Adam Wolisz

Technische Universität Berlin | TUB · Department of Telecommunication Systems

Performance of vehicle-to-vehicle (V2V) communications depends highly on the employed scheduling approach. While centralized network schedulers offer high V2V communication reliability, their operation is conventionally restricted to areas with full cellular network coverage. In contrast, in out-of-cellular-coverage areas, comparatively inefficient...

Performance of vehicle-to-vehicle (V2V) communications depends highly on the employed scheduling approach. While centralized network schedulers offer high V2V communication reliability, their operation is conventionally restricted to areas with full cellular network coverage. In contrast, in out-of-cellular-coverage areas, comparatively inefficient...

Fog Computing allows applications to address their latency and privacy requirements while coping with bandwidth limitations of Internet service providers (ISPs). Existing research on fog systems has so far mostly taken a very high-level view on the actual fog infrastructure. In this position paper, we identify and discuss the problem of having mult...

Fog Computing allows applications to address their latency and privacy requirements while coping with bandwidth limitations of Internet service providers (ISPs). Existing research on fog systems has so far mostly taken a very high-level view on the actual fog infrastructure. In this position paper, we identify and discuss the problem of having mult...

The network Quality of Service (QoS) metrics such as the access time, the bandwidth, and the packet loss play an important role in determining the Quality of Experience (QoE) of mobile applications. Various factors like the Radio Resource Control (RRC) states, the Mobile Network Operator (MNO) specific retransmission configurations, handovers trigg...

The network Quality of Service (QoS) metrics such as the access time, the bandwidth, and the packet loss play an important role in determining the Quality of Experience (QoE) of mobile applications. Various factors like the Radio Resource Control (RRC) states, the Mobile Network Operator (MNO) specific retransmission configurations, handovers trigg...

In this paper, we revisit the widely known performance anomaly that results in severe network utility degradation in WiFi networks when nodes use diverse modulation and coding schemes. The proportional-fair allocation was shown to mitigate this anomaly and provide a good throughput to the stations. It can be achieved through the selection of conten...

In limiting the rapid spread of highly infectious diseases like Covid-19 means to immediately identify individuals who had been in contact with a newly diagnosed infected person have proven to be important. Such potential victims can go into quarantine until tested thus constraining further spread. This note describes a concept of mobile device (e....

Despite exhibiting very high theoretical data rates, in practice, the performance of LTE-U/LAA and WiFi networks is severely limited under cross-technology coexistence scenarios in the unlicensed 5GHz band. As a remedy, recent research shows the need for collaboration and coordination among co-located networks. However, enabling such collaboration...

Future cities are to be not only an intelligent and green living environment but also provide human-centered public services at a lower cost. The Internet of Things (IoT) and artificial intelligence (AI) are two cornerstone technologies enabling the smart city concept, which are fusing into an organic whole in recent years. Some particular joint po...

Mobile network operators (MNO) can opportunistically use the licensed bands of the primary users (PU) provided that they monitor the spectrum and stop their transmission upon detection of the PU. As deploying spectrum sensors may be prohibitively expensive, the MNO can buy spectrum sensing service from sensing helpers in its proximity. However, suc...

Vehicle-to-vehicle (V2V) communications have distinct challenges that need to be taken into account when scheduling the radio resources. Although centralized schedulers (e.g., located on base stations) could be utilized to deliver high scheduling performance, they cannot be employed in case of coverage gaps. To address the issue of reliable schedul...

A recent proposal known as unlicensed LTE offers cost-effective capacity extension to the cellular network operators in which LTE operators bundle the unlicensed spectrum in 5GHz UNII bands with their licensed spectrum via carrier aggregation. But, unlicensed spectrum requires coexistence among the networks operating in the same spectrum, e.g., IEE...

This document reports the main experimental results obtained by applying the proposed ViFi system in another testbed, referred to as w-iLab.t I, aiming to further validate the performance improvement of ViFi when compared to a traditional fingerprinting indoor positioning system. Reference Publication: "ViFi: Virtual Fingerprinting WiFi-based Ind...

Widespread adoption of indoor positioning systems based on WiFi fingerprinting is at present hindered by the large efforts required for measurements collection during the offline phase. Two approaches were recently proposed to address such issue: crowdsourcing and RSS radiomap prediction, based on either interpolation or propagation channel model f...

Practical location estimation is never ideal and each location estimate is burdened with a certain level of error. In many use-case scenarios, knowing the magnitude of these errors can significantly improve the usability of the location estimates. The localization errors for different localization approaches are currently assessed using static perf...

Experimentation with computer networks under realistic conditions is a necessary step in debugging, profiling and validation towards real deployments and applications. Although the definition of relevant experimentation scenarios is usually relatively straightforward, their implementation and execution are unfortunately difficult and tedious. Gener...

Radio resources in vehicle-to-vehicle (V2V) communication can be scheduled either by a centralized scheduler residing in the network (e.g., a base station in case of cellular systems) or a distributed scheduler, where the resources are autonomously selected by the vehicles. The former approach yields a considerably higher resource utilization in ca...

Mobile network operators can expand their capacity by aggregating their licensed spectrum with the spectrum discovered opportunistically, i.e., spatiotemporally unused spectrum by other primary users. For an accurate identification of the spectral opportunities, the mobile network has to deploy multiple sensors or it can offload this task to nearby...

The accelerating penetration of physical environments by objects with information processing and wireless communication capabilities requires approaches to find potential communication partners and discover services. In the present work, we focus on passive discovery approaches in multi-channel wireless networks based on overhearing periodic beacon...

To avoid the foreseeable spectrum crunch, LTE operators have started to explore the option to directly use the underutilized unlicensed spectrum in 5 GHz UNII bands being mainly used by IEEE 802.11 (WiFi). However, as LTE is not designed with shared spectrum access in mind, it has a potential to seriously harm Wi-Fi. Currently suggested solutions f...

A major challenge in wide deployment of smart wireless devices, using different technologies and sharing the same 2.4 GHz spectrum, is to achieve coexistence across multiple technologies. The IEEE~802.11 (WLAN) and the IEEE 802.15.4e TSCH (WSN) where designed with different goals in mind and both play important roles for respective applications. Ho...

The IEEE 802.11 and the IEEE 802.15.4e TSCH were designed with different goals in mind and both play important roles for respective applications. However, they suffer from mutual interference and experience degraded performance while operating in the same space and spectrum band. To improve this situation we propose an approach to enable a cooperat...

Modern society has become increasingly reliant on mobile networks for their communication needs. Such networks are characterized by their dynamic, heterogeneous, complex, and data intensive nature, which makes them more amenable to automated mobile network optimization performed using “computational intelligence’’ (CI) techniques rather than tradit...

Leveraging a relay for communication is a promising approach for improving throughput, coverage, and energy eeciency in wireless networks. A mobile relay that is capable of positioning itself at diierent locations opens the possibility for dynamic optimization of the path quality between the source and the nomadic destination. How to optimally posi...

During the last years WLAN (IEEE 802.11) has become the primary wireless access technology. However, the fast evolution of peak data rates and the wide deployment of WLAN hotspots results in the backhaul connecting such small cells becoming a bottleneck. To provide a high capacity backhauling, we propose COUWBAT, a COgnitive Ultra-Wide BAckhaul Tra...

Individual localization services seldom satisfy the requirements for accurate, robust, punctual, and seamless location information. To enhance the provisioning, a set of challenges has to be addressed, pertaining to handover, fusion, and integration of individual localization services. In the following, we advertise the Standardized Localization Se...

To avoid the foreseeable spectrum crunch, LTE operators have started to explore the option to directly use 5 GHz unlicensed spectrum band being used by IEEE 802.11 (WiFi). However, as LTE is not designed with shared spectrum access in mind, there is a major issue of coexistence with WiFi networks. Current coexistence schemes to be deployed at the L...

To avoid the foreseeable spectrum crunch, LTE operators have started to explore the option to directly use 5 GHz unlicensed spectrum band being used by IEEE 802.11 (WiFi). However, as LTE is not designed with shared spectrum access in mind, there is a major issue of coexistence with WiFi networks. Current coexistence schemes to be deployed at the L...

Ubiquitous Wi-Fi access points (APs) constantly send out beacon and probe response frames to inform potential stations (STAs) about their existence. Beacon and probe responses can be extended by adding additional information (so-called beacon stuffing) making it possible to deliver this information to mobile devices (e.g. smart-phones equipped with...

Device-to-Device (D2D) communication has a high potential in reducing the amount of network traffic and improving the latency and energy efficiency of communication. Currently, D2D link establishment decisions are based on active probing between devices that wish to establish a D2D link. The main drawback of such approaches is a large overhead as d...

With the abundance of mobile connected devices and coexisting networks, localization solutions are inevitably subject to interference. In this paper, effects of interference on the performance of Fingerprinting Localization Algorithms (FPS) are studied both theoretically and through experimentation. The previously introduced theoretical framework b...

Location information of mobile devices is a foun-dational input to location-based services and a valuable source of context information in wireless networks. To maximize the value, we need location information that is accurate, robust, and promptly and seamlessly available. Unfortunately, individual localization services seldom satisfy all these re...

Aggregation of location estimates from multiple services for provisioning of location information enhances the accuracy and robustness of the final location information. Recent Internet of Things (IoT)-based localization service architectures therefore envision a " manager " for selecting and invoking pro-visioning services and, in the later step,...

Cross-technology communication (CTC) was proposed in recent literature as a way to exploit the opportunities of collaboration between heterogeneous wireless technologies. This paper presents LtFi, a system which enables to set-up a CTC between nodes of co-located LTE-U and WiFi networks. LtFi follows a two-step approach: using the air-interface LTE...

The popularity of Internet-based video services has significantly increased over the past years. The de facto standard technology for Internet-based Video on Demand is HTTP-Based Adaptive Streaming (HAS), which is also increasingly used for live services. A core component of a HAS client is the adaptation algorithm, which dynamically adjusts the vi...

The efficient management of radio resources in today's home or residential Wi-Fi networks is still an open research question. Due to the chaotic and unplanned deployment of Wi-Fi Access Points (APs) and the fact that all APs are managed individually by their owners, home Wi-Fi networks suffer from performance degradation due to contention and inter...

Nowadays, the usage of multiple virtual wireless networks on top of one physical AP is very common in home Wi-Fi networks. Be it Hotspots of Internet Service Providers (ISPs) or Mobile Network Operators (MNOs) used for offloading their traffic, community networks or plain so-called " Guest-Networks ". Whereas the home user (AP owner) in the best ca...

Despite the popularity of Fingerprinting Localization Algorithms (FPS), general theoretical frameworks for their performance studies have rarely been discussed in the literature. In this work, after setting up an abstract model for the FPS, we show that a fingerprinting-based localization problem can be cast as a Hypothesis Testing (HT) problem and...

We propose WiPLUS – a system that enables WiFi to deal with the stealthy invasion of LTE-U into the frequency bands used by WiFi. Using solely MAC layer information extracted passively, during runtime, out of the hardware registers of the WiFi NIC at the WiFi access point, WiPLUS is able to: i) detect interfering LTE-U signals, ii) compute their du...

Neighbor discovery is a fundamental task in wireless networks in order to find potential communication partners, discover services, and to efficiently access the wireless resource. In this paper we focus on the passive neighbor discovery in multi-channel environments. We present different discovery approaches with low computational complexity that...

We propose WiPLUS -- a system that enables WiFi to deal with the stealthy invasion of LTE-U into the frequency bands used by WiFi. Using solely MAC layer information extracted passively, during runtime, out of the hardware registers of the WiFi NIC at the WiFi access point, WiPLUS is able to: i) detect interfering LTE-U signals, ii) compute their d...

We propose WiPLUS – a system that enables WiFi to deal with the stealthy invasion of LTE-U into the frequency bands used by WiFi. Using solely MAC layer information extracted passively, during runtime, out of the hardware registers of the WiFi NIC at the WiFi access point, WiPlus is able to: i) detect interferring LTE-U signals, ii) compute their d...

Erratum to: I. Schieferdecker et al. (Eds.) Testing of Communicating Systems XIV DOI: 10.1007/978-0-387-35497-2

We present our current work-in-progress on the design and implementation of a hybrid TDMA/CSMA medium access architecture, hereafter referred to as hMAC, which can be used on top of commercial IEEE 802.11 off-the-shelf hardware. The software only solution is based on the popular Linux ATH9K softMAC driver and hence can be used with standard Linux s...

Classical control and management plane for computer networks is addressing individual parameters of protocol layers within an individual wireless network device. We argue that this is not sufficient in phase of increasing deployment of highly re-configurable systems, as well as heterogeneous wireless systems co-existing in the same radio spectrum w...

Classical control and management plane for computer networks is addressing individual parameters of protocol layers within an individual wireless network device. We argue that this is not sufficient in phase of increasing deployment of highly re-configurable systems, as well as heterogeneous wireless systems co-existing in the same radio spectrum w...

The current approach to roll out large scale IoT systems is to outsource the crucial parts of the system to cloud based services, such as message brokerage, devices management, or sensor data storage and processing. One core protocol for messaging in those settings is the widely adopted publish/subscribe protocol MQTT. Pub/sub protocols, however, w...

Despite popularity of Fingerprinting Localization Algorithms (FPS), general theoretical frameworks for their performance studies have rarely been discussed in the literature. In this work, after setting up an abstract model for the FPS, it is shown that fingerprinting-based localization problem can be cast as a Hypothesis Testing (HT) problem and t...

Localization services available on today's mobile devices are proprietary and leverage a limited set of sources of location information. Integration of new location estimation methods is therefore cumbersome, requiring adaptation to the specific interfaces of the proprietary location service. In addition , location-based applications are tightly in...

mmWave (millimeter-Wave) is a very promising technology for the future wireless communication. To mitigate its high attenuation characteristics, mmWave communication frequently employs directional beamforming for both transmission and reception. Localization commonly takes advantage of directionality in RF frequencies in urban and indoor environmen...

This paper describes a major effort to collect smart-phone data useful for indoor localization. Data has been collected with four Android phones according to numerous scenarios in each of four large buildings. The data includes time-stamped traces of various environmental, position, and motion sensors available on a smartphone, Wi-Fi and cellular s...

The internet of things (IoT) will enable a range of applications providing enhanced awareness and control of the physical environment. Current systems typically sense and actuate physical phenomena locally and then rely on a cloud-based publish/subscribe infrastructure for distribution of sensor and control data to end-users and external services....

The increased usage of IEEE 802.11 Wireless LAN (WLAN) in residential environments by unexperienced users leads to dense, unplanned and chaotic residential WLAN deployments. Often WLAN Access Points (APs) are deployed unprofitable in terms of radio coverage and interference conditions. In many cases the usage of the neighbor's AP would be beneficia...

We live in a world in which there is a great disparity between the lives of the rich and the poor. Information and communication technology (ICT) offers promise in bridging this digital divide through its focus on connecting human capacity with computing and informational content. It is well known that Internet access has the capability of fosterin...

Smartphones are an important target platform for research and development of indoor localization solutions. Due to the large diversity of smartphone hardware and OS services, making general statements about the performance of indoor localization algorithms in different environments remains very challenging. In this work we present a comprehensive r...

Omnipresent Wi-Fi access points (APs) periodically broadcast beacon frames to inform potential stations (STAs) about their existence. Beacon frames can be extended by adding additional information (so-called beacon stuffing) making it possible to deliver this information to mobile devices (smart-phones, tablets, etc. equipped with 802.11 interfaces...

Wireless embedded systems are becoming an increasingly important part of our lives. Information from such systems is almost exclusively meaningful when it is coupled with location information, or the location information itself is the desired knowledge to obtain. In this paper we explore a special sub-problem of location discovery: determining rela...

Industrial control systems have traditionally been built around dedicated wired solutions. The requirements of flexibility, mobility and cost have created a strong push towards wireless solutions, preferably solutions requiring low power. Simultaneously, the increased need for interoperability and integration with the wider Internet made a transiti...

Recently, HTTP-based adaptive streaming has become the de facto standard for video streaming over the Internet. It allows clients to dynamically adapt media characteristics to varying network conditions in order to ensure a high quality of experience, that is, minimize play-back interruptions, while maximizing video quality at a reasonable level of...

The combination of an aging population and nursing staff shortages implies the need for more advanced systems in the healthcare industry. Many key enablers for the optimization of healthcare systems require provisioning of location awareness for patients (e.g. with dementia), nurses, doctors, assets, etc. Therefore, many Indoor Positioning Systems...

Out of the plethora of approaches for indoor localization, WiFi-based fingerprinting offers attractive trade-off between deployment overheads and accuracy. This has motivated intense research interest resulting in many proposed algorithms which are typically evaluated only in a single or small number of discrete environments. When the end-user's en...

Swarm is a heterogeneous distributed collection of cooperating things. It enables an extension of the info-sphere into the physical world. This work presents a framework architecture proposal to the Swarm. Envisioning the Swarm ecosystem, challenges and characteristics were identified and a control plane for the framework was proposed. In order to...

Wireless radio communications systems form the basis for mobile network connections in the digital society. A limited amount of radio spectrum and a spatially densified use of wireless communications systems require a resource-efficient use of the spectrum. Mechanisms of cognitive radio may hold the key to a more efficient use of the available spec...

The interest for RF-based indoor localization, and in particular for WiFi RSSI-based fingerprinting, is growing at a rapid pace. This is despite the existence of a trade-off between the accuracy of location estimation and the density of a laborious and time consuming survey for collecting training fingerprints. A generally accepted concept of incre...

In dense deployments of residential WiFi networks individual users suffer performance degradation due to both contention and interference. While Radio Resource Management (RRM) is known to mitigate this effects its application in residential WiFi networks being by nature unplanned and individually managed creates a big challenge. We propose ResFi -...

The growing popularity of indoor localisation research has resulted in a significant amount of research papers describing and evaluating innovative localisation solutions. Unfortunately, the results from most of these research papers cannot easily be compared since they are evaluated in different environments, use different evaluation criteria and...

RF-based indoor localization is constantly gaining popularity, and WiFi-based fingerprinting algorithms belong to the most promising candidates due to their well-known advantages. While it is known that RF interference can adversely influence the accuracy of those algorithms, it is still unclear if this effect could be efficiently mitigated. To thi...

Real-time Ethernet is expected to become the core technology of future in-car communication networks. Applications such as online diagnosis, data- and firmware updates over the air or data from the backend will introduce bursty high bandwidth communication to the sensitive core of the cars communication network. With this work we show that - even f...

Over the last few years, the number of indoor localization solutions has grown exponentially, and a wide variety of different technologies and approaches are being explored. Unfortunately, there is currently no established standardized evaluation method for comparing their performance. As a result, each solution is evaluated in a different environm...

Cognitive Radio (CR) is a promising approach to overcome the spectrum crunch faced by today's enterprise and residential WiFi (IEEE 802.11) due to rapid growth of wireless devices and traffic load. However, the expected high-density CR Networks (CRN) will suffer from similar problems as we see today with WiFi, i.e. any uncoordinated spectrum access...

With the data traffic expected to grow nearly exponentially, concerns regarding excessive energy consumption in wireless networks have been also raised for home and enterprise environments. These two types of networks are discussed here jointly due to many similarities they exhibit, namely, similar propagation environments (dominantly indoor scenar...

With the data traffic growing nearly exponentially, concerns regarding excessive energy consumption in wireless networks have been raised for home and enterprise environments. These two types of networks are discussed here jointly because of the many similarities they exhibit, namely, propagation environments (dominantly indoor scenarios, high dive...

Cognitive Radio (CR) will enhance the efficiency in spectrum usage by re-using temporally unused licensed spectrum. A promising transmission scheme to utilize even very fragmented and fast changing spectrum is Non-Contiguous OFDM (NCOFDM). Unfortunately, NC-OFDM requires tight synchronization between sender and receiver, i.e. the receiver needs per...