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.

Effective Delay Control in Online Network Coding

Abstract: Motivated by streaming applications with stringent delay constraints, we consider the design of online network coding algorithms with timely delivery guarantees. Assuming that the sender is providing the same data to multiple receivers over independent packet erasure channels, we focus on the case of perfect feedback and heterogeneous erasure probabilities. Based on a general analytical framework for evaluating the decoding delay, we show that existing ARQ schemes fail to ensure that receivers with weak channels are able to recover from packet losses within reasonable time. To overcome this problem, we re-define the encoding rules in order to break the chains of linear combinations that cannot be decoded after one of the packets is lost. Our results show that sending uncoded packets at key times ensures that all the receivers are able to meet specific delay requirements with very high probability.

Minimizing Base Station Power Consumption

Abstract: We propose a new radio resource management algorithm which aims at minimizing the base station supply power consumption for multi-user MIMO-OFDM. Given a base station power model that establishes a relation between the RF transmit power and the supply power consumption, the algorithm optimizes the trade-off between three basic power-saving mechanisms: antenna adaptation, power control and discontinuous transmission. The algorithm comprises two steps: a) the first step estimates sleep mode duration, resource shares and antenna configuration based on average channel conditions and b) the second step exploits instantaneous channel knowledge at the transmitter for frequency selective time-variant channels. The proposed algorithm finds the number of transmit antennas, the RF transmission power per resource unit and spatial channel, the number of discontinuous transmission time slots, and the multi-user resource allocation, such that supply power consumption is minimized. Simulation results indicate that the proposed algorithm is capable of reducing the supply power consumption by between 25% and 40%, dependend on the system load.

Selective fusion location estimation (SELFLOC) for wireless access technologies

Abstract: In an RF environment serviced by 802.11, Bluetooth (TM), or other network transmitters, or combinations, location-estimation methods and systems can advantageously use redundancy to refine an estimated location of an RF receiver. In one embodiment, a method for finding a receiver's location includes receiving signals from fixed transmitters, calculating preliminary location estimates, and combining the estimates using predetermined reference information on the RF environment. The reference information preferably includes minimum mean-squared error optimizing coefficients.

Charging, accounting and billing management schemes in mobile telecommunication networks and the internet

Abstract: The current technological advances in mobile telecommunication networks and the Internet are about to alter existing business models. These different worlds converge and create an open market, where a large number of independent application/service providers will offer their services to users through a limited number of network providers. At the same time, the evolution of existing network technologies and the specification of new concepts requires new advanced and holistic solutions in several technical areas. One such area is related to the design and management of new sophisticated functions and protocols to support innovative, flexible, and efficient charging, accounting, and billing mechanisms. This survey article considers the key concepts of such mechanisms, and the requirements they impose upon the network infrastructure. The article presents the latest efforts undertaken by standardization bodies in the mobile telecommunication industry as well as by Internet Working Groups to meet these requirements.

Base station, control device, communication system and communication method

Abstract: A base station includes an acquisition unit for acquiring a packet transmitted from a terminal device to a mobile station, a priority calculation unit for calculating priority of transmission of the packet acquired by the acquisition unit to the mobile station, a weight processing unit for conducting weighting on the priority of the packet calculated by the priority calculation unit, a channel control unit for assigning a channel for transmission of the packet to the mobile station, to the packet based on the priority of the packet weighted by the weight processing unit, and a transmission unit for transmitting the packet to the mobile station on the channel assigned by the channel control unit.