Browsing by Author "Fernandes, Nuno"
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- Improving accuracy for OTD based 3G geolocation in real urban/suburban environmentsPublication . Vieira, Pedro; Silva, Nuno Oliveira e; Fernandes, Nuno; Rodrigues, António; Varela, LuísThis paper presents the recent research results about the development of a Observed Time Difference (OTD) based geolocation algorithm based on network trace data, for a real Universal Mobile Telecommunication System (UMTS) Network. The initial results have been published in [1], the current paper focus on increasing the sample convergence rate, and introducing a new filtering approach based on a moving average spatial filter, to increase accuracy. Field tests have been carried out for two radio environments (urban and suburban) in the Lisbon area, Portugal. The new enhancements produced a geopositioning success rate of 47% and 31%, and a median accuracy of 151 m and 337 m, for the urban and suburban environments, respectively. The implemented filter produced a 16% and 20% increase on accuracy, when compared with the geopositioned raw data. The obtained results are rather promising in accuracy and geolocation success rate. OTD positioning smoothed by moving average spatial filtering reveals a strong approach for positioning trace extracted events, vital for boosting Self-Organizing Networks (SON) over a 3G network.
- A SON Enhanced Algorithm for Observed Time Differences Based Geolocation in Real 3G NetworksPublication . Vieira, Pedro; Varela, Nuno; Fernandes, Nuno; Guedes, Nuno; Varela, Luis; Ribeiro, NunoThis paper presents a SON enhanced approach for OTD Based Geolocation in a real 3G UMTS Network. The algorithm was implemented using cell, measurement report and drivetest data, the last just for geolocation accuracy determination. It uses a dual convergence approach evolving Node B time reference estimation followed by trilateration, boosting convergence. A motion model Kalman filtering module was developed, and tuned for urban mobile. Around 35% of the events were geopositioned, which motivates using OTD measurements for geolocation in live networks. The median accuracy achieved by the algorithm was 178 m, which is rather promising, considering that OTD measurements have an intrinsic uncertainty of a UMTS chip, i.e, 78 m.