Inventors list

Assignees list

Classification tree browser

Top 100 Inventors

Top 100 Assignees

NEC (China)Co., Ltd.

NEC (China)Co., Ltd. Patent applications
Patent application number	Title	Published
20100169321	METHOD AND APPARATUS FOR CIPHERTEXT INDEXING AND SEARCHING - The present invention provides a method and apparatus for ciphertext indexing and searching. Indices of multiple levels are created for the encrypted files. Each item in the primary index includes a primary index item identifier and the ciphertext of the primary indexing information of the related file. The primary indexing information each includes an identifier(s) of the related secondary index item identifier(s) and the corresponding decryption information. Each item in the secondary index includes a secondary index item identifier and the ciphertext of the secondary indexing information. Information necessary for obtaining a file is included in the corresponding secondary indexing information. With the decryption information of the secondary indexing information in the decrypted primary indexing information, the ciphertext of the related secondary indexing information is decrypted so as to obtain information such as the decryption key of the file.	07-01-2010
20100109849	MULTI-OBJECTS POSITIONING SYSTEM AND POWER-CONTROL BASED MULTIPLE ACCESS CONTROL METHOD - The present invention provides a multi-objects positioning system and power-control based multiple access control method. The multi-objects positioning system according to the present invention comprises a plurality of tag devices carried by multiple objects and one or more positioning devices for determining the positions of the objects, wherein each of the tag devices includes a positioning device list for recording status information of the positioning devices. According to the present invention, tag device broadcasts Channel Request Packet (CRP) intermittently; positioning device, which is idle and receives the CRP, broadcasts Channel Allocation Packet (CAP) in its coverage range to allocate a channel to the tag device that is the sender of the CRP and inform information of the positioning device to other tag devices; tag device, which receives the CAP, updates its positioning device list according to the contents of the CAP; and the tag device adjusts transmission power of the CRP by referring to the positioning device list. With the present invention, the EN and HN problems existing in the prior arts can be solved effectively, and it is helpful to solve signal collision and improve spatio-temporal reuse capacity of the system.	05-06-2010