7743758
Link Performance of WiMAX PUSC
Link performance of WiMAX (802.16e) downlink and uplink using partial usage subchannelization (PUSC) is evaluated through link-level simulations. WiMAX using single transmit and two receive antennas is compared to a WiMAX system with four transmit and two receive antennas with closed-loop beamforming in the downlink and one transmit and eight receive antennas in the uplink. Two dimensional channel estimators are applied to estimate the channel frequency response using pilot symbols. Spatial channel modeling method is used to model the antenna correlations between multiple transmit and the multiple receive antennas. Link simulations demonstrate that significant link performance improvements can be achieved using closed-loop beamforming for downlink and using more receive antennas for uplink.
1118388
HRPD-A downlink voice/IP and data throughput and delay analysis
HRPD-A adds new forward and reverse link rates and a forward link multi-user packet capability at the MAC layer. Completed simulations reveal the performance characteristics of this system in the 1.9 GHz frequency band. These characteristics consist of capacities of voice/IP traffic and mixed data and voice/IP traffic. Downlink data traffic models consist of FTP, HTTP (Web browsing), WAP, and video streaming models. The simulation assumptions include the ITU channel models and 3GPP2 data traffic models
10478649
WiMAX Overview and System Performance
In this paper, the performance of WiMax network with DL SIMO, DL MIMO and UL SIMO is analyzed via system simulations. Two data traffic models are considered, namely Web browsing (HTTP) and full buffer sessions, operating in multi path fading channels such as the ITU pedestrian-B and vehicular-A channels. The control channel coverage and reliability of WiMAX using realistic overhead is also analyzed in this paper.
16170916
An Object-Oriented Product Data Management
Product Data Management (PDM) system enables the management of the entire product lifecycle and related information about its design, its manufacturing and its in-service. The interest of using the object-oriented approach for modeling, specifying and implementing PDM systems is detailed. Then an implementation method is proposed in order to clarify the instantiation of UML diagrams into database entities. Finally the system is implemented on J2EE platform. The used UML diagrams for the modeling and integration of product, process, and resource data is detailed in order to argue the interest of an object-oriented approach in such kind of PDM implementation.
44633498
Simulation of the defect removal process with queuing theory
38387680
An Adaptive MIMO System Based on Unified Belief Propagation Detection
An adaptive multiple input and multiple output (MIMO) system based on the unified belief propagation (BP) detection is proposed. A BP detector composed of a serial of component detectors is first presented. With a unified design of the BP detector, a multi-rate MIMO system adaptive to channel variations is then developed, which aims at achieving the maximal throughput performance. The usage of the unified BP detector eliminates the multiple detector modules at the receiver in conventional multi-mode adaptive MIMO systems. Further, the linear complexity to space time block length and parallel operation of the unified BP detection provide the advantages of low complexity, low detection delay and smooth switching between different data rates. With the average receiving signal-to-noise ratio (SNR) based switching mechanism, the proposed adaptive MIMO framework adaptively chooses the appropriate rate for the transmission. Simulation results are provided to show the BER and complexity performance of a specific BP detector as well as the throughput performance of the adaptive scheme.
10988574
Remote Video Monitoring Over the WWW
Remote video monitoring has become increasingly important for monitoring the security of destined locations. Traditional security monitoring systems using coaxial cables and VCR recording systems are expensive and ineffective. With the rapid growth of the Internet, it is now possible to use it as an intermediate transmission medium to support real-time video transmission. This paper proposes a web-based remote monitoring system known as iSecure. Apart from the essential live or stored video transmission, intelligent monitoring and web-based monitoring are also supported. As the transmission of live video data through the packet switched network environment of the Internet can result in packet loss and quality degradation, the iSecure system has implemented an adaptive transmission and recovery mechanism to enhance the quality of real-time video transmission. Intelligent monitoring for elevator security and face-based door access control applications has been incorporated. The iSecure system can be used as a framework for developing other intelligent remote monitoring applications.
707949
Single Event Upset: An Embedded Tutorial
With the continuous downscaling of CMOS technologies, the reliability has become a major bottleneck in the evolution of the next generation systems. Technology trends such as transistor down-sizing, use of new materials, and system on chip architectures continue to increase the sensitivity of systems to soft errors. These errors are random and not related to permanent hardware faults. Their causes may be internal (e.g., interconnect coupling) or external (e.g., cosmic radiation). To meet the system reliability requirements it is necessary for both the circuit designers and test engineers to get the basic knowledge of the soft errors. We present a tutorial study of the radiation-induced single event upset phenomenon caused by external radiation, which is a major source of soft errors. We summarize basic radiation mechanisms and the resulting soft errors in silicon. Soft error mitigation techniques with time and space redundancy are illustrated. An industrial design example, the IBM z990 system, shows how the industry is dealing with soft errors these days.