News Column

"Radio Communication System, Radio Base Station and Radio Communication Method" in Patent Application Approval Process

July 16, 2014



By a News Reporter-Staff News Editor at Telecommunications Weekly -- A patent application by the inventors Inoue, Yuki (Tokyo, JP); Abe, Tetsushi (Tokyo, JP), filed on August 15, 2012, was made available online on July 3, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Ntt Docomo, Inc.

The following quote was obtained by the news editors from the background information supplied by the inventors: "In a UMTS (Universal Mobile Telecommunications System) network, system features that are based on W-CDMA (Wideband Code Division Multiple Access) are maximized by adopting HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access) for the purposes of improving the spectral efficiency and improving the data rate. For this UMTS network, long-term evolution (LTE) has been under study for the purposes of further increasing high-speed data rates, providing low delay and so on.

"In the third-generation system, it is possible to achieve a transmission rate of maximum approximately 2 Mbps on the downlink by using a fixed band of approximately 5 MHz. In a system of the LTE scheme, it is possible to achieve a transmission rate of about maximum 300 Mbps on the downlink and about 75 Mbps on the uplink by using a variable band which ranges from 1.4 MHz to 20 MHz. In the UMTS network, for the purpose of achieving further broadbandization and higher speed, successor systems of LTE have been under study as well (for example, LTE-Advanced (LTE-A)). For example, in LTE-A, there is a plan to expand the maximum system band according to LTE specifications, which is 20 MHz, to approximately 100 MHz. In LTE-A, the maximum number of transmitting antennas according to LTE specifications is planned to be expanded from four antennas to eight antennas.

"In a system of the LTE scheme, a MIMO (Multi Input Multi Output) system is proposed (see, for example, non-patent literature 1), as a radio communication technique to transmit and receive data by a plurality of antennas and improve the data rate (spectral efficiency). In the MIMO system, a plurality of transmitting/receiving antennas are provided in the transmitter/receiver, so that different transmission information sequences are transmitted from different transmitting antennas at the same time. On the receiver side, taking advantage of the fact that fading variation is produced differently between the transmitting/receiving antennas, it is possible to increase the data rate (spectral efficiency) by separating and detecting the information sequences that have been transmitted at the same time.

"In a system of the LTE scheme, single-user MIMO (SU-MIMO) transmission, in which transmission information sequences that are transmitted from different transmitting antennas at the same time are all directed to the same user, and multiple-user MIMO (MU-MIMO) transmission, in which transmission information sequences that are transmitted from different transmitting antennas at the same time are directed to different users, are defined. In these SU-MIMO transmission and MU-MIMO transmission, on the receiver side, an optimal PMI is selected from a codebook, in which a plurality of amounts of phase/amplitude control (precoding matrix (precoding weights)) to be set in the antennas of the transmitter and PMIs (Precoding Matrix Indicators) that are associated with this precoding matrix, are defined, and this is fed back to the transmitter as channel information (CSI: Channel State Information). On the transmitter side, precoding for each transmitting antenna is performed based on the PMI fed back from the receiver, and transmission information sequences are transmitted."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "Technical Problem

"Generally, a plurality of antennas to be used in. MIMO transmission have the same characteristics (directivity, beam width and so on) and are arranged apart. The antennas do not change their characteristics between a plurality of communication types. In such MIMO transmission, the antennas to use are selected depending on the capacities of user terminals, so that, even in the situation where individual user terminals perform communication to support separate types of communication, it is still possible to easily perform signaling for a plurality of user terminals at the same time.

"Implementing MIMO transmission by using antennas that have varying antenna configurations depending on the communication type, instead of arranging a plurality of antennas having the same characteristics, is under study. In such MIMO transmission, when individual user terminals perform communication to support separate types of communication, a plurality of antenna configurations coexist at the same time. Consequently, it is not possible to select the antenna configuration to use as in above-described general MIMO transmission, and it is difficult to execute signaling for a plurality of user terminals at the same time.

"The present invention has been made in view of the above, and it is therefore an object of the present invention to provide a radio communication system, radio base station and radio communication method that can execute adequate signaling even when, in MIMO transmission using an antenna that has varying antenna configurations depending on the type of communication, individual user terminals perform communication to support separate types of communication.

"Solution to Problem

"A radio communication system according to the present invention is a radio communication system to include a radio base station to form a cell and user terminals to establish wireless connection with the radio base station, and, in this radio communication system: the radio base station has: an antenna that has varying antenna configurations between at least two types of communication, and that can transmit signals to all areas which the radio base station covers, in an antenna configuration to support at least one communication type 1; a resource allocation control section that allocates radio resources to a downlink signal including capacities of a user terminal and a signal type to match a communication type; a multiplexing section that multiplexes a reference signal on a resource block; a precoding weight generating section that generates a precoding weight which allows the antenna to form a number of beams to match the communication type; and a precoding multiplication section that multiplies a downlink signal to supply to the antenna by the precoding weight generated by the precoding weight generating section; and the user terminal has: a quality measurement section that measures channel quality from the reference signal included in the downlink signal; a feedback information generating section that generates feedback information pertaining to communication quality using the measured channel quality; and a transmission section that feeds back the feedback information generated by the feedback information generating section to the radio base station via an uplink.

"A radio base station according to the present invention is a radio base station having: an antenna that has varying antenna configurations between at least two types of communication and that can transmit signals to all areas which the radio base station covers, in an antenna configuration to support at least one communication type 1; a resource allocation control section that allocates radio resources to a downlink signal including capacities of a user terminal and a signal type to match a communication type; a multiplexing section that multiplexes a reference signal on a resource block; a precoding weight generating section that generates a precoding weight which allows the antenna to form a number of beams to match the communication type; and a precoding multiplication section that multiplies a downlink signal to supply to the antenna by the precoding weight generated by the precoding weight generating section.

"A radio communication method according to the present invention is a radio communication method for allowing a user terminal to establish wireless connection and communicates with a radio base station, and, in this radio communication method: the radio base station has an antenna that has varying antenna configurations between at least two types of communication and that can transmit signals to all areas which the radio base station covers, in an antenna configuration to support at least one communication type 1; and the radio base station: allocates radio resources to a downlink signal including capacities of a user terminal and a signal type to match a communication type; multiplexes a reference signal on a resource block; generates a precoding weight which allows the antenna to form a number of beams to match the communication type; and multiplies a downlink signal to supply to the antenna by the generated precoding weight; and the user terminal: measures channel quality from the reference signal included in the downlink signal; generates feedback information pertaining to communication quality using the measured channel quality; and feeds back the generated feedback information to the radio base station via an uplink.

"According to the present invention, a radio base station has an antenna to have an antenna configuration which has varying antenna configurations between at least two types of communication, and an antenna configuration which can transmit signals in communication type 1, which is at least one of them, to all areas the radio base station covers, multiplexes reference signals on resource blocks and transmits these, and furthermore feeds back channel quality that is measured based on reference signals from user terminals UE, corresponding to each communication type. By this means, in MIMO transmission to use antennas having varying antenna configurations depending on the type of communication, even when individual user terminals perform communication to support separate types of communication, it is still possible to adequately transmit and receive (signaling) reference signals and feedback signals, which are necessary in communication, between the radio base station and user terminals.

"Technical Advantage of the Invention

"According to the present invention, in MIMO transmission to use antennas that have varying antenna configurations depending on the type of communication, it is still possible to execute adequate signaling even when individual user terminals perform communication to support separate types of communication.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 provides schematic diagrams for explaining N communication types that are provided by an array antenna in a radio base station according to the present embodiment;

"FIG. 2 is a schematic diagram for explaining a weight control for antenna elements constituting an array antenna;

"FIG. 3 is a schematic diagram for explaining a weight control for a first communication type;

"FIG. 4 is a schematic diagram for explaining a weight control for a second communication type;

"FIG. 5 is a schematic diagram for explaining a weight control for a third communication type;

"FIG. 6 provides diagrams showing the reference signal arrangement in resource blocks under the first, second, third and fourth communication types and mixed operation;

"FIG. 7 is a diagram showing a basic sequence between a radio base station and user terminals constituting a radio communication system according to the present embodiment;

"FIG. 8 is a diagram for explaining a configuration of a radio communication system having mobile station apparatuses and a radio base station according to the present embodiment;

"FIG. 9 is a block diagram showing a configuration of a radio base station according to the present embodiment; and

"FIG. 10 is a block diagram showing a configuration of a mobile station apparatus according to the present embodiment."

URL and more information on this patent application, see: Inoue, Yuki; Abe, Tetsushi. Radio Communication System, Radio Base Station and Radio Communication Method. Filed August 15, 2012 and posted July 3, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4571&p=92&f=G&l=50&d=PG01&S1=20140626.PD.&OS=PD/20140626&RS=PD/20140626

Keywords for this news article include: Ntt Docomo Inc.

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Source: Telecommunications Weekly


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