Yanming Shen

LayerP2P: Using Layered Video Chunks in P2P Live Streaming

Although there are several successful commercial deployments of live P2P streaming systems, the current designs; lack incentives for users to contribute bandwidth resources; lack adaptation to aggregate bandwidth availability; and exhibit poor video quality when bandwidth availability falls below bandwidth supply. In this paper, we propose, prototype, deploy, and validate LayerP2P, a P2P live streaming system that addresses all three of these problems. LayerP2P combines layered video, mesh P2P distribution, and a tit-for-tat-like algorithm, in a manner such that a peer contributing more upload bandwidth receives more layers and consequently better video quality. We implement LayerP2P (including seeds, clients, trackers, and layered codecs), deploy the prototype in PlanetLab, and perform extensive experiments. We also examine a wide range of scenarios using trace-driven simulations. The results show that LayerP2P has high efficiency, provides differentiated service, adapts to bandwidth deficient scenarios, and provides protection against free-riders.

Using layered video to provide incentives in P2P live streaming

In this paper, we design a distributed incentive mechanism for mesh-pull P2P live streaming networks. In our system, a video is encoded into layers with lower layers having more importance. The system is heterogeneous with peers having different uplink bandwidths. We design a distributed protocol in which a peer contributing more uplink bandwidth receives more layers and consequently better video quality. Previous approaches consider single-layer video, where each peer receives the same video quality no matter how much bandwidth it contributes to the system. The simulation results show that our approach can provide differentiated video quality commensurate with a peers contribution to other peers, and can also discourage free-riders. Furthermore, we also compare our layered approach with a multiple description coding (MDC) approach, and conclude that the layered approach is more promising, primarily due to its higher coding efficiency.

Substream Trading: Towards an open P2P live streaming system

We consider the design of an open P2P live-video streaming system. When designing a live video system that is both open and P2P, the system must include mechanisms that incentivize peers to contribute upload capacity. We advocate an incentive principle for live P2P streaming: a peerpsilas video quality is commensurate with its upload rate. We propose substream trading, a new P2P streaming design which not only enables differentiated video quality commensurate with a peerpsilas upload contribution but can also accommodate different video coding schemes, including single-layer coding, layered coding, and multiple description coding. Extensive trace-driven simulations show that substream trading has high efficiency, provides differentiated service, low start-up latency, synergies among peers with different Internet access rates, and protection against free-riders.

An effective solution for trademark image retrieval by combining shape description and feature matching

Trademark image retrieval (TIR), a branch of content-based image retrieval (CBIR), is playing an important role in multimedia information retrieval. This paper proposes an effective solution for TIR by combining shape description and feature matching. We first present an effective shape description method which includes two shape descriptors. Second, we propose an effective feature matching strategy to compute the dissimilarity value between the feature vectors extracted from images. Finally, we combine the shape description method and the feature matching strategy to realize our solution. We conduct a large number of experiments on a standard image set to evaluate our solution and the existing solutions. By comparison of their experimental results, we can see that the proposed solution outperforms existing solutions for the widely used performance metrics.

Byte-focal: a practical load balanced switch

Recently, a novel switch architecture, the load balanced (LB) switch proposed by C.S. Chang et al. (2000, 2002) opened a new avenue for designing a large-capacity packet switch. The load balanced switch consists of two stages. First, a load-balancing stage spreads arriving packets equally among all linecards. Then, a forwarding stage transfers packets from the linecards to their final output destination. The load balanced switch does not need any centralized scheduler and can achieve 100% throughput under a broad class of traffic distributions. However, the load balanced switch may cause packets at the output port to be out of sequence. Several schemes have been proposed to tackle the out-of-sequence problem of the load balanced switch. However, they are either too complex to implement, or introduce a large additional delay. In this paper, we present a practical load balanced switch, called the byte-focal switch, which uses packet-by-packet scheduling to significantly improve the delay performance over switches of comparable complexity.

P2P Video Live Streaming with MDC: Providing Incentives for Redistribution

In this paper, we consider applying multiple description coding in mesh-pull P2P live streaming networks to provide incentives for redistribution. In our system, a video is encoded into multiple descriptions with each description having equal importance. We consider a heterogeneous system with peers having different uplink bandwidths. We design a distributed protocol in which a peer contributing more uplink bandwidth receives more descriptions and consequently better video quality. Previous approaches consider single-layer video, where each peer receives the same video quality no matter how much bandwidth it contributes to the system. The simulation results show that our approach can provide differentiated video quality commensurate with a peers contribution to other peers.

Streaming layered encoded video using peers

Peer-to-peer video streaming has emerged as an important means to transport stored video. The peers are less costly and more scalable than an infrastructure-based video streaming network which deploys a dedicated set of servers to store and distribute videos to clients. In this paper, we investigate streaming layered encoded video using peers. Each video is encoded into hierarchical layers which are stored on different peers. The system serves a client request by streaming multiple layers of the requested video from separate peers. The system provides unequal error protection for different layers by varying the number of copies stored for each layer according to its importance. We evaluate the performance of our proposed system with different copy number allocation schemes through extensive simulations. Finally, we compare the performance of layered coding with multiple description coding.

Efficient Unknown Tag Identification Protocols in Large-Scale RFID Systems

Owing to its attractive features such as fast identification and relatively long interrogating range over the classical barcode systems, radio-frequency identification (RFID) technology possesses a promising prospect in many practical applications such as inventory control and supply chain management. However, unknown tags appear in RFID systems when the tagged objects are misplaced or unregistered tagged objects are moved in, which often causes huge economic losses. This paper addresses an important and challenging problem of unknown tag identification in large-scale RFID systems. The existing protocols leverage the Aloha-like schemes to distinguish the unknown tags from known tags at the slot level, which are of low time-efficiency, and thus can hardly satisfy the delay-sensitive applications. To fill in this gap, two filtering-based protocols (at the bit level) are proposed in this paper to address the problem of unknown tag identification efficiently. Theoretical analysis of the protocol parameters is performed to minimize the execution time of the proposed protocols. Extensive simulation experiments are conducted to evaluate the performance of the protocols. The results demonstrate that the proposed protocols significantly outperform the currently most promising protocols.

Completely Pinpointing the Missing RFID Tags in a Time-Efficient Way

Radio Frequency Identification (RFID) technology has been widely used in inventory management in many scenarios, e.g., warehouses, retail stores, hospitals, etc. This paper investigates a challenging problem of complete identification of missing tags in large-scale RFID systems. Although this problem has attracted extensive attention from academy and industry, the existing work can hardly satisfy the stringent real-time requirements. In this paper, a Slot Filter-based Missing Tag Identification (SFMTI) protocol is proposed to reconcile some expected collision slots into singleton slots and filter out the expected empty slots as well as the unreconcilable collision slots, thereby achieving the improved time-efficiency. The theoretical analysis is conducted to minimize the execution time of the proposed SFMTI. We then propose a cost-effective method to extend SFMTI to the multi-reader scenarios. The extensive simulation experiments and performance results demonstrate that the proposed SFMTI protocol outperforms the most promising Iterative ID-free Protocol (IIP) by reducing nearly 45% of the required execution time, and is just within a factor of 1.18 from the lower bound of the minimum execution time.

A Multiple Hashing Approach to Complete Identification of Missing RFID Tags

Owing to its superior properties, such as fast identification and relatively long interrogating range over barcode systems, Radio Frequency Identification (RFID) technology has promising application prospects in inventory management. This paper studies the problem of complete identification of missing RFID tag, which is important in practice. Time efficiency is the key performance metric of missing tag identification. However, the existing protocols are ineffective in terms of execution time and can hardly satisfy the requirements of realtime applications. In this paper, a Multi-hashing based Missing Tag Identification (MMTI) protocol is proposed, which achieves better time efficiency by improving the utilization of the time frame used for identification. Specifically, the reader recursively sends bitmaps that reflect the current slot occupation state to guide the slot selection of the next hashing process, thereby changing more empty or collision slots to the expected singleton slots. We investigate the optimal parameter settings to maximize the performance of the MMTI protocol. Furthermore, we discuss the case of channel error and propose the countermeasures to make the MMTI workable in the scenarios with imperfect communication channels. Extensive simulation experiments are conducted to evaluate the performance of MMTI, and the results demonstrate that this new protocol significantly outperforms other related protocols reported in the current literature.