Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-04-10
2003-01-07
Le, Thanh Cong (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C455S446000, C455S452200
Reexamination Certificate
active
06505045
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF INVENTION
1. Field of Invention
The present invention is directed generally to wireless communication networks and, more particularly, to methods for configuring and assigning channels for wireless networks.
2. Description of the Background
Wireless local area networks (WLANs) were originally intended to allow wireless connections to a wired local area network (LAN), such as where premises wiring systems were nonexistent or inadequate to support conventional wired LANS. A block diagram of a typical WLAN
10
is illustrated in FIG.
1
. The WLAN
10
includes a mobile device
12
including a network adapter (NA)
14
, a number of access points (APs)
16
1-x
, and a wired LAN
18
. The APs
16
are typically radio base stations, each mounted in a separate fixed position and connected to the wired LAN
18
. The NA
14
communicates with the APs
16
by formatted wireless communication signals to provide an interface between the computing device
12
and the wired LAN
18
. Because network adapters
14
are now available in compact PC card form, WLANs are often used to service mobile computing devices, such as laptop computers and personal digital assistants (PDAs), thus providing mobile connectivity to data networks, such as the Internet or an intranet.
In designing a WLAN, care must be taken in locating the APs
16
to ensure adequate radio coverage throughout the service area of the WLAN
10
, while minimizing the costs associated with the installation of each AP
16
. The APs
16
must be configured to eliminate coverage gaps and to provide adequate coverage for areas of highly-concentrated wireless traffic. The APs
16
, however, must not be placed so closely that proximate APs
16
interfere with each other. Implementing a WLAN
10
inside a building complicates the design because the layout and construction of the building affect the wireless signal transmissions between the NAs
14
and the APs
16
. For example, while wood, plaster, and glass are not serious barriers to the WLAN radio transmissions, brick and concrete walls can attenuate the signals beyond an acceptable threshold. In addition, the greatest obstacle to the wireless transmissions between the NAs
14
and APs
16
commonly found in all building environments is metal. For example, the metal used in desks, filing cabinets, reinforced concrete, and elevator shafts can significantly attenuate the signals transmitted between the NAs
14
and the APs
16
, thus degrading network performance.
In addition, the communication schemes for transmitting signals between the NAs
14
of the mobile devices
12
and the APs
16
are typically contention-oriented, such as the IEEE 802.11 protocol, in order that all the mobile units in the environment may share the limited bandwidth resource. Such a contention-oriented protocol makes signal interference between the APs
16
undesirable because if one AP
16
can “hear” another, it will defer to the other just as it would defer to a mobile device transmitting within its coverage area. Thus, signal interference between APs
16
degrades performance. Similarly, if a mobile device
12
can be heard by more than one AP
16
, all the APs
16
in communication with the mobile device will defer.
Accordingly, there exists a need for a method for designing a wireless network to provide adequate coverage which minimizes cost and maximizes network performance. There also exists a need for a method for designing a wireless network to handle concentrated areas of traffic, yet which does not introduce interference between access points.
BRIEF SUMMARY OF;INVENTION
The present invention is directed to a method for establishing the location of access points for a network providing wireless communications coverage for an environment. According to one embodiment, the method includes determining a coverage radius of an access point at certain locations within the environment, determining an average coverage radius of the access points for the environment based on the determined coverage radii, and positioning the access points at locations within the environment to provide continuous wireless coverage for the environment based on the average coverage radius.
According to another embodiment, the present invention is directed to a method for assigning channels for access points for a network providing wireless communications coverage for an environment, including assigning a weight indicative of overlapping coverage for each pair of access points having overlapping coverage, and assigning a channel to each of the access points based on certain sums of the weights to minimize coverage overlap between access points operating at the same channel.
According to another embodiment, the present invention is directed to a method for configuring access points of a network providing wireless communications coverage for an environment, including determining a coverage radius of an access point at certain locations within the environment, determining an average coverage radius of the access points for the environment based on the determined coverage radii, positioning the access points at locations within the environment to provide continuous wireless coverage for the environment based on the average coverage radii, assigning a weight indicative of overlapping coverage for each pair of to access points having overlapping coverage, and assigning a channel to each of the access points based on certain sums of the weights to minimize coverage overlap between access points operating at the same channel.
The present invention represents an advantage over prior means- for configuring a wireless network in that it provides a method for configuring a wireless network to provide adequate coverage which minimizes cost and maximizes network performance. The present invention also represents an advantage in that it provides a method for configuring a wireless network to handle concentrated areas of traffic, yet minimizes interference between access points. These and other advantages of the present invention will be apparent from the detailed description hereinbelow.
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Scarati C. et.: “Radio coverage for cellular networks planning: A methodological approach”Proceedings of the International Conference on Communications (ICC). Geneva, May 23-26, 1993, New York, IEEE, US, vol. 3, May. 23, 1993 (1993-05-03), pp. 940-945, XP010137001 ISBN: 0-7803-0950-2.
Hills Alexander H.
Schlegel Jon P.
Carnegie Mellon University
Cong Le Thanh
Nguyen Thuan T.
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