A base station judges whether backup channel of the base station has therein a channel which is not an operating channel of another base station configuring an adjacent cell by the channel management unit, and, if there is at least one channel which is not an operating channel of the another base st
A base station judges whether backup channel of the base station has therein a channel which is not an operating channel of another base station configuring an adjacent cell by the channel management unit, and, if there is at least one channel which is not an operating channel of the another base station, performs fairness processing according to a prescribed etiquette to have one of the channels as an operating channel of the base station, and, if not, determines a base station which requests a release of an operating channel from the another based on the basis of a degree of satisfaction defined as a function of an offered communication traffic within a cell, a transmission rate depending on a propagation environment between the base station and a wireless communication terminal and an actually allocated operating channel number, and performs negotiation processing to cause a release of an operating channel.
대표청구항▼
1. A channel using method performed by a base station configuring a cell including wireless communication terminals by using a plurality of channels of white space, comprising: a judgment process judging whether or not there is an exclusively-available channel which is not an operating channel of ad
1. A channel using method performed by a base station configuring a cell including wireless communication terminals by using a plurality of channels of white space, comprising: a judgment process judging whether or not there is an exclusively-available channel which is not an operating channel of adjacent base stations within backup channels usable by the base station;a fairness process which, when there is at least one exclusively-available channel in the judgment process, determines the one exclusively-available channel as a new operating channel of the base station, wherein the fairness process comprises:a first judging step judges whether there is at least one channel which is neither an operating channel nor backup channel of the adjacent base stations among the backup channels of the base station;when there is at least one channel which is neither an operating channel nor backup channel of the adjacent base stations, a first selecting step selects the one channel of the first judging step as the new operating channel; andwhen there is not at least one channel which is neither an operating channel nor backup channel of the adjacent base stations, a second judging step judges whether the satisfaction degree of the base station is minimum among the adjacent base stations;a third judging step judges whether there is a second cell that has a satisfaction degree that is the same as the satisfaction degree of the cell having the base station when the second judging step determines that the satisfaction degree of the base station is minimum among the adjacent base stations;a fourth judging step judging whether the second cell has a greater number of back up channels than the cell of the base station when the third judging step determines that there is the second cell that has the satisfaction degree that is the same as the satisfaction degree of the cell having the base station; anda second selecting step selects any one of the backup channels of the base station as the new operating channel for exclusive use when the satisfaction degree of the base station has been judged minimum in the second judging step and the cell of the base station has a fewer number of the backup channels in comparison with the second cell that has the satisfaction degree that is the same as the cell having the base station as judged in the third and the fourth judging steps; anda negotiation process which, when there is no channel which is not the operating channel of the adjacent base stations, determines within the adjacent base stations using plural operating channels a certain base station to request a release of a certain operating channel based on a comparison of satisfaction degrees between the base station and the certain base station and causes the certain base station to completely release the certain operating channel,wherein each of the satisfaction degree is defined as a same mathematical function of communication traffic within the cell, a transmission rate depending on a propagation environment between the base station and the wireless communication terminals and a number of actually allocated operating channels of white space,wherein in the negotiation process, the base station and the certain base station exchange information of their satisfaction degree with each other using a medium access control message or under control of a centralized server, andwherein the negotiation process causes at least one of the adjacent base stations to completely release an operating channel on condition that the satisfaction degree of the base station is minimum in comparison with the satisfaction degree of the adjacent base station or the satisfaction degree of the adjacent base station is invariable while repeating the series of processes after the judgment process, and the satisfaction degree of both of them are not reversed even when the adjacent base station releases the operating channel. 2. The channel using method according to claim 1, wherein the negotiation process comprises: a judging step judges whether the satisfaction degree of the base station is minimum compared to the adjacent base stations;a destination selecting step selecting a most satisfied base station of which satisfaction degree after losing its any one operating channel is maximum among the adjacent base stations;a channel selecting step selecting the certain operating channel of the most satisfied base station, which is used by least number of the adjacent base stations;an executing step negotiating each of the certain base station using the certain operating channel to obtain the certain operating channel. 3. The channel using method according to claim 2, the satisfaction degree of a targeted base station is calculated by: CS=NOPE/MaxCPE(W×λ/(R/NCPE))orCS=NOPE/ΣCPE(W×λ/R) where CS represents the satisfaction degree, NOPE represents the number of actually allocated operating channel of targeted base station, NCPE denotes the number of the wireless communication terminals in the cell of the targeted base station, W denotes a weight of each the wireless communication terminal depending on subscriber's membership, λ denotes communication traffic of each the terminal, R denotes transmission capacity per channel of each the terminal depending on its distance from the targeted base station, and ΣCPE denotes total computation of all wireless communication terminals in the cell. 4. The channel using method according to claim 2, further comprising: a self judgment process judging whether or not service quality in the cell of the base station is enough to avoid the negotiation process by estimating a number of satisfied wireless communication terminals in the cell, wherein the satisfaction of each wireless communication terminal depends on subscriber's membership. 5. The channel using method according to claim 2, further comprising: a waiting process waiting a specified time period before the judgment process in order to collect a status of channel usage in the adjacent base stations by receiving signals of super frame header or coexistence beaconing protocol. 6. The channel using method according to claim 5, wherein: in the waiting process, the specified time period increases with increase of the satisfaction degree or the number of actually allocated operating channel of the base station for the purpose of providing an order of priority to obtain an operating channel. 7. The channel using method according to claim 2, wherein: in the executing step, the base station and the certain base station exchange information of their satisfaction degrees with each other using a medium access control message or under control of the centralized server. 8. The channel using method according to claim 2, wherein the satisfaction degree of a targeted base station is calculated by: CS=NOPE/MaxCPE(W×λ/(R/NCPE))orCS=NOPE/ΣCPE(W×λ/R)where CS represents the satisfaction degree, NOPE represents the number of actually allocated operating channel of targeted base station, NCPE denotes the number of the wireless communication terminals in the cell of the targeted base station, W denotes a weight of each the wireless communication terminal depending on subscriber's membership, λ denotes communication traffic of each the terminal, R denotes transmission capacity per channel of each the terminal depending on its distance from the targeted base station, and ΣCPE denotes total computation of all wireless communication terminals in the cell,wherein in the negotiation process, the base station and the certain base station exchange information of their satisfaction degrees with each other using the medium access control message or under control of the centralized server, andwherein in the executing step, the base station and the certain base station exchange information of their satisfaction degrees with each other using the medium access control message or under control of the centralized server. 9. The channel using method according to claim 1, the negotiation process comprising the steps of: transmitting a medium access control message of a channel negotiation request from the base station as a negotiation source to the certain base station as a negotiation destination, wherein the medium access control message of the channel negotiation request includes an ID identifying the channel negotiation request, an ID of the negotiation destination, the satisfaction degree of the negotiation source, the satisfaction degree after establishment of negotiation and a negotiation channel number;transmitting a medium access control message of a channel negotiation response from the negotiation destination which has received the channel negotiation request to the negotiation source, the medium access control message of the channel negotiation response includes an ID identifying the channel negotiation response, an ID of the negotiation source, the satisfaction degree of the negotiation destination, the satisfaction degree after the establishment of negotiation, a channel number to be released, and a channel release time;transmitting a medium access control message of a channel negotiation response acknowledgement from the negotiation source to the negotiation destination; andtransmitting a medium access control message of a channel release from the negotiation destination to the negotiation source to notify the negotiation source and any cell adjacent to the negotiation destination. 10. The channel using method according to claim 2, the negotiation process comprising the steps of: transmitting a medium access control message of a channel negotiation request from the base station as a negotiation source to the certain base station as a negotiation destination, wherein the medium access control message of the channel negotiation request includes an ID identifying the channel negotiation request, an ID of the negotiation destination, the satisfaction degree of the negotiation source, the satisfaction degree after establishment of negotiation and a negotiation channel number;transmitting a medium access control message of a channel negotiation response from the negotiation destination which has received the channel negotiation request to the negotiation source, the medium access control message of the channel negotiation response includes an ID identifying the channel negotiation response, an ID of the negotiation source, the satisfaction degree of the negotiation destination, the satisfaction degree after the establishment of negotiation, a channel number to be released, and a channel release time;transmitting a medium access control message of a channel negotiation response acknowledgement from the negotiation source to the negotiation destination; andtransmitting a medium access control message of a channel release from the negotiation destination to the negotiation source to notify the negotiation source and any cell adjacent to the negotiation destination. 11. The channel using method according to claim 1, wherein the satisfaction degree decreases with an increase in a number of the wireless communication terminals. 12. A multichannel wireless communication system, comprising: a plurality of base stations configuring a cell including wireless communication terminals by using a single or plurality of channels of white space; anda management device managing information on a backup channel usable by each of the plurality of base stations;wherein the management device judges, for one base station, whether there is an exclusively-available channel not operated by adjacent base stations which are adjacent to the one base station, within the backup channels usable by the one base station, andwhen there is at least one exclusively-available channel judged in the management device, the management device determines the one exclusively-available channel as a new operating channel of the base station, according to a fairness process, wherein the fairness process includes:a first judging step judges whether there is at least one channel which is neither an operating channel nor backup channel of the adjacent base stations among the backup channels of the base station;when there is at least one channel which is neither an operating channel nor backup channel of the adjacent base stations, a first selecting step selects the one channel of the first judging step as the new operating channel; andwhen there is not at least one channel which is neither an operating channel nor backup channel of the adjacent base stations, a second judging step judges whether the satisfaction degree of the base station is minimum among the adjacent base stations;a third judging step judges whether there is a second cell that has a satisfaction degree that is the same as the satisfaction degree of the cell having the base station when the second judging step determines that the satisfaction degree of the base station is minimum among the adjacent base stations;a fourth judging step judging whether the second cell has a greater number of back up channels than the cell of the base station when the third judging step determines that there is the second cell that has the satisfaction degree that is the same as the satisfaction degree of the cell having the base station; anda second selecting step selects any one of the backup channels of the base station as the new operating channel for exclusive use when the satisfaction degree of the base station has been judged minimum in the second judging step and the cell of the base station has a fewer number of the backup channels in comparison with the second cell that has the satisfaction degree that is the same as the cell having the base station as judged in the third and the fourth judging steps;when there is no exclusively-available channel not operated, the management device selects a certain base station to which a request is made for complete release of a certain operating channel based on a comparison of satisfaction degrees between the one base station and the certain base station wherein each of the satisfaction degree is determined as a same mathematical function of communication traffic within the cell depending on a propagation environment between the base station and the wireless communication terminals and a number of the actually allocated operating channels of white space, and performs channel negotiation with the selected base station, andwherein the management device causes at least one of the adjacent base stations to completely release an operating channel on condition that the satisfaction degree of the one base station is minimum in comparison with the satisfaction degree of the adjacent base station or the satisfaction degree of the adjacent base station is invariable while repeating the series of processes after the judgment process, and the satisfaction degree of both of them are not reversed even when the adjacent base station releases the operating channel. 13. A base station configuring a cell which includes wireless communication terminals by using a plurality of channels of a frequency of a white space, comprising: a channel management unit which judges whether there is an exclusively-available channel which is not operated by adjacent base stations within backup channels which are determined by spectrum sensing and usable by the base station, and when there is at least one exclusively-available channel determines one exclusively-available channel as a new operating channel of the base station, and when there is not a channel which is not operated, determines a certain base station to request a release of a certain operating channel based on a comparison of satisfaction degrees between the base station and the certain base station and the satisfaction degree calculated for each of the base station and the adjacent base stations is defined as a function of communication traffic within a cell, a transmission rate depending on a propagation environment between the base station and the wireless communication terminals, and a number of actually allocated operating channels, and causes the certain base station to completely release the operating channel of white space; andwherein the channel management unit includes:a first judging step judges whether there is at least one channel which is neither an operating channel nor backup channel of the adjacent base stations among the backup channels of the base station;when there is at least one channel which is neither an operating channel nor backup channel of the adjacent base stations, a first selecting step selects the one channel of the first judging step as the new operating channel; andwhen there is not at least one channel which is neither an operating channel nor backup channel of the adjacent base stations, a second judging step judges whether the satisfaction degree of the base station is minimum among the adjacent base stations;a third judging step judges whether there is a second cell that has a satisfaction degree that is the same as the satisfaction degree of the cell having the base station when the second judging step determines that the satisfaction degree of the base station is minimum among the adjacent base stations;a fourth judging step judging whether the second cell has a greater number of back up channels than the cell of the base station when the third judging step determines that there is the second cell that has the satisfaction degree that is the same as the satisfaction degree of the cell having the base station; anda second selecting step selects any one of the backup channels of the base station as the new operating channel for exclusive use when the satisfaction degree of the base station has been judged minimum in the second judging step and the cell of the base station has a fewer number of the backup channels in comparison with the second cell that has the satisfaction degree that is the same as the cell having the base station as judged in the third and the fourth judging steps. 14. The base station according to claim 13, wherein the channel management unit further comprises: a judging step judges whether the satisfaction degree of the base station is minimum compared to the adjacent base stations;a destination selecting step selecting a most satisfied base station of which satisfaction degree after losing its any one operating channel is maximum among the adjacent base stations;a channel selecting step selecting the certain operating channel of the most satisfied base station, which is used by least number of the adjacent base stations;an executing step negotiating each of the certain base station using the certain operating channel to obtain the certain operating channel,wherein in the executing step, the base station and the certain base station exchange information of their satisfaction degrees with each other using a medium access control message or under control of the centralized server, andwherein in the executing step, at least one of the adjacent base stations completely releases an operating channel on condition that the satisfaction degree of the base station is minimum in comparison with the satisfaction degree of the adjacent base station or the satisfaction degree of the adjacent base station is invariable while repeating the series of processes, and the satisfaction degree of both of them are not reversed even when the adjacent base station releases the operating channel. 15. The base station according to claim 13, wherein the satisfaction degree decreases with an increase in a number of the wireless communication terminals.
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이 특허에 인용된 특허 (2)
Cho,Sung Hyun; Yun,Sang Boh; Park,Won Hyoung; Han,Young Nam; Kim,Hoon; Koo,Ja Yong, Apparatus and method for allocating subchannels adaptively according to frequency reuse rates in an orthogonal frequency division multiple access system.
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