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Institution

NTT DoCoMo

About: NTT DoCoMo is a based out in . It is known for research contribution in the topics: Base station & Mobile station. The organization has 4032 authors who have published 8655 publications receiving 160533 citations.


Papers
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Proceedings ArticleDOI
08 Jul 2014
TL;DR: This paper studies the problem of reducing the delay of downloading data from cloud storage systems by leveraging multiple parallel threads, assuming that the data has been encoded and stored in the clouds using fixed rate forward error correction (FEC) codes with parameters (n, k).
Abstract: In this paper, we study the problem of reducing the delay of downloading data from cloud storage systems by leveraging multiple parallel threads, assuming that the data has been encoded and stored in the clouds using fixed rate forward error correction (FEC) codes with parameters (n, k). That is, each file is divided into k equal-sized chunks, which are then expanded into n chunks such that any k chunks out of the n are sufficient to successfully restore the original file. The model can be depicted as a multiple-server queue with arrivals of data retrieving requests and a server corresponding to a thread. However, this is not a typical queueing model because a server can terminate its operation, depending on when other servers complete their service (due to the redundancy that is spread across the threads). Hence, to the best of our knowledge, the analysis of this queueing model remains quite uncharted. Recent traces from Amazon S3 show that the time to retrieve a fixed size chunk is random and can be approximated as a constant delay plus an i.i.d. exponentially distributed random variable. For the tractability of the theoretical analysis, we assume that the chunk downloading time is i.i.d. exponentially distributed. Under this assumption, we show that any work-conserving scheme is delay-optimal among all on-line scheduling schemes when k = 1. When k > 1, we find that a simple greedy scheme, which allocates all available threads to the head of line request, is delay optimal among all on-line scheduling schemes. We also provide some numerical results that point to the limitations of the exponential assumption, and suggest further research directions.

96 citations

Patent
Satoru Adachi1, Choong Seng Boon1, Sadaatsu Kato1, Minoru Etoh1, Thiow Keng Tan1 
22 Sep 2003
TL;DR: In this paper, a method of decoding encoded moving picture data may be provided, which may include computer implemented steps performed by a processor of a computer system to implement the following steps: decoding the encoded moving pictures data into decoded pictures; storing the encoded pictures in a decoded picture buffer; if a picture is an IDR picture, making unused for reference the at least one reference picture stored in the decoded Picture Buffer; and if a flag associated with the IDR Picture has a second value, emptying the decoding picture buffer.
Abstract: According to an embodiment, a method of decoding encoded moving picture data may be provided. The method may include: computer implemented steps performed by a processor of a computer system to implement the following steps: decoding the encoded moving picture data into decoded pictures; storing the decoded pictures in a decoded picture buffer, wherein the decoded pictures in the decoded picture buffer include at least one reference picture and at least one non-reference picture; if a picture is an IDR picture, making unused for reference the at least one reference picture stored in the decoded picture buffer; if a flag associated with the IDR picture has a first value, deleting from the decoded picture buffer an decoded picture made unused for reference; and if the flag associated with the IDR picture has a second value, emptying the decoded picture buffer.

96 citations

Patent
14 Apr 2006
TL;DR: An apparatus for controlling an operation of a plurality of communication layers in a layered communication system comprises means for providing a property of the communication channel, a storage element for storing a first plurality of sets of parameters defining different operation modes of a first communication layer of the plurality of communications layers and a selector for selecting a first set of parameters from the first plurality, and a second set of parameter selection from the second plurality, in dependence on the channel property and an optimization goal.
Abstract: An apparatus for controlling an operation of a plurality of communication layers in a layered communication system comprises means for providing a property of the communication channel, a storage element for storing a first plurality of sets of parameters defining different operation modes of a first communication layer of the plurality of communication layers and for providing a second plurality of sets of parameters defining different operation modes of a second communication layer of the plurality of communication layers, a selector for selecting a first set of parameters from the first plurality of sets of parameters and for selecting a second set of parameters from the second plurality of sets of parameters in dependence on the channel property and an optimization goal and means for providing the first set of parameters to the first communication layer and the second set of parameters to the second communication layer. Therefore, an efficient exploitation of communication resources can be achieved.

96 citations

Patent
06 Nov 2009
TL;DR: In this article, a mobile station according to the present invention includes: a dedicated signaling reception unit (12) configured to receive a dedicated signal including a priority for a frequency or a group of frequencies of each radio access network; and a camp-on processing unit (13) configurable to select a campon cell based on the priority or a radio quality in each cell, wherein when a predetermined flag is set to the dedicated signaling received by the dedicated signal reception unit, the camp-ON processing unit(13) is configured to select the camp on cell based upon the radio
Abstract: A mobile station according to the present invention includes: a dedicated signaling reception unit ( 12 ) configured to receive a dedicated signaling including a priority for a frequency or a group of frequencies of each radio access network; and a camp-on processing unit ( 13 ) configured to select a camp-on cell based on the priority or a radio quality in each cell, wherein when a predetermined flag is set to the dedicated signaling received by the dedicated signaling reception unit ( 12 ), the camp-on processing unit ( 13 ) is configured to select the camp-on cell based on the radio quality in each cell, from a plurality of cells that use a different frequency but reside within an identical radio access network, and to select the camp-on cell based on the priority included in the dedicated signaling, from a plurality of cells within a different radio access network.

96 citations

Patent
07 Mar 2014
TL;DR: In this article, a wireless base station which uses a plurality of component carriers to communicate with user terminals is provided with: a setting unit which sets, in the component carriers, first carrier-type subframes capable of being received respectively by the plurality of user terminals having different capabilities, and second carrier-termed subframe capable of receiving by a portion of the user terminals; and a transmitting unit which uses the first carrier type and the second carrier type to transmit downlink signals to the users.
Abstract: The purpose of the present invention is to effectively utilize frequency resources, even in cases when a mixture of a plurality of user terminals having different capabilities is present. A wireless base station which uses a plurality of component carriers to communicate with user terminals is provided with: a setting unit which sets, in the component carriers, first carrier-type subframes capable of being received respectively by a plurality of user terminals having different capabilities, and second carrier-type subframes capable of being received by a portion of the plurality of user terminals; and a transmitting unit which uses the first carrier type and the second carrier type to transmit downlink signals to the user terminals. The setting unit sets at least one of the plurality of component carriers so as to cause the first carrier-type subframes and the second carrier-type subframes therein to dynamically change.

96 citations


Authors

Showing all 4032 results

NameH-indexPapersCitations
Amit P. Sheth10175342655
Harald Haas8575034927
Giuseppe Caire8282540344
Craig Gentry7522239327
Raj Jain6442430018
Karl Aberer6355417392
Fumiyuki Adachi54101015344
Ismail Guvenc5245113893
Frank Piessens5239110381
Wolfgang Kellerer495029383
Yoshihisa Kishiyama4837911831
Ravi Jain481607467
Josef A. Nossek4862310377
Tadao Nagatsuma4743011117
Christian Bettstetter4620411051
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202164
2020143
2019240
2018269
2017193
2016173