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Patent Issued for Method for Performing Handover, User Equipment, Base Station, and Radio Communication System

June 17, 2014



By a News Reporter-Staff News Editor at Journal of Technology -- A patent by the inventors Takano, Hiroaki (Tokyo, JP); Sakoda, Kazuyuki (Tokyo, JP), filed on September 30, 2013, was published online on June 3, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8743833 is assigned to Sony Corporation (Tokyo, JP).

The following quote was obtained by the news editors from the background information supplied by the inventors: "In Long Term Evolution-Advanced (LTE-A), which is the next-generation cellular communication standard that is discussed in Third Generation Partnership Project (3GPP), introduction of technology called carrier aggregation (CA) has been studied. The carrier aggregation is technology that forms a communication channel between a user equipment (UE) and a base station (BS, or evolved Node B (eNB)) by aggregating a plurality of frequency bands that are supported in LTE, for example, and thereby improves communication throughput. Each frequency band included in one communication channel by the carrier aggregation is called a component carrier (CC). The bandwidths of frequency bands that are available in LTE are 1.4 MHz, 3.0 MHz, 5.0 MHz, 10 MHz, 15 MHz, and 20 MHz. Accordingly, if five bands of 20 MHz are aggregated as component carriers, a communication channel of 100 MHz in total can be formed.

"Component carriers that are included in one communication channel in the carrier aggregation are not necessarily contiguous to one another in the frequency direction. The mode in which component carriers are arranged contiguous to one another in the frequency direction is called a contiguous mode. On the other hand, the mode in which component carriers are arranged not contiguous to one another is called a non-contiguous mode.

"Further, in the carrier aggregation, the number of component carriers in an uplink and the number of component carriers in a downlink are not necessarily equal. The mode in which the number of component carriers in an uplink and the number of component carriers in a downlink are equal is called a symmetric mode. On the other hand, the mode in which the number of component carriers in an uplink and the number of component carriers in a downlink are not equal is called an asymmetric mode. For example, in the case of using two component carriers in an uplink and three component carriers in a downlink, it is asymmetric carrier aggregation.

"Further, in LTE, any one of frequency division duplex (FDD) and time division duplex (TDD) can be used as duplex operation. Because the direction of a link (uplink or downlink) of each component carrier does not change in time in FDD, FDD is better suited to the carrier aggregation compared to TDD.

"A handover, which is a basic technique for achieving the mobility of a user equipment in the cellular communication standard, is one of important subjects in LTE-A. In LTE, a user equipment measures a communication quality over a channel with a serving base station (a currently connected base station) and communication qualities with peripheral base stations and transmits a measurement report containing measurements to the serving base station. Receiving the measurement report, the serving base station determines whether to execute a handover based on the measurements contained in the report. Then, if it is determined that a handover is to be executed, a handover is carried out among a source base station (the serving base station before a handover), the user equipment, and a target base station (a serving base station after a handover) in accordance with a prescribed procedure (e.g. cf. Patent Literature 1 below)"

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

"However, no case has been reported where active consideration is given to how to carry out a handover procedure in a radio communication involving the carrier aggregation.

"In the above-described existing handover procedure, processing such as request for a handover, confirmation of the request, issue of a handover command or random access to a target base station is performed based on the assumption that one communication channel is composed of one component carrier. In a radio communication involving the carrier aggregation also, it is desirable to perform such processing in the same manner as the existing procedure in order not to cause a significant impact on a system or a device which is widely used today.

"In light of the foregoing, it is desirable to provide a novel and improved method for performing a handover, user equipment, base station, and radio communication system that can carry out a handover during a radio communication involving the carrier aggregation without causing a significant impact on an existing system or device.

"Solution to Problem

"According to some embodiments, a base station includes a radio communication unit configured to establish communication with a mobile communication terminal using a plurality of component carriers. The base station further includes a control unit configured to transmit a command to the mobile communication terminal to reduce the plurality of component carriers to one prior to handover of communication between the mobile communication terminal and the base station to another base station.

"According to some embodiments, a mobile communication terminal includes a radio communication unit configured to establish communication with a base station using a plurality of component carriers. The mobile communication terminal further includes a control unit configured to receive a command from the base station to reduce the plurality of component carriers to one prior to handover of communication between the mobile communication terminal and the base station to another base station.

"According to some embodiments, a communication system includes a first base station and a mobile communication terminal. The first base station includes a radio communication unit configured to establish communication with a mobile communication terminal using a plurality of component carriers. The first base station further includes a first control unit configured to transmit a command to the mobile communication terminal to reduce the plurality of component carriers to one prior to handover of communication between the mobile communication terminal and the base station to a second base station. The mobile communication terminal includes a second control unit configured to reduce the plurality of component carriers to one upon reception of the command from the first base station.

"According to some embodiments, a non-transitory computer readable medium having instructions stored thereon, which when executed by a processor in a base station causes the processor to establish communication with a mobile communication terminal using a plurality of component carriers. The instructions further cause the processor to transmit a command to the mobile communication terminal to reduce the plurality of component carriers to one prior to handover of communication between the mobile communication terminal and the base station to another base station.

"Advantageous Effects of Invention

"As described above, the method for performing a handover, the user equipment, the base station, and the radio communication system according to the embodiments of the present invention can carry out a handover during a radio communication involving the carrier aggregation without causing a significant impact on an existing system or device."

URL and more information on this patent, see: Takano, Hiroaki; Sakoda, Kazuyuki. Method for Performing Handover, User Equipment, Base Station, and Radio Communication System. U.S. Patent Number 8743833, filed September 30, 2013, and published online on June 3, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8743833.PN.&OS=PN/8743833RS=PN/8743833

Keywords for this news article include: Technology, Sony Corporation.

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Source: Journal of Technology


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