Wireless terminal roaming

Patent metadata

Field	Value
Publication number	US-10863400-B1
Application number	US-201916585581-A
Country	US
Kind code	B1
Filing date	Sep 27, 2019
Priority date	Sep 27, 2019
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

Disclosed are methods and systems for improved wireless terminal roaming. In some embodiments, a management module determines access point density metrics for a plurality of centrally managed access points of a communications site. The density metric considers an average RSSI of access point signals received by other access points of the site, and each access point's contribution to the average. A determination of whether a particular wireless terminal roams is based on the density metrics of the source and target access point, as well as statistics relating to a current capacity of each of the access points. The disclosed embodiments may determine that a wireless terminal should transition/roam away from an access point even when that access point's RSSI value at the wireless terminal is above a threshold that would cause traditional methods to inhibit roaming.

First claim

The invention claimed is:

1. A system, comprising:
hardware processing circuitry;
one or more hardware memories storing instructions that when executed configure the hardware processing circuitry to perform operations comprising:
receiving, from each of a plurality of access points (APs), AP measured received signal strength indication (RSSI) values of AP generated signals,
receiving, from a current access point (AP) associated with a wireless terminal, a wireless terminal measured RSSI value for each of a signal generated by the current AP and a second signal generated by a candidate AP,
aggregating the AP measured RSSI values of AP generated signals, the AP generated signals generated by different APs, and
instructing the wireless terminal to transition from the current AP to the candidate AP based at least in part on the aggregation of the AP measured RSSI values of AP generated signals, and the wireless terminal measured RSSI values.

2. The system of claim 1 , further comprising determining the wireless terminal measured RSSI value of the signal generated by the current AP is above a predefined threshold, wherein the instructing is based on the determination.

3. The system of claim 1 , the operations further comprising determining a standard deviation of the AP measured RSSI values of AP generated signals, wherein the instructing of the wireless terminal is further based on the standard deviation.

4. The system of claim 3 , the operations further comprising determining, for each of the AP measured RSSI values, a difference between the AP measured RSSI value and the aggregation; and
determining, for each of the AP measured RSSI values, a contribution of the AP measured RSSI value by dividing the respective difference by the standard deviation; and
separately aggregating the determined contributions of AP measured RSSI values of candidate AP generated signals;
wherein the instructing of the wireless terminal is further based on the separate aggregation.

5. The system of claim 4 , the operations further comprising:
separately aggregating, for each of a plurality of APs including the current AP associated with the wireless terminal, the contributions of AP measured RSSI values of signals generated by the respective AP; and
determining, for each of the plurality of APs, a density of the AP based on the APs aggregated contributions, the determined densities including a first density for the current AP associated with the wireless terminal and a second density for the candidate AP, wherein the instructing of the wireless terminal to transition to the candidate AP is based on the second density.

6. The system of claim 5 , the operations further comprising
determining a first difference between an RSSI value measured by the current AP associated with the wireless terminal and an RSSI value measured by the candidate AP; and
determining a second difference between a number of wireless terminals associated with the current AP and a number of wireless terminals associated with the candidate AP, wherein the instructing of the wireless terminal to transition to the candidate AP is based on the first difference and the second difference.

7. The system of claim 6 , wherein the instructing of the wireless terminal to transition to the candidate AP further comprises relating the first difference to an aggregation of the first density and the second density.

8. The system of claim 7 , wherein the instructing of the wireless terminal to transition to the candidate AP is based on a relation of the first difference to (C 1 *first density)+(C 2 *second density)−(C 3 *the second difference), where C 1 , C 2 , and C 3 are coefficients.

9. The system of claim 8 , the operations further comprising
determining a difference between the wireless terminal measured RSSI values of the current and candidate AP generated signals; and
comparing the difference to a transition threshold, wherein the instructing of the wireless terminal to transition is based on the comparison.

10. The system of claim 9 , the operations further comprising:
determining pairs of APs included in the plurality of APs;
determining differences between wireless terminal measured RSSI values of signals generated by the pairs; and
determining the transition threshold based on the determined differences.

11. The system of claim 10 , the operations further comprising
determining, for each pair of the determined pairs of APs, a value of C 1 *a density of a first AP in the pair+C 2 *a second density of a second AP of the pair−C 3 *a difference between a number of wireless terminals associated with each of the first and second APs of the pair;
aggregating the values;
determining the transition threshold based on the aggregated values.

12. The system of claim 8 , the operations further comprising:
receiving a third AP RSSI value, the third RSSI value a wireless terminal measured RSSI value of a signal generated by a third AP;
determining a third difference between the wireless terminal measured RSSI value of a signal generated by the current AP and the third AP RSSI value; and
determining a fourth difference between a number of stations associated with the current AP and a number of stations associated with the third AP, wherein the instructing of the wireless terminal is based on the third difference and the fourth difference.

13. The system of claim 12 , wherein the densities of each AP include a third density of the third AP, the operations further comprising determining a second relation between the third difference and (C 1 *first density)+(C 2 *third density)−(C 3 *the fourth difference), wherein the instructing of the wireless terminal is based on the second relation.

14. The system of claim 13 , wherein determining the first relation comprises determining a fifth difference by subtracting (C 1 *first density)+(C 2 *second density)−(C 3 *the second difference) from the first difference, and wherein determining the second relation comprises determining a sixth difference by subtracting (C 1 *first density)+(C 2 *third density)−(C 3 *the fourth difference), from the third difference, wherein the instructing of the wireless terminal comprises selecting the candidate AP in response to the fifth difference being larger than the sixth difference.

15. A method performed by hardware processing circuitry of a multi-access point controller, comprising:
receiving, from each of a plurality of access points (APs), AP measured received signal strength indication (RSSI) values of AP generated signals,
receiving, from a current access point (AP) associated with a wireless terminal, a wireless terminal measured RSSI value for each of a signal generated by the current AP and a signal generated by a candidate AP,
aggregating the AP measured RSSI values of AP generated signals, the AP generated signals generated by different APs; and
instructing the wireless terminal to transition from the current AP to the candidate AP based at least in part of the aggregation of the AP measured RSSI values of AP generated signals, and the wireless terminal measured RSSI values.

16. The method of claim 15 , further comprising determining the wireless terminal measured RSSI value of the current AP generated signal is above a predefined threshold, wherein the instructing is based on the determination.

17. The method of claim 15 , further comprising:
determining, for each of the AP measured RSSI values, a difference between the AP measured RSSI value and the aggregation;
determining, for each of the AP measured RSSI values, a contributi

Assignees

• Juniper Networks Inc

Inventors

• Wang Wenfeng
• Thomas Jacob

Classifications

• H04W48/20 Primary

  Selecting an access point · CPC title

• H04W36/30

  by measured or perceived connection quality data · CPC title

• H04W36/302

  due to low signal strength · CPC title

• H04W36/00837 Primary

  Determination of triggering parameters for hand-off · CPC title

• H04W36/26

  by agreed or negotiated communication parameters · CPC title