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Roni Even - One of the best experts on this subject based on the ideXlab platform.
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RTP Header Extension for the RTP Control Protocol (RTCP) Source Description Items
2016Co-Authors: Magnus Westerlund, Bo Burman, Mo Zanaty, Roni EvenAbstract:Source Description (SDES) items are normally transported in the RTP Control Protocol (RTCP). In some cases, it can be beneficial to speed up the delivery of these items. The main case is when a new Synchronization Source (SSRC) joins an RTP session and the receivers need this Source's identity, relation to other Sources, or its Synchronization context, all of which may be fully or partially identified using SDES items. To enable this optimization, this document specifies a new RTP header extension that can carry SDES items.
Perkins C. - One of the best experts on this subject based on the ideXlab platform.
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Sending multiple RTP streams in a single RTP session: grouping RTP control protocol (RTCP) reception statistics and other feedback
'RFC Editor', 2021Co-Authors: Lennox J., Westerlund M., Wu Q., Perkins C.Abstract:RTP allows multiple RTP streams to be sent in a single session but requires each Synchronization Source (SSRC) to send RTP Control Protocol (RTCP) reception quality reports for every other SSRC visible in the session. This causes the number of RTCP reception reports to grow with the number of SSRCs, rather than the number of endpoints. In many cases, most of these RTCP reception reports are unnecessary, since all SSRCs of an endpoint are normally co-located and see the same reception quality. This memo defines a Reporting Group extension to RTCP to reduce the reporting overhead in such scenarios
Scott T Grafton - One of the best experts on this subject based on the ideXlab platform.
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coupling between theta oscillations and cognitive control network during cross modal visual and auditory attention supramodal vs modality specific mechanisms
PLOS ONE, 2016Co-Authors: Wuyi Wang, Shivakumar Viswanathan, Taraz G Lee, Scott T GraftonAbstract:Cortical theta band oscillations (4–8 Hz) in EEG signals have been shown to be important for a variety of different cognitive control operations in visual attention paradigms. However the Synchronization Source of these signals as defined by fMRI BOLD activity and the extent to which theta oscillations play a role in multimodal attention remains unknown. Here we investigated the extent to which cross-modal visual and auditory attention impacts theta oscillations. Using a simultaneous EEG-fMRI paradigm, healthy human participants performed an attentional vigilance task with six cross-modal conditions using naturalistic stimuli. To assess supramodal mechanisms, modulation of theta oscillation amplitude for attention to either visual or auditory stimuli was correlated with BOLD activity by conjunction analysis. Negative correlation was localized to cortical regions associated with the default mode network and positively with ventral premotor areas. Modality-associated attention to visual stimuli was marked by a positive correlation of theta and BOLD activity in fronto-parietal area that was not observed in the auditory condition. A positive correlation of theta and BOLD activity was observed in auditory cortex, while a negative correlation of theta and BOLD activity was observed in visual cortex during auditory attention. The data support a supramodal interaction of theta activity with of DMN function, and modality-associated processes within fronto-parietal networks related to top-down theta related cognitive control in cross-modal visual attention. On the other hand, in sensory cortices there are opposing effects of theta activity during cross-modal auditory attention.
Perner Martin - One of the best experts on this subject based on the ideXlab platform.
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Fault-tolerant clock distribution in grid-like networks
2019Co-Authors: Perner MartinAbstract:This thesis investigates how to design a system to distribute and use a clock signal in a grid-like network, as employed in, e.g., SoCs and NoCs. Ideally, the clock is generated by multiple components and has self-stabilization and fault-tolerance properties, i.e., recovers from transient faults even under permanent faults. These clock generation components can be distributed over the whole chip to provide a clock signal for every part of the chip. This, however, comes at a price: The increase in wire length between the components increases the skew between the generating components, and hence the clock skew at the clock boundaries between the components. Furthermore, such clock generation systems are expensive in terms of chip area, and usually require a fully-connected topology. Hence, putting the clock generating components in close proximity is favorable. However, just generating such a clock somewhere in a chip is not enough: After all, the clock signal needs to be distributed to all components that need it. The challenge for clock distribution is to not diminish or even remove the self-stabilization and fault- tolerance properties of the generated clock during distribution. To this end, we present a clock distribution system, HEX, that allows recovery from transient faults under permanent faults. Since HEX, which is based on a hexagonal grid, shows a large spread in the node-to-node skew under faults, we explored alternative interconnection topologies. Under the assumption that a suitable clock gen- eration is able to provide a skew bounded by the difference in the wire delay between its components, the TRIX topology has been identified as the best trade-off between performance and implementation efficiency. For TRIX, a transistor cell model of the clock distribution node has been constructed as well. Given that the distributed clock propagates like a wave through the grid, it provides a Synchronization Source for the nodes of the grid already. However, the achievable degree of synchrony is not enough to be able to utilize the synchronous design paradigm for communication between the nodes of the grid. We show that high-speed communication is nevertheless feasible in such multi-synchronous GALS architectures, however, by using a FIFO buffer for mitigating the clock skew and thus allowing data transmission in every clock cycle. Using a special buffer management approach, our communication scheme can be guaranteed to be self-stabilizing when the underlying clocking system is. Hence, our communication scheme is fully compatible with, but not limited to, HEX and TRIX.von Martin PernerZusammenfassung in deutscher SpracheTechnische Universität Wien, Dissertation, 2019(VLID)450854
Magnus Westerlund - One of the best experts on this subject based on the ideXlab platform.
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RTP Header Extension for the RTP Control Protocol (RTCP) Source Description Items
2016Co-Authors: Magnus Westerlund, Bo Burman, Mo Zanaty, Roni EvenAbstract:Source Description (SDES) items are normally transported in the RTP Control Protocol (RTCP). In some cases, it can be beneficial to speed up the delivery of these items. The main case is when a new Synchronization Source (SSRC) joins an RTP session and the receivers need this Source's identity, relation to other Sources, or its Synchronization context, all of which may be fully or partially identified using SDES items. To enable this optimization, this document specifies a new RTP header extension that can carry SDES items.
