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.

Resource control system, resource control method, and base station and mobile station suitable for use in the same

Abstract: An object of the present invention is to enable the improvement of Qos and efficient use of resources with regard to the entire system by performing resource control of an own cell in cooperation with that of peripheral cells. The present invention provides a resource control system used for packet communication between a mobile station and each of a first and a second base stations. The first base station includes the judgment unit for judging whether or not the Qos of a packet to be communicated with the mobile station is ensured in the packet communication with the mobile station, or judging whether or not the resources necessary for a packet to be communicated with the mobile station are secured; and the second base station interface for requesting the second base station to suppress the use of resources when the Qos is judged not to be ensured, or the necessary resources are judged not to be secured. The second base station includes a resource use suppression unit, which suppresses the use of resources for the packet communication with the mobile station in accordance with the request from the first base station.

Dynamic TDD support in the LTE-B enhanced Local Area architecture

Abstract: The Third Generation Partnership Project (3GPP) has been studying dynamic allocation of sub-frames to uplink (UL) or downlink (DL) in Time Division Duplex (TDD), called ‘Dynamic TDD,’ since the Long Term Evolution (LTE) Rel. 11 timeframe. At the same time, 3GPP is also standardizing Enhanced Local Area (eLA) small-cell heterogeneous architectures for inclusion in LTE-B (LTE Rel. 12) as a solution offering high data rate to user terminals (UEs) along with high system capacity through spatial reuse of spectrum. In this paper, we focus on a particular eLA architecture proposed by DOCOMO, called the Phantom Cell architecture, that has the option to support dynamic TDD. For an arbitrarily-located UE in an eLA cell network, we apply results from stochastic geometry to derive expressions for the distribution of DL signal to interference plus noise ratio (SINR) at an arbitrary UE and the distribution of UL SINR at its serving eLA base station (BS). We use these results to study aspects of eLA cell system design, and the sensitivity of SINR to the extent of coordination across eLA cells employing dynamic TDD.

Analysis of TDD Cellular Interference Mitigation Using Busy-Bursts

Abstract: This paper presents a new analytical framework for the analysis of inter-cellular timeslot allocation over TDMA (time division multiple access) based air-interfaces using TDD (time division duplexing). The analysis is used to evaluate the delay- throughput performance of an adaptive decentralized inter- cell interference mitigation technique that exploits the inherent channel reciprocity of TDD. The main principle is that receivers upon successful transmission of a packet transmit a busy burst on a succeeding minislot. Potential transmitters in neighboring cells sense the minislot prior to signal transmission. With this mechanism, inter-cell interference to the existing link is avoided. The performance of this MAC (medium access control) protocol is compared against blind timeslot allocation. The new MAC protocol is shown to facilitate network self-organization, offering superior delay and throughput compared to the state of the art, with modest overhead and complexity requirements.

Sensor ranking: A primitive for efficient content-based sensor search

Abstract: The increasing penetration of the real world with embedded and globally networked sensors enables the formation of a Web of Things (WoT), where high-level state information derived from sensors is embedded into Web representations of real-world entities (e.g. places, objects). A key service for the WoT is searching for entities which exhibit a certain dynamic state at the time of the query, which is a challenging problem due to the dynamic nature of the sought state information and due to the potentially huge scale of the WoT. In this paper we introduce a primitive called sensor ranking to enable efficient search for sensors that have a certain output state at the time of the query. The key idea is to efficiently compute for each sensor an estimate of the probability that it matches the query and process sensors in the order of decreasing probability, such that effort is first spent on sensors that are very likely to actually match the query. Using real data sets, we show that sensor ranking can significantly improve the efficiency of content-based sensor search.

Radio repeater and radio relay transmission method

Abstract: A radio repeater including at least first and second relay systems, each including a reception antenna configured to receive a radio signal, a loop interference suppressor, connected to the reception antenna, configured to suppress a loop interference signal in the received radio signal from said reception antenna, an amplifier configured to amplify the loop interference-suppressed radio signal from the loop interference suppressors, and a transmission antenna having a polarization characteristic, which is orthogonal to a polarization characteristic of said reception antenna, configured to transmit the output of said amplifier.