Patent Publication Number: US-6711148-B1

Title: Method for configuring a wireless network

Description:
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 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 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. 
    
    
     DESCRIPTION OF THE FIGURES 
     For the present invention to be clearly understood and readily practiced, the present invention will be described in conjunction with the following figures, wherein: 
     FIG. 1 is a block diagram of a wireless local area network (WLAN); 
     FIG. 2 is a flowchart illustrating a method for configuring the access points of the WLAN of FIG. 1 according to one embodiment of the present invention; 
     FIG. 3 is a graphical representation of the coverage area of an access point of the WLAN of FIG. 1; 
     FIG. 4 is a graphical representation for establishing the location of the access points of the WLAN of FIG. 1 for a single floor environment according to one embodiment of the present invention where the width of the floor is no greater than the average coverage radius of the access points times {square root over (2)}; 
     FIGS. 5 and 6 are graphical representations for establishing the location of the access points of the WLAN of FIG. 1 for a multi-floor environment according to one embodiment of the present invention where the width of the floors is no greater than the average coverage radius of the access points times {square root over (2)}; 
     FIGS. 7-10 are graphical representations for establishing the location of the access points of the WLAN of FIG. 1 for a single floor environment according to one embodiment of the present invention where the width of the floor is greater than the average coverage radius of the access points times {square root over (2)}; 
     FIGS. 11-15 are graphical representations for establishing the location of the access points of the WLAN of FIG. 1 for a multi-floor environment according to one embodiment of the present invention where the width of the floors are greater than the average coverage radius of the access points times {square root over (2)}; 
     FIG. 16 is a flowchart illustrating a method for assigning channels for the access points of the WLAN of FIG. 1 according to one embodiment of the present invention; 
     FIG. 17 is a graphical representation of the method of FIG. 16 for assigning channels for the access points; and 
     FIG. 18 is a flowchart illustrating a method for assigning channels for the access points of the WLAN of FIG. 1 according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to one embodiment, the present invention is directed to a method for configuring the access points of a wireless network, such as the WLAN  10  illustrated in FIG. 1, for a particular environment such as, for example, an indoor environment. The WLAN  10  may be, for example, an IEEE 802 compliant network. The wired LAN  18  may be in communication with the APs  16  through a router, such as a 7500 series router available from Cisco Systems, Inc., a number of switches, such as Catalyst® 5000 and 1924 series switches, and a hub, such as a Bay Networks 2813 hub. These components may communicate, for example, via 100BASE-T, 10BASE-T, 100BASE-FL, and 10BASE-FL communication links. 
     The computing device  12  may be, for example, a laptop computer or a digital personal assistant (PDA), and may communicate with the APs  16 , and therefore the wired LAN  18 , via the network adapter (NA)  14 . The NA  14  may include a transmitter, a receiver, an antenna, and hardware to provide a data interface between the computing device  12  and the APs  16 . According to one embodiment, the NA  14  is a compact PC card installed in the computing device  12 . The WLAN  10  may operate, for example, in the unlicensed ISM bands at 915 MHz, 2.4 GHz, and 5.7 GHz. Spread spectrum techniques such as, for example, direct sequence and frequency hopping, may be used at these frequencies. 
     The APs  16  may be, for example, WavePoint™ access points, available from Lucent Technologies, Inc. Each AP  16  may be a wireless base station that is mounted in a fixed position. Each AP  16  allows network adapter-equipped computing devices  12  to communicate with the wired LAN  18 . The APs  16  may include a transmitter, receiver, an antenna, and a bridge. The bridge routes packets of data to and from the wired LAN  18  as appropriate. The APs  16  may be configured to ensure adequate wireless signal coverage throughout the service area of the WLAN  10 . APs  16  typically have a range of up to 250 meters in an open environment. However, in an indoor environment, the range may be reduced to 30-60 meters because of building obstacles. For an embodiment in which some of the APs  16  are mounted within a building, this requires that the APs  16  be configured within the building to provide adequate coverage despite the many obstacles to wireless signal transmission presented by the building. 
     FIG. 2 is a flow chart illustrating the method for configuring the APs  16  of a wireless network according to one embodiment of the present invention. The method will be described with reference to the WLAN  10  illustrated in FIG. 1, although benefits of the present invention may be realized in using the method of the present invention to configure other types of wireless networks. The method begins at block  20 , where a set of signal strength measurements within the environment is generated. The set may be generated by placing an AP  16  at various locations within the environment and measuring its radiation pattern, accounting for the signal propagation obstacles in the environment The signal strength measurements may be made in all areas of the environment requiring network coverage, with particular attention paid to the construction of the environment, so that the characteristics within each part of the environment of a particular construction type are understood. Based on the set of signal strength measurements, the environment may be conceptually divided into regions which are relatively isolated from each other, from a wireless signal propagation perspective. Each of these regions may be treated independently in the subsequent steps of the illustrated method. 
     At block  22 , the coverage radius of the APs  16  at particular locations within the environment are determined. The coverage radius may be the point from the AP  16  at which the signal strength attenuates below some threshold level, and may be determined based on the generated set of signal strength measurements. According to one embodiment of the present invention in which the wireless network is to service a one-story building (or a multi-story building only requiring wireless connectivity coverage for only a single floor or where certain floors of a multi-floor building are to be treated separately), the coverage radii of the APs  16  on the floor on which they are located are determined. For an embodiment of the present invention in which the wireless network is to service a multi-story building, in addition to determining the coverage radii of the APs  16  on which they are located, the coverage radii on the floors immediately above and immediately below the floor on which the APs  16  are located are determined. 
     At block  24 , the average coverage radii of the APs  16  within the environment are calculated. The average coverage radii may be determined based on the prior measurements. For an embodiment in which the environment is a one-story building (or a multi-floor building requiring wireless coverage for only a single floor or for a multi-floor building in which all or some of the floors are treated separately), the average coverage radii for the floor on which the APs  16  are located are determined. For an embodiment in which the environment includes two or more contiguous floors of a building, the average coverage radii for the floor on which the APs  16  are located are determined as well as the average coverage radii on the immediately adjacent floors. As used herein, R denotes the average coverage radius of an AP  16  on the floor on which the AP  16  is located, and R′ denotes the average coverage radius of the AP  16  on an immediately adjacent floor. Typically R′ will be less than R because of the attenuation of radio signals through floors of the building. Based on R and R′, the coverage radius of a particular AP  16  located on a particular floor may be conceptualized as three coaxial cylinders  40 ,  42 ,  44 , as illustrated in FIG.  3 . The cylinder  40  represents the coverage area for the AP  16  for the floor on which it is located. The cylinders  42  and  44  represent the coverage area of the AP  16  on the floors immediately above and below the floor on which the AP  16  is located, respectively. The height of each cylinder  40 ,  42 ,  44 , may be conceptualized as the height of the floors of the building. 
     At block  26 , the locations of the APs  16  are established according to an initial design. According to one embodiment, the location of the APs  16  are established to provide adequate signal coverage in all areas of the environment requiring wireless access. For such an embodiment, this may be conceptualized as arranging the coverage area cylinders  40 ,  42 ,  44  for each AP  16  such that at least a portion of one cylinder  40 ,  42 ,  44  extends into all areas of the environment. The coverage area cylinders  40 ,  42 ,  44  for separate APs  16  may overlap. Such overlapping, however, may be minimized to reduce the potential interference between the separate APs  16 . 
     The initial design may be generated according to calculated parameters. The first parameter, denoted D, represents the distance between the APs  16  on the same floor of the building, and may be calculated according to the following equation:                D   =     R          2        [     1   +       1   -       [     1   -       (       R   ′          /        R     )     2       ]     2           ]             ,       where                 0     &lt;       R   ′          /        R     &lt;   1.             (   1   )                         
     The second parameter, denoted D′, represents the spacing between the APs  16  on adjacent floors of the building, and may be calculated according to: 
     
       
           D′=D /{square root over (2)}= D /{square root over (2)}/2.  (2) 
       
     
     Note that for an embodiment of the present invention in which the wireless network is to be implemented in a one-story building (or to only provide wireless access on one floor of a multi-floor building or where certain floors of a multi-floor building are to be treated separately), R′=0 and D=R{square root over (2)}. 
     Examples of establishing the location of the APs  16  for different indoor environments are described hereinbelow with reference to FIGS. 4-15. 
     Having established the location of the APs  16  according to an initial design, the process continues to block  28 , where the coverage radius for each of the APs  16  of the network  10  is measured. This may be accomplished, for example, by measuring the signal strength for each of the APs  16 . 
     From block  28 , the process advances to block  30  where the channel for each of the APs  16  is determined. The channels may be assigned based on the degree of overlapping coverage between APs  16 , which may be determined from the measured coverage radii of the APs  16  (block  28  ). The channels may be, for example, frequency allocations for networks employing frequency division multiple access (FDMA), or time slot allocations for networks employing time division multiple access (TDMA). According to one embodiment, the channels may be assigned to the APs  16  to minimize the overlapping coverage areas for co-channel APs  16 . Minimization of overlapping co-channel APs  16  is often desirable for wireless networks to reduce performance degradation. Methods for assigning channels for the APs  16  will be described hereinbelow with respect to FIGS. 16-18. 
     At block  32 , it is then determined whether the configuration of APs  16  is acceptable based on the measurements. The configuration may not be acceptable if, for example, coverage gaps and/or excessive co-channel coverage overlaps exist. If the configuration is not acceptable, the process flow continues to block  34  where the APs  16  are reconfigured to realize an acceptable configuration. That is, the APs  16  may, for example, be reconfigured to eliminate coverage gaps and/or reduce co-channel coverage overlaps. The process flow then returns to block  28 , where the coverage radius for each of the APs  16  is measured. 
     Conversely, if at block  32  it is determined that the design is acceptable, the process flow advances to block  36 , where the final configuration and the measured coverage radius for each of the APs  16  may be documented. 
     Establishing the locations of the APs  16  for the wireless network is now further discussed with reference to the following examples. 
     EXAMPLE 1 
     FIG. 4 illustrates one embodiment of the present invention, in which a wireless network is to be implemented for a single floor of a building  50 , in which the width of the floor is no greater than R{square root over (2)}. The described method for establishing the location of the APs  16  may be followed, for example, where the building  50  has one story, where only one floor of a multi-floor building  50  require wireless coverage, or where certain floors of a multi-floor building are to be treated separately. 
     According to one embodiment, a first AP  16   1  may be positioned at the intersection of a line extending at an angle relative to a corner A of the building  50 , such as at a 45° degree angle, and a line B-B′ bisecting the building  50  lengthwise. The location of the AP  16   1  may be adjusted such that the coverage area of the AP  16   1  extends to two corners (A, A′) of the building  50 . 
     Subsequently, a second AP  16   2  may be placed a distance D along bisector B-B′ from the first AP  16   1 , where D=R{square root over (2)}. The location of the second AP  162  may be adjusted, and the coverage radius of the AP  16   2  re-measured, such that the coverage area of the second AP  16   2  at the edges of the building  50  coincides with the coverage area of the first AP  16   1 . The process may be repeated until each area of the floor of the building  50  is within the coverage area of at least one AP  16 , as illustrated in FIG.  4 . 
     EXAMPLE 2 
     FIGS. 5 and 6 illustrate another embodiment of the present invention, in which a wireless network is to be implemented to provide wireless coverage for a number of contiguous floors of a multi-floor building  50  where the width of the floors is no greater than R{square root over (2)}. According to one embodiment, as illustrated in FIG. 5, a first AP  16 , may be placed on a second floor of the contiguous floors of the building  50  at the intersection of an edge of the building  50  and the line B-B′ bisecting the building  50  lengthwise. The position of the first AP  16   1  may be adjusted such as, for example, by moving the first AP  16   1  along the bisecting line B-B′ such that the coverage area of the first AP  16   1  on a first floor of the building  50  immediately below the second floor, having an approximate coverage radius of R′, extends to two corners (A, A′) of the building on the first floor. It should be noted that the reference here and elsewhere to “first” and “second” floors does not necessarily refer to the first and second floor of a building as those terms are conventionally used, but instead refer to any two floors of a multi-floor building. 
     If the width of the building  50  is greater than 2R′, then each floor may be treated independently, such as according to the embodiment discussed hereinbefore with respect to Example  1 . For the illustrated embodiment, the coverage areas of the APs  16  for the second floor of the building are shown in solid lines, and the coverage areas of the APs  16  on the first floor of the building are shown in dashed lines, regardless of on what floor the APs  16  are located. 
     As illustrated in FIG. 6, a second AP  16   2  may be placed a distance D′ from the first AP  16   1  on the first floor, where D′ is determined according to equation (2). The location of the second AP  16   2  on the first floor may be adjusted such that the edges of the coverage areas of the second AP  16   2  coincide with the edges of the first AP  16   1  on both the first and second floors. 
     A third AP  16   3  may be placed at a distance D′from the second AP  16   1  on the second floor. The location of the third AP  16   3  on the second floor may be adjusted such that the edges of the coverage areas of the third AP  16   3  coincide with the edges of the second AP  16   2  on both the first and second floors. Additional APs  16  may placed alternately on the first and second floors in the described fashion until complete wireless coverage is provided on the first and second floors. 
     To provide wireless coverage for additional contiguous floors of the building  50  having a width no greater than R{square root over (2)}, a number of APs  16  may be placed on the third floor of the building directly above the APs  16  located on the first floor (assuming the second floor is between the first and third floor). The locations of the APs  16  on the third floor may be adjusted such that the APs  16  on the second and third floors provide complete wireless coverage for the third floor. In addition, a number of APs  16  may be placed on the fourth floor of the building directly above the APs  16  located on the second floor (assuming the third floor is between the second and fourth floors). The locations of the APs  16  on the fourth floor may be adjusted such that the APs  16  on the third and fourth floors provide complete wireless coverage on the fourth floor. Additional APs  16  may be placed on additional contiguous floors of the building  50  and their locations adjusted according to the above-described method to provide wireless coverage on the additional floors of the building. 
     EXAMPLE 3 
     FIGS. 7-10 illustrate another embodiment of the present invention, in which a wireless network is implemented on one floor of a building  50  whose width is greater than R{square root over (2)}. The described method for establishing the location of the APs  16  may be followed, for example, where the building  50  has one story, where only one floor of a multi-floor building  50  requires wireless coverage, or where certain floors of a multi-floor building are to be treated separately. 
     According to one embodiment, as illustrated in FIG. 7, a first AP  16 , may be located at the distance R from a corner A of the building  50  along a line extending from the corner, such as on a 45° angle. The location of the first AP  16   1  may be adjusted such that its coverage area extends to the corner of the building  50 . According to one embodiment, the position of the first AP  16   1  may be adjusted by moving the first AP  16   1  along the line extending 45° from the corner A of the building  50 . 
     As illustrated in FIG. 8, the process of locating the first AP  16 , may be repeated such that additional APs  16  are located along one edge of the building  50 . For example, the position of a second AP  16   2  may be determined by ascertaining the point at which the coverage area of the first AP  16   1  intersects the edge of the building  50  and placing the second AP  16   2  at the distance R from that point along a 45° degree angle extending from the point. The position of the second AP  16   2  may be adjusted such that the coverage area of the second AP  16   2  extends to the point where the coverage of the first AP  16   1  intersects the edge of the building  50 . In a similar fashion, additional APs  16  may be located along one edge of the building  50 , as illustrated in FIG. 8, and around the other edges of the building  50 , as illustrated in FIG.  9 . 
     According to one embodiment, additional APs  16  may be located in the interior of the building  50 , for example, as illustrated in FIG. 10, by positioning the additional APs  16  along a line extending parallel from an edge of the-building  50  at a distance D from an adjacent AP  16 . The location of the APs  16  may be adjusted by measuring their respective coverage radii and readjusting their position to assure that coverage is continuous throughout the floor of the building  50 . 
     EXAMPLE 4 
     FIGS.  11 — 15  illustrate another embodiment of the present invention, in which a wireless network is to be implemented on first and second contiguous floors of a building  50  where the width of the floors is greater than R{square root over (2)}. As discussed hereinbefore, the reference to “first” and “second” floor does not necessarily refer to the first and second floors of the building, but rather any two floors of a multi-floor building. 
     According to one embodiment, as illustrated in FIG. 11, a first AP  16   1  may be located at a corner A of the building  50  on the second floor. A second AP  16   2  may be located on the first floor at the distance D′ from the corner of the building  50  along a line extending from the corner A, such as on a 45° angle. The locations of the first and second APs  16   1,2  may be adjusted to assure that the edges of the coverage areas on the first floor intersect at two sides of the building  50 . In the illustrated embodiment, the coverage areas of the APs  16  for the second floor of the building  50  are shown in solid lines, and the-coverage areas of the APs  16  for the first floor of the building  50  are shown in dashed lines, regardless of the floor on which the APs  16  are located. 
     As illustrated in FIG. 12, a third AP  16   3  may located on a side the second floor of the building  50  along a line extending, for example, 45° from the location of the second AP  16   2 . The location of the third AP  16   3  may be adjusted to assure that the edges of the coverage areas of the second and third APs  16   2,3  intersect at the side of the building  50  on the first floor and to assure that the first, second, and third APs  16   1-3  provide continuous coverage on the second floor. A fourth AP  16   4  may be located on the first floor of the building  50  at the distance D′ from the third AP  16   3  along a line extending from the third AP  16   3 , such as on a 45° angle. The location of the fourth AP  16   4  may be adjusted to assure that the APs  16   1-4  provide continuous wireless coverage on the first and second floors. 
     The process of locating the APs  16  on alternating floors of the building  50  may be repeated until coverage is provided along the sides of the building  50  extending from the corner A where the first AP  16   1  was positioned, as illustrated in FIG.  13 . Additional APs  16  may then be positioned on alternating floors of the building  50  in a similar fashion along the remaining sides of the building  50 , as illustrated in FIG.  14 . 
     According to one embodiment, additional APs  16  may be placed to provide coverage for the interior of the building  50  along parallel lines extending perpendicularly from a side of the building  50  on the same floor and at a distance D from an adjacent AP  16 , as illustrated in FIG.  15 . The coverage radii of the APs  16  may be measured and the their respective positions adjusted as necessary to assure that continuous coverage is provided on both the first and second floors. 
     To provide-wireless coverage on additional contiguous floors of the building  50 , a number of APs  16  may be located on a third floor in positions directly above the locations of the APs  16  on the first floor of the building  50  (assuming the second floor is between the first and third floors). The locations of the APs  16  on the third floor may be adjusted such that the APs  16  on the second and third floors provide complete wireless coverage for the third floor. In addition, a number of APs  16  may be placed on the fourth floor of the building  50  directly above the APs  16  located on the second floor (assuming the third floor is between the second and fourth floors). The locations of the APs  16  on the fourth floor may be adjusted such that the APs  16  located on the third and fourth floors provide complete wireless coverage on the fourth floor. Additional APs  16  may be placed on additional floors of the building  50  and their respective positions adjusted according to the above-described process to provide wireless coverage on the additional floors of the building  50 . 
     As discussed hereinbefore, where-regions of the environment, such as certain floors of the building  50 , may be conceptually divided into regions which are relatively isolated from each other, from a signal propagation perspective, these regions may be treated independently in establishing the locations of the APs  16  for the wireless network. In addition, where certain regions of the environment are expected to have increased wireless traffic capacity, such as for classrooms and lecture halls, translating into effectively smaller coverage radii for the APs  16 , these regions may be treated independently in establishing the locations of the APs  16 . 
     The process of establishing the locations of the APs  16  for a wireless network, such as described hereinbefore, may be facilitated, for example, by software code to be executed by a processor of a computing device, such as a workstation or a personal computer. The software code may use any suitable computer language such as, for example, C or C++ and may use, for example, conventional or object-oriented techniques. The software code may be stored as a series of instructions or commands on a computer readable medium, such as a random access memory (RAM), a read only memory (ROM), a magnetic medium such as a hard-drive or a floppy disk, or an optical medium such as a CD-ROM. 
     For example, the software code may include instructions, which when executed by a processor, cause the processor to calculate the parameters D and D′ based on the measured values for R and R′, and generate text and/or graphical instructions for implementing the wireless network based on the parameters of the particular environment such as, for example, the width of the floor(s) and the number of contiguous floors for which continuous wireless coverage is sought. 
     FIG. 16 is a block diagram of the process flow for assigning channels for the APs  16  according to one embodiment of the present invention. It should be recognized that the process is applicable for both indoor and outdoor wireless environments. 
     The process begins at block  60  where a weight is assigned to each respective pair of APs  16  having overlapping coverage areas. The assigned weight may be, for example, indicative of the degree of coverage overlap between the respective pairs of APs  16 . For example, for an indoor environment, the weight may be indicative of the number of square feet of floor area of overlapping coverage or, for an outdoor environment, the weight may be indicative of the number of square miles of overlapping coverage. According to one embodiment, the weight may be determined based on the strength of a signal received by one AP  16  from another AP  16 , because the signal strength is indicative of the degree of overlapping coverage between the two APs  16 . 
     From block  60 , the process advances to block  62  where the sum of weights for each AP  16  is determined. That is, for a particular AP  16 , the weights for all of the other APs  16  having overlapping coverage with that particular AP  16  are summed. At block  64 , a channel is assigned to the AP  16  having the greatest sum of weights. Where two or more APs  16  have the same greatest sum, a channel may be assigned to just one. 
     From block  64 , the process advances to block  66  where, of the APs  16  not having channels assigned thereto, the AP  16  having the greatest sum of weights and which has overlapping coverage with an AP  16  having an assigned channel is selected. Where two or more such APs  16  have the same greatest sum, just one of the APs  16  may be selected. 
     At decision block  68 , it is then determined whether a channel is available for the selected AP  16  which provides no co-channel overlapping coverage with another AP  16 . If there is such a channel, the process advances to block  70 , where that channel is assigned to the selected AP  16 . Conversely, if there is not such a channel, the process advance to block  72 , where the selected AP  16  is assigned a channel that minimizes the sum of weights for co-channel APs  16 . 
     From both blocks  70  and  72  the process advances to block  74 , where it is determined whether there remains an AP  16  for which a channel has not been assigned. If there is a remaining unassigned AP  16 , the process returns to block  66 . Conversely, if there are no remaining unassigned APs  16 , the process continues to block  76 , where the process is terminated because all of the APs  16  have been assigned a channel. 
     FIG. 17 is a graphical representation for assigning channels for the APs  16  according the process described hereinbefore with respect to FIG.  16 . For purposes of the illustrated example, it is assumed that three different channels are available for the wireless network, denoted as channels A, B, and C, although for other wireless network embodiments, a different number of channels may be employed. 
     In the graphical representation, the APs  16  are represented by nodes N 1-8 . For each pair of APs  16  having overlapping coverage, a line is provided between their corresponding nodes N 1-8 , with an associated number representing the degree of the overlapping coverage. For example, as shown in FIG. 17, the overlapping coverage between nodes N 1  and N 2  has been assigned a weight of 10, and the overlapping coverage between nodes N 1  and N 3  has been assigned a weight of 11. In addition, as shown in FIG. 17, there is no overlapping coverage, for example, between nodes N 1  and N 4 . Accordingly, the “sum of weights” for a particular AP  16  corresponds to the sum of the weights assigned to each of the lines connected to the node representative of that particular AP  16 . Note that the locations of the nodes N 1-8  in the graphical representation illustrated in FIG. 17 need not be representative of the configuration of the APs  16 . Rather, the assigned weights of overlapping coverage between the nodes is based on the coverage area measurements of the APs  16  for a particular configuration. 
     Reviewing the graphical representation of FIG. 17, it can been seen that the node having the greatest sum of weights is node N 3 , with a sum of fifty-nine. Accordingly, the AP  16  corresponding to node N 3  is assigned a channel, which for the illustrated example is channel A. Of the unassigned nodes, the node having the greatest sum of weights and which has overlapping coverage with node N 3  is node N 2 , with a sum of fifty-one. Thus, node N 2  may be assigned either channel B or channel C to avoid co-channel overlap with node N 3 . For purposes of the illustrated example, node N 3  is assigned the channel B. 
     Next, of the unassigned nodes, the node having the greatest sum of weights and which has overlapping coverage with an assigned node (i.e., either node N 2  or N 3 ) is node N 4 , with a sum of forty-five. To avoid co-channel overlapping coverage with both nodes N 2  and N 3 , node N 4  may be assigned the channel C. Having assigned channels for nodes N 2-4 , the unassigned node having the greatest sum of weights and having overlapping coverage with an assigned node (i.e., either of nodes N 2-4 ) is node N 5 , with a sum of thirty-five. As can been seen, there is no channel available for node N 5  which provides no co-channel overlapping coverage with an already-assigned node. Accordingly, node N 5  is assigned a channel which minimizes co-channel overlapping coverage. In the illustrated example, node N 5  is assigned the channel B because node N 5  has the least overlapping coverage with node N 2 . 
     This process may be repeated in a similar fashion until all of the nodes (and hence corresponding APs  16  ) have been assigned a channel. Note that node N 8 , which for the illustrated example has overlapping coverage with only node N 7 , may be assigned either channel A or C to avoid overlapping coverage with node N 7 . 
     FIG. 18 is a block diagram of a process for assigning channels for the APs  16  of a wireless network according to another embodiment of the present invention. The process begins at block  80 , where all the possible combinations of channel assignments for the APs  16  are generated using all the available channels. The process flow then advances to block  82 , where for each of the generated combinations, the sum of the weights for co-channel APs  16  having overlapping coverage is calculated. The process flow then continues to block  84 , where the APs  16  are assigned channels according to the channel assignment combination which minimizes the sum of the weights of co-channel APs  16  having overlapping coverage. 
     The processes of FIGS. 16 and 18 for assigning channels for the APs  16  of the wireless network  10  may be facilitated, for example, by software code to be executed by a processor of a computing device, such as a workstation or a personal computer. The software code may use any suitable computer language such as, for example, C or C++ and may use, for example, conventional or object-oriented techniques. The software code may be stored as a series of instructions or commands on a computer readable medium, such as a random access memory (RAM), a read only memory (ROM), a magnetic medium such as a hard-drive or a floppy disk, or an optical medium such as a CD-ROM. 
     For example, the software code may include instructions, which when executed by a processor, cause the processor to implement the process of assigning channels according to the process illustrated in FIG.  16 . For example, according to such an embodiment, the software code may include instructions, which when executed by the processor, cause the processor to determine the sum of the weights of the overlapping coverage for each of the APs  16  of the networks  10  based on the measured coverage areas of the APs  16  and to assign channels to the APs  16  to minimize co-channel overlapping coverage. 
     In addition, the software code may include instructions, which when executed by a processor, cause the processor to implement the process of assigning channels according to the process illustrated in FIG.  18 . For example, according to such an embodiment, the software code may include instructions, which when executed by the processor, cause the processor to generate all the possible channel assignment combinations for the APs  16  using the available channels, calculate the sum of the weights of co-channel overlapping coverage for APs, and selecting the combination of channel assignments which minimizes the sum of the weights of co-channel overlapping coverage. It may be recognized that the computer-implemented execution of the process illustrated in FIG. 18 may take longer than the computer-implemented execution of the process illustrated in FIG. 16 because the process of FIG. 18 requires the generation and evaluation of all the possible channel assignment combinations. It may further be recognized that while the process of FIG. 16, may yield an acceptable result with less execution time, the process of FIG. 18 will yield an optimal channel assignment configuration for minimizing co-channel overlapping coverage. 
     Although the present embodiment has been described herein with reference to certain embodiments, those of ordinary skill in the art will recognize that many modifications and variations of the present invention may be implemented. The foregoing description and the following claims are intended to cover all such modifications and variations.