Source: http://www.google.com/patents/US20030050012?dq=6462713
Timestamp: 2015-07-31 04:05:36
Document Index: 752917188

Matched Legal Cases: ['art 16', 'art 18', 'arts 16', 'art 18', 'art 18', 'art 16']

Patent US20030050012 - Assembly, and associated method, for facilitating channel frequency ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsAn assembly, and an associated method, for an ad hoc network, such as an independent basic service set defined in an IEEE 802.11 protocol specification. A channel map is created and maintained at each mobile station of the ad hoc network. The channel map is populated with channel characteristic indicia...http://www.google.com/patents/US20030050012?utm_source=gb-gplus-sharePatent US20030050012 - Assembly, and associated method, for facilitating channel frequency selection in a communication system utilizing a dynamic frequency selection schemeAdvanced Patent SearchPublication numberUS20030050012 A1Publication typeApplicationApplication numberUS 10/097,977Publication dateMar 13, 2003Filing dateMar 14, 2002Priority dateSep 7, 2001Also published asEP1955555A1, EP1955555A4, US6738599, US7535868, US20050013275, WO2003024129A1Publication number097977, 10097977, US 2003/0050012 A1, US 2003/050012 A1, US 20030050012 A1, US 20030050012A1, US 2003050012 A1, US 2003050012A1, US-A1-20030050012, US-A1-2003050012, US2003/0050012A1, US2003/050012A1, US20030050012 A1, US20030050012A1, US2003050012 A1, US2003050012A1InventorsSimon Black, Steven Gray, Venkatesh VaddeOriginal AssigneeBlack Simon A., Steven Gray, Venkatesh VaddeExport CitationBiBTeX, EndNote, RefManPatent Citations (5), Referenced by (45), Classifications (10), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetAssembly, and associated method, for facilitating channel frequency selection in a communication system utilizing a dynamic frequency selection scheme
BRIEF DESCRIPTION OF THE DRAWINGS [0026]FIG. 1 illustrates a functional block diagram of a communication system in which an embodiment of the present invention is embodied as a portion thereof. [0027]FIG. 2 illustrates a representation of an exemplary channel map formed pursuant to operation of an embodiment of the present invention. [0028]FIG. 3 illustrates a representation of the format of exemplary channel characteristic indicia contained in the channel map shown in FIG. 2. [0029]FIG. 4 illustrates a method flow diagram listing the method steps of the method of operation of an embodiment of the present invention.
DETAILED DESCRIPTION [0030] Referring first to FIG. 1, a communication system, shown generally at 10, forms an ad hoc network of mobile stations 12. Here, N mobile stations, 12-1 through 12-N, together define the ad hoc network. The number of members of the ad hoc network is a non-static number, and mobile stations forming members of the network change over time due to, e.g., movement of individual ones of the mobile stations or change of state of individual ones of the mobile stations. [0031] In the exemplary implementation, the mobile stations forming the ad hoc network of the communication system 10 form a wireless local area network (WLAN) that is operable pursuant to an IEEE 802.11 standard. While the following description of operation of an embodiment of the present invention shall describe its implementation as a portion of a communication system operable generally pursuant to the IEEE 802.11 standard, operable at the 5 GHz range, the teachings of the present invention are analogously applicable in other types of communication systems, and an embodiment of the present invention can analogously be described with respect to implementation in other types of communication systems. [0032] The IEEE 802.11 standard sets forth operational parameters related to an independent basic service set (IBSS) in which mobile stations 12 that form members of the IBSS operate in an ad hoc networking mode in which the mobile stations communicate with one another without the use of a fixed-site central control device, referred in the IEEE 802.11 operating protocol as an access point. [0033] The IEEE 802.11 standard pertaining to deployment of a communication system at the 5 GHz frequency band in Europe sets forth system requirements for WLAN systems to distribute electromagnetic energy emanations over the allocated frequency band. As the frequency band is an unlicensed band, communications, or other electromagnetic transmissions, might also be generated concurrent to operation of the WLAN system. Dynamic frequency selection (DFS) is required to select the frequencies within the allocated band that are available upon which to define communication channels. Through dynamic frequency selection, frequencies within the band used by other communication systems, such as microwave communication networks and radar devices, are noted and excluded from availability to be used by the WLAN system for communications between the mobile stations thereof. As the IBSS forms an infrastructure-free, ad hoc network, operations required pursuant to the dynamic frequency selection process require their implementation by the mobile stations that form the network. [0034] Instead of a central control device, one of the mobile stations (STAs) 12 of the network is designated as a DFS (dynamic frequency selection) owner that, for at least a designated period, controls the DFS functions. As any of the mobile stations might be designated as the DFS owner, each of the mobile stations must have the capacity of performing the functions of the DFS owner. [0035] An embodiment of the present invention facilitates the capability of a mobile station to perform the dynamic frequency selection operation required to select a channel frequency upon which to designate a communication channel for communications in the ad hoc network. In the exemplary implementation, each of the mobile stations includes an embodiment of the present invention, providing each mobile station with the capability of selecting information regarding the radio environment about the mobile stations of the ad hoc network to permit proper selection of channel frequencies to be used upon which to define communication channels for communications between the mobile stations. [0036] Operation of an embodiment of the present invention further provides for the communication of channel quality information between the mobile stations of the ad hoc network. The mobile station 12-1 is exemplary of each of the other mobile stations 12-2 through 12-N. And, the mobile station includes, in conventional manner, transceiver circuitry, here including a transmit circuit part 16 and a receive circuit part 18. The mobile station is also shown to include apparatus 22 of an embodiment of the present invention. The apparatus is formed of elements represented functionally in the figure. The elements forming the apparatus are implemented in any desired manner, such as, in part, as algorithms executable by processing circuitry. The apparatus is coupled both to the transmit and receive circuit parts 16 and 18. [0037] The apparatus includes a channel map 24 that contains a listing 26. The listing forms a sequence of channel frequencies 28 and characteristic indicia 32 associated with respective ones of the channel frequencies. [0038] The apparatus further includes a channel characteristic supplier 36 that operates to populate the listing of the channel map with values of the characteristic indicia 32. Here, the channel characteristic supplier is represented to be coupled to the channel map by way of the line 38 to provide the values of the characteristic indicia thereto. [0039] The channel characteristic supplier includes a channel frequency measurer 38 that is coupled to receive indications of channel conditions of various channel frequencies to which the receive circuit part 18 tunes. In one implementation, the channel characteristic supplier instructs the receive circuit part 18 to tune to different channel frequencies, and the measurer operates to measure energy levels, and detect for data generated on, the channel frequencies to which the receive circuit part tunes. And, the receive circuit part also detects channel map information communicated by other mobile stations of the ad hoc network. A channel map information detector 42 is here representative of functionality of the channel characteristic supplier to detect the channel map information communicated to the mobile station by other mobile stations in the network. Values determined by the measurer 38 form local values of channel characteristic indicia, and the channel information detector forms global values of channel characteristic indicia. [0040] The channel characteristic supplier 36 here further includes a combiner 44 selectably operable to combine global and local values of the channel characteristic indicia theretogether. The combiner, in one implementation, operates to compare local values with corresponding global values. If the local value differs, greater than a selected amount, with corresponding global values, the local value is substituted for the global value and provided to the channel map. Otherwise, the values are combined together, such as to form a combined, average value. And, the average value is provided to the channel map to populate the appropriate listing to input with such value. [0041] Thereby, during operation of the apparatus 22, a channel map is created, and maintained, with indications of channel characteristic indicia of various channel frequencies. The values stored at the channel map are retrieved and used when the mobile station forms the DFS owner during a selected time period. Here, the DFS controller 46, coupled to the channel map, is representative of the functioning of the mobile station as a DFS owner. The DFS controller operates, when the mobile station forms the DFS owner, to select the channel frequency upon which to define communication channels for communication between the mobile stations of the ad hoc network. Selections made by the DFS controller are responsive to values of the channel characteristic indicia 32 stored at the channel map. And, the contents of the channel map are selectably provided to the transmit circuit part 16 for communication therefrom to other mobile stations of the ad hoc network. [0042]FIG. 2 illustrates the channel map 24 of the apparatus 22 shown in FIG. 1. The channel map shown in the figure is exemplary of a channel map created, and maintained, during operation of an embodiment of the present invention. In the exemplary implementation, the channel map provides a manner by which to rank candidate channel frequencies based upon channel qualities indicated by values of the channel characteristic indicia. Here, the listing includes a channel, identified by number, in the column 28 for each channel to which a mobile station is tunable. And, the column 32 includes corresponding channel characteristic indicia associated with such channels. When the channel characteristic indicia is based, in whole or in part, upon channel characteristic indicia measured elsewhere, the values stored at the channel map are referred to as being global characteristic values. In the exemplary implementation, each of the columns, columns 28 and 32, are of single-octet bit lengths. [0043] In exemplary operation of the apparatus 22 (shown in FIG. 1) together with the DFS controller 46 (also shown in FIG. 1) permits any mobile station of the ad hoc network to become a DFS owner and select the channel frequency at which communication channels are defined and upon which communications are effectuated between the mobile stations of the network. Channel frequencies that are occupied by a radar system or microwave system are removed from consideration for availability to be used by the ad hoc network. And, channel frequencies upon which unrecognized BSS (basic service set) communications, i.e., non-IEEE802.11-type communications, are also removed from consideration for selection. And, channel frequencies utilized by another 802.11 basic service set are additionally removed from consideration for usage. Amongst the remaining channel frequencies that might be available, selection is made of the channel frequencies that exhibit the best characteristics, e.g., the channel frequencies that exhibit the smallest levels of energy-based interference are selected. [0044] In assessing the quality of the channel frequency, verification of the following symptoms are verified in the exemplary implementation. First, determination is made whether repeating CCA patterns are evident upon the channel frequency. Such repeating patterns indicate radar transmission. And, determination is made whether valid preambles or signal fields are detected. If so, such detection indicates that other basic service sets are operating at the channel frequency. And, determination is made of energy-based levels. The greater the energy-based levels, the greater the severity of interference at the channel frequency. [0045] Thereby, each mobile station measures characteristics upon the channel frequencies to which the receive circuit part of the mobile station becomes tuned. [0046] Thereby, each mobile station measures channel frequencies to determine whether BSSs, valid preambles, and repeating CCA patterns are communicated upon the channel frequency to which the receive circuit part is tuned. And, additionally, energy levels of noise on the channel frequency are also measured. Responsive to such determinations and measurements, the channel frequency used by the ad hoc network to communicate thereon is selected. [0047] The duration of the scans is implementation-dependent. And, the channel maps of the respective mobile stations of the network are created and information thereof is exchanged between the mobile stations. [0048]FIG. 3 illustrates the format of an exemplary entry of channel characteristic indicia 32 forming part of the listing forming the channel map 24 shown in FIGS. 1 and 2. Here, the channel characteristic indicia is formed of a single octet in length formed of eight bits, designated 0 through 7 in the figure. The three most significant bits form the first sub-field 52, the next most-significant-bit 54 forms a BSS flag, the fifth most-significant-bit forms a foreign PLCP header flag 56, and the sixth most-significant-bit forms a periodicity flag 58. And, the following bit forms a local flag 62 while the least most-significant-bit forms another local flag 64. [0049] The energy sub-field is of values that define a measurement of the severity of energy-based interference measured during a measurement interval. The BSS flag is of a logical one or a logical zero value, dependent upon whether a BSS was detected at the channel frequency by either reception of a beacon, or a probe response frame, or, alternately, reception of a valid frame with either the toDS, or fromDS, flag set. Otherwise, the flag is set to a logical zero value. [0050] The foreign PLCP header flag is set if at least one PLCP preamble is detected at the channel frequency, but no valid SIGNAL field was subsequently detected. Otherwise, the foreign PLCP flag is set to a logical zero value. [0051] The periodicity flag is set if at least two consecutive CCA busy on/off patterns are periodic. A signal is classified as being periodic if at least two consecutive CCA busy duration and CCA busy intervals are identical. The margin of error for such measurements is no more than plus or minus one time slot. Otherwise, the flag value is set to a zero logical value. [0052] The unmeasured local flag 62 is set to a logical one value if the channel has not been measured. Otherwise, the flag is set to a logical zero value. And, the local flag 64 is set to a logical one value if the channel characteristics for the channel in the global channel map have been overridden by the local mobile station. Otherwise, the local flag value is set to a logical zero value. [0053] By using this exemplary encoding scheme, and by ignoring the local bits of each octet and thereafter sorting the channel quality octets in decreasing order of magnitude, the smallest-value octet indicates the channel frequency that exhibits the best communication conditions. The larger the magnitude of the octet, the less desirable that use of the channel frequency would be. [0054]FIG. 4 illustrates a method flow diagram, shown generally at 72, representative of an embodiment of the present invention. The method facilitates dynamic frequency selection of a channel frequency used by communication station of an ad hoc network of communication stations to communicate thereon. [0055] First, and as indicated by the block 74, at least a first channel map is formed at least at a first communication station of the ad hoc network. The first channel map stores channel characteristic indicia associated with a first channel frequency and at least a second channel frequency. Then, and as indicated by the block 76, the at least first channel map is populated with the channel characteristic indicia. And, as indicated by the block 78, values of the channel characteristic indicia are selectably used to select the channel frequency to be used by the communication stations to communicate thereon. [0056] Thereby, a manner is provided by which to select channel frequencies to be used to effectuate communication of data between communication stations of an ad hoc network. As a channel map is created and maintained at each mobile station, any of the mobile stations is able to form a DFS owner to select the channel frequency to be used to communicate thereon. [0057] The previous descriptions are of preferred examples for implementing the invention, and the scope of the invention should not necessarily be limited by this description. 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systemWO2008121161A2 *Nov 10, 2007Oct 9, 2008Raytheon CoMethod and system for using selected bearer channels* Cited by examinerClassifications U.S. Classification455/62, 455/446International ClassificationH04L12/56, H04W72/02, H04W84/18, H04W84/12Cooperative ClassificationH04W84/18, H04W72/02, H04W84/12European ClassificationH04W72/02Legal EventsDateCodeEventDescriptionMay 10, 2004ASAssignmentOwner name: NOKIA CORPORATION, FINLANDFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BLACK, SIMON A.;GRAY, STEVEN;VADDE, VENKATA;REEL/FRAME:015309/0460;SIGNING DATES FROM 20031216 TO 20040428Sep 20, 2007FPAYFee paymentYear of fee payment: 4Sep 21, 2011FPAYFee paymentYear of fee payment: 8May 9, 2015ASAssignmentOwner name: NOKIA TECHNOLOGIES OY, FINLANDFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NOKIA CORPORATION;REEL/FRAME:035602/0133Effective date: 20150116RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About 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