SYSTEM FOR ALLOCATING CHANNELS IN A MULTI-RADIO WIRELESS LAN ARRAY

• US 20090028098A1
• Filed: 03/09/2006
• Published: 01/29/2009
• Est. Priority Date: 03/09/2005
• Status: Active Grant

• Current Assignee: Cambium Networks Limited (Cambium Networks Corporation)
• Original Assignee: Xirrus Incorporated
• Inventors: Gates, Dirk Ion, Mathews, James Kirk
• Granted Patent: US 8,934,416 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H01Q 1/007 specially adapted for indoor communication
• CPC Class Codes: H01Q 19/106 using two or more intersecting plane surfaces, e.g. corner reflector antennas
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation
• CPC Class Codes: H04W 80/02 Data link layer protocols
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

A channel allocation system for allocating channels in a frequency band to a plurality of radios in close proximity so as to minimize co-channel interference. One method for allocating channels involves initially tuning each of the plurality of radios to the same one of the plurality of channels. All of the radios then receive signals from whatever sources and a signal score is determined for each radio. The radios are then tuned to another one of the plurality of channels. The steps of receiving a signal and determining a signal score for each radio are repeated for each of the remaining channels until all channels have been used. The signal scores are then tested against a table of mapping schemes to determine maximum isolation.

Claims

1. A method for allocating channels in a wireless access device having a plurality of radios capable of operating on a plurality of channels, each channel having a frequency band with a center frequency, each center frequency spaced at equal frequency intervals with a larger frequency band, where any one channel may have at least one adjacent channel located in the next frequency band, the method comprising:

allocating one of the plurality of channels to each one of the plurality of radios, where each of the allocated channels is not adjacent to any one of the other allocated channels.

2. A method for allocating channels in a wireless access device having a plurality of radios capable of operating on a plurality of channels, each channel having a frequency band with a center frequency, each center frequency spaced at equal frequency intervals with a larger frequency band, where any one channel has at least one adjacent channel located in the next frequency band, the method comprising:

allocating one of the plurality of channels to each one of the plurality of radios, where each of the allocated channels is not adjacent to any one of the other allocated channels until at least one radio is not allocated a channel because the only channels remaining are adjacent to at least one allocated channel; and

allocating a remaining channel to a radio having a radial separation of 90°

to 150°

from the radio having the allocated channel that is adjacent to the remaining channel.

3. A method for allocating channels in a wireless access device having a plurality of radios capable of operating on a plurality of channels, each channel having a frequency band with a center frequency, each center frequency spaced at equal frequency intervals with a larger frequency band, where any one channel has at least one adjacent channel located in the next frequency band, the method comprising:

allocating one of the plurality of channels to a first radio;

allocating a second one of the plurality of channels a number n_ch channels away from the first one of the plurality of channels to an adjacent radio;

allocating a third one of the plurality of channels a second number n_cha of channels smaller than n_ch, to a next adjacent radio.

4. A method according to claim 3 further comprising the step of generating at least one channel mapping scheme.

5. A method according to claim 4 further comprising the step of storing the at least one channel mapping scheme in non-volatile memory.

6. A method according to claim 3 where the plurality of radios comprises a twelve radio circular array, each radio allocated to one of the twelve channels of the 802.11a specification, where n_ch=16 and n_cha=12 and adjacent channel assignment is limited to radios having a radial separation of 900, 120°

and 150°

apart.

7. A method according to claim 6 further comprising the step of generating at least one channel mapping scheme.

8. A method according to claim 7 further comprising the step of storing the at least one channel mapping scheme in non-volatile memory.

9. A method for allocating channels in a wireless access device having a plurality of radios capable of operating on a plurality of channels, the method comprising:

initially tuning each of the plurality of radios to the same one of the plurality of channels;

receiving signals on all the radios;

determining a signal score at each radio;

tuning each of the plurality of radios to another one of the plurality of channels;

receiving signals on all the radios;

determining signal scores at each radio;

repeating the steps of tuning, receiving and determining signal scores until all of the available channels have been used; and

testing the signal scores against a table of mapping schemes to determine maximum isolation.

10. A method according to claim 9 where the step of determining a signal score at each radio comprises the step of calculating a channel usage factor.

11. A method according to claim 10 where the step of calculating the channel usage factor comprises the steps of:

determining a relative signal strength (RSSI)′

,

determining a packet length;

determining a bit rate;

determining a non-wireless access device signal duty cycle; and

calculating;

[(Packet length/bit rate)*(100+RSSI)]+[(Non wireless access device Signal Duty Cycle)*70].

12. A method according to claim 10 further comprising:

configuring a spectrum usage matrix by tabulating the channel usage factor for each radio on each channel potentially available