Telecommunications – Transmitter and receiver at separate stations – Optimum frequency selection
Reexamination Certificate
2002-03-14
2004-05-18
Tran, Sinh (Department: 2681)
Telecommunications
Transmitter and receiver at separate stations
Optimum frequency selection
C455S447000, C455S450000, C455S451000, C455S452100, C455S454000, C455S423000, C455S424000, C370S338000, C370S329000, C370S330000
Reexamination Certificate
active
06738599
ABSTRACT:
The present invention relates generally to communications in a communication system, such as a WLAN (wireless local area network) operable pursuant to an IEEE 802.11 standard in an unregulated spectrum band that utilizes a dynamic frequency selection (DFS) scheme. More particularly, the present invention relates to an assembly, and an associated method, by which to facilitate dynamic channel frequency selection pursuant to the dynamic frequency selection in an infrastructure-free, ad hoc network of communication stations in which any of the communication stations of the ad hoc network is able to select the channel frequency to be used to effectuate communications. Channel maps are maintained at each of the communication stations of the network. The channel maps contain channel characteristic indicia associated with conditions upon channels defined about various frequencies. When a communication station is designated as a DFS owner, i.e., is placed in charge of the channel frequency selection, the indicia stored at the channel map thereof is used in the channel frequency selection.
BACKGROUND OF THE INVENTION
Many varied advancements in technology have permitted the introduction, and popularization, of new types of communication systems as well as improvements to existing types of communication systems. Generally, in such new, as well as such improved, communication systems, the rates at which the data is transmitted, as well as the corresponding amount of data permitted to be communicated, has increased.
New types of, as well as improvements to existing, radio communication systems are exemplary of communication systems made possible as a result of advancements in communication technologies. Communication channels of a radio communication system are formed upon radio links, thereby obviating the need for conventional wireline connections to be formed between communication stations operable therein. Some radio communication systems, for instance, take advantage of the lack of wireline connections to form mobile communication systems in which one or more of the communication stations operable therein is capable of movement, not affixed in fixed positions.
Communication capacity of a communication system is sometimes limited due to bandwidth limitations. That is to say, the bandwidth capacity of the communication channel, or channels, available to the communication system to communicate data is sometimes limited. And, the limited capacity of the communication channel, or channels, limits the increase of the communication capacity of the communication system.
Communication channel bandwidth limitations are sometimes particularly acute in a radio communication system. Generally, a limited portion of the electromagnetic spectrum is allocated to a radio communication system upon which to define communication channels to communicate thereon. The communication capacity of the communication system is, many times, limited by such allocation. And, sometimes, the only manner by which to increase the communication capacity of the radio communication system is through more efficient use of the allocated spectrum.
The use of digital communication techniques permits the bandwidth efficiency of communications in the communication system to be increased. Use of such digital communication techniques is of particular advantage for use in a radio communication system due to the particular need efficiently to utilize the spectrum allocated thereto upon which to define communication channels thereon. Information that is to be communicated using digital communication techniques is digitized. The digitized information is formatted, such as into data packets, and the formatted data is communicated between communication stations. Individual ones, or groups, of the data packets can be communicated at discrete intervals and, once communicated, concatenated together to recreate the informational content of the digitized information.
As the data packets can be communicated at discrete intervals, a communication channel need not be dedicated for a single communication session between a pair of communication stations. Instead, the channel can be shared amongst a plurality of communication station-pairs to effectuate a plurality of separate communication sessions. Multiple increases in the communication capacity of a communication system are sometimes, thereby, provided.
Conventional LANs (local area networks) typically utilize a data packet protocol by which to communicate between nodes, i.e., communication stations, of the LANs. Wireless networks, operable in manners analogous to operation of conventional wired LANs, have also been developed and communicate data packets by way of communication channels defined upon a radio link, thereby to effectuate communications between communication stations.
A standard protocol promulgated by the IEEE (Institute of Electrical and Electronic Engineers), the 802.11 standard, sets forth the operational parameters of a wireless LAN.
Proposals have been set forth to utilize an unlicensed frequency band located at 5 GHz for WLANs. A variant of the 802.11 standard has also been promulgated for such WLANs.
Due to the unlicensed nature proposed of this 5 GHz frequency band, more than one WLAN might be installed over a common geographical area. And, other types of radio communication systems might also be installed over the same geographical area to operate, or to have frequency harmonics that have significant components at the 5 GHz band. Therefore, while the unstructured nature of an unlicensed band provides significant design freedom in the design of a communication system to be operable therein, the same unlicensed nature of the band also increases the possibility that signals generated during operation of one of the communication systems within the frequency band might generate signals that interfere with operation of another communication system operable at the same frequency band.
Use of frequency levels within the allocated band that exhibit lowest amounts of interference would best ensure that communication qualities of communications would not be degraded. Appropriate selection of the frequency levels is needed. And, subsequent reselection of the frequency levels is needed as communication conditions at the selected frequency level change.
The 802.11 standard sets forth system requirements for ad hoc networks, i.e., infrastructure-free networks of mobile stations (STAs). So, not only is there a need for dynamic frequency selection of the channel frequencies at which communication stations communicate data packets, but, also, the selection scheme must not be predicated upon use of a fixed control system.
A manner by which to provide for dynamic frequency selection in an ad hoc network of mobile stations is, therefore, needed.
It is in light of this background information related to communications in a radio communication system that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides apparatus, and an associated method, for facilitating communications in a communication system that utilizes a dynamic frequency selection scheme. In a dynamic frequency selection scheme, the channel frequencies used to effectuate communication of data between communication stations operable therein are not set, but rather, are dynamically selected. A radio communication system to be operable pursuant to an IEEE 802.11 standard in the 5 GHz frequency band is exemplary of a communication system that utilizes a dynamic frequency selection scheme.
Through operation of an embodiment of the present invention, dynamic channel frequency selection pursuant to the dynamic frequency selection scheme is facilitated in an infrastructure-free, ad hoc network of communication stations. Any of the communication stations of the ad hoc network is able to select the channel frequencies to be used to effectuate communications.
In one aspect of the present invention, channel maps are maintained at each of the communication stations of t
Black Simon A.
Gray Steven
Vadde Venkatesh
Fraccaroli Federico
Nguyen David
Nokia Corporation
Tran Sinh
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