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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
Kazuaki Takeda1, Qin Mu1, Liu Liu1, Lan Chen1
31 Jul 2013
TL;DR: In this paper, a radio base station that transmits downlink control information for a user terminal by using an enhanced downlink channel that is frequency-division-multiplexed with a downlink shared data channel is designed to make it possible to adequately form the search space candidates to be used in the blind decoding of downlink information when the radio resource region for downlink channels is expanded.
Abstract: The present invention is designed to make it possible to adequately form the search space candidates to be used in the blind decoding of downlink control information when the radio resource region for downlink control channels is expanded. The radio base station of the present invention is a radio base station that transmits downlink control information for a user terminal by using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, and has a configuring section that configures, for the user terminal, a plurality of resource sets that are each formed by including a plurality of resource blocks allocated to the enhanced downlink control channel, and a determining section that determines enhanced control channel elements to constitute a plurality of search space candidates such that the plurality of search space candidates of each resource set are all placed in different resource blocks.

126 citations

Proceedings ArticleDOI
29 Nov 2004
TL;DR: Simulation results show that the computational complexity of the proposed adaptive selection algorithm from the viewpoint of the number of real multiplications is reduced to approximately 1/6 and 1/1900, respectively, compared to that of the original QRM-MLD.
Abstract: The paper proposes an adaptive selection algorithm for surviving symbol replica candidates based on the maximum reliability in ML detection with QR decomposition and M-algorithm (QRM-MLD) for OFCDM MIMO multiplexing. In the proposed algorithm, symbol replica candidates newly-added at each stage are ranked for each surviving symbol replica from the previous stage using multiple quadrant detection. Then, branch metrics are calculated only for the limited number of symbol replica candidates with high reliability based on an iterative loop in increasing order of the accumulated branch metrics from the candidate with the minimum one. Simulation results show that the computational complexity of the proposed algorithm from the viewpoint of the number of real multiplications is reduced to approximately 1/6 and 1/1900, respectively, compared to that of the original QRM-MLD and that of the conventional MLD with squared Euclidian distance calculations for all symbol replica candidates, assuming the identical achievable average block error rate (BLER) performance in 4-by-4 MIMO multiplexing with 16QAM data modulation. The results also show that 1-Gbps throughput is achieved at the E/sub b//N/sub 0/ per receiver antenna of approximately 9 dB using the adaptive selection algorithm in QRM-MLD associated with 16QAM modulation and turbo coding with coding rate of 8/9, assuming a 100-MHz bandwidth for a twelve-path Rayleigh fading channel (rms delay spread, 0.26 /spl mu/sec; maximum Doppler frequency, 20 Hz).

125 citations

Journal ArticleDOI
TL;DR: This paper proposes adaptive control of the number of surviving symbol replica candidates, Sm, based on the minimum accumulated branch metric of each stage in maximum-likelihood detection employing QR decomposition and the M-algorithm in orthogonal frequency-division multiplexing with multiple-input-multiple-output (MIMO)multiplexing.
Abstract: This paper proposes adaptive control of the number of surviving symbol replica candidates, Sm (m denotes the stage index), based on the minimum accumulated branch metric of each stage in maximum-likelihood detection employing QR decomposition and the M-algorithm (QRM-MLD) in orthogonal frequency-division multiplexing with multiple-input-multiple-output (MIMO) multiplexing. In the proposed algorithm, Sm at the mth stage (1lesmlesNt, N t is the number of transmission antenna branches) is independently controlled using the threshold value calculated from the minimum accumulated branch metric at that stage and the estimated noise power. We compared the computational complexity of QRM-MLD employing the proposed algorithm with that of conventional methods at the same average packet error rate assuming the information bit rate of 1.048 Gb/s in a 100-MHz channel bandwidth (i.e., frequency efficiency of approximately 10 bit/s/Hz) using 16QAM modulation and turbo coding with the coding rate of 8/9 in 4-by-4 MIMO multiplexing. Computer simulation results show that the average computational complexity of the branch metrics, i.e., squared Euclidian distances, of the proposed adaptive independent Sm control method is decreased to approximately 38% that of the conventional adaptive common Sm control and to approximately 30% that of the fixed Sm method (Sm=M=16), assuming fair conditions such that the maximum number of surviving symbol replicas at each stage is set to Mcirc=16

124 citations

Proceedings ArticleDOI
Libo Song1, U. Deshpande1, Ulas C. Kozat2, David Kotz1, Ravi Jain2 
23 Apr 2006
TL;DR: This work evaluates a series of predictors that reflect possible dependencies across time and space while benefiting from either individual or group mobility behaviors, and examines voice applications and the use of handoff prediction for advance bandwidth reservation.
Abstract: Wireless local area networks (WLANs) are emerging as a popular technology for access to the Internet and enterprise networks. In the long term, the success of WLANs depends on services that support mobile network clients. Although other researchers have explored mobility prediction in hypothetical scenarios, evaluating their predictors analytically or with synthetic data, few studies have been able to evaluate their predictors with real user mobility data. As a first step towards filling this fundamental gap, we work with a large data set collected from the Dartmouth College campus-wide wireless network that hosts more than 500 access points and 6,000 users. Extending our earlier work that focuses on predicting the next-visited access point (i.e., location), in this work we explore the predictability of the time of user mobility. Indeed, our contributions are two-fold. First, we evaluate a series of predictors that reflect possible dependencies across time and space while benefiting from either individual or group mobility behaviors. Second, as a case study we examine voice applications and the use of handoff prediction for advance bandwidth reservation. Using application-specific performance metrics such as call drop and call block rates, we provide a picture of the potential gains of prediction. Our results indicate that it is difficult to predict handoff time accurately, when applied to real campus WLAN data. However, the findings of our case study also suggest that application performance can be improved significantly even with predictors that are only moderately accurate. The gains depend on the applications’ ability to use predictions and tolerate inaccurate predictions. In the case study, we combine the real mobility data with synthesized traffic data. The results show that intelligent prediction can lead to significant reductions in the rate at which active calls are dropped due to handoffs with marginal increments in the rate at which new calls are blocked.

124 citations

Patent
05 Apr 2004
TL;DR: In this article, a system, method and computer program product are provided for accessing security or content analysis functionality utilizing a mobile communication device, including an operating system installed on a mobile device capable of communicating via a wireless network.
Abstract: A system, method and computer program product are provided for accessing security or content analysis functionality utilizing a mobile communication device. Included is an operating system installed on a mobile communication device capable of communicating via a wireless network. Further provided is an application program installed on the mobile communication device and executed utilizing the operating system for performing tasks. A scanning subsystem remains in communication with the application program via an application program interface. Such scanning subsystem is adapted for accessing security or content analysis functionality in conjunction with the tasks performed by the application program.

124 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