Difference between revisions of "Resource:Seminar"

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===Latest===
===Latest===
{{Latest_seminar
{{Latest_seminar
|abstract=Low-density parity-check (LDPC) codes have been widely used for Forward Error Correction (FEC) in wireless networks because they can approach the capacity of wireless links with lightweight encoding complexity. Although LoRa networks have been developed for many applications, they still adopt simple FEC codes, i.e., Hamming codes, which provide limited FEC capacity, causing unreliable data transmissions and high energy consumption of LoRa nodes. To close this gap, this paper develops LLDPC, which realizes LDPC coding in LoRa networks. Three challenges are addressed. 1) LoRa employs Chirp Spread Spectrum (CSS) modulation, which only provides hard demodulation results without soft information. However, LDPC requires the Log-Likelihood Ratio (LLR) of each received bit for decoding. We develop an LLR extractor for LoRa CSS. 2) Some erroneous bits may have high LLRs (i.e., wrongly confident in their correctness), significantly affecting the LDPC decoding efficiency. We use symbol-level information to fine-tune the LLRs of some bits to improve the LDPC decoding efficiency. 3) Soft Belief Propagation (SBP) is typically used as the LDPC decoding algorithm. It involves heavy iterative computation, resulting in a long decoding latency, which prevents the gateway from sending timely an acknowledgment. We take advantage of recent advances in graph neural networks for fast belief propagation in LDPC decoding. Extensive simulations on a large-scale synthetic dataset and in-filed experiments reveal that LLDPC can extend the lifetime of the default LoRa by 86.7% and reduce the decoding latency of the SBP algorithm by 58.09×.
|abstract=The massive connection of LoRa brings serious collision interference. Existing collision decoding methods cannot effectively deal with the adjacent collisions that occur when the collided symbols are adjacent in the frequency spectrum. The decoding features relied on by the existing methods will be corrupted by adjacent collisions. To address these issues, we propose Paralign, which is the first LoRa collision decoder supporting decoding LoRa collisions with confusing symbols via parallel alignment. The key enabling technology behind Paralign is tha there is no spectrum leakage with periodic truncation of a chirp. Paralign leverages the precise spectrum obtained by aligning the de-chirped periodic signals from each packet in parallel for spectrum filtering and power filtering. To aggregate correlation peaks in different windows of the same symbol, Paralign matches the peaks of multiple interfering windows to the interested window based on the time offset between collided packets. Moreover, a periodic truncation method is proposed to address the multiple candidate peak problem caused by side lobes of confusing symbols. We evaluate Paralign using USRP N210 in a 20-node network. Experimental results demonstrate that Paralign can significantly improve network throughput, which is over 1.46× higher than state-of-the-art methods.
|confname=SenSys' 22
|confname=ToSN '23
|link=https://dl.acm.org/doi/pdf/10.1145/3560905.3568547
|link=https://dl.acm.org/doi/10.1145/3571586
|title=LLDPC: A Low-Density Parity-Check Coding Scheme for LoRa Networks
|title=Decoding LoRa Collisions via Parallel Alignment
|speaker=Wengliang
|speaker=Kai Chen
|date=2023-12-21}}
|date=2024-01-04}}
{{Latest_seminar
{{Latest_seminar
|abstract=Network update enables Software-Defined Networks (SDNs) to optimize the data plane performance. The single update focuses on processing one update event at a time, i.e. , updating a set of flows from their initial routes to target routes, but it fails to handle continuously arriving update events in time incurred by high-frequency network changes. On the contrary, the continuous update proposed in “Update Algebra” can handle multiple update events concurrently and respond to the network condition changes at all times. However, “Update Algebra” only guarantees the blackhole-free and loop-free update. The congestion-free property cannot be respected. In this paper, we propose Coeus to achieve the continuous update while maintaining consistency, i.e. , ensuring the blackhole-free, loop-free, and congestion-free properties simultaneously. Firstly, we establish the continuous update model based on the update operations in update events. With the update model, we dynamically reconstruct the operation dependency graph (ODG) to capture the relationship between update operations and link utilization variations. Then, we develop a composition algorithm to eliminate redundant operations in update events. To further speed up the update procedure, we present a partition algorithm to split the operation nodes of the ODG into a series of suboperation nodes that can be executed independently. The partition algorithm is proven to be optimal. Finally, extensive evaluations show that Coeus can improve the update speed by at least 179% and reduce redundant operations by at least 52% compared with state-of-the-art approaches when the arrival rate of update events equals three times per second.
|abstract=Human activity recognition is important for a wide range of applications such as surveillance systems and human-computer interaction. Computer vision based human activity recognition suffers from performance degradation in many real-world scenarios where the illumination is poor. On the other hand, recently proposed WiFi sensing that leverage ubiquitous WiFi signal for activity recognition is not affected by illumination but has low accuracy in dynamic environments. In this paper, we propose WiMix, a lightweight and robust multimodal system that leverages both WiFi and vision for human activity recognition. To deal with complex real-world environments, we design a lightweight mix cross attention module for automatic WiFi and video weight distribution. To reduce the system response time while ensuring the sensing accuracy, we design an end-to-end framework together with an efficient classifier to extract spatial and temporal features of two modalities. Extensive experiments are conducted in the real-world scenarios and the results demonstrate that WiMix achieves 98.5% activity recognition accuracy in 3 scenarios, which outperforms the state-of-the-art 89.6% sensing accuracy using WiFi and video modalities. WiMix can also reduce the inference latency from 1268.25ms to 217.36ms, significantly improving the response time.
|confname=ToN' 22
|confname=MASS '23
|link=https://ieeexplore.ieee.org/document/9690589/
|link=https://ieeexplore.ieee.org/abstract/document/10298524
|title=Continuous Network Update With Consistency Guaranteed in Software-Defined Networks
|title=WiMix: A Lightweight Multimodal Human Activity Recognition System based on WiFi and Vision
|speaker=Yaliang
|speaker=Haotian
|date=2023-12-21}}
|date=2024-01-04}}
{{Latest_seminar
{{Latest_seminar
|abstract=With the reduced hardware costs of omnidirectional cameras and the proliferation of various extended reality applications, more and more 360° videos are being captured. To fully unleash their potential, advanced video analytics is expected to extract actionable insights and situational knowledge without blind spots from the videos. In this paper, we present OmniSense, a novel edge-assisted framework for online immersive video analytics. OmniSense achieves both low latency and high accuracy, combating the significant computation and network resource challenges of analyzing 360° videos. Motivated by our measurement insights into 360° videos, OmniSense introduces a lightweight spherical region of interest (SRoI) prediction algorithm to prune redundant information in 360° frames. Incorporating the video content and network dynamics, it then smartly scales vision models to analyze the predicted SRoIs with optimized resource utilization. We implement a prototype of OmniSense with commodity devices and evaluate it on diverse real-world collected 360° videos. Extensive evaluation results show that compared to resource-agnostic baselines, it improves the accuracy by 19.8% – 114.6% with similar end-to-end latencies. Meanwhile, it hits 2.0× – 2.4× speedups while keeping the accuracy on par with the highest accuracy of baselines.
|abstract=In wireless networks, the Named Data Networking (NDN) architecture maximizes contents’ availability throughout multiple network paths based on multicast-based communication combined with stateful forwarding and caching in intermediate nodes. Despite its benefits, the downside of the architecture resides in the packet flooding not efficiently prevented by current forwarding strategies and mainly associated with the native flooding of the architecture or malicious packets from Interest Flooding Attack (IFA). This work introduces iFLAT, a multicriteria-based forwarding strategy for i nterest FL ooding mitig AT ion on named data wireless networking. It follows a cross-layer approach that considers: (i) the Received Signal Strength (RSS) to adjust itself to the current status of the wireless network links, (ii) the network traffic ( meInfo ) to detect flooding issues and traffic anomalies, and (iii) a fake Interest Blacklist to identify IFA-related flooding. In doing so, the strategy achieves better efficiency on Interest flooding mitigation, addressing both native and IFA types of flooding. We evaluated the proposed strategy by reproducing a Flying Ad hoc Network (FANET) composed of Unmanned Aerial Vehicles (UAVs) featured by the NDN stack deployed in all nodes. Simulation results show that iFLAT can effectively detect and mitigate flooding, regardless of its origin or nature, achieving greater packet forwarding efficiency than competing strategies. In broadcast storm and IFA scenarios, it achieved 25.75% and 37.37% of traffic reduction, whereas Interest satisfaction rates of 16.36% and 51.78% higher, respectively.
|confname=INFOCOM '23
|confname=TMC '23
|link=https://ieeexplore.ieee.org/document/10229105
|link=https://ieeexplore.ieee.org/document/9888056
|title=OmniSense: Towards Edge-Assisted Online Analytics for 360-Degree Videos
|title=A Multicriteria-Based Forwarding Strategy for Interest Flooding Mitigation on Named Data Wireless Networking
|speaker=Mengfan
|speaker=Zhenghua
|date=2023-12-21}}
|date=2024-01-04}}
{{Latest_seminar
{{Latest_seminar
|abstract=Remote Direct Memory Access (RDMA) is widely used in high-performance computing (HPC) and data center networks. In this paper, we first show that RDMA does not work well with existing load balancing algorithms because of its traffic flow characteristics and assumption of in-order packet delivery. We then propose ConWeave, a load balancing framework designed for RDMA. The key idea of ConWeave is that with the right design, it is possible to perform fine granularity rerouting and mask the effect of out-of-order packet arrivals transparently in the network datapath using a programmable switch. We have implemented ConWeave on a Tofino2 switch. Evaluations show that ConWeave can achieve up to 42.3% and 66.8% improvement for average and 99-percentile FCT, respectively compared to the state-of-the-art load balancing algorithms.
|abstract=While recent work explored streaming volumetric content on-demand, there is little effort on live volumetric video streaming that bears the potential of bringing more exciting applications than its on-demand counterpart. To fill this critical gap, in this paper, we propose MetaStream, which is, to the best of our knowledge, the first practical live volumetric content capture, creation, delivery, and rendering system for immersive applications such as virtual, augmented, and mixed reality. To address the key challenge of the stringent latency requirement for processing and streaming a huge amount of 3D data, MetaStream integrates several innovations into a holistic system, including dynamic camera calibration, edge-assisted object segmentation, cross-camera redundant point removal, and foveated volumetric content rendering. We implement a prototype of MetaStream using commodity devices and extensively evaluate its performance. Our results demonstrate that MetaStream achieves low-latency live volumetric video streaming at close to 30 frames per second on WiFi networks. Compared to state-of-the-art systems, MetaStream reduces end-to-end latency by up to 31.7% while improving visual quality by up to 12.5%.
|confname=SIGCOMM '23
|confname=MobiCom '23
|link=https://dl.acm.org/doi/abs/10.1145/3603269.3604849
|link=https://dl.acm.org/doi/abs/10.1145/3570361.3592530
|title=Network Load Balancing with In-network Reordering Support for RDMA
|title=MetaStream: Live Volumetric Content Capture, Creation, Delivery, and Rendering in Real Time
|speaker=Jiyi
|speaker=Jiale
|date=2023-12-21}}
|date=2024-01-04}}
{{Resource:Previous_Seminars}}
{{Resource:Previous_Seminars}}

Revision as of 20:20, 2 January 2024

Time: Thursday 9:00-10:30
Address: 4th Research Building A518
Useful links: Readling list; Schedules; Previous seminars.

Latest

  1. [ToSN '23] Decoding LoRa Collisions via Parallel Alignment, Kai Chen
    Abstract: The massive connection of LoRa brings serious collision interference. Existing collision decoding methods cannot effectively deal with the adjacent collisions that occur when the collided symbols are adjacent in the frequency spectrum. The decoding features relied on by the existing methods will be corrupted by adjacent collisions. To address these issues, we propose Paralign, which is the first LoRa collision decoder supporting decoding LoRa collisions with confusing symbols via parallel alignment. The key enabling technology behind Paralign is tha there is no spectrum leakage with periodic truncation of a chirp. Paralign leverages the precise spectrum obtained by aligning the de-chirped periodic signals from each packet in parallel for spectrum filtering and power filtering. To aggregate correlation peaks in different windows of the same symbol, Paralign matches the peaks of multiple interfering windows to the interested window based on the time offset between collided packets. Moreover, a periodic truncation method is proposed to address the multiple candidate peak problem caused by side lobes of confusing symbols. We evaluate Paralign using USRP N210 in a 20-node network. Experimental results demonstrate that Paralign can significantly improve network throughput, which is over 1.46× higher than state-of-the-art methods.
  2. [MASS '23] WiMix: A Lightweight Multimodal Human Activity Recognition System based on WiFi and Vision, Haotian
    Abstract: Human activity recognition is important for a wide range of applications such as surveillance systems and human-computer interaction. Computer vision based human activity recognition suffers from performance degradation in many real-world scenarios where the illumination is poor. On the other hand, recently proposed WiFi sensing that leverage ubiquitous WiFi signal for activity recognition is not affected by illumination but has low accuracy in dynamic environments. In this paper, we propose WiMix, a lightweight and robust multimodal system that leverages both WiFi and vision for human activity recognition. To deal with complex real-world environments, we design a lightweight mix cross attention module for automatic WiFi and video weight distribution. To reduce the system response time while ensuring the sensing accuracy, we design an end-to-end framework together with an efficient classifier to extract spatial and temporal features of two modalities. Extensive experiments are conducted in the real-world scenarios and the results demonstrate that WiMix achieves 98.5% activity recognition accuracy in 3 scenarios, which outperforms the state-of-the-art 89.6% sensing accuracy using WiFi and video modalities. WiMix can also reduce the inference latency from 1268.25ms to 217.36ms, significantly improving the response time.
  3. [TMC '23] A Multicriteria-Based Forwarding Strategy for Interest Flooding Mitigation on Named Data Wireless Networking, Zhenghua
    Abstract: In wireless networks, the Named Data Networking (NDN) architecture maximizes contents’ availability throughout multiple network paths based on multicast-based communication combined with stateful forwarding and caching in intermediate nodes. Despite its benefits, the downside of the architecture resides in the packet flooding not efficiently prevented by current forwarding strategies and mainly associated with the native flooding of the architecture or malicious packets from Interest Flooding Attack (IFA). This work introduces iFLAT, a multicriteria-based forwarding strategy for i nterest FL ooding mitig AT ion on named data wireless networking. It follows a cross-layer approach that considers: (i) the Received Signal Strength (RSS) to adjust itself to the current status of the wireless network links, (ii) the network traffic ( meInfo ) to detect flooding issues and traffic anomalies, and (iii) a fake Interest Blacklist to identify IFA-related flooding. In doing so, the strategy achieves better efficiency on Interest flooding mitigation, addressing both native and IFA types of flooding. We evaluated the proposed strategy by reproducing a Flying Ad hoc Network (FANET) composed of Unmanned Aerial Vehicles (UAVs) featured by the NDN stack deployed in all nodes. Simulation results show that iFLAT can effectively detect and mitigate flooding, regardless of its origin or nature, achieving greater packet forwarding efficiency than competing strategies. In broadcast storm and IFA scenarios, it achieved 25.75% and 37.37% of traffic reduction, whereas Interest satisfaction rates of 16.36% and 51.78% higher, respectively.
  4. [MobiCom '23] MetaStream: Live Volumetric Content Capture, Creation, Delivery, and Rendering in Real Time, Jiale
    Abstract: While recent work explored streaming volumetric content on-demand, there is little effort on live volumetric video streaming that bears the potential of bringing more exciting applications than its on-demand counterpart. To fill this critical gap, in this paper, we propose MetaStream, which is, to the best of our knowledge, the first practical live volumetric content capture, creation, delivery, and rendering system for immersive applications such as virtual, augmented, and mixed reality. To address the key challenge of the stringent latency requirement for processing and streaming a huge amount of 3D data, MetaStream integrates several innovations into a holistic system, including dynamic camera calibration, edge-assisted object segmentation, cross-camera redundant point removal, and foveated volumetric content rendering. We implement a prototype of MetaStream using commodity devices and extensively evaluate its performance. Our results demonstrate that MetaStream achieves low-latency live volumetric video streaming at close to 30 frames per second on WiFi networks. Compared to state-of-the-art systems, MetaStream reduces end-to-end latency by up to 31.7% while improving visual quality by up to 12.5%.

History

2024

2023

2022

2021

2020

  • [Topic] [ The path planning algorithm for multiple mobile edge servers in EdgeGO], Rong Cong, 2020-11-18

2019

2018

2017

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