Neighbor discovery in a wireless system

Abstract

Beacons may be grouped to facilitate neighbor discovery in a wireless network. For example, neighboring access devices such as IEEE 802.11 access points may cooperate to transmit beacons in a group. In this way, a wireless device seeking to discover the neighboring access devices may scan for the beacons for a shorter period of time. An indication may be provided to enable a wireless device to more efficiently scan the beacons. For example, the indication may indicate the channel the wireless device should scan to receive the next beacon that is to be transmitted. In addition, the indication may include information relating to the transmission time of the next beacon.

1 . A method of using beacon-related information, comprising:
 using, by a wireless device, an indication regarding transmission of at least one next beacon by at least one neighboring access point, wherein each beacon of the at least one next beacon comprises an identifier of an associated wireless network; and   scanning, by the wireless device, for the at least one next beacon.   
   
   
       2 . The method of  claim 1 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       3 . The method of  claim 2 , wherein the indication further identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       4 . The method of  claim 1 , wherein the indication identifies any channels that are not being used by the at least one neighboring access point. 
   
   
       5 . The method of  claim 1 , wherein:
 the indication comprises a function; and   using the indication comprises using the function to determine at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted.   
   
   
       6 . The method of  claim 1 , wherein using the indication comprises determining when and on which channel to scan for the at least one next beacon. 
   
   
       7 . The method of  claim 1 , further comprising waking from a power save mode to scan, during a wake time period, for the at least one next beacon from the at least one neighboring access point;
 wherein using the indication comprises determining at least one channel to scan and at least one time to scan during the wake time period.   
   
   
       8 . The method of  claim 1 , wherein:
 the at least one next beacon comprises a set of beacons that are grouped together in time and by radio channel; and   the wireless device uses the indication to scan for the set of beacons.   
   
   
       9 . The method of  claim 1 , wherein:
 the at least one next beacon comprises a plurality of beacons transmitted during a defined time period;   the wireless device uses the indication to scan for the plurality of beacons transmitted during the defined time period; and   each of the beacons is associated with a different wireless network.   
   
   
       10 . The method of  claim 9 , wherein successive beacons are separated in time by one of a set of defined spacings. 
   
   
       11 . The method of  claim 1 , wherein:
 the wireless device scans for a first beacon on a first channel;   the at least one next beacon comprises a second beacon; and   the wireless device identifies, based on the indication and the first channel, a second channel to scan for the second beacon.   
   
   
       12 . The method of  claim 11 , wherein:
 the at least one next beacon further comprises a third beacon; and   the wireless device identifies, based on the indication and the second channel, a third channel to scan for the third beacon.   
   
   
       13 . The method of  claim 1 , wherein:
 the wireless device receives the indication from an access point; or   the indication is programmed into the wireless device.   
   
   
       14 . The method of  claim 1 , wherein the wireless device uses the indication to identify neighboring access points between which the wireless device may roam. 
   
   
       15 . The method of  claim 1 , wherein the wireless device uses the indication to reduce beacon scan time. 
   
   
       16 . The method of  claim 1 , wherein the wireless device uses the indication to increase time spent in power save mode. 
   
   
       17 . An apparatus for using beacon-related information, comprising:
 a scan controller adapted to use an indication regarding transmission of at least one next beacon by at least one neighboring access point, wherein each beacon of the at least one next beacon comprises an identifier of an associated wireless network; and   a scanner adapted to scan for the at least one next beacon.   
   
   
       18 . The apparatus of  claim 17 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       19 . The apparatus of  claim 18 , wherein the indication further identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       20 . The apparatus of  claim 17 , wherein:
 the indication comprises a function; and   the scan controller is further adapted to use the function to determine at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted.   
   
   
       21 . The apparatus of  claim 17 , further comprising a mode controller adapted to cause the scanner to wake from a power save mode to scan, during a wake time period, for the at least one beacon from the at least one neighboring access point;
 wherein the scan controller is further adapted to determine, based on the indication, at least one channel to scan and at least one time to scan during the wake time period.   
   
   
       22 . The apparatus of  claim 17 , wherein
 the at least one next beacon comprises a set of beacons that are grouped together in time; and   the scan controller is further adapted to use the indication to cause the scanner to scan for the set of beacons.   
   
   
       23 . The apparatus of  claim 17 , wherein:
 the at least one next beacon comprises a plurality of beacons transmitted during a defined time period;   the scan controller is further adapted to use the indication to cause the scanner to scan for the plurality of beacons transmitted during the defined time period; and   each of the beacons is associated with a different wireless network.   
   
   
       24 . The apparatus of  claim 23 , wherein successive beacons are separated in time by one of a set of defined spacings. 
   
   
       25 . The apparatus of  claim 17 , wherein the scan controller is further adapted to use the indication to identify neighboring access points between which the apparatus may roam. 
   
   
       26 . The apparatus of  claim 17 , wherein the scan controller is further adapted to use the indication to reduce beacon scan time, increase time spent in power save mode, or reduce beacon scan time and increase time spent in power save mode. 
   
   
       27 . An apparatus for using beacon-related information, comprising:
 means for using an indication regarding transmission of at least one next beacon by at least one neighboring access point, wherein each beacon of the at least one next beacon comprises an identifier of an associated wireless network; and   means for scanning for the at least one next beacon.   
   
   
       28 . The apparatus of  claim 27 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       29 . The apparatus of  claim 28 , wherein the indication further identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       30 . The apparatus of  claim 27 , wherein:
 the indication comprises a function; and   the means for using the indication determines at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted.   
   
   
       31 . The apparatus of  claim 27 , further comprising means for waking the means for scanning from a power save mode to scan, during a wake time period, for the at least one beacon from the at least one neighboring access point;
 wherein the means for using the indication determines, based on the indication, at least one channel to scan and at least one time to scan during the wake time period.   
   
   
       32 . The apparatus of  claim 27 , wherein:
 the at least one next beacon comprises a set of beacons that are grouped together in time; and   the means for using the indication uses the indication to cause the means for scanning to scan for the set of beacons.   
   
   
       33 . The apparatus of  claim 27 , wherein:
 the at least one next beacon comprises a plurality of beacons transmitted during a defined time period;   the means for using the indication uses the indication to cause the means for scanning to scan for the plurality of beacons transmitted during the defined time period; and   each of the beacons is associated with a different wireless network.   
   
   
       34 . The apparatus of  claim 33 , wherein successive beacons are separated in time by one of a set of defined spacings. 
   
   
       35 . The apparatus of  claim 27 , wherein the means for using the indication uses the indication to identify neighboring access points between which the apparatus may roam. 
   
   
       36 . The apparatus of  claim 27 , wherein the means for using the indication uses the indication to reduce beacon scan time, increase time spent in power save mode, or reduce beacon scan time and increase time spent in power save mode. 
   
   
       37 . A computer program product comprising:
 computer-readable medium comprising code for causing at least one computer to:
 use an indication regarding transmission of at least one next beacon by at least one neighboring access point, wherein each beacon of the at least one next beacon comprises an identifier of an associated wireless network; and 
 scan for the at least one next beacon. 
   
   
   
       38 . The computer program product of  claim 37 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       39 . The computer program product of  claim 38 , wherein the indication further identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       40 . The computer program product of  claim 37 , wherein:
 the indication comprises a function; and   the code for causing the at least one computer to use the indication comprises code for causing the at least one computer to determine at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted.   
   
   
       41 . The computer program product of  claim 37 , wherein the computer-readable medium further comprises code for causing the at least one computer to wake from a power save mode to scan, during a wake time period, for the at least one beacon from the at least one neighboring access point;
 wherein the code for causing the at least one computer to use an indication comprises code for causing the at least one computer to determine at least one channel to scan and at least one time to scan during the wake time period.   
   
   
       42 . The computer program product of  claim 37 , wherein:
 the at least one next beacon comprises a set of beacons that are grouped together in time; and   the code for causing the at least one computer to scan comprises code for causing the at least one computer to scan for the set of beacons.   
   
   
       43 . The computer program product of  claim 37 , wherein:
 the at least one next beacon comprises a plurality of beacons transmitted during a defined time period;   the code for causing the at least one computer to scan comprises code for causing the at least one computer to scan for a plurality of beacons transmitted during a defined time period; and   each of the beacons is associated with a different wireless network.   
   
   
       44 . The computer program product of  claim 43 , wherein successive beacons are separated in time by one of a set of defined spacings. 
   
   
       45 . The computer program product of  claim 37 , wherein the code for causing the at least one computer to use the indication comprises code for causing the at least one computer to identify neighboring access points between which the at least one computer may roam. 
   
   
       46 . The computer program product of  claim 37 , wherein the code for causing the at least one computer to use the indication comprises code for causing the at least one computer to use the indication to reduce beacon scan time, increase time spent in power save mode, or reduce beacon scan time and increase time spent in power save mode. 
   
   
       47 . A method of providing beacons by an access point, comprising:
 cooperating, with at least one other access point, to determine when to transmit beacons of associated time division multiplexed wireless networks, wherein each beacon comprises an identifier of one of the time division multiplexed wireless networks; and   transmitting the beacons of at least one of the networks.   
   
   
       48 . The method of  claim 47 , wherein the access points transmit the beacons so that the beacons are not overlapping in time. 
   
   
       49 . The method of  claim 47 , wherein all of the beacons, to be sent by the access points using a given channel, are sent consecutively in time. 
   
   
       50 . The method of  claim 47 , further comprising maintaining at least one defined spacing between successive transmissions of the beacons. 
   
   
       51 . The method of  claim 50 , wherein, when a next beacon and a previous beacon are sent on different channels, the at least one defined spacing is more than a channel switching time of a radio of a wireless device that is adapted to receive the next beacon and the previous beacon. 
   
   
       52 . The method of  claim 47 , wherein:
 the access points repetitively transmit a group of the beacons associated with at least a portion of the wireless networks;   each beacon in the group of beacons is associated with a different one of the wireless networks; and   the access points transmit the beacons in each group within a defined period of time.   
   
   
       53 . The method of  claim 52 , wherein the defined period of time is less than a beacon interval. 
   
   
       54 . The method of  claim 47 , wherein the access points cooperate to successively transmit, in turn, one of the beacons associated with each of the wireless networks. 
   
   
       55 . The method of  claim 47 , wherein cooperating comprises establishing beacon transmission times to:
 reduce a total time used to transmit a set of non-time overlapping beacons; and   provide reduced beacon scan time and total search time for a wireless device that is adapted to receive the beacons.   
   
   
       56 . The method of  claim 47 , further comprising:
 determining a beacon transmission time of one of the access points; and   using the beacon transmission time to establish target beacon transmit times for a set of the access points in a given geographical area.   
   
   
       57 . The method of  claim 47 , further comprising generating an indication regarding transmission of at least one next beacon by the at least one other access point. 
   
   
       58 . The method of  claim 57 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       59 . The method of  claim 58 , wherein the indication identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       60 . The method of  claim 57 , wherein the indication comprises a function for determining at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       61 . The method of  claim 57 , wherein the indication identifies, based on a first channel, a second channel to scan for the at least one next beacon. 
   
   
       62 . The method of  claim 61 , wherein the indication identifies, based on the second channel, a third channel to scan for the at least one next beacon. 
   
   
       63 . The method of  claim 47 , further comprising transmitting an indication identifying any channels that are not being used by the access points. 
   
   
       64 . An access point apparatus for providing beacons, comprising:
 a controller adapted to cooperate, with at least one other access point, to determine when to transmit beacons of associated time division multiplexed wireless networks, wherein each beacon comprises an identifier of one of the time division multiplexed wireless networks; and   a transmitter for transmitting the beacons of at least one of the networks.   
   
   
       65 . The apparatus of  claim 64 , wherein the access points transmit the beacons so that the beacons are not overlapping in time. 
   
   
       66 . The apparatus of  claim 64 , wherein all of the beacons, to be sent by the access points using a given channel, are sent consecutively. 
   
   
       67 . The apparatus of  claim 64 , wherein the access points maintain at least one defined spacing between successive transmissions of the beacons. 
   
   
       68 . The apparatus of  claim 64 , wherein the controller is further adapted to cooperate to establish transmission times for the beacons to:
 reduce a total time used to transmit a set of non-time overlapping beacons; and   provide reduced beacon scan time and total search time for a wireless device that is adapted to receive the beacons.   
   
   
       69 . The apparatus of  claim 64 , wherein the controller is further adapted to:
 determine a beacon transmission time of one of the access points; and   use the beacon transmission time to establish target beacon transmit times for a set of the access points in a given geographical area.   
   
   
       70 . The apparatus of  claim 64 , further comprising an indication generator adapted to generate an indication regarding transmission of at least one next beacon by the at least one other access point. 
   
   
       71 . The apparatus of  claim 70 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       72 . The apparatus of  claim 71 , wherein the indication identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       73 . The apparatus of  claim 70 , wherein the indication comprises a function for determining at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       74 . An access point apparatus for providing beacons, comprising:
 means for cooperating, with at least one other access point, to determine when to transmit beacons of associated time division multiplexed wireless networks, wherein each beacon comprises an identifier of one of the time division multiplexed wireless networks; and   means for transmitting the beacons of at least one of the networks.   
   
   
       75 . The apparatus of  claim 74 , wherein the access points transmit the beacons so that the beacons are not overlapping in time. 
   
   
       76 . The apparatus of  claim 74 , wherein all of the beacons, to be sent by the access points using a given channel, are sent consecutively. 
   
   
       77 . The apparatus of  claim 74 , further comprising means for maintaining at least one defined spacing between successive transmissions of the beacons. 
   
   
       78 . The apparatus of  claim 74 , wherein the means for cooperating further establishes beacon transmit times to:
 reduce a total time used to transmit a set of non-time overlapping beacons; and   provide reduced beacon scan time and total search time for a wireless device that is adapted to receive the beacons.   
   
   
       79 . The apparatus of  claim 74 , further comprising:
 means for determining a beacon transmission time of one of the access points; and   means for using the beacon transmission time to establish target beacon transmit times for a set of the access points in a given geographical area.   
   
   
       80 . The apparatus of  claim 74 , further comprising means for generating an indication regarding transmission of at least one next beacon by the at least one other access point. 
   
   
       81 . The apparatus of  claim 80 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       82 . The apparatus of  claim 81 , wherein the indication identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       83 . The apparatus of  claim 80 , wherein the indication comprises a function for determining at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       84 . A computer program product for an access point comprising:
 computer-readable medium comprising code for causing at least one computer to:
 cooperate, with at least one other access point, to determine when to transmit beacons of associated time division multiplexed wireless networks, wherein each beacon comprises an identifier of one of the time division multiplexed wireless networks; and 
 transmit the beacons of at least one of the networks. 
   
   
   
       85 . The computer program product of  claim 84 , wherein the access points transmit the beacons so that the beacons are not overlapping in time. 
   
   
       86 . The computer program product of  claim 84 , wherein all of the beacons, to be sent by the access points using a given channel, are sent consecutively. 
   
   
       87 . The computer program product of  claim 84 , wherein the access points maintain at least one defined spacing between successive transmissions of the beacons. 
   
   
       88 . The computer program product of  claim 84 , wherein the computer-readable medium further comprises code for causing the at least one computer to establish beacon transmission times to:
 reduce a total time used to transmit a set of non-time overlapping beacons; and   provide reduced beacon scan time and total search time for a wireless device that is adapted to receive the beacons.   
   
   
       89 . The computer program product of  claim 84 , wherein the computer-readable medium further comprises code for causing the at least one computer to:
 determine a beacon transmission time of one of the access points; and   use the beacon transmission time to establish target beacon transmit times for a set of the access points in a given geographical area.   
   
   
       90 . The computer program product of  claim 84 , wherein the computer-readable medium further comprises code for causing the at least one computer to generate an indication regarding transmission of at least one next beacon by the at least one other access point. 
   
   
       91 . The computer program product of  claim 90 , wherein the indication identifies at least one channel upon which the at least one next beacon will be transmitted. 
   
   
       92 . The computer program product of  claim 91 , wherein the indication identifies at least one time at which the at least one next beacon will be transmitted. 
   
   
       93 . The computer program product of  claim 90 , wherein the indication comprises a function for determining at least one time at which the at least one next beacon will be transmitted and/or at least one channel upon which the at least one next beacon will be transmitted.