3 results about "Radio relay" patented technology

There is provided techniques for controlling an RIS. The RIS comprises a controller entity and a reflector entity. The reflector entity is associated with configurable reflection properties defining how radio waves that impinge the reflector entity are reflected. The reflection properties are controlled by the controller entity. A method is performed by a network node. The method comprises determining that the RIS to refrain from reflecting signals communicated in radio waves between the network node and a user equipment. The method comprises, in response thereto, providing an indication to the controller entity for the RIS to enter a non-relay mode according to which the reflector entity is to apply a default configuration of the reflection properties.

The present invention relates to the field of communications, and more particularly to methods and a system for providing high-speed communications on a high-speed railway. The technical result is a better quality communication channel provided by train-to-ground radio relay links. The claimed system for providing high-speed communications on a high-speed railway comprises an internal and an external data exchange network. The internal network unites tail-end radio frequency modules mounted in the rear part of a train and equipped with narrow-band antennae, head-end radio frequency modules mounted in the front part of the train and equipped with narrow-band antennae, and switching equipment capable of processing signals from said modules and of providing network devices connected to said equipment with access to the external data exchange network. The external data exchange network unites base stations equipped with narrow-band antennae, said base stations being capable of establishing communication with the tail-end and head-end radio frequency modules in the train and being arranged in proximity to the railway clearance along the path of travel of the train. The antennae of the base stations and of the radio frequency modules in the train are configured to radiate radio waves in a short millimeter wave band.

The invention belongs to the technical field of high-speed rail communication security, and discloses a high-speed rail communication secure transmission method based on active RIS assistance. Comprising the following steps: constructing a high-speed rail communication system comprising a base station, an active RIS, a mobile relay and an eavesdropper; establishing a channel model; defining a reflection coefficient matrix of the active RIS; deriving received signal expressions of the mobile relay and the eavesdropper; calculating the signal-to-noise ratio of the mobile relay and the eavesdropper, and solving the channel capacity of the mobile relay and the eavesdropper according to the Shannon theorem; establishing an optimization problem taking the minimum transmitting power of the base station as a target, and setting a constraint condition; the beamforming vector of the base station and the phase shift matrix of the active RIS are jointly optimized, and an optimization problem is solved through an alternating optimization algorithm so as to realize the minimization of the transmitting power of the base station; seamless coverage and stable connection in the high-speed running process of the train are ensured, and the high-reliability requirement of high-speed rail communication is met.