Jehn-Ruey Jiang

FLoD: A Framework for Peer-to-Peer 3D Streaming

Interactive 3D content on Internet has yet become popular due to its typically large volume and the limited network bandwidth. Progressive content transmission, or 3D streaming, thus is necessary to enable real-time content interactions. However, the heavy data and processing requirements of 3D streaming challenge the scalability of client-server delivery methods. We propose the use of peer-to-peer (P2P) networks for 3D streaming, and argue that due to the non-linear access patterns of 3D content, P2P 3D streaming is a new class of applications apart from existing media streaming and requires new investigations. We also present FLoD, the first P2P 3D streaming framework that allows clients of 3D virtual globe or virtual environment (VE) applications to obtain relevant data from other clients while minimizing server resource usage. To demonstrate how FLoD applies to real-world scenarios, we build a prototype system that adapts JPEG 2000-based 3D mesh streaming for P2P delivery. Experiments show that server-side bandwidth usage can thus be reduced, while simulations indicate that P2P 3D streaming is fundamentally more scalable than client-server approaches.

Adaptive splitting and pre-signaling for RFID tag anti-collision

In an RFID system a reader requests tags to send their IDs by RF signal backscattering for the purpose of identification. When multiple tags respond to the request simultaneously, tag collisions occur and the tag identification performance is degraded. There are several tag anti-collision protocols proposed for reducing tag collisions. The protocols can be categorized into two classes: ALOHA-based and tree-based protocols that include deterministic tree-based and probabilistic counter-based subclasses of protocols. ALOHA-based protocols have the tag starvation problem; deterministic tree-based protocols have the problem that their performances are influenced by the length and/or the distribution of tag IDs. On the contrary, probabilistic counter-based protocols do not have such problems. In this paper, we propose a probabilistic counter-based tag anti-collision protocol, called ASPS, to reduce tag collisions by adaptively splitting tags encountering collisions into several groups according to the estimated number of tags to be split, and to reduce the number of messages sent between the reader and tags by utilizing a pre-signaling bit. We simulate and analyze ASPS and compare it with related ones to show its advantages.

Cohorts structures for fault-tolerant k entries to a critical section

We propose a structure named Cohorts to solve the problem of the access control of multiple entries to a critical section. Our solution is formalized as forming quorums in a k-coterie. It is resilient to node failures and/or network partitioning, invokes constant expected message cost and has comparably high availability.

k-coteries for fault-tolerant k entries to a critical section

The authors extend the concept of coterie into k-coterie for k entries to a critical section. A structure named Cohorts is proposed to construct quorums in a k-coterie. The solution is resilient to node failures and/or network partitioning and has a low communication cost. The Cohorts structure is further improved to increase the availabilities of 1-entry critical sections.<<ETX>>

ALRD: AoA Localization with RSSI Differences of Directional Antennas for Wireless Sensor Networks

In this paper, we fit RSSI values into a parabola function of the AoA between 0° and 90° by applying quadratic regression analysis. We also set up two-directional antennas with perpendicular orientations at the same position and fit the difference of the signal RSSI values of the two antennas into a linear function of the AoA between 0° and 90° by linear regression analysis. Based on the RSSI-fitting functions, we propose a novel localization scheme, called AoA Localization with RSSI Differences (ALRD), for a sensor node to quickly estimate its location with the help of two beacon nodes, each of which consists of two perpendicularly orientated directional antennas. We apply ALRD to a WSN in a 10 × 10  m indoor area with two beacon nodes installed at two corners of the area. Our experiments demonstrate that the average localization error is 124 cm. We further propose two methods, named maximum-point minimum-diameter and maximum-point minimum-rectangle, to reduce localization errors by gathering more beacon signals within 1 s for finding the set of estimated locations of maximum density. Our results demonstrate that the two methods can reduce the average localization error by a factor of about 29%, to 89 cm.

Scalable AOI-Cast for Peer-to-Peer Networked Virtual Environments

Networked virtual environments (NVEs) are computer-generated virtual worlds where users interact by exchanging messages via network connections. Each NVE user often pays attention to only a limited visibility sphere called area of interest (AOI) where interactions occur. The dissemination of messages to other users within the AOI (i.e., the AOI neighbors) thus is a fundamental NVE operation referred to as AOI-cast. Existing studies on NVE scalability have focused on system scalability, or the ability for the system to handle a growing number of total users, by using multicast or peer-to-peer (P2P) architectures. However, another overlooked, yet important form of scalability relates to the handling of a growing number of users within the AOI (or AOI scalability). In this paper, we propose two AOI-cast schemes, called VoroCast and FiboCast, to improve the AOI scalability of P2P-based NVEs. VoroCast constructs a spanning tree across all AOI neighbors based on Voronoi diagrams, while FiboCast dynamically adjusts the messaging range by a Fibonacci sequence, so that AOI neighbors would receive updates at frequencies based on their hop counts from the message originator. Simulations show that the two schemes provide better AOI scalability than existing approaches.

Selection strategies for peer-to-peer 3D streaming

In multi-user networked virtual environments such as Second Life, 3D streaming techniques have been used to progressively download and render 3D objects and terrain, so that a full download or prior installation is not necessary. As existing client-server architectures may not scale easily, 3D streaming based on peer-to-peer (P2P) delivery is recently proposed to allow users to acquire 3D content from other users instead of the server. However, discovering the peers who possess relevant data and have enough bandwidth to answer data requests is non-trivial. A naive query-response approach thus may be inefficient and could incur unnecessary latency and message overhead. In this paper, we propose a peer selection strategy for P2P-based 3D streaming, where peers exchange information on content availability incrementally with neighbors. Requestors can thus discover suppliers quickly and avoid time-consuming queries. A multi-level area of interest (AOI) request is also adopted to avoid request contention due to concentrated requests. Simulation results show that our strategies achieve better system scalability and streaming performance than a naive query-response approach.

Peer-to-Peer 3D Streaming

Virtual worlds have become very popular in recent years, with trends toward larger worlds and more user-generated content. The growth of 3D content in virtual worlds will make real-time content streaming (or 3D streaming) increasingly attractive for developers. To meet the demands of a large user base while lowering costs, peer-to-peer (P2P) content delivery holds the promise for a paradigm shift in how future virtual worlds will be deployed and used. The authors define both the problem and solution spaces for P2P 3D streaming - by outlining its requirements and challenges - and categorize existing proposals.

Extending Dijkstra's shortest path algorithm for software defined networking.

This paper extends the well-known Dijkstras shortest path algorithm to consider not only the edge weights but also the node weights for a graph derived from the underlying SDN topology. We use Pyretic to implement the extended Dijkstras algorithm and compare it with the original Dijkstras algorithm and the unit-weighted Dijkstras algorithm under the Abilene network topology in terms of end-to-end latency with the Mininet tool. As shown by the comparisons, the extended Dijkstras algorithm outperforms the other algorithms.

Anonymous Path Routing in Wireless Sensor Networks

How to secure data communication is an important problem in wireless sensor networks (WSNs). General solutions to the problem are to encrypt the packet payload with symmetric keys. But those solutions only prevent the packet content from being snooped or tampered. Adversaries still can learn network topology by the traffic analysis attack. In this paper, we propose an anonymous path routing (APR) protocol for WSNs. In APR, data are encrypted by pair-wise keys and transmitted with anonyms between neighboring sensor nodes and anonyms between the source and destination nodes of a multi-hop communication path. The encryption prevents adversaries from disclosing the data, and the anonymous communication prevents adversaries from observing the relation of the packets for further attacks. We implement APR on the MICAz platform to evaluate its overheads for demonstrating its applicability in practical WSNs.