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.

Receiver, transmitter and radio communication method

Abstract: A mobile station includes: a physical channel segmentation unit to receive radio signals including multiple orthogonal signals which are orthogonal to each other, and multiple non-orthogonal signals which are not orthogonal to each other; and data demodulating/decoding units to extract the non-orthogonal signal addressed to the mobile station from the multiple non-orthogonal signals by demodulating and cancelling the radio signal addressed to another mobile station by use of the orthogonal signals included in the radio signals received by the physical channel segmentation unit, and demodulate the signal included in the orthogonal signals and addressed to the mobile station, and the extracted non-orthogonal signal addressed to the mobile station.

Method and apparatus for packet transmission with header compression

Abstract: A sender converts a non-compressed packet, which is to be transmitted, into a full-header packet including a full header or a header-compressed packet including a compressed header, and sends the converted packet to a receiver The receiver receives the packet transmitted from the sender, and converts the received packet into a decompressed packet In cases the full-header packet or header-compressed packet is lost between the sender and receiver, the receiver keeps header-compressed packers received during an interval from the packet loss to the next earliest reception of a full-header packet, and decompresses the compressed headers of the kept header-compressed packets on the basis of contents of the full header of the full-header packet

Geographically adjacent access router discovery and caching for mobile nodes

Abstract: A geographically adjacent access router discovery system discovers geographically adjacent access routers through a distributed process in which mobile node(s) associated with a current access router may receive beacon signals from geographically adjacent access points. A link layer ID included in the beacon signals may be used by the system to identify corresponding geographically adjacent access routers. Network layer addresses of geographically adjacent access routers may be mapped to corresponding link layer IDs and cached by the system. The cache may be used to identify a network layer address from the link layer ID received in a beacon signal.

Minimization of drive tests solution in 3GPP

Abstract: Providing network coverage and quality of service (QoS) is an important task of a cellular network operator. This is because cellular spectrum is normally licensed under certain coverage obligations, and operators need to be competitive in market. To improve their networks, operators often send engineers in the field to collect radio measurements, to discover problems such as coverage holes in the network, and to determine whether certain parameter tuning is needed. However, such conventional "drive tests" require large Operation Expenditure (OPEX), while the collected measurements can only give limited snap shots of the entire network. In their Release 10 (Rel-10) specification, 3GPP studied and specified solutions to reduce this OPEX for drive tests, under the work item named ?Minimization of Drive Tests (MDT)." The solution utilizes the user (customer) equipments (UEs) to collect field measurements, including radio measurements and location information. This article describes in details the solution adopted in 3GPP MDT; how they were developed and intended to be used.

High-efficiency linear power amplifier

Abstract: A transmission signal and a pilot signal are predistorted by a digital predistorter 13 by use of a power-series model, and the predistorted output is converted by a digital-analog converter 14 to an analog signal. The analog signal is up converted by a frequency converter 15 to an RF-band signal, which is transmitted after being power-amplified by a Doherty amplifier 16. The pilot signal is extracted by a pilot signal extractor 17 from the output from the Doherty amplifier, and the extracted pilot signal is down converted by a frequency converter 18 to a baseband signal. The baseband pilot signal is converted by an analog-digital converter 19 to a digital pilot signal. A control part 21 detects an odd-order distortion component from the digital pilot signal, and based on the detected result, controls parameters of the digital predistorter.