News Column

Patent Issued for Transmission Power Determination Method, Communication Device and Program

February 13, 2014



By a News Reporter-Staff News Editor at Computer Weekly News -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Sawai, Ryo (Tokyo, JP); Kimura, Ryota (Tokyo, JP), filed on July 19, 2010, was published online on January 28, 2014.

The patent's assignee for patent number 8639281 is Sony Corporation (Tokyo, JP).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a transmission power determination method, a communication device and a program.

"Discussions have been taking place recently regarding secondary usage of a spectrum assigned for primary usage to provide a secondary communication service depending on the use condition of the spectrum. For example, the standard specification for allowing an unused channel contained in a spectrum of the U.S. digital TV broadcast (TV white spaces) to be available for radio communication has been studied in the IEEE802.22 working group (cf. 'IEEE802.22 WG on WRANs', [online], [Searched on Jan. 5, 2009], Internet http://www.ieee802.org/22/>).

"Further, according to the report from FCC (Federal Communications Commission) on November 2008, the discussions are directed toward permitting secondary usage of TV white spaces by using a communication device that fulfills a certain condition and has received an authorization. The FCC's report accepts the above-described standard specification of IEEE802.22 which is the pioneering work on the standardization of secondary usage of TV white spaces and further coverts the moves of a new study group in IEEE. Technically, because it is required to perform signal detection at the level of -114[dBm] (SNR is about -19[dB] when NF (Noise Figure) is 11[dB], for example) with use of existing technology, for example, an auxiliary function such as geo-location database access is expected to be necessary (cf. 'SECOND REPORT AND ORDER AND MEMORANDUM OPINION AND ORDER', [online], [Searched on Jul. 10, 2009], Internet http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-08-260A1.pd- f>). Further, the FCC is searching for opening a 250 MHz band, which is a part of a 5 GHz band, as a new channel for secondary usage.

"Furthermore, in the EU, there are moves afoot to universally allocate a dedicated control channel called CPC (Cognitive Pilot Channel) for making DSA (Dynamic Spectrum Access) under a long-term strategy. Allocation of CPC is incorporated in the agenda of ITU (International Telecommunication Union)-WP11 in 2011. Technological studies for a secondary usage system that makes DSA are also being progressed in IEEE SCC (Standards Coordinating Committee) 41.

"In such a background, several research reports have been released recently concerning secondary usage of a spectrum in the case of assuming a broadcasting system, a satellite communication system, a mobile communication system or the like as a primary system. For example, Alan Bok et al., 'Cognitive Radio System using IEEE802.11a over UHF TVWS', Motorola, October 2008 proposes a system architecture in the case of operating a radio system with use of the IEEE802.22 standard on TV white spaces of UHF (Ultra High Frequency). Further, D.Gueny et al.,'Geo-location database technique for incumbent protection in the TV White space', DySPAN, October 2008 also intends use of TV white spaces and proposes a form that utilizes positional information of a service area of a primary system as external information.

"On the occasion of secondary usage of a spectrum, it is generally necessary for a system on the part of secondary usage (secondary system) to carry out the operation that does not degrade the communication quality of a primary system. Therefore, when transmitting a radio signal in the secondary system, it is desirable to control its transmission power so as to avoid interference on a node of the primary system.

"Regarding such control of a transmission power, in the case of secondary usage of TV white spaces as proposed by Alan Bok et al. or D.Gueny et al., it can be confirmed beforehand that a channel for secondary usage is not used at all, and it is thus possible to determine in many cases that a transmission power at the maximum level can be used. On the other hand, H.Fujii and H.Yoshino (NTT docomo), 'Spectrum sharing by adaptive transmit power control for low priority system and its achievable capacity', CrownCom, May 2008 proposes a technique that protects a node of a high-priority system by adaptively controlling a transmission power in a low-priority system.

"Further, Inage et al., 'Spectrum Sharing Based on Capacity Conservation Ratio of Primary User', IEICE Technical Report SR2009, May 2009 proposes a technique that, when a system such as a mobile communication system in which the receiving environment of a terminal varies depending on location due to fading or the like is the primary system, adopts the ratio of capacity (capacity conservation ratio) between before and after secondary usage in the primary system as a protection criterion and makes transmission power control for satisfying the capacity conservation ratio."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "In order to make full effective use of a limited spectrum, it is not sufficient to achieve secondary usage of the above-described white space, which is a spectrum in an area where a communication service related to primary usage (which is referred to hereinafter as a first communication service) is not provided. One reason is that secondary usage of the white space is utilization of a spectrum that is apparently available in the long and medium terms in a particular region, and an actual opportunity of usage is limited to an area where there are only a small number of users of the first communication service. Further, as for secondary usage of the TV white space in the United States, for example, it is predicted that part of the spectrum is auctioned and a spectrum left for secondary usage is small.

"Given such a situation, one possible approach is to make secondary usage of a spectrum within a service area of the first communication service under permission of a coordinator (e.g. a base station) of the first communication service, for example. Another possible approach is to make secondary usage of a spectrum that is unavailable for the first communication service in an area inside or in the peripheral part of a service area of the first communication service where signal receiving conditions are relatively unsuitable due to shadowing (shielding), fading or the like. In such cases of secondary usage, it is expected that a node of the primary system (which is referred to hereinafter as a primary usage node) and a node of the secondary system (which is referred to hereinafter as a secondary usage node) are located closer to each other. Therefore, a mechanism of transmission power control that suppresses interference with enhanced adaptability is desirable. For example, because the technique taught by Inage et al. decreases the entire capacity of the primary system in one cell at a constant rate and allocates the amount of decrease to the secondary system, there remains a possibility it becomes difficult to receive a radio signal (primary signal) locally in one primary usage node due to interference of the secondary usage node in the nearby vicinity.

"In light of the foregoing, it is desirable to provide a novel and improved transmission power determination method, communication device and program that can improve the adaptability of transmission power control on the occasion of secondary usage of a spectrum and suppress interference on the primary system.

"According to an embodiment of the present invention, there is provided a method for determining an acceptable transmission power for a second communication service making secondary usage of a spectrum assigned to a first communication service, including the step of determining the acceptable transmission power based on quality of a radio signal required in the first communication service, an interference level or a noise level in the first communication service, and a path loss on a communication path about one or more secondary usage node that transmits a radio signal of the second communication service.

"In this configuration, an acceptable transmission power for a second communication service making secondary usage of a spectrum is determined adaptively based on quality of a radio signal required in the first communication service, an interference level or a noise level in the first communication service, and a path loss on a communication path about one or more secondary usage node that transmits a radio signal of the second communication service.

"The quality of a radio signal required in the first communication service may be represented by using a reception level of a radio signal required in the first communication service and a signal to interference and noise ratio.

"The method may further include the steps of: acquiring location data from a database that stores the location data indicating a location of a primary usage node that receives a radio signal of the first communication service; and calculating the path loss on the communication path about the one or more secondary usage node based on the location of the primary usage node indicated by the location data and a location of the one or more secondary usage node.

"The method may be executed by a primary usage node that has access to the database, and may further include the step of notifying the determined acceptable transmission power from the primary usage node to any node among the one or more secondary usage node.

"The method may be executed by a node acting as a coordinator of the second communication service among the one or more secondary usage node.

"The method may be executed by a node acting as a coordinator of the second communication service among the one or more secondary usage node, and when the node acting as the coordinator is not able to acquire location data indicating a location of a primary usage node that receives a radio signal of the first communication service in the step of determining the acceptable transmission power, the acceptable transmission power may be determined by counting in a margin for reducing a possibility of causing interference on the primary usage node.

"The margin may have a value depending on an expected number of the secondary usage node.

"According to another embodiment of the present invention, there is provided a communication device including: a communication unit that is able to transmit a radio signal of a second communication service making secondary usage of a spectrum assigned to a first communication service; and a control unit that determines an acceptable transmission power for the second communication service, wherein the control unit determines the acceptable transmission power based on quality of a radio signal required in the first communication service, an interference level or a noise level in the first communication service, and a path loss on a communication path about one or more secondary usage node that transmits a radio signal of the second communication service.

"According to another embodiment of the present invention, there is provided a program causing a computer as a control unit, the computer controlling a communication device including a communication unit that is able to transmit a radio signal of a second communication service making secondary usage of a spectrum assigned to a first communication service, wherein: the control unit determines an acceptable transmission power for the second communication service based on quality of a radio signal required in the first communication service, an interference level or a noise level in the first communication service, and a path loss on a communication path about one or more secondary usage node that transmits a radio signal of the second communication service.

"According to another embodiment of the present invention, there is provided a communication device including: a communication unit that is able to communicate with a secondary usage node that transmits a radio signal of a second communication service making secondary usage of a spectrum assigned to a first communication service; and a control unit that determines an acceptable transmission power for the second communication service, wherein the control unit determines the acceptable transmission power based on quality of a radio signal required in the first communication service, an interference level or a noise level in the first communication service, and a path loss on a communication path about one or more secondary usage node.

"According to another embodiment of the present invention, there is provided a program causing a computer as a control unit, the computer controlling a communication device including a communication unit that is able to communicate with a secondary usage node that transmits a radio signal of a second communication service making secondary usage of a spectrum assigned to a first communication service, wherein: the control unit determines an acceptable transmission power for the second communication service based on quality of a radio signal required in the first communication service, an interference level or a noise level in the first communication service, and a path loss on a communication path about one or more secondary usage node.

"According to the embodiments of the present invention described above, it is possible to provide a transmission power determination method, a communication device and a program that can improve the adaptability of transmission power control on the occasion of secondary usage of a spectrum and suppress interference on the primary system

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1A is a diagram showing a first example in which a primary usage node receives interference by secondary usage of a spectrum.

"FIG. 1B is a diagram showing a second example in which a primary usage node receives interference by secondary usage of a spectrum.

"FIG. 2A is a first diagram to describe the effect of interference depending on a communication scheme and a channel direction.

"FIG. 2B is a second diagram to describe the effect of interference depending on a communication scheme and a channel direction.

"FIG. 2C is a third diagram to describe the effect of interference depending on a communication scheme and a channel direction.

"FIG. 2D is a fourth diagram to describe the effect of interference depending on a communication scheme and a channel direction.

"FIG. 3A is a first diagram to describe interference between second communication services.

"FIG. 3B is a second diagram to describe interference between second communication services.

"FIG. 4 is an explanatory view to describe an overview of a communication system according to a first embodiment.

"FIG. 5 is a block diagram showing an example of a logical configuration of a management node according to the first embodiment.

"FIG. 6 is a flowchart showing an example of a flow of a transmission power determination process according to the first embodiment.

"FIG. 7 is a flowchart showing an example of a flow of a transmission power distribution process according to the first embodiment.

"FIG. 8 is a block diagram showing an example of a logical configuration of a terminal device according to the first embodiment.

"FIG. 9 is a flowchart showing an example of a flow of a transmission power control process in a terminal device according to the first embodiment.

"FIG. 10 is an explanatory view to describe an overview of a communication system according to a second embodiment.

"FIG. 11 is a block diagram showing an example of a logical configuration of a management node according to the second embodiment.

"FIG. 12 is a block diagram showing an example of a logical configuration of a terminal device according to the second embodiment.

"FIG. 13 is a flowchart showing an example of a flow of a transmission power determination process according to the second embodiment.

"FIG. 14 is an explanatory view to describe an application to TV band."

For additional information on this patent, see: Sawai, Ryo; Kimura, Ryota. Transmission Power Determination Method, Communication Device and Program. U.S. Patent Number 8639281, filed July 19, 2010, and published online on January 28, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=28&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1400&f=G&l=50&co1=AND&d=PTXT&s1=20140128.PD.&OS=ISD/20140128&RS=ISD/20140128

Keywords for this news article include: Sony Corporation.

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