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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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Patent
12 May 1995
TL;DR: In this article, the average value of the received power per transmission power control period of a desired signal from the base station was measured, and the difference ΔRSSI between the current average value and that of one of the previous power control periods was detected.
Abstract: A transmission power control method of a mobile station in a CDMA (Code Division Multiple Access) system which primarily controls transmission power of the mobile station by using a closed loop control which enables high accuracy power control. When the received power at the base station of a signal from the mobile station suddenly increases owing to the state of buildings surrounding the mobile station, the transmission power of the mobile station must be quickly reduced to prevent the interference to other mobile stations. The mobile station measures an average value of the received power per transmission power control period of a desired signal from the base station, and detects the difference ΔRSSI between the current average value and that of one of the previous transmission power control periods. If ΔRSSI exceeds a reference power difference ΔPth, transmission power PT corresponding to ΔRSSI is set by using an open loop transmission power control to quickly reduce the transmission power of the mobile station. If ΔRSSI is lower than ΔPth, the transmission power PT is determined in accordance with the transmission power control bit sent from the base station.

61 citations

Proceedings ArticleDOI
01 Feb 2013
TL;DR: This work studies mechanisms for RF calibration that can enable distributed high-performing large-scale MIMO operation and proposes methods for relative calibration of the APs in order to ensure TDD reciprocity while not relying on an explicitly self-calibrating RF design.
Abstract: Distributed large-scale MIMO is a promising option for coping with the projected explosion in mobile traffic. It involves multiple Access Points (APs) that are connected to a central server via wired backhaul and act as a distributed MIMO transmitter, serving multiple users via spatial precoding. As is well known, large downlink (DL) spectral efficiencies can be achieved with TDD operation, pilots sent in the uplink (UL), and DL-UL channel reciprocity. With APs made of inexpensive hardware and connected via, e.g., Ethernet, synchronization and reciprocity calibration are the main hurdle for implementing a truly distributed MU-MIMO system. This work studies mechanisms for RF calibration that can enable distributed high-performing large-scale MIMO operation. We propose methods for relative calibration of the APs in order to ensure TDD reciprocity while not relying on an explicitly self-calibrating RF design. As our analysis and simulations suggest, the proposed methods significantly outperform existing self calibration methods without requiring additional signaling overhead and can enable TDD reciprocity for calibration of non-colocated networks.

61 citations

Patent
10 Apr 2002
TL;DR: In this paper, a system and method for using subnet relations to determine paging areas, for performing authentication and association, and to activate access network interfaces in wireless communication devices in a heterogeneous access network is presented.
Abstract: A system and method for using subnet relations to determine paging areas, for performing authentication and association, and to activate access network interfaces in wireless communication devices in a heterogeneous access network. Paging areas are generated using subnet relations by determining mobility agent servers within a predetermined number of subnet relations from a last active mobility agent server. Authentication and association are also accomplished using subnet relations. Access network interfaces can also be turned on and off based on subnet relations thereby conserving battery power.

61 citations

Proceedings ArticleDOI
Gerhard Bauch1, J.S. Malik1
17 May 2004
TL;DR: This work discusses the problem of choosing the cyclic delays and proposes an interleaving and multiple access strategy which guarantees that all users obtain the maximum possible diversity advantage using FEC codes with a limited constraint length.
Abstract: Cyclic delay diversity is a simple transmit diversity technique for coded OFDM systems with multiple transmit antennas. It does neither require an extended guard interval nor modifications of the standard OFDM receiver. We discuss the problem of choosing the cyclic delays and propose a solution which enables us to exploit the full spatial diversity in flat fading and. frequency-selective channels with unknown delay spread. As a result, the spatial diversity is transformed into frequency diversity between neighbouring subcarriers. This imposes certain restrictions on the channel coding and interleaving scheme. Furthermore, we address multi user aspects and propose an interleaving and multiple access strategy which guarantees that all users obtain the maximum possible diversity advantage using FEC codes with a limited constraint length.

61 citations

Proceedings ArticleDOI
05 Jul 2009
TL;DR: This paper describes the SVEF, the first open-source framework for experimental assessment of H.264 Scalable Video coding streaming Evaluation Framework, and provides the experimental performance evaluation of an SVC cross-layer in-network scheduler in a Wireless LAN hot spot scenario.
Abstract: This paper describes the H.264 Scalable Video coding streaming Evaluation Framework (SVEF). This is the first open-source framework for experimental assessment of H.264 Scalable Video Coding (SVC) delivery over real networks. Effectively adapting of the transport of an H.264 SVC stream to time-varying, bandwidth constrained, and loss prone networks is an important research area. However, very little experimental work has been performed due to the unavailability of real-time H.264 SVC players, the limitations of existing decoding software libraries when challenged with network-imparied received SVC streams (e.g., affected by random loss of Network Abstraction Layer Units - NALUs), and the lack of solutions for SVC streaming support. SVEF overcomes these issues by developing missing components and by integrating them in a hybrid online/offline experimental framework. We believe SVEF will be of significant help to the research community interested in experimentally benchmarking their own proposed SVC adaptation approaches and delivery mechanisms. As a proof-of-concept of SVEF, we provide the experimental performance evaluation of an SVC cross-layer in-network scheduler in a Wireless LAN hot spot scenario.

61 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