Piotr Gawłowicz

UniFlex: A framework for simplifying wireless network control

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 devices co-existing in the same radio spectrum. They demand harmonized, frequently even coordinated adaptation of multiple parameters in different protocol layers (cross-layer) in multiple network devices (cross-node). We propose UniFlex, a framework enabling unified and flexible radio and network control. It provides an API enabling coordinated cross-layer control and management operation over multiple wireless network nodes. The controller logic may be implemented either in a centralized or distributed manner. This allows to place time-sensitive control functions close to the controlled device (i.e., local control application), off-load more resource hungry control application to compute servers and make them work together to control entire network. The UniFlex framework was prototypically implemented and provided to the research community as open-source. We evaluated the framework in a number of use-cases, what proved its usability.

A unified radio control architecture for prototyping adaptive wireless protocols

Experimental optimization of wireless protocols and validation of novel solutions is often problematic, due to limited configuration space present in commercial wireless interfaces as well as complexity of monolithic driver implementation on SDR-based experimentation platforms. To overcome these limitations a novel software architecture is proposed, called WiSHFUL, devised to allow: i) maximal exploitation of radio functionalities available in current radio chips, and ii) clean separation between the logic for optimizing the radio protocols (i.e. radio control) and the definition of these protocols.

Cross-Technology Interference Nulling for Improved LTE-U/WiFi Coexistence

Smart antennas can unlock the potential of unlicensed spectrum by letting the coexisting networks transmit concurrently without harmful interference. This is possible by strategically allocating the antenna degrees-of-freedom for both beamforming toward the intended receiver and interference nulling toward the victim receiver(s). Our solution, named Xzero, achieves this goal for the particular case of LTE-unlicensed (LTE-U) and WiFi by overcoming the challenges of cross-technology interference nulling by a null search at the LTE-U BS with assistance from the WiFi network. Our demo shows a running prototype of Xzero implemented using USRP SDR platform running srsLTE and commodity WiFi hardware. We illustrate the change in the airtime of colocated WiFi and LTE-U networks upon activation of Xzero and fast reconfiguration of the null beam upon a change in WiFi nodes location.

NxWLAN: Towards transparent and secure usage of neighbors' access points in residential WLANs

The increased popularity of IEEE 802.11 LANs (WLANs) in residential (home) environments leads to dense, unplanned and thus chaotic deployments. Access Points (APs) are frequently deployed unfavorably in terms of radio coverage and use interfering frequency/power settings. In fact, in some parts of a ones apartment the usage of the neighbors AP might be preferred as it might provide better signal quality than the own AP. Moreover, the network performance could be dramatically improved by balancing the network load over spatially co-located neighbor APs operating on different radio channels or having asymmetric workloads. We address these problems by presenting NxWLAN (Neighborhood extensible WLAN) which enables the secure virtual extension of users home WLANs in residential environments through enabling the usage of neighboring APs operating on the same or on different radio channels. NxWLAN requires no additional software to be installed on the client STAs while providing the same level of security as the home AP, e.g. WPA2, without revealing any kind of security credentials to untrusted neighboring APs. In this paper we prove, by prototyping and simulating the NxWLAN solution, that it is operational, performant and easy to deploy using off-the-shelf hardware. Moreover, we provide the full source code of our prototype to the community as open-source.