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.

Voice call handover mechanisms in next-generation 3GPP systems

Abstract: The evolved 3GPP system is a hybrid mobile network architecture supporting several radio access technologies and several mobility mechanisms. In this article we briefly review the architecture and key components of this system, with particular emphasis on how it can support voice call mobility in several deployment scenarios. First, we present the so-called single-radio voice call continuity mechanisms that enable mid-call handover of VoIP calls from E-UTRAN access to the legacy UTRAN/GERAN or lxRTT access. Then we focus on deployment scenarios that do not support voice services on E-UTRAN and present the so-called fallback mechanisms that enable handover from E-UTRAN to UTRAN/GERAN or lxRTT at the beginning of a voice call. Finally, we address the application- layer voice call handover mechanisms enabled by the IP multimedia subsystem. Our conclusion is that the next generation of 3GPP systems are highly sophisticated mobile communication systems that support extended voice call mobility mechanisms, capable of addressing all commercial deployment needs.

Method and apparatus for communication efficient private information retrieval and oblivious transfer

Abstract: A method, article of manufacture and apparatus for performing private retrieval of information from a database is disclosed. In one embodiment, the method comprising obtaining an index corresponding to information to be retrieved from the database and generating a query that does not reveal the index to the database. The query is an arithmetic function of the index and a secret value, wherein the arithmetic function includes a multiplication group specified by a modulus of a random value whose order is divisible by a prime power, such that the prime power is an order of the random value. The secret value is an arithmetic function of the index that comprises a factorization into prime numbers of the modulus. The method further comprises communicating the query to the database for execution of the arithmetic function against the entirety of the database.

Software operation monitoring apparatus and software operation monitoring method

Abstract: A software operation monitoring apparatus for monitoring an operation of software under execution, including: a policy information storing unit configured to store policy information for distinguishing a monitoring target operation and out-of-monitoring operation of software; an execution history recording unit configured to record an execution history of the software; a first analysis unit configured to detect the monitoring target operation from the operation of the software under execution based on the policy information; and a second analysis unit configured to analyze the execution history recorded in the execution history recording unit for the operation detected by the first analysis unit, and determine an existence of a gap of the software from a normal operation.

Non-Orthogonal Multiple Access for mmWave Drone Networks With Limited Feedback

Abstract: Unmanned aerial vehicle (UAV) base stations (BSs) can be a promising solution to provide connectivity and quality-of-service guarantees during temporary events and after disasters. In this paper, we consider a scenario where UAV-BSs are serving a large number of mobile users in a hot spot area (e.g., in a stadium). We introduce non-orthogonal multiple-access (NOMA) transmission at UAV-BSs to serve more users simultaneously considering user distances as the available feedback for a user ordering during NOMA formulation. With millimeter-wave transmission and multi-antenna techniques, we assume that UAV-BS generates directional beams and multiple users are served simultaneously within the same beam. However, due to the limitations of physical vertical beamwidth of the UAV-BS beam, it may not be possible to cover the entire user region at UAV altitudes of practical relevance. During such situations, a beam scanning approach is proposed to maximize the achievable sum rates. We develop a comprehensive framework over which outage probabilities and respective sum rates are derived rigorously and we investigate the optimal operational altitude of UAV-BS to maximize the sum rates using our analytical framework. Our analysis shows that NOMA with distance feedback can provide better outage sum rates than orthogonal multiple access.

Method for relaying information received via a first channel to a second channel and relay apparatus

Abstract: A method for relaying information received via a first channel to a second channel, in which the first channel has a first subcarrier at the first frequency and having assigned a block of information including a plurality of information units and in which the second channel has a first subcarrier at the first frequency and a second subcarrier at a second frequency, a transmission property for the second channel at the first frequency being worse than a transmission property for the second channel at the second frequency, comprises the step of assigning the block of information from the first subcarrier of the first channel to the second subcarrier of the second channel.