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.

Novel Broadband Planar Reflectarray With Parasitic Dipoles for Wireless Communication Applications

Abstract: A novel broadband planar reflectarray with parasitic dipoles is presented for wireless communication applications. A unit cell of the microstrip reflectarray consists of a printed main dipole with a pair of parasitic dipoles. The introduction of parasitic dipoles can effectively extend the reflection phase range beyond 360°, which overcomes the problem of an inadequate phase range when using thicker substrates for a wider operational bandwidth. The parasitic dipole reflectarrray (PDR) is applied to a wideband CDMA (WCDMA) system to eliminate blind spots in communication between the base station and mobile users. A practical link budget analysis demonstrates the effectiveness of the proposed planar reflectarray.

User association and load balancing for cellular massive MIMO

Abstract: Massive MIMO is expected to play a key role in coping with the predicted mobile-data traffic explosion. Indeed, in combination with small cells and TDD operation, it promises large throughputs per unit area with low latency. In this paper we focus on the problem of balancing the load across networks with massive MIMO base-stations (BSs). The need for load balancing arises from variations in the user population density and is more pronounced in small cells due to the large variability in coverage area. We consider methods for load balancing over networks with small and large massive MIMO BSs. As we show, the distinct operation and properties of massive MIMO enable practical resource-efficient load-balancing methods with near-optimal performance.

Non-orthogonal multiple access (NOMA): Concept, performance evaluation and experimental trials

Abstract: Non-orthogonal multiple access (NOMA) has been attracting a lot of attention as a promising downlink multiple access scheme for LTE enhancements and 5G. This paper introduces an overview of the concept, performance evaluation gains and our experimental trials related to NOMA. The goal is to clarify the benefits of NOMA over orthogonal multiple access (OMA) such as OFDMA adopted by Long-Term Evolution (LTE), also its combination with MIMO is discussed. Using computer simulations, NOMA performance gains are assessed from both link-level and system-level perspectives. Also, our NOMA test-bed and the measurement results are explained. Our evaluation results and measurements show that NOMA provides higher gains compared to OFDMA. These gains are more than 30%.

Mobile communication terminal, information processing apparatus, relay server apparatus, information processing system, and information processing method

Abstract: A cellular phone 100 is provided with a data transmitter 102, a detection result receiver 103, and a virus management information storage 104. The data transmitter 102 transmits data to a virus detecting apparatus 20. The detection result receiver 103 receives as virus management information a result of detection on whether the data transmitted by the data transmitter 102 includes a computer virus. The virus management information storage 104 stores the data and the virus management information about the data in association with each other.

Weighted Averaging for Denoising With Overcomplete Dictionaries

Abstract: We consider the scenario where additive, independent, and identically distributed (i.i.d) noise in an image is removed using an overcomplete set of linear transforms and thresholding. Rather than the standard approach, where one obtains the denoised signal by ad hoc averaging of the denoised estimates provided by denoising with each of the transforms, we formulate the optimal combination as a conditional linear estimation problem and solve it for optimal estimates. Our approach is independent of the utilized transforms and the thresholding scheme, and as we illustrate using oracle-based denoisers, it extends established work by exploiting a separate degree of freedom that is, in general, not reachable using previous techniques. Our derivation of the optimal estimates specifically relies on the assumption that the utilized transforms provide sparse decompositions. At the same time, our work is robust as it does not require any assumptions about image statistics beyond sparsity. Unlike existing work, which tries to devise ever more sophisticated transforms and thresholding algorithms to deal with the myriad types of image singularities, our work uses basic tools to obtain very high performance on singularities by taking better advantage of the sparsity that surrounds them. With well-established transforms, we obtain results that are competitive with state-of-the-art methods.