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- Interference study between wireless microphone systems and TV white space devicesPublication . Dionísio, Rogério Pais; Marques, Paulo; Rodriguez, JonathanThis work focus on a coexistence study between wireless microphone systems and secondary users of the TV White Spaces, using a Monte-Carlo methodology. Exclusion areas around wireless microphone receivers, for co-channel and adjacent channel interference, are computed, considering indoor and outdoor scenarios. Using this methodology, impact and tendencies of several parameters over the probability of interference are analyzed, like spectral channel spacing, separation distance and propagation scenario. As an example, for outdoor scenarios, the spectral spacing between primary system and secondary users, ranging from 0 MHz (co-channel operation) to 16 MHz (2 DVB-T channels) results in a protection distance of 13.9 km and 2.2 km, respectively.
- Cross-platform demonstrator combining spectrum sensing and a geo-location databasePublication . Dionísio, Rogério Pais; Ribeiro, José Carlos; Ribeiro, Jorge Miguel Afonso; Marques, Paulo; Rodriguez, JonathanAfter the digital switchover, a secondary access of the so-called TV White Spaces should not interfere with primary users, such as DVB-T systems and local wireless microphone devices. One consensual method for secondary spectrum users to avoid interference is to combine geo-location database with spectrum sensing. This paper describes an experimental platform that combines wireless microphone sensors with a web-based geo-location database access. Software defined radios and Internet technologies are the enabling tools in use. From test trials in a real scenario, the platform was capable to update a list of vacant channel from the geo-location database, using reliable information from blind sensing algorithms.
- Experimental assessment of a propagation model for TV white spacesPublication . Dionísio, Rogério Pais; Marques, Paulo; Rodriguez, JonathanThis paper describes outdoor field measurements in television white spaces (TVWS) carried out in Munich, Germany. Fixed and mobile measurements in rural, sub-urban and urban scenarios showed that the modified Hata model is appropriate to describe the path loss over distances up to few kilometers, and may be used in the process to populate a geo-location database.
- Load forecasting in WIFI access points over the LTE networkPublication . Marques, Hugo; Torres, Pedro; Marques, Paulo; Dionísio, Rogério Pais; Rodriguez, JonathanThe concept of smart cities grew with the need to rethink the use of urban spaces based on the constant technological advances and respecting sustainability. Today the urbanism and the methodologies to think about the city are changing, as citizens want more access to digital information on almost everything. Therefore, cities need to be planned and equipped with infrastructures that enable connectivity between the citizens’ devices and the digital information. This challenge raises technological problems, such as traffic management, in an attempt to guarantee fair network access to all users. Solutions based on wireless resource management and self-organizing networks are key when design the connectivity for these smart cities. This paper presents a study on forecasting the daily load of Wi-Fi city hotspots, taking also in consideration the weather conditions. This is particularly interesting to predict the network load and resource requirements needed to ensure proper quality of service is provided to the hotspot users. The study was performed in a Wi-Fi hotspot located in the city of Castelo Branco, Portugal. The results show the ARIMA model is capable of identifying and forecasting seasonality events for one week in advance including its capability to correlate the number of hotspot users with weather conditions.
- TV white spaces maps computation through interference analysisPublication . Dionísio, Rogério Pais; Marques, Paulo; Rodriguez, JonathanFor the characterization of TV White Spaces (TVWS), an extensive simulation of the impact of interfering signals was undertaken in a generalized scenario. The simulation for these investigations was derived from a Monte Carlo methodology using SEAMCAT, and the results include the computation of TVWS maps as it can be done with the access to a geo-location database, or based on autonomous sensing only. Geo-location database approach is shown to utilize TVWS spectrum more efficiently. The impact of Professional Wireless Microphone Systems (PWMS) devices on the availability of TVWS is also analyzed and imposes additional limitations of the maximum power emitted by secondary spectrum users.
- Combination of a geolocation database access with infrastructure sensing in TV bandsPublication . Dionísio, Rogério; Ribeiro, Jorge Miguel Afonso; Marques, Paulo; Rodriguez, JonathanThis paper describes the implementation and the technical specifications of a geolocation database assisted by a spectrum-monitoring outdoor network. The geolocation database is populated according to Electronic Communications Committee (ECC) report 186 methodology. The application programming interface (API) between the sensor network and the geolocation database implements an effective and secure connection to successfully gather sensing data and sends it to the geolocation database for post-processing. On the other hand, the testbed allows authorized TV white space devices to gain access to the services of the geolocation database, according to a draft implementation of Internet Engineering Task Force (IETF) Protocol to Access White Space (PAWS) Two experimental methodologies are available with the testbed: one focused on coexistence studies with commercial wireless microphones, when the testbed is used for sensing only, and another for demonstration purposes, when the testbed is also used to emulate wireless microphone signals. Overall, this hybrid approach is a promising solution for the effective use of TV white spaces and for the coexistence with digital TV broadcast signals, or dynamic incumbent systems, such as unregistered wireless microphones.
- Using deep neural networks for forecasting cell congestion on LTE networks: a simple approachPublication . Torres, Pedro; Marques, Hugo; Marques, Paulo; Rodriguez, JonathanPredicting short-term cellular load in LTE networks is of great importance for mobile operators as it assists in the efficient managing of network resources. Based on predicted behaviours, the network can be intended as a proactive system that enables reconfiguration when needed. Basically, it is the concept of self-organizing networks that ensures the requirements and the quality of service. This paper uses a dataset, provided by a mobile network operator, of collected downlink throughput samples from one cell in an area where cell congestion usually occurs and a Deep Neural Network (DNN) approach to perform short-term cell load forecasting. The results obtained indicate that DNN performs better results when compared to traditional approaches.
- TV white spaces with geo-location database access: practical considerations and trials in EuropePublication . Dionísio, Rogério Pais; Ribeiro, José Carlos; Ribeiro, Jorge Miguel Afonso; Marques, Paulo; Rodriguez, JonathanThis chapter describes outdoor transmission tests and field measurements in TV white spaces (TVWS) carried out in Europe. TVWS Measurements in Germany showed that the extended Hata model is appropriate to describe the path loss over distances up to a few kilometers. During the TVWS trial in Slovenia, we combine infrastructure sensing with geo-location database access to protect not only DVB-T, but also wireless microphone (WM) signals from TVWS devices interference.