As mobile networks evolve toward next-generation architectures in which cellular and IP-based voice services are increasingly converged,SIMBox-based call routing has emerged as an important issue in modern telecommuni...As mobile networks evolve toward next-generation architectures in which cellular and IP-based voice services are increasingly converged,SIMBox-based call routing has emerged as an important issue in modern telecommunication networks.By converting Voice over IP(VoIP)traffic into local cellular calls,SIMBox appliances allow IP-originated calls to appear as domestic cellular calls.Although SIMBox usage is not inherently fraudulent,detecting SIMBox-routed calls is important for identifying abnormal call-routing behavior and supporting network-side and client-side security applications.In this paper,we propose a client-side framework for SIMBox-routed call detection.Calls routed through SIMBox infrastructure are identified by exploiting acoustic artifacts introduced by VoIP-to-VoLTE codec transcoding.Variable-length call recordings are segmented into fixed-duration windows and analyzed using supervised classifiers to capture spectral patterns associated with transcoding operations.Unlike network-side SIMBox detection methods that rely on carrier-controlled metadata such as call detail records,subscriber identifiers,or cell-location patterns,our approach focuses on acoustic evidence observable from the call audio itself.We evaluate the proposed framework using two datasets:25706 codec-processed voice samples generated from 12853 source recordings with the ITU-T G.191 Software Tool,and 200 real-world call samples collected through a commercial SIMBox platform(DINSTAR UC2000-VE)under realistic call-routing conditions.Among five evaluated models,the CNN-based classifiers achieve the best performance,reaching an F1-score of 1.00.These results show that audio-level codec artifacts can serve as reliable indicators for detecting SIMBox-routed voice calls at the client side,and offer a promising direction for securing converged voice services in 5G and beyond.展开更多
The new H.264 video coding standard achieves significantly higher compression performance than MPEG-2. As the MPEG-2 is popular in digital TV, DVD, etc., bandwidth or memory space can be saved by transcoding those str...The new H.264 video coding standard achieves significantly higher compression performance than MPEG-2. As the MPEG-2 is popular in digital TV, DVD, etc., bandwidth or memory space can be saved by transcoding those streams into H.264 in these applications. Unfortunately, the huge complexity keeps transcoding from being widely used in practical applications. This paper proposes an efficient transcoding architecture with a smart downscaling decoder and a fast mode decision algorithm. Using the proposed architecture, huge buffering memory space is saved and the transcoding complexity is reduced. Performance of the proposed fast mode decision algorithm is validated by experiments.展开更多
To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dyn...To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dynamically determining the transcoder's objective bit rate, according to the bandwidth variation of the wireless channel and the buffer occupancy. Then the transient performance, steady performance, and computational complexity of the algorithm are analyzed. Finally, the experiment results demonstrate that the algorithm can improve the synthetic performance of rate control through the compromise between the end-to-end delay and the playout quality.展开更多
基金supported by the Institute of Information&Communications Technology Planning&Evaluation(IITP)grant funded by the Korea Government(MSIT)(2021-0-00511,Robust AI and Distributed Attack Detection for Edge AI Security,50%)(RS-2024-00439762,Developing Techniques for Analyzing and Assessing Vulnerabilities,and Tools for Confidentiality Evaluation in Generative AI Models,50%).
摘要As mobile networks evolve toward next-generation architectures in which cellular and IP-based voice services are increasingly converged,SIMBox-based call routing has emerged as an important issue in modern telecommunication networks.By converting Voice over IP(VoIP)traffic into local cellular calls,SIMBox appliances allow IP-originated calls to appear as domestic cellular calls.Although SIMBox usage is not inherently fraudulent,detecting SIMBox-routed calls is important for identifying abnormal call-routing behavior and supporting network-side and client-side security applications.In this paper,we propose a client-side framework for SIMBox-routed call detection.Calls routed through SIMBox infrastructure are identified by exploiting acoustic artifacts introduced by VoIP-to-VoLTE codec transcoding.Variable-length call recordings are segmented into fixed-duration windows and analyzed using supervised classifiers to capture spectral patterns associated with transcoding operations.Unlike network-side SIMBox detection methods that rely on carrier-controlled metadata such as call detail records,subscriber identifiers,or cell-location patterns,our approach focuses on acoustic evidence observable from the call audio itself.We evaluate the proposed framework using two datasets:25706 codec-processed voice samples generated from 12853 source recordings with the ITU-T G.191 Software Tool,and 200 real-world call samples collected through a commercial SIMBox platform(DINSTAR UC2000-VE)under realistic call-routing conditions.Among five evaluated models,the CNN-based classifiers achieve the best performance,reaching an F1-score of 1.00.These results show that audio-level codec artifacts can serve as reliable indicators for detecting SIMBox-routed voice calls at the client side,and offer a promising direction for securing converged voice services in 5G and beyond.
基金Project (No. CNGI-04-15-2A) supported by the China Next Gen-eration Internet (CNGI)
摘要The new H.264 video coding standard achieves significantly higher compression performance than MPEG-2. As the MPEG-2 is popular in digital TV, DVD, etc., bandwidth or memory space can be saved by transcoding those streams into H.264 in these applications. Unfortunately, the huge complexity keeps transcoding from being widely used in practical applications. This paper proposes an efficient transcoding architecture with a smart downscaling decoder and a fast mode decision algorithm. Using the proposed architecture, huge buffering memory space is saved and the transcoding complexity is reduced. Performance of the proposed fast mode decision algorithm is validated by experiments.
基金the National High Technology Research and Development Program (2007AA1Z24002003AA1Z2210).
摘要To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dynamically determining the transcoder's objective bit rate, according to the bandwidth variation of the wireless channel and the buffer occupancy. Then the transient performance, steady performance, and computational complexity of the algorithm are analyzed. Finally, the experiment results demonstrate that the algorithm can improve the synthetic performance of rate control through the compromise between the end-to-end delay and the playout quality.