Method for scanning radio frequency channels

• US 7,167,696 B2
• Filed: 02/18/2004
• Issued: 01/23/2007
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Autocell Laboratories Incorporated
• Inventors: Backes, Floyd, Bridge, Laura
• Primary Examiner(s): Appiah, Charles
• Assistant Examiner(s): HOLLIDAY, JAIME MICHELE
• Application Number:
  US10/780,841
• Publication Number:
  US 20050026610A1
• Time in Patent Office: 1,070 Days
• Field of Search: 455/161.1, 455/161.2, 455/161.3, 455/166.2, 455/434, 455/176.1, 455/515, 455/186.1, 455/516
• US Class Current: 455/161.1
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 47/125 by balancing the load, e.g. traffic engineering
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/10015 Access to distributed or replicated servers, e.g. using brokers
• CPC Class Codes: H04W 16/04 Traffic adaptive resource partitioning
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 16/10 Dynamic resource partitioning
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 28/08 Load balancing or load distribution transferring a connection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 28/0862 of same hierarchy level
• CPC Class Codes: H04W 28/0983 for optimizing bandwidth or throughput
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/18 : for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/20 : for optimising the interference level
• CPC Class Codes: H04W 36/32 : by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 4/02 : Services making use of location information
• CPC Class Codes: H04W 40/08 : based on transmission power
• CPC Class Codes: H04W 40/18 : based on predicted events
• CPC Class Codes: H04W 40/36 : due to handover
• CPC Class Codes: H04W 48/06 : based on traffic conditions
• CPC Class Codes: H04W 48/08 : Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/16 : Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/17 : Selecting a data network PoA [Point of Attachment]
• CPC Class Codes: H04W 48/20 : Selecting an access point
• CPC Class Codes: H04W 52/0216 : using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/10 : Open loop power control
• CPC Class Codes: H04W 52/18 : TPC being performed according to specific parameters
• CPC Class Codes: H04W 52/225 : Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/226 : using past references to control power, e.g. look-up-table
• CPC Class Codes: H04W 52/228 : using past power values or information
• CPC Class Codes: H04W 52/24 : using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/245 : taking into account received signal strength
• CPC Class Codes: H04W 52/246 : where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/247 : where the output power of a terminal is based on a path parameter sent by another terminal
• CPC Class Codes: H04W 52/283 : Power depending on the position of the mobile
• CPC Class Codes: H04W 52/285 : taking into account the mobility of the user
• CPC Class Codes: H04W 52/286 : during data packet transmission, e.g. high speed packet access [HSPA]
• CPC Class Codes: H04W 52/287 : when the channel is in stand-by
• CPC Class Codes: H04W 52/288 : taking into account the usage mode, e.g. hands-free, data transmission, telephone
• CPC Class Codes: H04W 52/34 : TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 52/343 : taking into account loading or congestion level
• CPC Class Codes: H04W 52/367 : Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/50 : at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 60/00 : Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 64/00 : Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 64/006 : with additional information processing, e.g. for direction or speed determination
• CPC Class Codes: H04W 72/02 : Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/52 : based on load
• CPC Class Codes: H04W 72/54 : based on quality criteria
• CPC Class Codes: H04W 74/00 : Wireless channel access
• CPC Class Codes: H04W 74/002 : Transmission of channel access control information
• CPC Class Codes: H04W 76/10 : Connection setup
• CPC Class Codes: H04W 8/04 : Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 80/00 : Wireless network protocols or protocol adaptations to wireless operation
• CPC Class Codes: H04W 80/04 : Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 : Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 84/22 : with access to wired networks
• CPC Class Codes: H04W 88/08 : Access point devices
• CPC Class Codes: H04W 92/18 : between terminal devices
• CPC Class Codes: H04W 92/20 : between access points
• CPC Class Codes: Y02B 70/30 : Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

The performance and ease of management of wireless communications environments is improved by a mechanism that enables access points (APs) to perform automatic channel selection. A wireless network can therefore include multiple APs, each of which will automatically choose a channel such that channel usage is optimized. Furthermore, APs can perform automatic power adjustment so that multiple APs can operate on the same channel while minimizing interference with each other. Wireless stations are load balanced across APs so that user bandwidth is optimized. A movement detection scheme provides seamless roaming of stations between APs.

Claims

1. A method comprising the steps of:

scanning a plurality of radio frequency channels during a scan interval;

receiving messages on each of the plurality of radio frequency channels during the scan interval;

maintaining a scan table having an entry for each device from which a message is received during the scan interval;

maintaining a channel map having an entry for each of the plurality of radio frequency channels on which a message was received, each entry containing a device ID of a device that sent a message on the corresponding channel;

sorting the channel map into a triplet channel map, wherein each successive group of three entries is associated with three successive channels, wherein the average power is stored in the entry for each channel;

selecting a channel from the triplet channel map, by selecting the channel from the triplet with the lowest center average power;

transmitting preclaim messages on the selected channel during a preclaim interval;

receiving messages on the selected channel and updating the scan table based on each message received during the preclaim interval;

calculating an adjacency vector sum, the vector sum representing the sum of all average power levels on all channels;

transmitting claim messages on the selected channel during a claim interval;

the claim messages including the adjacency vector sum;

receiving messages on the selected channel during the claim interval;

maintaining a claim table having an entry for each device ID that sent a message on the selected channel during the claim interval;

evaluating the claim table at the end of to claim interval, wherein evaluating comprises the steps of;

If the claim table has no entries, causing the apparatus to commence communications with other devices via the selected channel;

If the claim table has entries, then checking to see if the selected channel was occupied at the beginning of the claim interval, and if the selected channel was not occupied at the beginning of the claim interval, causing the apparatus to return to scanning channels during a scan interval;

If the selected channel was occupied at the beginning of the claim interval, checking to see if all the claim table entries contain power levels that are less than a power level that was recorded on the selected channel before the claim interval, and if all the claim table entries contain power levels that are less than the power level that was recorded on the selected channel before the claim interval, then causing the apparatus to commence communications with other devices via the selected channel;

If any claim table entry contains a power level that is greater than the power level that was recorded on the selected channel before the claim interval, then comparing the adjacency vector sum to an adjacency vector that was received in one of the messages, and if the adjacency vector sum is greater than the adjacency vector received, causing the apparatus to commence communications with other devices via the selected channel, otherwise causing the apparatus to return to scanning channels during a scan interval.

2. The method of claim 1 wherein the step of maintaining a channel map maintains, for each entry, the device ID of a device that sent a message or messages on the channel at the highest average power.

3. The method of claim 2 further comprising the step of ascertaining dining the scan interval whether any power level recorded in the channel map exceeds a threshold power level, and if so, the logic causes the apparatus to enter a standby mode.

4. The method of claim 2 furthering comprising the step of ascertaining during the preclaim interval whether the scan table includes too many entries, and if so, the logic causes the apparatus to enter a standby mode.