Nec Corporation

Tsuguo Maru

Masashi Hirabe

Masaki Ichihara

Kazuyoshi Taguchi

According to the present invention, when wireless communication is performed, a signal can be formed into a spiral beam (H), the spiral pitch of the signal can be changed, and a plurality of spiral beams (H) with different spiral pitches can be transmitted and received. The present invention pertains to a wireless signal transmitting antenna () including a signal emitting means (A) having N number of antenna elements (A, . . . , AN) (where N is an integer satisfying N&#x2265;2) equally spaced on a circumference of circle, and a signal distribution means (B) for generating, from an input first signal (S), N number of second signals (G, . . . , GN) having a phase difference from one another and outputting the N number of second signals (G, . . . , GN) to the N number of antenna elements (A, . . . , AN), respectively, so that a spiral beam (H) with the equiphase surface inclined spirally is output from the signal emitting means (A).

Wireless signal transmitting antenna, wireless signal receiving antenna, wireless signal transmitting system, wireless signal transmitting method, and wireless signal receiving method

When wireless communication is performed, a signal can be formed into a spiral beam (H), the spiral pitch of the signal can be changed, and a plurality of spiral beams (H) with different spiral pitches can be transmitted and received. A wireless signal transmitting antenna () includes a signal emitting means (A) having N number of antenna elements (A, . . . , AN) (where N is an integer satisfying N&#x2265;2) equally spaced on a circumference of circle, and a signal distribution means (B) for generating, from an input first signal (S), N number of second signals (G, . . . , GN) having a phase difference from one another and outputting the N number of second signals (G, . . . , GN) to the N number of antenna elements (A, . . . , AN), respectively, so that a spiral beam (H) with the equiphase surface inclined spirally is output from the signal emitting means (A).

In a MIMO communication system that includes a transmitter and a receiver and forms line-of-sight orthogonal channels between the transmitter-side transmitting antenna and the receiver-side receiving antenna, the MIMO communication system is provided between the transmitting antenna and the receiving antenna with an optimum antenna-to-antenna spacing shortening unit to shorten an optimum antenna-to-antenna spacing by changing the phase rotation of a carrier wave used for directly opposed waves between opposed antennas, and the phase rotation of a carrier wave used for intersecting waves between oblique antennas in such a manner that the amount by which one of the phase rotations changes is different from that by which the other phase rotation changes.

MIMO communication system for propagation environment including deterministic communication channel, and antennas for MIMO communication system

A Multiple-Input/Multiple-Output (MIMO) communication system having deterministic channels between a transmission side where a plurality of transmission antennas are arranged and a reception side where a plurality of reception antennas are arranged and used in a line-of-sight environment. The system includes a channel matrix calculation processing unit for calculating a channel matrix for constructing orthogonal channels as a channel on a transmission or reception side or both of the transmission and reception sides. The plurality of transmission antennas and the plurality of reception antennas comprising the channel matrix are horizontally arranged with respect to a ground.

MIMO communication system having deterministic communication path and antenna arrangement method therfor

A wireless communication apparatus of the present invention comprises a plurality of branches, a tap output combining section, an adaptive blind processing section and a diversity combining section. Each of the plurality of branches comprises a tap processing section generates a tap output signal and a received signal vector on a basis of a received signal and a tap coefficient in a space diversity method. The tap output combining section calculates by linking the tap output signal as a tap output combination signal. The adaptive blind processing section generates the tap coefficient by an adaptive blind processing on a basis of the tap output combination signal and the received signal vector. The diversity combining section performs a diversity combination of the tap output signals. The adaptive blind processing section uses an evaluation condition so that the tap output combination signal be minimal.

Wireless communication apparatus and wireless communication method

A MIMO communication system having deterministic channels the orthogonality of which can be ensured even if a reflected wave other than the direct wave is present during line-of-sight communication is provided. The MIMO communication system is used in a line-of-sight environment and has deterministic channels between the transmission side where a plurality of transmission antennas are arranged and the reception side where a plurality of reception antennas are arranged. The transmission side, the reception side, or both transmission and reception sides of the MIMO communication system have a channel matrix calculation processing means for calculating a channel matrix for establishing an orthogonal channel as a communication channel. The transmission and reception antennas forming the channel matrix are horizontally arranged with respect to the ground.

MIMO communication system having deterministic channels and antenna arrangement method therfor

The present invention is intended to provide an LDPC coding scheme which is capable of efficiently implementing a high-performance and high-speed encoder and decoder of an error correcting code suitable for the field of communications such as mobile communications. As to the configuration, a Tanner graph for representing codes with variable nodes and check nodes is used to classify the individual nodes into a plurality of categories. For calculating a probability propagation in iterative decoding, weighting previously determined for each category is performed on a log-likelihood ratio (LLR) subjected to propagation.

Encoder and decoder by LDPC coding

A MIMO decoder, which is capable of changing a search area of a transmission signal vector in accordance with a change in a channel matrix, includes: a generalized inverse vector matrix calculation unit for calculating a generalized inverse matrix of Moore-Penrose derived from a channel matrix indicative of a radiowave propagation environment; a search area limiting processing unit for performing weighting for each eigenvector calculated from the channel matrix in inverse proportion to a square root of an eigenvalue corresponding to the eigenvector, and determines the search area of the transmission signal vector centered at the generalized inverse matrix solution of Moore-Penrose based on the weighted result; and a most likelihood estimation unit for searching for a transmission signal vector by use of a most likelihood estimation based on the search area determined by the search area limiting processing unit.

MIMO decoder and MIMO decoding method

In a high-speed search system for CDMA, plural (M) symbols which are subjected to spread frequency coding with a spreading code called as a short code are prepared when synchronization of the spreading code is established before synchronization of carrier is established in a mobile station used in a CDMA cellular system, data which are obtained by forming an orthogonal code with the polarities of the M symbols are set as a down signal, and when the orthogonal code concerned is detected, coherent integration is performed by a correlator having combinations of the polarities which can be possibly taken by the code over the plural symbols (of M) constituting the code.

High-speed cell search system for CDMA

The present invention is directed to providing a spatial-multiplexed signal detection method that can improve the characteristics of spatial and temporal iterative decoding that is based on turbo principles. According to the method, when implementing factorization of conditional probability referred to as 'likelihood' such that the conditional probability can be represented by the product of a plurality of conditional probabilities, the conditional probability being obtained for a received signal sequence in a spatial and temporal iterative decoding configuration based on turbo principles of soft-input soft-output detectorand soft-input soft-output decoder, the conditional probability for which factorization is possible is divided into a plurality of groups. When calculating this likelihood, the ordering among groups in which probabilities are calculated can be ordered such that groups that contain events that serve as the conditions of conditional probabilities in the groups are processed earlier. When calculating the probabilities in the groups, a metric operation method is used that uses semi-rings for estimating transmission sequences by means of the ratio of likelihoods of two exclusive events.

Spatial-multiplexed signal detection method and spatial and temporal iterative decoder that uses this method

An interleaving order generator for a turbo encoder/decoder prevents bottlenecks incurred when temporarily storing a generated interleaving pattern. An interleaving order generator, an interleaver, a turbo encoder, and a turbo decoder realizes a minimum parameter transfer to reduce bottlenecks in the interface, even when the data rate is varied and the interleave length is frequently changed. The interleaving order generator enables a sufficient data transfer rate for providing multi-media services.

Interleaving order generator, interleaver, turbo encoder, and turbo decoder

A high-speed turbo decoder using a BCJR (Bahi, Cocke, Jelinek, and Raviv) algorithm or a BCJR algorithm which makes approximation by ACS computation (Add-Compare-Select computation) includes a supplier for supplying a plurality of pipelined stages of gamma metrics as a section for performing at least one of alpha metric computation and beta metric computation in the BCJR algorithm, an ACS computation portion which is constituted by a plurality of stages of cascade connections and receives the plurality of pipelined gamma metrics, a receiver that receives a computation result obtained by the ACS computation portion and updates state metrics every plurality of stages (K stages), and a memory for storing state metrics for every K stages.

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Tokyo, Japan

Tsuguo Maru