US-20260129634-A1 - LOW LATENCY LOW OVERHEAD ESTIMATION OF PATHLOSS TO NEIGHBORING ACCESS POINTS

US20260129634A1US 20260129634 A1US20260129634 A1US 20260129634A1US-20260129634-A1

Abstract

A method to optimize roaming of a wireless client in a wireless local area network includes receiving, at a serving access point (AP), a value indicative of transmit power for at least one neighbor AP, and sending the value indicative of transmit power for the at least one neighbor AP from the serving AP to a wireless client that is associated with the serving AP. The wireless client may then calculate a pathloss between the at least one neighbor AP and the wireless client based on the value indicative of transmit power for the at least one neighbor AP less a downlink RSSI of a Clear to Send (CTS) message received from the at least one neighbor AP, and then estimate an uplink RSSI at the at least one neighbor AP based on a value indicative of transmit power for the wireless client less the pathloss.

Inventors

Brian D. Hart
Binita Gupta

Assignees

CISCO TECHNOLOGY, INC.

Dates

Publication Date: 20260507
Application Date: 20251009

Claims (20)

1 . A method comprising: receiving, at a serving access point (AP), a value indicative of transmit power for at least one neighbor AP; and sending the value indicative of transmit power for the at least one neighbor AP from the serving AP to a wireless client that is associated with the serving AP.
2 . The method of claim 1 , wherein the value indicative of transmit power is a value indicative of conducted transmit power.
3 . The method of claim 1 , wherein the value indicative of the transmit power is a transmit power that is used by the at least one neighbor AP to transmit a Clear to Send (CTS) message in response to a Request to Send (RTS) message sent by the wireless client.
4 . The method of claim 1 , further comprising receiving the value indicative of transmit power for the at least one neighbor AP from a controller that controls the serving AP and the at least one neighbor AP.
5 . The method of claim 1 , further comprising receiving the value indicative of transmit power for the at least one neighbor AP from the at least one neighbor AP.
6 . The method of claim 1 , further comprising sending the value indicative of transmit power for the at least one neighbor AP as part of at least one of a Neighbor Report Response frame a Basic Service Set (BSS) Transition Management (BTM) frame, and a Reduced Neighbor Report (RNR) frame in a beacon signal transmitted by the serving AP.
7 . The method of claim 1 , wherein the value indicative of transmit power is a value indicative of transmit power over a primary 20 MHz channel.
8 . The method of claim 1 , further comprising the wireless client calculating a pathloss between the at least one neighbor AP and the wireless client based on the value indicative of transmit power for the at least one neighbor AP less a downlink received signal strength indicator (RSSI) of a message received from the at least one neighbor AP.
9 . The method of claim 8 , further comprising the wireless client calculating an estimated uplink RSSI at the at least one neighbor AP based on a value indicative of transmit power of the wireless client less the pathloss.
10 . The method of claim 9 , further comprising selecting the at least one neighbor AP as a target AP to which to roam based on the estimated uplink RSSI at the at least one neighbor AP.
11 . A device comprising: an interface configured to enable network communications; a memory; and one or more processors coupled to the interface and the memory, and configured to: receive a value indicative of transmit power for at least one neighbor AP; and send the value indicative of transmit power for the at least one neighbor AP from the device to a wireless client, wherein the device is a serving access point (AP) to which the wireless client is associated.
12 . The device of claim 11 , wherein the value indicative of transmit power is a value indicative of conducted transmit power.
13 . The device of claim 11 , wherein the value indicative of the transmit power is a transmit power used by the at least one neighbor AP to transmit a Clear to Send (CTS) message in response to a Request to Send (RTS) message sent by the wireless client.
14 . The device of claim 11 , wherein the one or more processors are further configured to receive the value indicative of transmit power for the at least one neighbor AP from a controller that controls the device and the at least one neighbor AP.
15 . The device of claim 11 , wherein the one or more processors are further configured to receive the value indicative of transmit power for the at least one neighbor AP from the at least one neighbor AP.
16 . The device of claim 11 , wherein the one or more processors are further configured to send the value indicative of transmit power for the at least one neighbor AP as part of at least one of a Neighbor Report Response frame, a Basic Service Set (BSS) Transition Management (BTM) frame, and as part of a Reduced Neighbor Report (RNR) frame in a beacon signal transmitted by the device.
17 . The device of claim 11 , wherein the value indicative of transmit power is a value indicative of transmit power over a primary 20 MHz channel.
18 . One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor, cause the processor to: receive, at a serving access point (AP), a value indicative of transmit power for at least one neighbor AP; and send the value indicative of transmit power for the at least one neighbor AP from the serving AP to a wireless client that is associated with the serving AP.
19 . The one or more non-transitory computer readable storage media of claim 18 , wherein the value indicative of transmit power is a value indicative of conducted transmit power.
20 . The one or more non-transitory computer readable storage media of claim 18 , wherein the instructions are configured to send the value indicative of transmit power for the at least one neighbor AP as part of at least one of a Neighbor Report Response frame, a Basic Service Set (BSS) Transition Management (BTM), and as part of a Reduced Neighbor Report (RNR) frame in a beacon signal transmitted by the serving AP.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to U.S. Provisional Ser. No. 63/717,341 , filed Nov. 7, 2024, the contents of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The present disclosure relates to operations of a wireless local area network (WLAN). BACKGROUND Networking architectures have grown increasingly complex in communications environments, particularly wireless networking environments, such as those that employ IEEE 802.11 wireless local area network (WLAN) technology, also known as Wi-Fi® wireless networking technology. One feature of a WLAN is the ability of a wireless client device (client) to roam from one wireless access point (AP) to another AP as the client moves in an area covered by the WLAN. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram depicting a sequence flow for a wireless client, a serving access point (AP) and neighbor APs in connection with client roaming supported by Client Pathloss Estimation Logic and AP Transmit (TX) Power Notification Logic, according to an example embodiment. FIG. 2 shows a table maintained by Client Pathloss Estimation Logic that may be used to determine pathloss to a given neighbor AP, and to estimate an uplink (UL) Received Signal Strength Indicator (RSSI) value at the given neighbor AP, according to an example embodiment. FIG. 3 shows elements of a Basic Service Set (BSS) Transition Management (BTM) Request frame or Neighbor Report Response frame that may be employed to supply TX power indications to a wireless client, according to an example embodiment. FIG. 4 shows elements of a BTM Request frame or Neighbor Report Response frame, in the context of a multilink device (MLD), that may be employed to supply TX power indications to a wireless client, according to an example embodiment. FIG. 5 shows elements of a Reduced Neighbor Report element that may be employed to supply TX power indications to a wireless client, according to an example embodiment. FIG. 6A is a flowchart showing a series of operations that may be executed by AP TX Power Notification Logic at a neighbor AP, according to an example embodiment. FIG. 6B is a flowchart showing a series of operations that may be executed by AP TX Power Notification Logic at a serving AP, according to an example embodiment. FIG. 6C is a flowchart showing a series of operations that may be executed at Client Pathloss Estimation Logic, according to an example embodiment. FIG. 7 is a block diagram of a computing device that may be configured to execute AP TX Power Notification Logic or Client Pathloss Estimation Logic, according to an example embodiment. DETAILED DESCRIPTION Overview In an embodiment, a method to optimize roaming of a wireless client in a wireless local area network is provided. The method includes receiving, at a serving access point (AP), a value indicative of transmit power for at least one neighbor AP, and sending the value indicative of transmit power for the at least one neighbor AP from the serving AP to a wireless client that is associated with the serving AP. The wireless client may then calculate a pathloss between the at least one neighbor AP and the wireless client based on the value indicative of transmit power for the at least one neighbor AP less a downlink RSSI of a message (e.g., a Clear to Send (CTS) message) received from the at least one neighbor AP, and then estimate an uplink RSSI at the at least one neighbor AP based on a value indicative of transmit power of the wireless clientless the pathloss. In another embodiment, a device is provided. The device may be a serving AP and includes an interface configured to enable network communications, a memory, and one or more processors coupled to the interface and the memory, and configured to: receive a value indicative of transmit power for at least one neighbor AP, and send the value indicative of transmit power for the at least one neighbor AP from the device to a wireless client. The wireless client may then calculate a pathloss between the at least one neighbor AP and the wireless client based on the value indicative of transmit power for the at least one neighbor AP less a downlink RSSI of a message (e.g., a Clear to Send (CTS) message) received from the at least one neighbor AP, and then estimate an uplink RSSI at the at least one neighbor AP based on a value indicative of transmit power of the wireless client less the pathloss. EXAMPLE EMBODIMENTS In a wireless local area network (WLAN) or Wi-Fi® wireless network, one or more wireless APs provide wireless Radio Frequency (RF) coverage over which one or more wireless devices (e.g., mobile phones, wearable devices, tablets, etc., i.e., clients) can connect to the APs in order to connect to one or more data networks (e.g., the public Internet, an enterprise network operated by an enterprise entity (e.g., a business, institution, university, etc.)), and/or the like. When multiple APs are available, a client may