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.
1781908
An EM-Based Time-Domain Channel Estimation Algorithm Using a priori Information
Based on the expectation-maximization (EM) algorithm, an iterative time-domain channel estimation approach capable of using a priori information is proposed for orthogonal frequency division multiplexing (OFDM) systems in this letter: it outperforms its noniterative counterpart in terms of estimation accuracy as well as bit error rate (BER) performance. Numerical simulations demonstrate that an SNR gain of 1 dB at BER = 10 -4 with only one iteration and estimation mean square error (MSE) which nearly coincides with the Cramer-Rao bound (CRB) in the low SNR region can be obtained, thanks to the efficient use of a priori information.
18823520
A Pursuit-Evasion Algorithm Based on Hierarchical Reinforcement Learning
This paper proposed a pursuit-evasion algorithm based on the Option method from hierarchical reinforcement learning and applied it into multi-robot pursuit-evasion game in 2D-Dynamic environment. The algorithm efficiency is studied by comparing it with Q-learning. We decompose the complex task with option method, and divide the learning process into two parts: High-level learning and Low-level learning, then design a new mechanism in order to make the learning process perform parallel. The simulation result shows the Option algorithm can efficiently reduce the complexity of pursuit-evasion task, avoid traditional reinforcement learning curse of dimensionality, and improve the learning result.
6059000
Preserving User Location Privacy in Mobile Data Management Infrastructures
Location-based services, such as finding the nearest gas station, require users to supply their location information. However, a user's location can be tracked without her consent or knowledge. Lowering the spatial and temporal resolution of location data sent to the server has been proposed as a solution. Although this technique is effective in protecting privacy, it may be overkill and the quality of desired services can be severely affected. In this paper, we suggest a framework where uncertainty can be controlled to provide high quality and privacy-preserving services, and investigate how such a framework can be realized in the GPS and cellular network systems. Based on this framework, we suggest a data model to augment uncertainty to location data, and propose imprecise queries that hide the location of the query issuer and yields probabilistic results. We investigate the evaluation and quality aspects for a range query. We also provide novel methods to protect our solutions against trajectory-tracing. Experiments are conducted to examine the effectiveness of our approaches.
4714436
Notice of RetractionCost Comparison and Control Based on GLM and Panel Data Model: Evidence from Major Citrus Producing Areas in China
All the major citrus producing areas in China are facing the intensive competition from international market. The problem of how to find an efficient path to decrease citrus production cost by analyzing production cost of citrus and how to promote effective cooperation between regions to deal with the pressure of international market through integrating resources of the regions, has become an important problem that all the major citrus producing areas focus on. The paper firstly compares citrus production cost of the major citrus producing areas, and then reveals the reason causing cost differentiation in the central and eastern areas according to general linear model and panel data, finally proposes several suggestions to control citrus production cost.
13218093
Notice of Violation of IEEE Publication PrinciplesAchieving flexible task delegation in role-based agent teams
Teamwork has become increasingly important to many disciplines. In our opinion, an effective design of a teamwork language should be able to handle unexpected uncertainties and allow for the conceptual specification of teamwork knowledge for reuse. This paper introduces RoB-MALLET, a teamwork language based on the concepts of role and role variable. An important characteristic of our notion of role is that it includes the specific operations that an agent filling the role must perform in a specific setting as well as their ordering constraints. Taking this view on the definition of role has enabled us to present the responsibility of roles, to reason about the assignment of real agents to roles, and to achieve a certain level of plan reusability. Finally, we present several experiments that explore plan reusability of RoB-MALLET, show that it is flexible in supporting simultaneity of invocation and evaluate its efficiency in supporting teamwork.
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.