NEC

About: NEC is a company organization based out in Tokyo, Japan. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 33269 authors who have published 57670 publications receiving 835952 citations. The organization is also known as: NEC Corporation & NEC Electronics Corporation.

A capacitor-over-bit-line (COB) cell with a hemispherical-grain storage node for 64 Mb DRAMs

Abstract: A novel capacitor-over-bit-line (COB) cell with a hemispherical-grain (HSG) poly-Si storage node has been developed. This memory cell provides large storage capacitance by increasing the effective surface area of a simple storage node and is manufacturable by optical delineation. The feasibility of the COB cell for 64-Mb DRAMs has been verified by a 64-kb test memory with 1.8- mu m/sup 2/ cells using a 0.4- mu m design rule, storage capacitance of 30 fF, 7-nm-SiO/sub 2/-equivalent dielectric film, and a storage node height of 0.5 mu m. >

Location registration and paging procedure for mobile communication

Abstract: A mobile communication system in which overlapping location areas are defined by radio base stations on an autonomous distribution basis. In a first embodiment, a mobile station registers the location thereof when moved in a radio zone which is not included in a location area notified by a radio base station and held therein. In a second embodiment, the mobile station registers the location when entered a radio zone in which location area being notified by the radio base station does not include the radio zone where the mobile station registered the location last. In a first and a second embodiment, the mobile station memorizes radio zones which it has passed after location registration as route information and may report the route information to a radio base station in the event of next location registration. The radio base station sequentially includes in the location area the radio zones which frequently appear in the route information. In a third embodiment, in response to a terminating call meant for the mobile station, a mobile switching center sends a calling signal meant for the mobile station to all of the radio base stations. In response, each radio base station effects calling if the own location area where it is situated is coincident with a location area included in the calling signal. In a fourth to a sixth embodiment, each radio base station measures the traffic of registration signals or that of calling signals so as to increase or decrease the number of radio zones included in the own location area in matching relation to the measured traffic.

VirtualScan: a new compressed scan technology for test cost reduction

Abstract: This work describes the VirtualScan technology for scan test cost reduction. Scan chains in a VirtualScan circuit are split into shorter ones and the gap between external scan ports and internal scan chains are bridged with a broadcaster and a compactor. Test patterns for a VirtualScan circuit are generated directly by one-pass VirtualScan ATPG, in which multi-capture clocking and maximum test compaction are supported. In addition, VirtualScan ATPG avoids unknown-value and aliasing effects algorithmically without adding any additional circuitry. The VirtualScan technology has achieved successful tape-outs of industrial chips and has been proven to be an efficient and easy-to-implement solution for scan test cost reduction.

Modeling and analysis of a variable bit rate video multiplexer

Abstract: The authors develop a new analytic model for a variable bit rate video source, which can model a variety of video applications by a suitable choice of model parameters. Using the model they studied the performance of a video multiplexer that multiplexes several full motion video sources. The video sources were assumed to use a layered coding technique. A service strategy is proposed that guarantees delivery of packets marked essential, whereas nonessential packets may be dropped in the event of congestion. The study showed that with layered coding, good tail probabilities can be obtained for a given number of sources at the expense of some loss for nonessential packets. The performance of the video multiplexer was investigated when the video sources were correlated, and when independent video sources with different thresholds for essential packet rate were multiplexed together. >

Optimal dense coding with mixed state entanglement

Abstract: I investigate dense coding with a general mixed state on the Hilbert space Cd ⊗ Cd shared between a sender and receiver. The following result is proved. When the sender prepares the signal states by mutually orthogonal unitary transformations with equal a priori probabilities, the capacity of dense coding is maximized. It is also proved that the optimal capacity of dense coding χ* satisfies ER(ρ) ≤ χ* ≤ ER(ρ) + log2 d, where ER(ρ) is the relative entropy of entanglement of the shared entangled state.