Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1999-09-13
2004-04-06
Trost, William (Department: 2683)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S328000, C370S329000, C455S515000, C375S213000
Reexamination Certificate
active
06717926
ABSTRACT:
The present invention relates generally to communications in a multi-rate capable communication system, such as a WLAN (wireless local area network) operable generally pursuant to the IEEE 802.11 standard. More particularly, the present invention relates to an apparatus, and an associated method, by which to broadcast beacon signals to mobile stations operable in the radio communication system. Broadcast of the beacon signals according to an embodiment of the present invention facilitates efficient usage of bandwidth allocated for communication in a radio communication system, thereby to permit increased efficiency of communications in the radio communication system.
BACKGROUND OF THE INVENTION
A communication system provides for communication of information between a sending station and a receiving station by way of a communication channel. Information to be communicated by the sending station to the receiving station is converted into a form to permit its communication upon the communication channel. A wide variety of different types of communication systems have been developed and are regularly utilized to effectuate communication of information between sending and receiving stations.
New types of communication systems have been, and continue to be, developed and constructed as a result of advancements in communication technologies. A radio communication system is representative of a type of communication system which has benefited from advancements in communication technologies. Increased communication mobility is provided in a radio communication system as radio-links are utilized to form communication channels in a radio communication system in contrast to the conventional need to utilize wireline connections.
The communication capacity of a radio communication system, however, is sometimes constricted by bandwidth limitations. Only a limited amount of the electromagnetic spectrum is allocated to be used by a particular radio communication system. In other words, when the communication capacity is limited by the bandwidth allocated to the radio communication system, an increase in communication capacity requires more efficient utilization of the allocated bandwidth.
Digital communication techniques, for instance, can be used in a manner by which to increase the bandwidth efficiency of communications upon a communication channel in a communication system. Due to the particular need to efficiently utilize the bandwidth allocated in the radio communication system, the use of such digital techniques is particularly advantageously utilized in a radio communication system.
Digital communication techniques typically involve digitizing information, i.e., data, which is to be communicated into digital form to form digital bits. The digitized bits are sometimes then formatted into sequences which form packets of which one or more packets together form a frame. The terms packet and frame shall be, at times, used interchangeably herein to refer generally to digital data which is to be communicated. The sequences of the data forming the packets or frames can be communicated at discrete intervals and thereafter connected theretogether to recreate the informational content of the data.
Because packets or frames of data can be communicated at discrete intervals, a frequency band need not be dedicated solely for the communication of data generated by one sending station for transmission to one receiving station, as conventionally required in analog communications. Instead, the frequency band can be shared amongst a plurality of different sending and receiving station pairs. Because the same frequency band can be utilized to effectuate communications by the plurality of pairs of communication stations, improved communication capacity is possible.
Conventional LANs communicate packets of data to effectuate communications therein. Wireless networks, operable in manners analogous LANs, referred to as WLANs (wireless local area networks) have also been developed and are utilized to communicate data over a radio-link.
The standards of operation of an exemplary WLAN are set forth in the IEEE (Institute of Electrical and Electronic Engineers) 802.11 specification. The standard set forth in the specification provides for multi-user communications. Data is formatted into frames and sent over a radio-link.
As presently-promulgated, the IEEE 802.11 specification defines a contention period (CP) and contention free period (CFP). The contention period defines a random access period during which any sending station is permitted random access to communicate a frame of data. And, the contention free period defines a period in which data is permitted to be communicated responsive to a polling procedure in which allocations are made as to when a sending station is permitted to communicate a frame of data.
The specification, as presently-promulgated, requires that the contention free period be initiated by the broadcast of a beacon signal. And, subsequent beacon signals are broadcast at a beacon interval. A beacon frame is sent during the contention period (CP) as well as the contention free period (CFP). The beacon signal is utilized, amongst other things, for purposes of synchronization of mobile stations operable in the system.
As presently-promulgated, the specification requires that the beacon signals be transmitted at a lowest mandatory rate to insure that all mobile stations operable in the system are able to detect and utilize the informational content of the beacon signal. This existing requirement to broadcast always the beacon signal at the lowest mandatory rate can be an inefficient use of the limited bandwidth.
For instance, if the lowest mandatory rate is a bit rate of 1 Mb/s and in an example situation having eleven mobile stations in which ten mobile stations are operable at a much higher bit rate, e.g., 11 Mb/s, and only one mobile station is operable at the lower bit rate of 1 Mb/s, all of the beacon signals are broadcast at the 1 Mb/s data rate. As the majority of mobile stations are operable at a much higher data rate, the existing requirement of transmitting each of the beacon signals at the lower data rate inefficiently utilizes the limited time available within a contention free period within which to communicate information.
If a manner could be provided by which to broadcast beacon signals in a more efficient manner, improved communication efficiency would result.
It is in light of this background information related to multi-rate, multi-user communication systems that the significant improvements of the present invention have evolved.
SUMMARY OF THE INVENTION
The present invention, accordingly, advantageously provides apparatus and an associated method, by which to transmit beacon signals broadcast to mobile stations operable in a radio communication system such as a (wireless local area network) operable pursuant to an IEEE 802.11 standard.
Operation of an embodiment of the present invention permits increased communication efficiency by selectably broadcasting beacon signals at higher bit rates than a minimum allowable bit rate.
In one aspect of the present invention, a first beacon signal is broadcast to initiate a contention free period (CFP). The first beacon signal is broadcast at a lowest allowable rate to ensure that every mobile station operable in the communication system is able to detect the content of the beacon signal. Subsequent beacon signals are generated at a beacon interval, and subsequent beacon signals are generated at data rates corresponding to the data rates at which subsequent communications are to be effectuated. The communications are sorted such that communications to be effectuated at higher data rates are effectuated first. Thereby, the beacon signal generated immediately subsequent to the first beacon signal is generated at a data rate corresponding to the highest data rate at which communications shall be effectuated during the contention free period. Thereafter, a subsequent beacon signal is generated at a next-to-highest data rate at which communic
Deboille Mickael
Tobita Hiroshi
Le Danh
Nokia Corporation
Trost William
LandOfFree
Apparatus and associated method, by which to transmit beacon... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and associated method, by which to transmit beacon..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and associated method, by which to transmit beacon... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3192710