Apart from providing high system capacity it is essential for mobile communications systems as UNITS to operate with low electromagnetic emission. Smart antennas are one promising technology to establish exposure redu...
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ISBN:
(纸本)0780382927
Apart from providing high system capacity it is essential for mobile communications systems as UNITS to operate with low electromagnetic emission. Smart antennas are one promising technology to establish exposure reduction while upholding system capacity requirements. In this context, the main objective of this paper is to assess the performance improvements of practically applicable beamforming concepts for UNITS networks. The concepts illuminated are fixed as we as adaptive beamforming. To obtain suitable assessments we especially attend three essential aspects. First, proper SINR modelling is considered including spatially formed inter- / intra-cell interference as well as pilot pollution prevailing UNITS networks. Special interest is secondly given on the interaction between UMTS specific radio-resource management algorithms as power- / load control and the smart antenna concepts considered. Finally, we investigate mixed data rate traffic which is expected for UNITS. The simulations are carried out utilizing a combination of UNITS physical and dynamic system level simulators.
In this article we analyze the impact of channel estimation by means of the secondary common pilot channel (S-CPICH) on linear precoding in W-CDMA systems. The pilot sequences on the S-CPICH are transmitted over a fix...
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ISBN:
(纸本)0780382927
In this article we analyze the impact of channel estimation by means of the secondary common pilot channel (S-CPICH) on linear precoding in W-CDMA systems. The pilot sequences on the S-CPICH are transmitted over a fixed grid of beams, causing a systematic channel estimation error at the receiver. Consequently, the adapted rake receiver coefficients will be corrupted due to the use of the S-CPICH, which will lead to an incoherent superposition of the signal components when conventional adaptive space time precoders are employed. Assuming partial channel state information (CSI) at the transmitter we show how the effect of S-CPICH based channel estimation can be reduced or even removed, resulting in an enhanced system performance.
To enable new context-aware applications and services in future communication systems, wireless sensornetworks (WSNs) are required to capture the context surrounding the service user and service related objects. This...
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ISBN:
(纸本)9781424415014
To enable new context-aware applications and services in future communication systems, wireless sensornetworks (WSNs) are required to capture the context surrounding the service user and service related objects. This paper introduces a novel configurable architecture for a WSN system that is able to deliver context information from the sensors to the user in different application environments, and allows its efficient integration into third generation (3G) mobile communication systems in particular into the IP multimedia subsystem (IMS). The proposed architecture offers significant advantages compared to the ZigBee architecture.
The problem of sensor network localization has been addressed with several localization algorithms. These algorithms can be categorized into centralized schemes which require that computations be performed at base nod...
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ISBN:
(纸本)9781424415014
The problem of sensor network localization has been addressed with several localization algorithms. These algorithms can be categorized into centralized schemes which require that computations be performed at base nodes and distributed schemes which divide the network into sub-networks that localize themselves. In this work, we theoretically compare the transmission capacities of a general centralized algorithm against a distributed localization scheme to investigate the practicality of the schemes. We propose a simple model of the transmission overhead required for transmitting localization information and investigate the effect of the number of node links.
This paper introduces a new trust model and a reputation system for wireless sensornetworks based on a sensed continuous data. It establishes the continuous version of the beta reputation system introduced in [1] and...
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ISBN:
(纸本)9781424415014
This paper introduces a new trust model and a reputation system for wireless sensornetworks based on a sensed continuous data. It establishes the continuous version of the beta reputation system introduced in [1] and applied to binary events and presents a new Gaussian Reputation System for sensornetworks (GRSSN). We introduce a theoretically sound Bayesian probabilistic approach for mixing second-hand information from neighbouring nodes with directly observed information.
The received electromagnetic wave is converted to the electronic signal by the sensor, then the electronic signal is transformed into data flow by a high speed ADC for processing with the circuit composed of FPGA. The...
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ISBN:
(纸本)9780769538594
The received electromagnetic wave is converted to the electronic signal by the sensor, then the electronic signal is transformed into data flow by a high speed ADC for processing with the circuit composed of FPGA. The worked data is accumulated to the system computer for judging read and analysis. The system is applied mainly in the remote sensing information acquisition and processing. The system has 250MHz sampling rate and USB2.0 bus, so it also can be applied in other information acquisition fields.
Wireless sensornetworks (WSN), as a cutting-edge techniques in information acquisition and processing, can be widely used in many areas. WSN used in fault localization system on power grid cables is the research focu...
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ISBN:
(纸本)9781424465408
Wireless sensornetworks (WSN), as a cutting-edge techniques in information acquisition and processing, can be widely used in many areas. WSN used in fault localization system on power grid cables is the research focus of intelligent power grid. We improve the traditional DV Hop algorithm and propose a feasible method of failure localization which can.
This paper presents the e-SENSE middleware architecture for distributed processing of context information in dynamic wireless sensornetworks. At the lower layer, sensor nodes organize into clusters spontaneously base...
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ISBN:
(纸本)9781424415014
This paper presents the e-SENSE middleware architecture for distributed processing of context information in dynamic wireless sensornetworks. At the lower layer, sensor nodes organize into clusters spontaneously based on shared context. These clusters form the basis for the service-oriented processing layer, where the functionality of the sensor network is expressed using service task graphs supporting distributed execution of applications. The higher layer is responsible for complex context inference and recognition. As a concrete example we evaluate the distributed recognition of human activities in a car assembly process.
In this paper, we propose a simulation-based analysis of the impact of data fusion mechanisms in a Zigbee sensor network used to monitor a spatially constant binary phenomenon. The performance indicators of interest a...
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ISBN:
(纸本)9781424416875
In this paper, we propose a simulation-based analysis of the impact of data fusion mechanisms in a Zigbee sensor network used to monitor a spatially constant binary phenomenon. The performance indicators of interest are both physical layer-oriented (Bit Error Rate, BER) and networking-oriented (throughput, delay, and aggregate throughput). The considered topologies encompass both the absence and the presence of clustering. In the first class of scenarios, we analyze the impact, on the system performance, of the number of transmitting sensors, the Signal-to-Noise Ratio (SNR) at the sensors, and the presence of ACKnowledgment (ACK) messages. In the second class of scenarios, instead, we analyze the BER performance, in the presence of uniform and non-uniform clustering configurations. Data fusion is considered at the Access Point (AP) and, in clustered configurations, also at the clusterheads, which act as intermediate Fusion Centers (FCs). To the best of our knowledge, we are the first to characterize a Zigbee sensor network from a joint physical layer/networking perspective. Moreover, the proposed simulation results confirm recently obtained theoretical results.
Emerging applications such as network monitoring and sensor network data processing are requiring stream data processing technology. Due to the performance and storage constraints, we will not be able to Store the com...
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ISBN:
(纸本)9789806560468
Emerging applications such as network monitoring and sensor network data processing are requiring stream data processing technology. Due to the performance and storage constraints, we will not be able to Store the complete stream in main memory and as such processing the complete stream at one time will be impractical. For this reason, a succinct summarized data structure (e.g., histogram) is very essential to handle such a huge stream of data. Furthermore, a time based query or a sliding window query will be important for most stream applications. In this paper, we propose a histogram construction strategy which can overcome limited memory constraints for a continuous data stream and also effectively handle time information of stream data through the histogram merge technique. Several experiments show that the proposed method yields relatively low approximation errors for processing time based window queries in a limited memory environment.
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