17443935
Facilitating an Active Transmit-only RFID System Through Receiver-based Processing
Many asset tracking applications demand long-lived, low-cost, and continuous monitoring of a large number of items, which has posed a significant challenge to today's RFID design. In order to satisfy these requirements, we propose to adopt transmit-only tags without a receiver, which can offer both low power and low cost. In spite of their great potential, such a platform faces many challenges since it cannot sense the channel, causing the collisions among tag transmissions to be high. It is thus crucial to employ effective multi-user detection schemes at the tag reader to extract valid information from collided signals. Traditional detection schemes, such as successive cancellation, cannot be directly applied to the targeted system. Firstly, due to the simplicity of receiver-less transmit-only tags, there is no mechanism for feedback to the tags that is traditionally needed for accurate multi-user detection. More importantly, these schemes impose serious processing and memory requirements on the underlying system, which makes real-time tracking impossible. In this study, we address these challenges by performing a statistical estimation of the signal amplitude, and by dividing the received signal sequence (from all the tags) and assigning each block to one reader. We also adopt an online learning mechanism so that readers can anticipate the tags that belong to them. We show that the proposed detection algorithm can achieve low detection error under realistic system conditions.
37152915
Image Disorientation Auto-Recovery
Automatically detecting and correcting disoriented image frames in a content-related image sequence is a problem that must be addressed in many image and video applications. In this paper, we give a robust feature-based algorithm to efficiently detect and adjust the disorientation of images. Keyword image orientation, crop, Robert edge detection, line feature, Hough transformation.
44610157
A New Robust Bandpass Sampling Scheme for Multiple RF Signals in SDR System
Software defined radio (SDR) technology has been widely applied for its powerful universality and flexibility in the past decade. To address the issue of bandpass sampling of multiband signals, a novel and efficient method of finding the minimum valid sampling frequency is proposed. Since there are frequency deviations due to the channel effect and hardware instability in actual systems, we also consider the guard-bands between downconverted signal spectra in determining the minimum sampling frequency. In addition, the case that the spectra within the sampled bandwidth are located in inverse placement can be avoided by our proposed method, which will reduce the complexity of the succeeding digital signal process significantly. Simulation results illustrate that the proper minimum sampling frequency can be determined rapidly and accurately.
15564677
Handover Latency of MIPv6 Implementation in Linux
Mobile IPv6 (MIPv6) is proposed to enable network applications to continuously operate at the required quality of service in the wire or wireless IP network. Handover latency of MIPv6 is the main cause of packet loss and performance degradation and is too long for real-time and throughput-sensitive applications. Enhancement of basic MIPv6 with respect to handover latency has been studied widely. A L3 handover procedure can be divided into four phases: Movement Detection, CoA Configuration, Home agent Registration and Route Optimization. The latencies in different handover phases have been measured in an operated wireless LAN (WLAN) in order to determine the performance bottleneck of handover. The effect of handover latency on the sliding window of TCP and application layer protocol is also parsed with experiment. Further more, we modify the MIPv6 implementations of Linux on mobile node and home agent to verify the potential of performance improvement for MIPv6 protocol. The experiment result can help the enhancement of MIPv6 and application development.
24687403
A synthesis scheme for simultaneous scheduling, binding, partitioning and placement with resources operating at multiple voltages
One promising technique to reduce power consumption is to power a chip with multiple supply voltages. However, as noticed by M.C. Johnson and K. Roy (see ACM Trans. Design Auto. Electronic Syst., vol.2, p.227-48, 1997), multiple voltage designs can cause a number of serious layout problems. We have shown that the layout problems can be partially solved by the addition of a partitioning step into the synthesis flow. A more subtle solution to solve the layout problems requires placement also to be included in the design flow. We present a synthesis scheme, following a simulated annealing engine, to minimize power consumption and area with resources operating at multiple voltages under timing constraints. The scheme simultaneously considers many correlated factors, such as scheduling, binding, partitioning and placement, to reduce power consumption due to both functional units and interconnections between and among them. Experiments with a number of DSP benchmarks show that the proposed algorithm can achieve significant reduction in power and area.
15799724
An On-Off Queue Control Mechanism for Scalable Video Streaming over the IEEE 802.11e WLAN
In this paper, we study the issue of scalable video streaming over IEEE 802.11e EDCA WLANs. Our basic idea is to control the number of "active" nodes on the channel in order to reduce collisions under heavy traffic conditions. Specifically, we propose a distributed on-off queue control (OOQC) mechanism, which is designed to maintain high network throughput while keeping packet loss due to collision as low as possible. A low priority early drop (LPED) method is also employed to drop the packets at the queue according to packet relative priority index (RPI) provided by scalable video coding. Simulation results show that our proposed OOQC scheme significantly outperforms EDCA in received video quality.
14192001
Emergence of Social Norms in Complex Networks
This paper studies the problem that how social norms emerge even though agents are selfish and attempt to only maximize their own utility. We propose a new rule for social interactions. The rule is called Highest Rewarding Neighborhood (HRN). The HRN rule allows agents to remain selfish and be able to break relationships in order to maximize their utility. Our experiment shows that when agents are able to break unrewarding relationships that a Pareto-optimum strategy arises as the social normal. In addition we conclude the rate and amount of Pareto-optimum strategy that arises is dependent on the network structure when the networks are dynamic, and the rate is independent of the network structure when the networks are static.