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.

Booster, monitoring apparatus, booster system, control method and monitoring method

Abstract: A booster is provided which controls its gain to reduce the adverse effect of the booster noise on a base station. It receives a perch signal transmitted from a base station (180, 182 or the like); measures received power of the perch signal at the booster (100); receives information about the transmission power of the perch signal from the base station (180, 182 or the like); and measures the noise power of the amplified uplink signal at the booster (100). It controls the gain of the uplink signal and/or the gain of the downlink signal in response to the transmission power of the perch signal of the base station (180, 182 or the like), the received power of the perch signal at the booster (100), and the noise power of the amplified uplink signal at the booster (100).

Mobile communication system, base station, user device, and method

Abstract: A user device transmitting at least an uplink control channel using a single carrier scheme includes a channel quality indicator generating unit configured to generate a channel quality indicator indicating a downlink radio propagation condition; and a transmitting unit configured to transmit the uplink control channel including the channel quality indicator using a dedicated frequency band when no radio resource is allocated for transmission of an uplink data channel. The transmitting unit is configured to transmit a predetermined number of unit blocks in each slot period. If a system bandwidth is greater than a predetermined value, a set of factors used to multiply some of the unit blocks belonging to the same slot and containing the same information represents an orthogonal sequence; and a predetermined number of symbol elements constituting each of the some of the unit blocks represent at least a part of the channel quality indicator.

Beam axis detection and alignment for uniform circular array-based orbital angular momentum wireless communication

Abstract: Orbital angular momentum (OAM) provides a new dimension for multiplexing and consequently can improve the link capacity remarkably. In the scope of radio communication, uniform circular array (UCA) is usually used to generate OAM signals, where beam axis detection and alignment is a key factor that influences the detection of OAM signal and directly determines the capacity of OAM links. This study analyses the beam axis detection and alignment issues under the ideal (noiseless) condition. The authors first clarify the fact that for single-mode OAM transmission, the intensity of electric field in radial direction is characterised by the Bessel function of the first kind. Inspired by this property, they propose three practical methods for beam axis detection and alignment, that is, double parallelogram array method, double UCA method and single UCA method. Iterative translation and rotation strategy are applied to enhance the precision. Finally, the effectiveness of the proposed methods is justified by simulation.

Visualization of uncertainty in context aware mobile applications

Abstract: Context-aware mobile applications and systems have been extensively explored in the last decade and in the last few years we already saw promising products on the market. Most of these applications assume that context data is highly accurate. But in practice this information is often unreliable, especially when gathered from sensors or external sources. Previous research has argued that the system usability can be improved by displaying the uncertainty to the user. The research presented in this paper shows that it is not always an advantage to show the confidence of the context-aware application to the user. We developed a system for automatic form filling on mobile devices which fills in any web form with user data stored on the mobile device. The used algorithm generates rules which indicate with which probability which input field of a form should be filled in with which value. Based on this we developed two versions of our system. One shows the uncertainty of the system and one not. We then conducted a user study which shows that the user needs slightly more time and produces slightly more errors when the confidence of the system is visualized.

Multipath interference canceller for high-speed packet transmission with adaptive modulation and coding scheme in W-CDMA forward link

Abstract: This paper proposes a multipath interference canceller (MPIC) associated with orthogonal code-multiplexing with orthogonal variable spreading factor (OVSF) channelization codes that achieves high throughput performance with adaptive data modulation in multipath fading channels in the W-CDMA forward link, and evaluates its throughput performance by computer simulation. The simulation results elucidate that sufficient multipath interference suppression is achieved by a four-stage MPIC with 6-12 orthogonal code-multiplexing using one iterative channel estimation with pilot and decision feedback data symbols hard-decided after RAKE combining. We show that the maximum peak throughput using MPIC is approximately 2.1 fold that without MPIC in a 2-path Rayleigh fading channel and that the peak throughput of 8.0 Mbps is achieved using 64QAM data modulation within a 5-MHz bandwidth. Furthermore, the required average E/sub b//N/sub 0/ for satisfying the same throughput with MPIC is decreased by more than 2.0 dB.