Reality System for Visually Impaired People

In recent years, we have assisted with an impressive advance in augmented reality systems and computer vision algorithms, based on image processing and artificial intelligence. Thanks to these technologies, mainstream smartphones are able to estimate their own motion in 3D space with high accuracy. In this paper, we exploit such technologies to support the autonomous mobility of people with visual disabilities, identifying pre-defined virtual paths and providing context information, reducing the distance between the digital and real worlds. In particular, we present ARIANNA+, an extension of ARIANNA, a system explicitly designed for visually impaired people for indoor and outdoor localizati…

Privacy-Preserving Overgrid: Secure Data Collection for the Smart Grid

In this paper, we present a privacy-preserving scheme for Overgrid, a fully distributed peer-to-peer (P2P) architecture designed to automatically control and implement distributed Demand Response (DR) schemes in a community of smart buildings with energy generation and storage capabilities. To monitor the power consumption of the buildings, while respecting the privacy of the users, we extend our previous Overgrid algorithms to provide privacy preserving data aggregation (PP-Overgrid). This new technique combines a distributed data aggregation scheme with the Secure Multi-Party Computation paradigm. First, we use the energy profiles of hundreds of buildings, classifying the amount of &ldquo

An Inter-Technology Communication Scheme for WiFi/ZigBee Coexisting Networks

In this paper we show how inter-technology interference can be exploited to set-up a low-rate bi-directional communication channel between heterogeneous technologies, which coexist in ISM bands. In particular, we focus on WiFi and ZigBee networks, whose high density deployments make coexistence a critical issue. We monitor the transmission duration of the interference and, after recognizing ZigBee interference from WiFi off-the-shelf receivers, we precisely measure the channel busy intervals to map time duration to communication symbols. A similar approach is used on the ZigBee receivers for making the communication channel bidirectional. Extensive experimental results show the feasibility …

Performance of LoRa for Bike-Sharing Systems

Today bike sharing systems are becoming popular in many cities as short-distance transit vehicles. More than 18 million bicycles are available worldwide for public use and one of the main problems that afflicts such sharing systems is the loss of bikes, which can be stolen or simply left in unknown locations. Thus, many bikes are docked or tracked using GPS and costly cellular connections. In this paper, we consider the emerging Long Range (LoRa) technology for use in bike sharing systems. LoRa exploits free ISM bands and has been conceived for low power and low data rate applications. Additionally, LoRa is characterized by large cells and heterogeneous application domains, which may lead t…

Wireless MAC Processor Networking: A Control Architecture for Expressing and Implementing High-Level Adaptation Policies in WLANs

The current proliferation of unplanned wireless local area networks (WLANs) is creating the need for implementing different adaptation strategies to improve network performance under mutating and evolving interference scenarios. In this article, we envision a new solution for expressing and implementing high-level adaptation policies in WLANs, in contrast to the current approaches based on vendor-specific implementations. We exploit the hardware abstraction interface recently proposed by the wireless medium access control (MAC) processor (WMP) architecture and some flow-control concepts similar to the Openflow model for defining MAC adaptation policies. A simple control architecture for dis…

Interference Cancellation for LoRa Gateways and Impact on Network Capacity

In this paper we propose LoRaSyNc (LoRa receiver with SyNchronization and Cancellation), a second generation LoRa receiver that implements Successive Interference Cancellation (SIC) and time synchronization to improve the performance of LoRa gateways. Indeed, the chirp spread spectrum modulation employed in LoRa experiences very high capture probability, and cancelling the strongest signal in case of collisions can significantly improve the cell capacity. An important feature of LoRaSyNc is the ability to track the frequency and clock drifts between the transmitter and receiver, during the whole demodulation of the interfered frame. Due to the use of low-cost oscillators on end-devices, a s…

MAClets: Active MAC Protocols over hard-coded devices

We introduce MAClets, software programs uploaded and executed on-demand over wireless cards, and devised to change the card's real-time medium access control operation. MAClets permit seamless reconfiguration of the MAC stack, so as to adapt it to mutated context and spectrum conditions and perform tailored performance optimizations hardly accountable by an once-for-all protocol stack design. Following traditional active networking principles, MAClets can be directly conveyed within data packets and executed on hard-coded devices acting as virtual MAC machines. Indeed, rather than executing a pre-defined protocol, we envision a new architecture for wireless cards based on a protocol interpr…

Error-Based Interference Detection in WiFi Networks

In this paper we show that inter-technology interference can be recognized by commodity WiFi devices by monitoring the statistics of receiver errors. Indeed, while for WiFi standard frames the error probability varies during the frame reception in different frame fields (PHY, MAC headers, payloads) protected with heterogeneous coding, errors may appear randomly at any point during the time the demodulator is trying to receive an exogenous interfering signal. We thus detect and identify cross-technology interference on off-the-shelf WiFi cards by monitoring the sequence of receiver errors (bad PLCP, bad PCS, invalid headers, etc.) and develop an Artificial Neural Network (ANN) to recognize t…

Cross-Technology WiFi/ZigBee Communications: Dealing With Channel Insertions and Deletions

In this letter, we show how cross-technology interference can be exploited to set up a low-rate bidirectional communication channel between heterogeneous WiFi and ZigBee networks. Because of the environment noise and receivers' implementation, the cross-technology channel can be severely affected by insertions and deletions of symbols, whose effects need to be taken into account by the coding scheme and communication protocol.

Deploying Virtual MAC Protocols Over a Shared Access Infrastructure Using MAClets

Network virtualization has been extensively researched in the last years as a key enabler for improving the network performance. However, virtualization in wireless networks pose some unique challenges: first, the usual over-provisioning approach for providing isolation between multiple virtual entities is not viable; second, the partitioning criteria are often ambiguous, since the actual resources perceived by each entity depend on many external (and time-varying) factors. In this demo, we show an effective virtualization solution for wireless local area networks, solving the problem of isolation and flexible resource paritioning, based on the concept of MAClets. MAClets are software progr…

BusyBee: Low Rate WiFi-ZigBee Communications without Gateways

Nowadays, the overcrowding of ISM bands is becoming an evident limitation for the performance and widespread us- age of 802.11 and 802.15.4 technologies. In this demo, we prove that it is possible to opportunistically exploit the inter- technology interference between 802.11 and 802.15.4 to build an unconventional low-rate communication channel and sig- nalling protocol, devised to improve the performance of each contending technology. Differently from previous solutions, inter-technology communications do not require the deploy- ment of a gateway with two network interfaces, but can be activated (when needed) directly between two heterogeneous nodes, e.g. a WiFi node and a ZigBee node. Thi…

A flexible and reconfigurable 5G networking architecture based on context and content information

The need for massive content delivery is a consolidated trend in mobile communications, and will even increase for next years. Moreover, while 4G maturity and evolution is driven by video contents, next generation (5G) networks will be dominated by heterogeneous data and additional massive diffusion of Internet of Things (IoT). The current network architecture is not sufficient to cope with such traffic, which is heterogeneous in terms of latency and QoS requirements, and variable in space and time. This paper proposes architectural advances to endow the network with the necessary flexibility helping to adapt to these varying traffic needs by providing content and communication services whe…

A decentralized load control architecture for smart energy consumption in small islands

Abstract In this paper we propose the adoption of Overgrid, a new decentralized load control architecture, for balancing the energy production variations introduced with the adoption of renewable sources, facilitating and improving the smart energy retrofit. The system is presented and applied for managing the aggregated daily load profile of a community of domestic end-users in the island of Lampedusa, Italy, exploiting the load profiles gathered in a real measurement campaign. The Overgrid Demand Response (DR) architecture is used for managing the residential flexible loads, estimating the aggregated power demand without any centralized server and creating a virtual “community” of smart b…

Method of changing the operation of wireless network nodes

Overgrid: A Fully Distributed Demand Response Architecture Based on Overlay Networks

In this paper, we present Overgrid, a fully distributed peer-to-peer (P2P) architecture designed to automatically control and implement distributed demand response (DR) schemes in a community of smart buildings with energy generation and storage capabilities. As overlay networks in communications establish logical links between peers regardless of the physical topology of the network, the Overgrid is able to apply some power balance criteria to its system of buildings, as they belong to a virtual microgrid, regardless of their physical location. We exploit an innovative distributed algorithm, called flow updating, for monitoring the power consumption of the buildings and the number of nodes…

Making WiFi work in multi-hop topologies: Automatic negotiation and allocation of airtime

We propose a solution for mitigating the performance impairments of CSMA/CA protocols in multi-hop topologies based on the dynamic adaptation of the contention process experienced by nodes in a wireless network. A distributed protocol is used to negotiate the channel airtime for a node as a function of the traffic requirements of its neighbourhood, taking into account bandwidth reserved for the control operations. A mechanism is provided for a node to tune its contention window depending on its allocated airtime. Different from previous schemes, a node's contention window is fixed in size unless the traffic requirements of its neighbourhood change. The scheme is implemented on legacy commer…

Demo - Dynamic Adaptations of WiFi Channel Widths Without TX/RX Coordination

Most modern standards for wireless communications support physical layer adaptations, in terms of dynamic selection of channel central frequency, transmission power, modulation format, etc., in order to increase link robustness under time-varying propagation and interference conditions. In this demo, we demonstrate that another powerful solution for extending physical layer flexibility in OFDM-based technologies is the dynamic adaptation of the channel width. Although some standards already define the possibility of utilizing multiple channel widths (e.g. 20MHz, 10MHz, 5MHz for IEEE 802.11a standards), such an utilization is limited to a static configuration of a value defined during the ne…

MAC learning

Cognition as a way to deal with the challenges of future wireless networks has been largely considered by the recent literature, with a main focus on physical layer adaptability and dynamic spectrum access. In this demo, we show how a simple cognition mechanism can be also applied at the MAC layer, by exploiting the emerging paradigm of programmable wireless cards. The idea is using the formal definition of simple MAC protocol components and platform-independent representation of channel events gathered from the wireless node, for emulating the behavior of protocols which are not currently running on the network, learning about their expected performance, and dynamically reconfiguring the w…

Exploiting programmable architectures for WiFi/ZigBee inter-technology cooperation

The increasing complexity of wireless standards has shown that protocols cannot be designed once for all possible deployments, especially when unpredictable and mutating interference situations are present due to the coexistence of heterogeneous technologies. As such, flexibility and (re)programmability of wireless devices is crucial in the emerging scenarios of technology proliferation and unpredictable interference conditions. In this paper, we focus on the possibility to improve coexistence performance of WiFi and ZigBee networks by exploiting novel programmable architectures of wireless devices able to support run-time modifications of medium access operations. Differently from software…

ErrorSense: Characterizing WiFi Error Patterns for Detecting ZigBee Interference

Recent years have witnessed the increasing adoption of heterogeneous wireless networks working in unlicensed ISM bands, thus creating serious problems of spectrum overcrowding. Although ZigBee, Bluetooth and WiFi networks have been natively designed for working in presence of interference, it has been observed that several performance impairments may occur because of heterogeneous sensitivity to detect or react to the presence of other technologies. In this paper we focus on the WiFi capability to detect interfering ZigBee links. Despite of the narrowband transmissions performed by ZigBee, in emerging scenarios ZigBee interference can have a significant impact on WiFi performance. Therefore…

A cultural heritage experience for visually impaired people

Abstract In recent years, we have assisted to an impressive advance of computer vision algorithms, based on image processing and artificial intelligence. Among the many applications of computer vision, in this paper we investigate on the potential impact for enhancing the cultural and physical accessibility of cultural heritage sites. By using a common smartphone as a mediation instrument with the environment, we demonstrate how convolutional networks can be trained for recognizing monuments in the surroundings of the users, thus enabling the possibility of accessing contents associated to the monument itself, or new forms of fruition for visually impaired people. Moreover, computer vision …

Control Architecture for Wireless MAC Processor Networking

Abstract: In these years, the proliferation of unplanned WLANs is creating the need of implementing different adaptation strategies for improving the network per- formance under mutating and evolving interference scenarios. Many vendors pro- pose undisclosed MAC/PHY optimization solutions, such as ambient noise immunity schemes, dynamic tuning of operating channels and contention parameters, etc., rely- ing on low-level implementations in the card hardware/firmware. In this paper we envision a new solution for expressing and implementing high-level adaptation policies in WLANs, in contrast to the current approaches based on vendor- specific implementations. We exploit the hardware abstracti…