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.

Packet transmission control apparatus and packet transmission control method

Abstract: A packet transmission control apparatus comprising a transmission resource usable for packet transmission; a storing part for storing wireless quality information of downlinks associated with transmission methods to be used for packet transmission; a deciding part for deciding, based on the wireless quality information of a downlink informed by a mobile station and based on the transmission resource usable for packet transmission, a transmission method to be used for packet transmission, while referring to the storing part; a re-deciding part for re-deciding a transmission method, which is to be used for packet transmission, such that the padding portion in a transport block constituting the packet is minimum; and a packet transmitting part for transmitting the packet by use of the re-decided transmission method.

A MIMO turbo equalizer for frequency-selective channels with unknown interference

Abstract: A new space-time turbo equalization algorithm is derived for frequency-selective multiple-input-multiple-output (MIMO) channels with unknown interference. The algorithm is an extension of our proposed MIMO equalization algorithm , which performs joint channel estimation, multiple users' signal detection, and decoding, all in an iterative manner. This paper's proposed algorithm uses estimates of the correlation matrix of composite unknown interference-plus-noise components to suppress the unknown interference while effectively separating multiple users' signals to be detected (referred to as "known user" later). The correlation matrix of the composite unknown interference-plus-noise components can be estimated by time averaging the instantaneous empirical correlation matrix over the training period. Since the iterative channel estimation yields better channel estimates as more iterations are performed, thereby the estimate of the correlation matrix of the unknown interference-plus-noise components also becomes more accurate. This results in better signal detection performances, even in the presence of unknown interferers. A series of computer simulations show that this paper's proposed algorithm can properly separate known users' signals while suppressing unknown interference.

Mobile Communication System, Mobile Station and Radio Base Station

Abstract: In case an HSDPA and a rising line enhancement are applied, an individual physical channel, a high-speed individual physical control channel and an enhanced individual physical control channel are caused to follow only a TPC bit of a serving cell. In case the received electric power of the enhanced individual physical data channel received is high, a non-serving cell instructs a mobile station (UE) to lower the transmission rate of the enhanced individual physical data channel thereby to prevent the degradation of a communication quality in a falling link while suppressing an interfering electric power from an adjoining cell in a rising link.

Variance and generalized constraints for C # generics

Abstract: Generic types in C$^{\sharp}$ behave invariantly with respect to subtyping. We propose a system of type-safe variance for C$^{\sharp}$ that supports the declaration of covariant and contravariant type parameters on generic types. To support more widespread application of variance we also generalize the existing constraint mechanism with arbitrary subtype assertions on classes and methods. This extension is useful even in the absence of variance, and subsumes equational constraints proposed for Generalized Algebraic Data Types (GADTs). We formalize the subtype relation in both declarative and syntax-directed style, and describe and prove the correctness of algorithms for constraint closure and subtyping. Finally, we formalize and prove a type safety theorem for a featherweight language with variant classes and generalized constraints.

Packet Coding for Strong Anonymity in Ad Hoc Networks

Abstract: Several techniques to improve anonymity have been proposed in the literature. They rely basically on multicast or on onion routing to thwart global attackers or local attackers respectively. None of the techniques provide a combined solution due to the incompatibility between the two components, as we show in this paper. We propose novel packet coding techniques that make the combination possible, thus integrating the advantages in a more complete and robust solution.