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1. Differentially-Private Incentive Mechanism for Crowdsourced Radio Environment Map Construction

   https://doi.org/10.1109/INFOCOM.2019.8737512  

   Hu, Yidan; Zhang, Rui (April 2019, IEEE INFOCOM 2019 - IEEE Conference on Computer Communications)

   Database-driven Dynamic Spectrum Sharing (DSS) is a promising technical paradigm for enhancing spectrum efficiency by allowing secondary user to opportunistically access licenced spectrum channels without interfering with primary users' transmissions. In database-driven DSS, a geo-location database administrator (DBA) maintains the spectrum availability in its service region in the form of a radio environment map (REM) and grant or deny secondary users' spectrum access requests based on primary users' activities. Crowdsourcing-based spectrum sensing has great potential in improving the accuracy of the REM at the DBA but requires strong incentives and privacy protection to simulate mobile users' participation. To tackle this challenge, this paper introduces a novel differentially-private reverse auction mechanism for crowdsourcing-based spectrum sensing. The proposed mechanism allows the DBA to select spectrum sensing participants under a budget constraint while offering differential bid privacy, approximate truthfulness, and approximate accuracy maximization. Extensive simulation studies using a real spectrum measurement dataset confirm the efficacy and efficiency of the proposed mechanism. 

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2. Differentially-Private Incentive Mechanism for Crowdsourced Radio Environment Map Construction

   Hu, Yidan; Zhang, Rui (April 2019, IEEE International Conference on Computer Communications)

   Database-driven Dynamic Spectrum Sharing (DSS) is a promising technical paradigm for enhancing spectrum efficiency by allowing secondary user to opportunistically access licenced spectrum channels without interfering with primary users' transmissions. In database-driven DSS, a geo-location database administrator (DBA) maintains the spectrum availability in its service region in the form of a radio environment map (REM) and grant or deny secondary users' spectrum access requests based on primary users' activities. Crowdsourcing-based spectrum sensing has great potential in improving the accuracy of the REM at the DBA but requires strong incentives and privacy protection to simulate mobile users' participation. To tackle this challenge, this paper introduces a novel differentially-private reverse auction mechanism for crowdsourcing-based spectrum sensing. The proposed mechanism allows the DBA to select spectrum sensing participants under a budget constraint while offering differential bid privacy, approximate truthfulness, and approximate accuracy maximization. Extensive simulation studies using a real spectrum measurement dataset confirm the efficacy and efficiency of the proposed mechanism. 

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3. Wideband Temporal Spectrum Sensing Using Cepstral Features

   https://doi.org/10.1109/WoWMoM.2019.8793002  

   Cheng, Hanke; Mark, Brian L.; Ephraim, Yariv (June 2019, 2019 IEEE 20th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM))

   Spectrum sensing enables secondary users in a cognitive radio network to opportunistically access portions of the spectrum left idle by primary users. Tracking spectrum holes jointly in time and frequency over a wide spectrum band is a challenging task. In one approach to wideband temporal sensing, the spectrum band is partitioned into narrowband subchannels of fixed bandwidth, which are then characterized via hidden Markov modeling using average power or energy measurements as observation data. Adjacent, correlated subchannels are recursively aggregated into channels of variable bandwidths, corresponding to the primary user signals. Thus, wideband temporal sensing is transformed into a multiband sensing scenario by identifying the primary user channels in the spectrum band. However, future changes in the configuration of the primary user channels in the multiband setup cannot generally be detected using an energy detector front end for spectrum sensing. We propose the use of a cepstral feature vector to detect changes in the spectrum envelope of a primary user channel. Our numerical results show that the cepstrum-based spectrum envelope detector performs well under moderate to high signal-to-noise ratio conditions. 

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4. Greedy Channel Selection for Dynamic Spectrum Access Radios

   https://doi.org/10.1109/ISCAS45731.2020.9180882  

   Lackpour, Alex; Rey, Xaime Rivas; Mainland, Geoffrey; Dandekar, Kapil R. (October 2020, 2020 IEEE International Symposium on Circuits and Systems)

   Dynamic Spectrum Access (DSA) radios typically select their radio channels according to their data networking goals, a defined DSA spectrum operating policy, and the state of the RF spectrum. RF spectrum sensing can be used to collect information about the state of the RF spectrum and prioritize which channels should be assigned for DSA radio waveform transmission and reception. This paper describes a Greedy Channel Ranking Algorithm (GCRA) used to calculate and rank RF interference metrics for observed DSA radio channels. The channel rankings can then be used to select and/or avoid channels in order to attain a desired DSA radio performance level. Experimental measurements are collected using our custom software-defined radio (SDR) system to quantify the performance of using GCRA for a DSA radio application. Analysis of these results show that both pre and post-detection average interference power metrics are the most accurate metrics for selecting groups of radio channels to solve constrained channel assignment problems in occupied gray space spectrum. 

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5. Spatio-temporal prediction of social connections

   https://doi.org/10.1145/3080546.3080551  

   Yang, Guolei; Züfle, Andreas (January 2017, Fourth International ACM Workshop on Managing and Mining Enriched Geo-Spatial Data)

   It is long known that a user's mobility pattern can be affected by his social connections. Users tend to visit same locations visited by their friends. In this paper we investigate the inverse problem: How does a set of user trajectories reflect their social connections. To this end, we define the social connection prediction problem. Given two users, predict the probability that they are friends by mining their historical trajectories. A first approach to do so is to exam how often the two users visit the same location at the same time, which suffers from the problem that different locations/times may have different predictive power. We propose a comprehensive prediction model that is able to capture this difference between locations and time slots. To demonstrate its effectiveness, we trained the proposed model using the publicly available Foursquare dataset. The result shows the proposed model is able to predict existence of social connections between randomly selected users significantly more accurate comparing with the naive method. 

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