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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Dynamic Service Selection For Service Composition With Time Constraints, Azlan Ismail, Jun Yan, Jun Shen
Dynamic Service Selection For Service Composition With Time Constraints, Azlan Ismail, Jun Yan, Jun Shen
Faculty of Informatics - Papers (Archive)
Service selection is a kind of planning approach that evaluates and selects from multiple services to form a composite plan. In service selection, we found one additional issue that has not been investigated yet namely time constraints consistency among composite services. This issue is significant because there are potential time constraints involved that might cause inconsistency between selected services although they can offer aggregated QoS that satisfy global requirements. Furthermore, there might be some unintended waiting time to be considered in the QoS aggregation. Thus, this paper contributes to the analysis on the problem caused by the time constraints and …
Differential Space-Time-Frequency Codes For Mb-Ofdm Uwb With Dual Carrier Modulation, Alfred Mertins, Le Chung Tran
Differential Space-Time-Frequency Codes For Mb-Ofdm Uwb With Dual Carrier Modulation, Alfred Mertins, Le Chung Tran
Faculty of Informatics - Papers (Archive)
In a multiple-input multiple-output (MIMO) multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) system, coherent detection where the channel state information (CSI) is assumed to be exactly known at the receiver requires the transmission of a large number of symbols for channel estimation, thus reducing the bandwidth efficiency. This paper examines the use of unitary differential space-time frequency codes (DSTFCs) in MB-OFDM UWB, which increases the system bandwidth efficiency due to the fact that no CSI is required for differential detection. The proposed DSTFC MB-OFDM system would be useful when the transmission of multiple channel estimation symbols is impractical or …
Unitary Differential Space-Time-Frequency Codes For Mb-Ofdm Uwb, Le Chung Tran, Alfred Mertins, E. Dutkiewicz, Xiaojing Huang
Unitary Differential Space-Time-Frequency Codes For Mb-Ofdm Uwb, Le Chung Tran, Alfred Mertins, E. Dutkiewicz, Xiaojing Huang
Faculty of Informatics - Papers (Archive)
In a multiple-input multiple-output (MIMO) multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) system, coherent detection where the channel state information (CSI) is assumed to be exactly known at the receiver requires the transmission of a large number of symbols for channel estimation, thus reducing the bandwidth efficiency. This paper examines the use of unitary differential space-time frequency codes (DSTFCs) in MB-OFDM UWB, which increases the system bandwidth efficiency due to the fact that no CSI is required for differential detection. The proposed DSTFC MB-OFDM system would be useful when the transmission of multiple channel estimation symbols is impractical or …
Space-Time-Frequency Code Implementation In Mb-Ofdm Uwb Communications: Design Criteria And Performance, Alfred Mertins, Le Chung Tran
Space-Time-Frequency Code Implementation In Mb-Ofdm Uwb Communications: Design Criteria And Performance, Alfred Mertins, Le Chung Tran
Faculty of Informatics - Papers (Archive)
This paper proposes a general framework of Space-Time-Frequency Codes (STFCs) for Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) Ultra-Wide Band (UWB) communications systems. A great similarity between the STFC MB-OFDM UWB systems and conventional wireless Complex Orthogonal Space-Time Block Code (CO STBC) Multiple-Input Multiple-Output (MIMO) systems is discovered. This allows us to quantify the pairwise error probability (PEP) of the proposed system and derive the general decoding method for the implemented STFCs. Based on the theoretical analysis results of PEP, we can further quantify the diversity order and coding gain of MB-OFDM UWB systems, and derive the design criteria for STFCs, …
Novel Cooperative Communication Schemes For Space-Time-Frequency Coded Mb-Ofdm Uwb, Le Chung Tran, Xiaojing Huang, Alfred Mertins, Eryk Dutkiewicz
Novel Cooperative Communication Schemes For Space-Time-Frequency Coded Mb-Ofdm Uwb, Le Chung Tran, Xiaojing Huang, Alfred Mertins, Eryk Dutkiewicz
Faculty of Informatics - Papers (Archive)
Cooperative communication has been intensively considered for general wireless and sensor networks. However, it has been almost untouched in Space-Time-Frequency Coded Multi-band OFDM Ultra-Wideband (STFC MB-OFDM UWB) systems. This paper thus proposes two cross-layer designs for cooperative communication, namely Simple Cooperative Communication Scheme (SCCS) and Advanced Cooperative Communication Scheme (ACCS), in slow fading scenarios. In the former, nodes always cooperate with one another despite the possibly erroneous reception at the partner nodes, while in the latter, nodes cooperate only in the case of successful reception. Simulations show that these schemes may considerably improve the performance of STFC MB-OFDM UWB without …
Mitagation Against Mai In A Space Time Spreading Software Defined Radio, Shinhan Wee, Montse Ros, Peter James Vial
Mitagation Against Mai In A Space Time Spreading Software Defined Radio, Shinhan Wee, Montse Ros, Peter James Vial
Faculty of Informatics - Papers (Archive)
A Software Defined Radio test bed using the Gnu Radio project was installed on Unix boxes and modified so that estimates of the channel state coefficients were taken for a Multiple Input Multiple output (MIMO) system to take advantage of space time transmission at a frqeuency of 2.4GHz. This system was modified to provide a Space Time Spreading test bed. The test bed was modified so that multiple access interference was experienced by off-setting different users data streams. The Walsh-Hadamard and Wysocki (low correlation) spreading sequences were deployed in the test bed to compare their Bit Error Rate performance. We …
Real-Time Single-Molecule Observation Of Rolling-Circle Dna Replication, Nathan A. Tanner, Joseph J. Loparo, Samir M. Hamdan, Slobodan Jergic, Nicholas E. Dixon, Antoine M. Van Oijen
Real-Time Single-Molecule Observation Of Rolling-Circle Dna Replication, Nathan A. Tanner, Joseph J. Loparo, Samir M. Hamdan, Slobodan Jergic, Nicholas E. Dixon, Antoine M. Van Oijen
Faculty of Science - Papers (Archive)
We present a simple technique for visualizing replication of individual DNA molecules in real time. By attaching a rolling-circle substrate to a TIRF microscope-mounted flow chamber, we are able to monitor the progression of single-DNA synthesis events and accurately measure rates and processivities of single T7 and Escherichia coli replisomes as they replicate DNA. This method allows for rapid and precise characterization of the kinetics of DNA synthesis and the effects of replication inhibitors.
Ranking Habitat Patches By Contribution To Network Connectivity: Tradeoffs Between Processing Time And Spatial Realisation, B Cook, Marjetta L. Puotinen, Rittick Borah
Ranking Habitat Patches By Contribution To Network Connectivity: Tradeoffs Between Processing Time And Spatial Realisation, B Cook, Marjetta L. Puotinen, Rittick Borah
Faculty of Science - Papers (Archive)
No abstract provided.