WO2024260954A1

WO2024260954A1 - Access point coordination for power saving

Info

Publication number: WO2024260954A1
Application number: PCT/EP2024/066899
Authority: WO
Inventors: Abhishek AMBEDE; Rocco Di Taranto; Leif Wilhelmsson
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-06-21
Filing date: 2024-06-18
Publication date: 2024-12-26
Anticipated expiration: 2025-12-21

Abstract

A method, system and apparatus are disclosed. A first access point (AP) station (STA) configured for a coordination process among a group of AP STAs is described. The group of AP STAs include the first AP and at least a second AP STA. The first AP STA is configured to and/or includes a communication interface and/or processing circuitry configured to cause transmission of a first message to the second AP STA, where the first message includes information indicating the first AP STA's preliminary planned power saving (PS) schedule aimed for reducing power consumption of the first AP STA. The PS schedule includes upcoming time periods of the first AP when the first AP STA is available or unavailable for communicating with other devices. Further, a second message is received from the second AP STA. The second message acknowledges at least receipt of the first message.

Description

ACCESS POINT COORDINATION FOR POWER SAVING

FIELD

The present disclosure relates to wireless communications, and in particular, to coordination of processes associated with wireless access points (APs).

INTRODUCTION

Wi-Fi, also known as Wireless Local Area Network (WLAN), is a technology that currently mainly operates in the 2.4 GHz, or the 5 GHz band, or the 6 GHz band. There are specifications regulating an access points' or wireless terminals' physical (PHY) layer, medium access layer (MAC) layer and other aspects in order to secure compatibility and inter-operability between different WLAN entities, e.g., between an access point and mobile terminals, both of which may be referred to as stations (STAs) herein. Wi-Fi is generally operated in license-exempt bands, and as such, communication over Wi-Fi may be subject to interference sources from any number of known and unknown devices. Wi-Fi is commonly used as wireless extensions to fixed broadband access, e.g., in domestic environments and hotspots, like airports, train stations and restaurants.

Mutli-AP networks

Wireless communication networks, such as Wi-Fi networks based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 WLAN standard, typically involve deployment of multiple access points (APs). Examples of multi-AP networks featuring high density AP deployments can be commonly found in enterprise offices, academic campuses, sports arenas, retail shops and malls, as well as industries. FIG. 1 shows an example of a multi-AP deployment with seven APs and corresponding hexagonal cells.

The APs in multi-AP networks are typically deployed with overlapping coverage areas, e.g., to ensure high quality of communication. This helps achieve sufficiently high signal to noise ratio (SNR), and/or signal to interference plus noise ratio (SINR), during communications in the entire deployment area for client devices being served, and to avoid zones with no coverage. This is especially true when the clients being served have stringent quality of service (QoS) requirements. FIG. 2 illustrates an example of a multi-AP network with five APs, i.e., AP1-AP5, with overlapping coverage areas illustrated using circles. The solid circles denote coverage areas with higher SNR/ SINR communication being possible, whereas the dotted circles denote coverage areas with lower SNR/ SINR communication being possible. The deployed APs are in the range of at least one other AP. For example, API is in range of AP4 and AP3, while AP3 is in range of all other four APs.

Some conventional practice includes selecting non-overlapping operating channels for neighboring APs in multi-AP networks, e.g., in order to avoid severe cochannel interference across their operating cells. However, as the IEEE 802.11 WLAN standard has evolved, wider and wider signal bandwidths are being supported (e.g., up to 160 MHz or up to 320 MHz), thereby resulting in higher probability of at least some overlap between operating channels of neighboring APs. If the total available bandwidth and the set of APs are fixed, then when the channel bandwidth is increased the number of non-overlapping channels may be correspondingly decreased, e.g., so that the distance between APs using the same channel also decreases. Thus, in the network shown above in FIG. 2, if wide signal bandwidths such as up to 320 MHz are used, the APs may operate using at least partially overlapping channels.

Power saving (PS) at APs in IEEE 802. J J WLANs

Typical APs of today consume significant power (e.g., tens of watts), and the power consumption is further emphasized for multi-link and multi-AP networks. Motivated by the worldwide attention and concerns related to sustainability, energy costs, etc., reducing AP power consumption has recently gained significant attention in IEEE 802.11 standardization discussions, especially in the IEEE 802.11 study group (SG) ultra high reliability (UHR), which may evolve into task group (TG) to develop the standard amendment that may define the future Wi-Fi 8.

The IEEE 802.11 WLAN standard and its recent major amendments already provide multiple standardized features for power consumption reduction at APs, by means of independent usage of these features by different APs while controlling communications in their respective basic service sets (BSSs). Additionally, in the UHR SG, some further AP PS features are being discussed, again by means of independent operations at APs.

The different AP PS features can broadly be categorized into two types:

• Type I, allowing larger power savings: where an AP intermittently pauses/ stops TX and RX operations with other devices and becomes inactive on one or more links to not consume any power or consume very little power (e.g., just enough to keep monitoring the operating channel),

• Type II, allowing lesser power savings: where an AP remains active but operates in reduced capability mode (e.g., reduced bandwidth) to consume lesser power than when operating in normal mode.

FIG. 3 shows a table that describes an example qualitative summary of different AP PS modes. The example table provides a qualitative summary of the different AP PS features that are already standardized or are being discussed in the UHR SG.

AP coordination in IEEE 802.11 WLANs

AP coordination to share reserved time and/or frequency and/or spatial resources, was an important candidate feature for IEEE 802.11 TGbe (i.e., developing a standard amendment for Wi-Fi 7). Many different multi-AP schemes were proposed having different underlying complexities, such as: Coordinated TDMA, Time Division Multiple Access (C-TDMA), Coordinated OFDMA, Orthogonal Frequency Division Multiple Access (C-OFDMA), Coordinated Spatial Reuse (C-SR), Coordinated Beamforming (C-BF), and Joint Transmissions (JT). Despite having different complexities, in all these schemes, a fundamental idea may be that an AP obtaining a (time-frequency) transmit opportunity (TXOP), i.e., a sharing AP, may share its TXOP with other APs, i.e., shared APs, in different manners to improve the overall throughput and/ or latency in multi-AP networks.

Thus, AP coordination is a topic in the UHR SG and a very strong candidate feature for future Wi-Fi 8. However, a key difference compared to the discussions in TGbe is the emphasis and focus on achieving simple AP coordination, without large overheads or complexities. Despite the multiple AP PS features, some key issues still remain to be addressed, especially for multi-AP networks:

• Some AP PS features are not discussed in IEEE 802.11, such as features that can be used to reduce the overall power consumption across multiple APs in a coordinated manner. For example, PS features are applicable for independently operating APs;

• If the data traffic is event-based and/or non-deterministic, APs cannot use the Type I AP PS features such that they can turn OFF or minimize their power consumption; o If APs were to use the Type I AP PS features, the associated non-AP devices would experience unacceptable service outages, especially if there are strict QoS requirements;

• If a currently unassociated non-AP device attempts to associate with some AP by means of active scanning (e.g., using probe request frames) or passive scanning (e.g., by trying to detect beacon frames), and if all APs in its range are currently in OFF state due to PS, the currently unassociated non-AP device may not be able to associate until at least one of them becomes available in ON state; and

• If a mobile non-AP device moves from its associated and currently ON AP’s coverage area to a currently OFF AP’s coverage area, the mobile non-AP device may face unfavorable service interruption due to delays while associating to the new AP.

SUMMARY

Aspects are provided in the independent claims, and embodiments thereof are provided in the dependent claims.

Some embodiments advantageously provide methods, systems, and apparatuses for coordination and/or scheduling of one or more steps (e.g., transmission/reception of signaling) associated with multiple APs.

One or more embodiments describe performing one or more steps to achieve PS at APs in a multi-AP network by means of coordination between two, or more, neighboring APs.

In one embodiment, a first AP shares its planned PS schedule describing upcoming ON and OFF time periods with a neighbor AP having an overlapping coverage area so that the neighboring AP can take appropriate actions while scheduling its own PS schedule, if any. In another embodiment, based on the information provided by the first AP, the neighbor AP may schedule its ON and OFF time periods such that at any time instance, at least one of the two APs is active and available to communicate with non-AP devices.

In some embodiments, a first AP sets up a ‘backup AP’ agreement with another AP, where the agreement includes the other AP acting as a stand-in ‘backup AP’ for serving the non-AP devices associated with the first AP during OFF time periods of the first AP. Multiple related embodiments are provided to detail aspects such as possible constraints for the communication with a backup AP, considerations for selection of a backup AP, information sharing with associated non-AP devices, etc.

The following is a nonlimiting list of example embodiments:

1. A method for coordination among a group of access points (AP) comprising a first AP and at least one other second AP, wherein: a. the first AP sends a first message to a second AP, the first message including information indicating the first AP’s preliminary planned power saving (PS) schedule aimed for reducing its own power consumption, wherein the PS schedule includes upcoming ON and OFF time periods of the first AP when it would be available or unavailable, respectively, for communicating with other devices, b. upon successfully receiving the first message, the second AP responds with a second message, the second message at least acknowledging the receipt of the first message.

2. The method of Embodiment 1, wherein the second message further includes: a. Either an acknowledgment of the first AP’s preliminary planned PS schedule, thereby resulting in it becoming the final planned PS schedule of the first AP; or b. a suggested modification to the first AP’ s preliminary planned PS schedule, thereby resulting in a modified final planned PS schedule of the first AP.

3. The method of Embodiment 2.b., wherein the first AP sends a third message to the second AP to notify regarding its final planned PS schedule.

4. The method of any one of Embodiments 1-3, wherein the second AP sets up its own PS schedule at least in part based on the planned PS schedule of the first AP.

5. The method of any one of Embodiments 1-4, wherein the first AP and the second AP align their respective PS schedules such that during one or more time instances, there is at least one AP turned ON and available for communicating with other devices.

6. The method of Embodiment 5, wherein alignment of the PS schedules is: a. explicitly and mutually agreed upon between the first AP and the second AP; or b. is based upon planning and decisions made by the APs without any explicit related agreement, however taking into account the PS schedule related information shared between them.

7. The method of any one of Embodiments 1-6, wherein the first AP sets up a ‘backup AP’ agreement with the second AP, wherein the agreement comprises the second AP acting as a stand-in ‘backup AP’ for serving the non-AP devices associated with the first AP during one or more OFF time periods of the first AP.

8. The method of Embodiment 7, wherein the ‘backup AP’ agreement involves communication constraints regarding any potential communication between the backup AP and the non-AP devices associated with the first AP, wherein the communication constraints are about one or more out of the following: a. the allowed direction of data communication - downlink, uplink, or both; b. the allowed type of data, e.g. - in terms of access category, AC, or traffic identifier (TID); c. the allowed type of communication, e.g. - interrupt-only; emergency-only, scheduled-only, both unscheduled and scheduled, etc.; and d. the allowed communication parameters, e.g. - transmit powers, modulation and coding schemes, primary 20 MHz transmission channel, transmission bandwidth, number of spatial streams, etc.

9. The method of any one of Embodiments 7 or 8, wherein the first AP sets up multiple ‘backup AP’ agreements with different APs corresponding to different OFF time periods.

10. The method of any one of Embodiments 7-9, wherein the first AP sets up multiple ‘backup AP’ agreements involving different backup APs serving different sets of associated non-AP devices during the same one or more OFF time periods.

11. The method of any one of Embodiments 7-10, wherein selection of a backup AP is at least partly based on one or more out of the following: a. the quality of service, QoS, requirements (e.g., acceptable QoS degradation) corresponding to one or more key non-AP devices associated with the first AP, wherein example of key non-AP devices could be devices that have the strictest QoS requirements; b. measurement reports (e.g., neighbor report, beacon report) or information collected by the first AP from the non-AP devices associated with it; c. positioning information available at the first AP; and d. measurement reports (e.g., channel load report) or information collected by the first AP from its neighboring APs.

12. The method of any one of Embodiments 7-11, wherein the first AP shares information with its associated non-AP devices via signaling, wherein the shared information includes: a. the final planned PS schedule of the first AP, and b. the identity (e.g., ID) of the one or more backup APs; and c. the communication constraints, if any, corresponding to the one or more backup APs.

13. The method of any one of Embodiments 7-12, wherein the primary 20 MHz sub -channel (s) of the one or more backup APs is(are) within the operating channel/ bandwidth of the first AP.

14. The method of any one of Embodiments 1-13, wherein while requesting or instructing a currently associated non-AP device to handover to a neighboring AP or one among a group of neighboring APs, an AP shares with the non-AP device the planned PS schedule of the neighboring one or more APs to which the non-AP device may attempt to associate with.

15. The method of any one of Embodiments 1-14, wherein if the first AP is communicating with two or more second APs and at least two out of them send the second message, they do so in FDMA fashion (i.e., simultaneously using different frequency resources) or TDMA (i.e., one after the other) fashion.

One or more embodiments ensure that associated client devices can consistently and reliably find a backup AP ready to serve them in case the currently associated AP turns OFF as planned, or even in case of sudden failure of the currently associated AP. This is especially attractive in scenarios when the data traffic is event-based and/or non-deterministic. Non-associated client devices may find with high probability at least one active AP to attempt to connect to, at any time, for example even during non-busy hours. Further, by leveraging coordination across multiple APs in a multi-AP network, one or more embodiments enable power savings at APs without causing large performance impact or severe service outages for client devices.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 shows an example of a multi-AP deployment with seven APs and corresponding hexagonal cells;

FIG. 2 shows an example of a multi-AP network;

FIG. 3 shows a table that describes an example qualitative summary of different AP PS modes;

FIG. 4 is a schematic diagram of an example network architecture illustrating a communication system according to the principles in the present disclosure;

FIG. 5 is a block diagram of an AP communicating with a non-AP STA over an at least partially wireless connection according to some embodiments of the present disclosure;

FIG. 6 is a schematic diagram of an example network architecture illustrating a communication system connected via an intermediate network to a host computer according to the principles in the present disclosure;

FIG. 7 is a block diagram of a host computer communicating via an access point with a non-AP STA over an at least partially wireless connection according to some embodiments of the present disclosure;

FIG. 8 is a flowchart illustrating example methods implemented in a communication system including a host computer, an access point and a non-AP STA for executing a client application at a non-AP STA according to some embodiments of the present disclosure;

FIG. 9 is a flowchart illustrating example methods implemented in a communication system including a host computer, an access point and a non-AP STA for receiving user data at a non-AP STA according to some embodiments of the present disclosure; FIG. 10 is a flowchart illustrating example methods implemented in a communication system including a host computer, an access point and a non-AP STA for receiving user data from the non-AP STA at a host computer according to some embodiments of the present disclosure;

FIG. 11 is a flowchart illustrating example methods implemented in a communication system including a host computer, an access point and a non-AP STA for receiving user data at a host computer according to some embodiments of the present disclosure; and

FIG. 12 is a flowchart of an example process in an AP STA according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to coordination and/or scheduling of one or more steps (e.g., transmission/reception of signaling) associated with multiple APs. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections.

In some embodiments, the term “access point” or “AP” is used interchangeably and may comprise, or be, a network node. The AP may include any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), relay node, integrated access and backhaul (IAB), donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The AP may also comprise test equipment. The AP may comprise a radio router, a radio transceiver, Wi-Fi access point, wireless local area network (WLAN) access point, a network controller, etc.

In some embodiments, the non-limiting term “device” is used to describe a wireless device (WD) and/or user equipment (UE) that may be used to implement some embodiments of the present disclosure. In some embodiments, the device may be and/or comprise an access point (AP) station (STA). In some embodiments, the device may be and/or comprise a non-access point station (non-AP STA). In some embodiments, the device may be any type of device capable of communicating with a network node, such as an AP, over radio signals. The device may be any radio communication device, target device, a portable device, device-to-device (D2D) device, machine type device or device capable of machine to machine communication (M2M), low-cost and/or low-complexity device, a sensor equipped with a device, a computer, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (loT) device, or a Narrowband loT (NB-IOT) device, Reduced Capability (RedCap) device, etc.

A device may be considered a network node and may include physical components, such as processors, allocated processing elements, or other computing hardware, computer memory, communication interfaces, and other supporting computing hardware. The network node may use dedicated physical components, or the node may be allocated use of the physical components of another device, such as a computing device or resources of a datacenter, in which case the network node is said to be virtualized. A network node may be associated with multiple physical components that may be located either in one location, or may be distributed across multiple locations.

Even though the descriptions herein may be explained in the context of one of a Downlink (DL) and an Uplink (UL) communication, it should be understood that the basic principles disclosed may also be applicable to the other of the one of the DL and the UL communication. In some embodiments in this disclosure, the principles may be considered applicable to a transmitter (e.g., a first STA) and a receiver (e.g., a second STA). For DL communication, a first STA may be the transmitter and the receiver is the second STA. For the UL communication, the transmitter may be the first STA and the receiver is the STA. In some embodiments, the first STA may be an AP or non-AP STA, and the second STA may be an AP or a non-AP STA.

In some embodiments, AP refers to single link AP devices as well as more advanced multi-link capable AP devices. In some other embodiments, STA refers to single link non-AP client devices as well as more advanced multi-link capable non-AP client devices. In some other embodiments, “ON AP” refers to a currently active AP that is available for communicating (i.e., transmit (TX) and receive (RX)) with other devices due to, e.g., being in an ON state during ongoing PS operations. In some embodiments, “OFF AP” refers to a currently inactive AP that is unavailable for communicating with other devices due to, e.g., being in an OFF state during ongoing PS operations.

Note also that some embodiments of the present disclosure may be supported by an IEEE 802.11 standard. IEEE 802.11 denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE 802.11 committee for short- range communications (e.g., tens of meters to a few hundred meters). Some embodiments may also be supported by standard documents disclosed in Third Generation Partnership Project (3GPP) technical specifications. That is, some embodiments of the description can be supported by the above documents (e.g., standard documents). In addition, all the terms disclosed in the present document may be described by the above standard documents.

Note that although terminology from one particular wireless system, such as, for example, IEEE 802.11, 3rd Generation Partnership Project (3GPP), Long Term Evolution (LTE), 5th Generation (5G) and/or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

Note further, that functions described herein as being performed by one or more of a first STA, second STA, transmitting STA, receiving STA, AP, non-AP STA, wireless device, network node, etc., may be distributed over a plurality of STAs, APs, non-AP STAs, wireless devices, network nodes, etc. In other words, it is contemplated that the functions of the devices described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 4 a schematic diagram of the communication system 10, according to one embodiment, constructed in accordance with the principles of the present disclosure. The communication system 10 in FIG. 4 is a non-limiting example and other embodiments of the present disclosure may be implemented by one or more other systems and/or networks. Referring to FIG. 4, system 10 may comprise a wireless local area network (WLAN). The devices in the system 10 may communicate over one or more spectrums, such as, for example, an unlicensed spectrum, which may include frequency bands typically used by Wi-Fi technology. One or more of the devices may be further configured to communicate over other frequency bands, such as shared licensed frequency bands, etc. The system 10 may include one or more service areas 12a, 12b, etc. (collectively referred to herein as “service area 12”), which may be defined by corresponding access points (APs) STAs 14a, 14b, etc. (collectively referred to herein as “AP STA 14”). A service area 12 may also correspond to and/or be associated with a coverage area, a cell, and/or a basic service set (BSS).

The AP STA 14 may or may not be connectable to another network, such as a core network over a wired or wireless connection. The system 10 includes a plurality of non-AP devices, such as, for example, non-AP STAs 16a, 16b, 16c (collectively referred to as non-AP STAs 16). Each of the non-AP STAs 16 may be located in one or more service areas 12 and may be configured to wirelessly connect to one or more AP STA 14. Note that although two AP STAs 14a and 14b and two non-AP STAs 16a and 16b are shown for convenience, the communication system may include many more non-AP STAs 16 and AP STAs 14. Each AP STA 14 may connect to/serve/configure/schedule/etc. one or more non-AP STAs 16.

It should be understood that the system 10 may include additional nodes and/or devices not shown in FIG. 4. In addition, the system 10 may include many more connections and/or interfaces than those shown in FIG. 4. Thus, the elements shown in FIG. 4 are presented for ease of understanding.

Also, it is contemplated that a non-AP STA 16 can be in communication and/or configured to separately communicate with more than one AP STA 14 and/or more than one type of AP STA 14. Furthermore, an AP STA 14 may be in communication and/or configured to separately communicate with other AP STAs 14, as described herein, which may be via wired and/or wireless communication channels.

A non-AP STA 16 is configured to include a non-AP STA Management Unit 17, which is configured to perform one or more non-AP STA 16 functions described herein. An AP STA 14 is configured to include an AP STA Management Unit 18, which is configured to perform one or more AP STA 14 functions described herein.

Example implementations, in accordance with an embodiment, of the AP STA 14 and non-AP STA 16 discussed in the preceding paragraphs will now be described with reference to FIG. 5. An AP STA 14 or a non-AP STA 16 may be generally referred to as a STA 19. For example, a first STA 19a may be an AP STA 14, and a second STA 19b may be a non-AP STA 16. System 10 may include one or more additional STAs 19n (which include AP STAs 14 and/or non-AP STAs 16), which may be in communication with STA 19a and/or STA 19b.

The AP STA 14 includes hardware 20 including a communication interface 22, processing circuitry 24, a processor 26, and memory 28. The communication interface 22 may be configured to communicate with any of the nodes/devices in the system 10 according to some embodiments of the present disclosure, such as with one or more other AP STAs 14 and/or one or more non-AP STAs 16. In some embodiments, the communication interface 22 may be formed as or may include, for example, one or more radio frequency (RF) transmitters, one or more RF receivers, and/or one or more RF transceivers, and/or may be considered a radio interface. In some embodiments, the communication interface 22 may also include a wired interface.

The processing circuitry 24 may include one or more processors 26 and memory, e.g., memory 28. In addition to a processor 26 and memory 28, the processing circuitry 24 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 26 may be configured to access (e.g., write to and/or read from) the memory 28, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

The AP STA 14 may further include software 30 stored internally in, for example, memory 28, or stored in external memory (e.g., database) accessible by the AP STA 14 via an external connection. The software 30 may be executable by the processing circuitry 24. The processing circuitry 24 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., AP STA 14. The memory 28 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 30 may include instructions stored in memory 28 that, when executed by the processor 26 and/or AP STA Management Unit 18 causes the processing circuitry 24 and/or configures the AP STA 14 to perform the processes described herein with respect to the AP STA 14.

Referring still to FIG. 5, the non-AP STA 16 includes hardware 32, which may include a communication interface 34, processing circuitry 36, a processor 38, and memory 40. The communication interface 34 may be configured to communicate with one or more AP STA 14 and/or other STA 19n, such as via wireless connection 35, and/or with other elements in the system 10, according to some embodiments of the present disclosure. In some embodiments, the communication interface 34 may be formed as or may include, for example, one or more radio frequency (RF) transmitters, one or more RF receivers, and/or one or more RF transceivers, and/or may be considered a radio interface. In some embodiments, the communication interface 34 may also include a wired interface. In some embodiments, AP STA 14 may be configured to communicate with another AP STA 14, non-AP STA 16, and/or STA 19n via wireless connection 35 and/or via a wired connection (not shown).

The processing circuitry 36 may include one or more processors 38 and memory, such as, the memory 40. Furthermore, in addition to a traditional processor and memory, the processing circuitry 36 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 38 may be configured to access (e.g., write to and/or read from) the memory 40, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the non-AP STA 16 may further include software 42 stored internally in, for example, memory 40, or stored in external memory (e.g., database) accessible by the non-AP STA 16 via an external connection. The software 42 may be executable by the processing circuitry 36. The processing circuitry 36 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by the non-AP STA 16. The memory 40 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software may include instructions stored in memory 40 that, when executed by the processor 38 and/or non-AP STA Management Unit 17, causes the processing circuitry 36 and/or configures the non-AP STA 16 to perform the processes described herein with respect to the non-AP STA 16.

In FIG. 5, the connection between the STAs 19 (i.e., AP STA 14, the non-AP STA 16, and STA 19n) is shown without explicit reference to any intermediary devices or connections. However, it should be understood that intermediary devices and/or connections may exist between these devices, although not explicitly shown.

Although FIG. 5 shows non-AP STA Management Unit 17 and AP STA Management Unit 18, as being within a processor, it is contemplated that this element may be implemented such that a portion of the element is stored in a corresponding memory within the processing circuitry. In other words, the element may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

FIG. 6 is a schematic diagram of a communication system 10, according to another embodiment of the present disclosure. In the example of FIG. 6, the access point STA 14 and non-AP STAs 16 may be similar to those of the example of FIG. 4, described herein. Additionally, in the example of FIG. 6, one or more AP STAs 14 and/or non-AP STAs 16 may form and/or be part of a service set network 44 (e.g., a basic service set, or any other network, set, and/or grouping of AP STAs 14 and non- AP STAs 16). The communication system 10 and/or service set network 44 may itself be connected to a host computer 46, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 46 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 48, 50 between the communication system 10 and/or the service set network 44 and the host computer 46 may extend directly from the service set network 44 to the host computer 46 or may extend via an optional intermediate network 52. The intermediate network 52 may be one of, or a combination of more than one of, a public, private or hosted network. The intermediate network 52, if any, may be a backbone network or the Internet. In some embodiments, the intermediate network 52 may comprise two or more sub-networks (not shown).

The communication system of FIG. 6 as a whole enables connectivity between one of the connected non-AP STAs 16 and the host computer 46. The connectivity may be described as an over-the-top (OTT) connection. The host computer 46 and the connected non AP-STAs 16 are configured to communicate data and/or signaling via the OTT connection, using the service set network 44, any intermediate network 52 and possible further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that at least some of the participating communication devices through which the OTT connection passes are unaware of routing of uplink and downlink communications. For example, an AP STA 14 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 46 to be forwarded (e.g., handed over) to a connected non-AP STA 16. Similarly, the AP STA 14 need not be aware of the future routing of an outgoing uplink communication originating from the non-AP STA 16 towards the host computer 46.

Example implementations, in accordance with an embodiment, of the non-AP STA 16, AP STA 14, and host computer 46 discussed in the preceding paragraphs will now be described with reference to FIG. 7. In the example of FIG. 7, the AP STA 14 and the non-AP STA 16 may have similar features and components as the AP STA 14 and non-AP STA 16 depicted in FIG. 5. Additionally, the host computer 46 comprises hardware (HW) 53 including a communication interface 54 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 10. The host computer 46 further comprises processing circuitry 56, which may have storage and/or processing capabilities. The processing circuitry 56 may include a processor 58 and memory 60. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 56 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 58 may be configured to access (e.g., write to and/or read from) memory 60, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Processing circuitry 56 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by host computer 46. Processor 58 corresponds to one or more processors 58 for performing host computer 46 functions described herein. The host computer 46 includes memory 60 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 62 and/or the host application 64 may include instructions that, when executed by the processor 58 and/or processing circuitry 56, causes the processor 58 and/or processing circuitry 56 to perform the processes described herein with respect to host computer 46. The instructions may be software associated with the host computer 46.

The software 62 of host computer 46 may be executable by the processing circuitry 56. The software 62 includes a host application 64. The host application 64 may be operable to provide a service to a remote user, such as a non-AP STA 16 connecting via an OTT connection 66 terminating at the non-AP STA 16 and the host computer 46. In providing the service to the remote user, the host application 64 may provide user data which is transmitted using the OTT connection 66. The “user data” may be data and information described herein as implementing the described functionality. In one embodiment, the host computer 46 may be configured for providing control and functionality to a service provider and may be operated by the service provider or on behalf of the service provider. The processing circuitry 56 of the host computer 46 may enable the host computer 46 to observe, monitor, control, transmit to and/or receive from the AP STA 14 and/or the non-AP STA 16. The processing circuitry 56 of the host computer 46 may include a host management unit 68 configured to enable the service provider to observe/monitor/control/transmit to/receive from/configure/etc. the AP STA 14 and/or the non-AP STA 16.

The communication interface 22 of AP STA 14 may be configured to facilitate a connection 66 to the host computer 46. The connection 66 may be direct or it may pass through a service set network 44 of the communication system 10 and/or through one or more intermediate networks 52 outside the communication system 10. The communication interface 34 of non-AP STA 16 may be configured to facilitate a connection 66 to the host computer 46. The connection 66 may be direct or it may pass through a service set network 44 of the communication system 10 and/or through one or more intermediate networks 52 outside the communication system 10.

The software 42 of non-AP STA 16 may include a client application 70. The client application 70 may be operable to provide a service to a human or non-human user via the non-AP STA 16, with the support of the host computer 46. In the host computer 46, an executing host application 64 may communicate with the executing client application 70 via the OTT connection 66 terminating at the non-AP STA 16 and the host computer 46. In providing the service to the user, the client application 70 may receive request data from the host application 64 and provide user data in response to the request data. The OTT connection 66 may transfer both the request data and the user data. The client application 70 may interact with the user to generate the user data that it provides.

In some embodiments, the inner workings of the AP STA 14, non-AP STA 16, and host computer 46 may be as shown in FIG. 6 and independently, the surrounding network topology may be that of FIG. 7.

In FIG. 7, the OTT connection 66 has been drawn abstractly to illustrate the communication between the host computer 46 and the non-AP STA 16 via the AP STA 14, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the non-AP STA 16 or from the service provider operating the host computer 46, or both. While the OTT connection 66 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

The wireless connection 35 between the non-AP STA 16 and the AP STA 14 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the non-AP STA 16 using the OTT connection 66, in which the wireless connection 35 may form the last segment. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc.

In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 66 between the host computer 46 and non-AP STA 16, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 66 may be implemented in the software 62 of the host computer 46 or in the software 42 of the non-AP STA 16, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 66 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 62, 42 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 66 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the AP STA 14, and it may be unknown or imperceptible to the AP STA 14. Some such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary wireless device signaling facilitating the host computer’s 46 measurements of throughput, propagation times, latency and the like. In some embodiments, the measurements may be implemented in that the software 62, 42 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 66 while it monitors propagation times, errors, etc.

Thus, in some embodiments, the host computer 46 includes processing circuitry 56 configured to provide user data and a communication interface 54 that is configured to forward the user data to a wireless network and/or cellular network for transmission to the non-AP STA 16. In some embodiments, the wireless network and/or cellular network also includes the AP STA 14 with a communication interface 22. In some embodiments, the AP STA 14 is configured to, and/or the AP STA 14 processing circuitry 24 is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the non-AP STA 16, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the non-AP STA 16.

In some embodiments, the host computer 46 includes processing circuitry 56 and a communication interface 54 that is configured to receive user data originating from a transmission from a non-AP STA 16 to an AP STA 14. In some embodiments, the non-AP STA 16 is configured to, and/or comprises a communication interface 34 and/or processing circuitry 36 configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the AP STA 14, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the AP STA 14.

FIG. 8 is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of FIGS. 4 and 5, in accordance with one embodiment. The communication system may include a host computer 46, an AP STA 14 and a non-AP STA 16, which may be those described with reference to FIG. 7. In a first step of the method, the host computer 46 provides user data (Block SI 00). In an optional substep of the first step, the host computer 46 provides the user data by executing a host application, such as, for example, the host application 64 (Block SI 02). In a second step, the host computer 46 initiates a transmission carrying the user data to the non-AP STA 16 (Block SI 04). In an optional third step, the AP STA 14 transmits to the non-AP STA 16 the user data which was carried in the transmission that the host computer 46 initiated, in accordance with the teachings of the embodiments described throughout this disclosure (Block SI 06). In an optional fourth step, the non-AP STA 16 executes a client application, such as, for example, the client application 70, associated with the host application 64 executed by the host computer 46 (Block SI 08).

FIG. 9 is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of FIG. 7, in accordance with one embodiment. The communication system may include a host computer 46, an AP STA 14 and a non-AP STA 16, which may be those described with reference to FIGS. 4 and 5. In a first step of the method, the host computer 46 provides user data (Block SI 10). In an optional substep (not shown) the host computer 46 provides the user data by executing a host application, such as, for example, the host application 64. In a second step, the host computer 46 initiates a transmission carrying the user data to the non-AP STA 16 (Block SI 12). The transmission may pass via the AP STA 14, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the non-AP STA 16 receives the user data carried in the transmission (Block SI 14).

FIG. 10 is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of FIG. 7, in accordance with one embodiment. The communication system may include a host computer 46, an AP STA 14 and a non-AP STA 16, which may be those described with reference to FIGS. 4 and 5. In an optional first step of the method, the non-AP STA 16 receives input data provided by the host computer 46 (Block SI 16). In an optional substep of the first step, the non-AP STA 16 executes the client application 70, which provides the user data in reaction to the received input data provided by the host computer 46 (Block SI 18). Additionally or alternatively, in an optional second step, the non-AP STA 16 provides user data (Block S120). In an optional substep of the second step, the non-AP STA 16 provides the user data by executing a client application, such as, for example, client application 70 (Block S122). In providing the user data, the executed client application 70 may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the non-AP STA 16 may initiate, in an optional third substep, transmission of the user data to the host computer 46 (Block S124). In a fourth step of the method, the host computer 46 receives the user data transmitted from the non-AP STA 16, in accordance with the teachings of the embodiments described throughout this disclosure (Block S126).

FIG. 11 is a flowchart illustrating an exemplary method implemented in a communication system, in accordance with one embodiment. The communication system may include a host computer 46, an AP STA 14 and a non-AP STA 16, which may be those described with reference to FIGS. 4 and 5. In an optional first step of the method, in accordance with the teachings of the embodiments described throughout this disclosure, the AP STA 14 receives user data from the non-AP STA 16 (Block S128). In an optional second step, the AP STA 14 initiates transmission of the received user data to the host computer 46 (Block S130). In a third step, the host computer 46 receives the user data carried in the transmission initiated by the AP STA 14 (Block S132).

FIG. 12 is a flowchart of an example process in a first STA 19 such as a first AP STA 14a. One or more Blocks and/or functions and/or methods performed by the first AP STA 14a may be performed by one or more elements of the first AP STA 14a such as by AP STA Management Unit 18 in processing circuitry 24, memory 28, processor 26, communication interface 22, etc. according to the example process/method. The first AP STA 14a is configured to cause transmission (Block S134) of a first message to the second AP STA 14b, where the first message includes information indicating the first AP STA’s preliminary planned power saving (PS) schedule aimed for reducing power consumption of the first AP STA 14a, and the PS schedule includes upcoming time periods of the first AP STA 14a when the first AP STA 14a is available or unavailable for communicating with other devices; and receive (Block SI 36), from the second AP STA 14b, a second message a least acknowledging receipt of the first message.

In some embodiments, the second message further includes an acknowledgment of the first AP STA’s preliminary planned PS schedule, where the first AP STA’s preliminary planned PS schedule becomes a final planned PS schedule of the first AP STA 14a; or a suggested modification to the first AP STA’s preliminary planned PS schedule. The first AP STA’s final planned PS schedule is different than the first AP STA’s preliminary planned PS schedule.

In some other embodiments, the method further includes transmitting a third message to the second AP STA 14b indicating the final planned PS schedule.

In some embodiments, the second AP STA 14b is configured to set up its own PS schedule at least in part based on the planned PS schedule of the first AP STA 14a.

In some other embodiments, the first AP STA 14a and the second AP STA 14b are configured to align their respective PS schedules, to have at least one of the first AP STA 14a and the second AP STA 14b turned ON and available for communicating with other devices.

In some embodiments, the alignment is explicitly and mutually agreed upon between the first AP STA 14a and the second AP STA 14b; or based upon planning and decisions made by the first and second AP STAs without any explicit related agreement and being based on PS schedule information shared between the first and second AP STAs 14a, 14b.

In some other embodiments, the method further includes setting up a backup AP agreement with the second AP STA 14b, where the backup AP agreement includes a rule usable by the second AP STA 14b to act as a stand-in backup AP for serving non- AP STAs 14 associated with the first AP STA 14a during one or more OFF time periods of the first AP STA 14a.

In some embodiments, the backup AP agreement involves communication constraints regarding any potential communication between a backup AP STA 14 and the non-AP STAs 16 associated with the first AP STA 14a, where the communication constraints are associated with one or more of an allowed direction of data communication, an allowed type of data, an allowed type of communication, and allowed communication parameters.

In some other embodiments, the method further includes setting up multiple backup AP agreements with different AP STAs 14 corresponding to different OFF time periods.

In some embodiments, the method further includes setting up additional multiple backup AP agreements involving different backup AP STAs 14 serving different sets of associated non-AP STAs 16 during the same one or more OFF time periods. In some other embodiments, selection of a backup AP STA 14 is at least partly based on one or more out of the following the quality of service (QoS) requirements corresponding to one or more key non-AP STAs 14 associated with the first AP STA 14a, measurement reports or information collected by the first AP STA 14a from the one or more non-AP STAs 16 associated with it, positioning information available at the first AP STA 14a, and other measurement reports or other information collected by the first AP STA 14a from its neighboring AP STAs 14.

In some embodiments, the method further includes sharing information with its associated non-AP STAs 16 via signaling including the final planned PS schedule of the first AP STA 14a, the identity of the one or more backup APs STAs 14, and the communication constraints corresponding to the one or more backup AP STAs 14.

In some other embodiments, primary 20 MHz sub-channels of the one or more backup AP STAs 14 are within an operating channel and/or bandwidth of the first AP STA 14a.

In some embodiments, while requesting or instructing a currently associated non-AP STA 16 to handover to a neighboring AP STA 14 or one among a group of neighboring AP STAs 14, one AP STA shares with the non-AP STAs 16 the planned PS schedule of the neighboring one or more AP STAs 14 to which the non-AP STA 16 is configured to associate with.

In some other embodiments, if the first AP STA 14a is communicating with two or more of the at least second AP STA 14b and at least two of the at least second AP STA 14b send the second message, the second message is transmitted based on a frequency division multiple access (FDMA) process or a time division multiple access (TDM A) process.

Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for coordination and/or scheduling of one or more steps (e.g., transmission/reception of signaling) associated with multiple APs.

One or more embodiments are described as applied to a wireless communication system based on the IEEE 802.11 WLAN standard. However, the embodiments herein are not limited as such and may apply to any other standard and/or communication protocols and/or technology. In some embodiments, power savings is achieved at APs in a multi-AP network by coordinating between APs and without causing performance impact (e.g., exceeding predetermined impact thresholds) or severe outages for client devices (e.g., that exceed a predetermined outage threshold).

Further, one or more embodiments describe AP STAs 14. However, the embodiments are not limited as such and may be appliable to non-AP STAs 16, STAs 19 or any other device.

Main Embodiment

In one embodiment (e.g., main embodiment), a method for coordination among a group of AP STAs 14 is described. The group of AP STAs 14 may include a first AP STAs 14a and at least one other second AP STA 14b. The first AP STA 14a may share its own PS schedule related information with a second AP STA 14b.

Specifically, the first AP STA 14a sends a first message to a second AP STA 14b, where the first message includes information indicating the first AP’s preliminary planned PS schedule, e.g., aimed for reducing its own power consumption. The PS schedule includes upcoming ON and OFF time periods of the first AP STA 14a when it would be available or unavailable, respectively, for communicating with other devices. Upon successfully receiving the first message, the second AP STA 14b responds with a second message, where the second message at least acknowledges the receipt of the first message. In another embodiment, the second message further includes: a) Either an acknowledgment of the first AP’s preliminary planned PS schedule, which may result in the final planned PS schedule of the first AP STA 14a; or b) a suggested modification to the first AP’s preliminary planned PS schedule, which may result in a modified final planned PS schedule of the first AP STA 14a.

In case b), the first AP STA 14a may send a third message to the second AP STA 14b to notify regarding its final planned PS schedule.

In some embodiments, the second AP STA 14b sets up its own PS schedule at least in part based on the planned PS schedule of the first AP STA 14a.

In some other embodiments, it is proposed that if the first AP STA 14a is communicating with two or more second AP STAs 14b and at least two of them send the second message, they do so in FDMA fashion (i.e., simultaneously using different frequency resources) or TDMA (i.e., one after the other) fashion.

In a nonlimiting example, a pair of APs STAs 14 include a first AP STA 14a and a second AP STA 14b, and : a) the first AP STA 14a sends a first message to the second AP STA 14b, where the first message includes information indicating the first AP’s preliminary planned PS schedule; and b) upon successfully receiving the first message, the second AP STA 14b responds with a second message which acknowledges both - the receipt of the first message as well as the planned PS schedule informed by the first AP STA 14a, thereby becoming the final planned PS schedule of the first AP STA 14a.

At least one embodiment (e.g., main embodiment) may be beneficial at least during handover for client devices (e.g., non-AP STAs 16), when the client devices move from being associated to one AP to being associated with another AP.

In some embodiments, if the handover process is based on concepts such as BSS transition management introduced in the IEEE 802.1 Iv amendment where an AP STA 14 can request its client device (e.g., no-AP STA 16) to transition to another AP STA 14 or to one among a set of other APs STAs 14, the requesting AP STA 14 shares the planned PS schedule of the other one or more AP STAs 14 with the client device such that the client device can make better-informed decisions on which of the other AP STAs 14 to try and associate with - preferably choosing an AP STA 14 that would be ON and available when the handover attempt is performed.

Key sub-embodiment 1:

In another embodiment (e.g., the first key sub-embodiment), based on the PS schedule related information, multiple AP STAs 14 align their respective PS schedules such that one or more (e.g., at most or all) time instances, there is at least one AP STA 14 turned ON and available for communicating with other devices. Such an alignment can either be explicitly and mutually agreed upon between the coordinating AP STAs 14, or can be based upon planning and decisions made by the AP STAs 14 without any explicit related agreement, however taking into account the PS schedule related information shared between them.

A key benefit of this sub-embodiment is that non-associated client devices may find with high probability at least one ON and available AP STAs 14 to attempt to connect to by using active or passive scanning, at any time (e.g., even during non-busy hours). This may help avoiding or minimizing occurrences of unfavorable delays during association such as due to all AP STAs 14 being OFF and unavailable. If the first AP STA 14a shares its own PS schedule with the second AP STA 14b and the second AP STA 14b performs similar sharing with the first AP STA 14a, the two AP STAs 14 could further mutually agree to align their PS schedules.

Key sub-embodiment 2:

In one embodiment (e.g., the second key sub-embodiment), coordinating AP STAs 14 set up ‘backup AP’ agreements among each other, where the ‘backup AP' agreements result at least one other AP STAs 14 acting as a stand-in ‘backup AP’ for serving the non-AP devices (e.g., non-AP STAs 16)associated with an AP STA 14 during one or more OFF time periods of that AP STA 14.

In a nonlimiting example, the first AP STA 14a sets up a ‘backup AP’ agreement with the second AP STA 14b, and the second AP STA 14b acts as the backup AP during all planned OFF time periods of the first AP STA 14a - whose information is shared by the first AP STA 14a with the second AP STA 14b by following the main embodiment.

In another embodiment, primary 20 MHz sub-channel(s) of the one or more backup APs is(are) within the operating channel/ bandwidth of the AP. With such an embodiment, it can be ensured that the non-AP devices (i.e., non-AP STAs 16) associated with an AP STA 14 that goes into OFF PS state would not have to switch to a completely different operating channel/ bandwidth to communicate with a backup AP.

Sub-embodiment related to communication constraints:

In a related sub-embodiment, the ‘backup AP’ agreement involves communication constraints regarding any potential communication between the backup AP STA 14 and the non-AP STAs 16 associated with the AP STA 14 for which backup is being set up, and the communication constraints are about one or more of the following: a) the allowed direction of data communication, e.g. downlink, uplink, or both; b) the allowed type of data, e.g. - in terms of access category, AC, or traffic identifier (TID); c) the allowed type of communication, e.g. - interrupt-only, emergency-only, scheduled-only, both unscheduled and scheduled, etc.; and d) the allowed communication parameters, e.g. - transmit powers, modulation and coding schemes, primary 20 MHz transmission channel, transmission bandwidth, number of spatial streams, etc. Sub-embodiments related to flexibility of ‘backup AP ’ agreements

In another sub-embodiment, an AP STA 14 may set up a ‘backup AP’ agreement with only one other AP STA 14, e.g., corresponding to one or more upcoming OFF time periods planned for a certain duration. In another sub-embodiment, an AP STA 14 could set up multiple ‘backup AP’ agreements with different AP STAs 14 corresponding to different OFF time periods. In yet another sub-embodiment, an AP STA 14 may set up multiple ‘backup AP’ agreements involving different backup APs serving different sets of associated non-AP STAs 16 during the same one or more OFF time periods.

The sub-embodiments discussed here may be very useful in scenarios such as those exemplified in FIGS. 1 and 2, wherein AP4 and AP3 respectively may leverage the availability of multiple neighboring APs which could potentially help as backup APs.

Sub-embodiments related to backup AP selection:

In another related sub-embodiment, selection of a backup AP STA 14 is at least partly based on the quality of service, QoS, requirements (e.g., acceptable QoS degradation) corresponding to one or more key non-AP STAs 16 associated with the AP STA 14 whose backup is being set up. Examples of key non-AP STAs 16 could be devices that have the strictest QoS requirements.

In yet another related sub-embodiment, selection of a backup AP STA 14 is at least partly based on measurement reports (e.g., neighbor report, beacon report) or information collected by the AP STA 14 for which backup is being set up from the non-AP STAs 16 associated with it, and/ or positioning information available at that AP STA 14. As an example usage, an AP STA 14 may propose a backup AP STA 14 to be the AP STA 14 among the one or more neighboring AP STAs 14 for which the strongest signal is received (on average) and/or by the largest number of non-AP STAs 16 associated with it.

In yet another related sub-embodiment, selection of a backup AP STA 14 is at least partly based on measurement reports (e.g., channel load report) or information collected by an AP STA 14 from the neighboring AP STAs 14. With such information, for example, an AP STA 14 may propose a backup AP STA 14 to be the AP STA 14 whose BSS is least loaded in terms of data traffic - thereby increasing the likelihood of good service for the non-AP STAs 16 when they may attempt to communicate with the backup AP STA 14. The sub-embodiments discussed here could again be useful in scenarios such as those exemplified in FIGS. 1 and 2 above, where AP4 and AP3 respectively could have the option to select a backup AP from multiple available neighboring APs.

Sub-embodiment related to signaling between an AP and its associated non-AP devices

In another sub-embodiment, an AP STA 14 shares information with its associated non-AP STAs 16 via signaling, where the shared information includes: a) the final planned PS schedule of the AP STA 14, and b) the identity (e.g., ID) of the one or more backup AP STA 14, and c) the communication constraints, if any, corresponding to the one or more backup AP STA 14.

Additional aspects

Communicating with a backup AP STA 14 may be a less time consuming procedure compared to a handover procedure (a STA can be for example already authenticated with the backup AP, typically the closest one among neighbor APs or the one with highest received signal strength) and the actual communications may be also more efficient from the immediate beginning (for example, some communication parameters may already be setup/leamed in advance between the backup AP and the STA, and/or the backup AP may accordingly select its communication parameters when it expects communications from non-AP devices associated with a neighbor AP).

Having a backup AP agreement, may be beneficial also in cases of AP’s failures (i.e., not planned OFF periods), as the STAs associated with the AP in failure may seamlessly associate with a neighbor backup AP without performing the whole handover procedure from scratch (i.e., with only some minimal required steps).

Aspects related to communication and interaction between coordinating APs

It may happen that some or all AP STAs 14 in a multi -AP network are connected to each other via a wired backhaul, and/or are managed by a central network controller entity (which may itself reside in one of the AP STAs 14). In such situations, some or all of the proposed communication and interaction between APs with respect to, e.g., sharing and aligning respective PS schedules, setting up backup AP agreements may be performed over the wired backhaul. Moreover, decisions such as those related to backup AP selection may be taken by the central network controller on behalf of one or more AP STAs 14. In such situations involving inter-AP communication and interaction via a wired backhaul, what would remain as over the air communication would be the communication and interaction between AP STAs 14 and non-AP STAs 16 (e.g., non-AP client devices) such as the aspects discussed in the signaling related embodiments above.

One or more embodiments may lead to clearly identifiable specification impact related to basic signaling protocols between communicating devices, e.g., between two or more access point devices, or between access point and non-access point devices. For example, appropriate signaling would need to be standardized to enable IEEE 802.11 WLAN compliant access points to undertake signaling between each other for coordinating for power saving purposes.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and/or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and/or functionality described herein may be performed by, and/or associated to, a corresponding module, which may be implemented in software and/or firmware and/or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD- ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following example embodiments.

Example Embodiments:

Embodiment Al . A first access point (AP) station (STA) configured for a coordination process among a group of AP STAs, the group of AP STAs comprising the first AP and at least a second AP STA, the first AP STA being configured to and/or comprising a communication interface and/or processing circuitry configured to: cause transmission of a first message to the second AP STA, the first message including information indicating the first AP STAs preliminary planned power saving (PS) schedule aimed for reducing power consumption of the first AP STA , the PS schedule including upcoming time periods of the first AP STA when the first AP STA is available or unavailable for communicating with other devices; and receive, from the second AP STA, a second message, the second message at least acknowledging receipt of the first message.

Embodiment A2. The first AP STA of Embodiment Al, wherein the second message further includes: an acknowledgment of the first AP STA’s preliminary planned PS schedule, the first AP STA’s preliminary planned PS schedule becoming a final planned PS schedule of the first AP STA; or a suggested modification to the first AP STA’s preliminary planned PS schedule, the first AP STA’s final planned PS schedule being different than the first AP STA’s preliminary planned PS schedule. Embodiment A3. The first AP STA of Embodiment A2, wherein the first AP STA is further configured to: cause transmission of a third message to the second AP STA indicating the final planned PS schedule.

Embodiment A4. The first AP STA of any one of Embodiments A1-A3, wherein the second AP STA is configured to set up its own PS schedule at least in part based on the planned PS schedule of the first AP STA.

Embodiment A5. The first AP STA of any one of Embodiments A1-A4, wherein the first AP STA and the second AP STA are configured to align their respective PS schedules, to have at least one of the first AP STA and the second AP STA turned ON and available for communicating with other devices during one or more time instances.

Embodiment A6. The first AP STA of Embodiment A5, wherein the alignment is: explicitly and mutually agreed upon between the first AP STA and the second AP STA; or based upon planning and decisions made by the first and second AP STAs without any explicit related agreement and being based on PS schedule information shared between the first and second AP STAs.

Embodiment A7. The first AP STA of any one of Embodiments A1-A6, wherein the first AP STA is further configured to: set up a backup AP agreement with the second AP STA, the backup AP agreement comprising a rule usable by the second AP STA to act as a stand-in backup AP for serving non-AP STAs associated with the first AP STA during one or more OFF time periods of the first AP STA.

Embodiment A8. The first AP STA of Embodiment A7, wherein the backup AP agreement involves communication constraints regarding any potential communication between a backup AP STA and the non-AP STAs associated with the first AP STA, the communication constraints being associated with one or more of: an allowed direction of data communication; an allowed type of data; an allowed type of communication; and allowed communication parameters. Embodiment A9. The first AP STA of any one of Embodiments A7 and A8, wherein the first AP STA is configured to: set up multiple backup AP agreements with different AP STAs corresponding to different OFF time periods.

Embodiment A10. The first AP STA of any one of Embodiments A7-A9, wherein the first AP STA is configured to: set up additional multiple backup AP agreements involving different backup AP STAs serving different sets of associated non-AP STAs during the same one or more OFF time periods.

Embodiment Al l. The first AP STA of any one of Embodiments A7-A10, wherein selection of a backup AP STA is at least partly based on one or more out of the following: the quality of service (QoS) requirements corresponding to one or more key non-AP STAs associated with the first AP STA; measurement reports or information collected by the first AP STA from the one or more non-AP STAs associated with it; positioning information available at the first AP STA; and other measurement reports or other information collected by the first AP STA from its neighboring AP STAs.

Embodiment A12. The first AP STA of any one of Embodiments A7-A11, wherein the first AP STA is configured to: share information with its associated non-AP STAs via signaling, the shared information including: the final planned PS schedule of the first AP STA; the identity of the one or more backup APs STAs; and the communication constraints corresponding to the one or more backup AP STAs.

Embodiment A13. The first AP STA of any one of Embodiments A7-A12, wherein primary 20 MHz sub-channels of the one or more backup AP STAs are within an operating channel and/or bandwidth of the first AP STA.

Embodiment A14. The first AP STA of any one of Embodiments A1-A13, wherein while requesting or instructing a currently associated non-AP STA to handover to a neighboring AP STA or one among a group of neighboring AP STAs, one AP STA shares with the non-AP STAs the planned PS schedule of the neighboring one or more AP STAs to which the non-AP STA is enabled to associate with.

Embodiment A15. The first AP STA of any one of Embodiments A1-A14, wherein if the first AP STA is communicating with two or more of the at least second AP STA and at least two of the at least second AP STA send the second message, the second message is transmitted based on a frequency division multiple access (FDMA) process or a time division multiple access (TDMA) process.

Embodiment Bl. A method in a first access point (AP) station (STA) configured for a coordination process among a group of AP STAs, the group of AP STAs comprising the first AP and at least a second AP STA, the method comprising: transmitting a first message to the second AP STA, the first message including information indicating the first AP STA’s preliminary planned power saving (PS) schedule aimed for reducing power consumption of the first AP STA , the PS schedule including upcoming time periods of the first AP STA when the first AP STA is available or unavailable for communicating with other devices; and receiving, from the second AP STA, a second message, the second message at least acknowledging receipt of the first message.

Embodiment B2. The method of Embodiment Bl, wherein the second message further includes: an acknowledgment of the first AP STA’s preliminary planned PS schedule, the first AP STA’s preliminary planned PS schedule becoming a final planned PS schedule of the first AP STA; or a suggested modification to the first AP STA’s preliminary planned PS schedule, the first AP STA’s final planned PS schedule being different than the first AP STA’s preliminary planned PS schedule.

Embodiment B3. The method of Embodiment B2, wherein the method further includes: transmitting a third message to the second AP STA indicating the final planned PS schedule.

Embodiment B4. The method of any one of Embodiments B1-B3, wherein the second AP STA is configured to set up its own PS schedule at least in part based on the planned PS schedule of the first AP STA. Embodiment B5. The method of any one of Embodiments B1-B4, wherein the first AP STA and the second AP STA are configured to align their respective PS schedules, to have at least one of the first AP STA and the second AP STA turned ON and available for communicating with other devices during one or more time instances.

Embodiment B6. The method of Embodiment B5, wherein the alignment is: explicitly and mutually agreed upon between the first AP STA and the second AP STA; or based upon planning and decisions made by the first and second AP STAs without any explicit related agreement and being based on PS schedule information shared between the first and second AP STAs.

Embodiment B7. The method of any one of Embodiments B1-B6, wherein the method further includes: setting up a backup AP agreement with the second AP STA, the backup AP agreement comprising a rule usable by the second AP STA to act as a stand-in backup AP for serving non-AP STAs associated with the first AP STA during one or more OFF time periods of the first AP STA.

Embodiment B8. The method of Embodiment B7, wherein the backup AP agreement involves communication constraints regarding any potential communication between a backup AP STA and the non-AP STAs associated with the first AP STA, the communication constraints being associated with one or more of: an allowed direction of data communication; an allowed type of data; an allowed type of communication; and allowed communication parameters.

Embodiment B9. The method of any one of Embodiments B7 and B8, wherein the method further includes: setting up multiple backup AP agreements with different AP STAs corresponding to different OFF time periods.

Embodiment BIO. The method of any one of Embodiments B7-B9, wherein the method further includes: setting up additional multiple backup AP agreements involving different backup AP STAs serving different sets of associated non-AP STAs during the same one or more OFF time periods. Embodiment Bl 1. The method of any one of Embodiments B7-B10, wherein selection of a backup AP STAis at least partly based on one or more out of the following: the quality of service (QoS) requirements corresponding to one or more key non-AP STAs associated with the first AP STA; measurement reports or information collected by the first AP STA from the one or more non-AP STAs associated with it; positioning information available at the first AP STA; and other measurement reports or other information collected by the first AP STA from its neighboring AP STAs.

Embodiment B 12. The method of any one of Embodiments B7-B11, wherein the method further includes: sharing information with its associated non-AP STAs via signaling, the shared information including: the final planned PS schedule of the first AP STA; the identity of the one or more backup APs STAs; and the communication constraints corresponding to the one or more backup AP STAs.

Embodiment B 13. The method of any one of Embodiments B7-B12, wherein primary 20 MHz sub-channels of the one or more backup AP STAs are within an operating channel and/or bandwidth of the first AP STA.

Embodiment B 14. The method of any one of Embodiments B1-B13, wherein while requesting or instructing a currently associated non-AP STA to handover to a neighboring AP STA or one among a group of neighboring AP STAs, one AP STA shares with the non-AP STAs the planned PS schedule of the neighboring one or more AP STAs to which the non-AP STA is enabled to associate with.

Embodiment Bl 5. The method of any one of Embodiments Bl -Bl 4, wherein if the first AP STA is communicating with two or more of the at least second AP STA and at least two of the at least second AP STA send the second message, the second message is transmitted based on a frequency division multiple access (FDMA) process or a time division multiple access (TDMA) process.

Claims

CLAIMS:

1. A first access point (AP) station (STA) (14a) configured for a coordination process among a group of AP STAs, the group of AP STAs comprising the first AP STA (14a) and at least a second AP STA (14b), the first AP STA being configured to and/or comprising a communication interface (22) and/or processing circuitry (24) configured to: cause transmission of a first message to the second AP STA, the first message including information indicating the first AP STAs preliminary planned power saving (PS) schedule aimed for reducing power consumption of the first AP STA, the PS schedule including upcoming ON and OFF time periods of the first AP STA when the first AP STA is available or unavailable, respectively, for communicating with other devices; and receive, from the second AP STA, a second message, the second message at least acknowledging receipt of the first message.

2. The first AP STA of Claim 1, wherein the second message further includes: an acknowledgment of the first AP STA’s preliminary planned PS schedule, the first AP STA’s preliminary planned PS schedule becoming a final planned PS schedule of the first AP STA; or a suggested modification to the first AP STA’s preliminary planned PS schedule, the first AP STA’s final planned PS schedule being different than the first AP STA’s preliminary planned PS schedule.

3. The first AP STA of Claim 2, wherein the first AP STA is further configured to: cause transmission of a third message to the second AP STA indicating the final planned PS schedule.

4. The first AP STA of any one of Claims 1-3, wherein the second AP STA is configured to set up its own PS schedule at least in part based on the planned PS schedule of the first AP STA.

5. The first AP STA of Claim 4, wherein the first AP STA and the second AP STA are configured to align their respective PS schedules, to have at least one of the first AP STA and the second AP STA turned ON and available for communicating with other devices during one or more time periods.

6. The first AP STA of Claim 5, wherein the alignment is: explicitly and mutually agreed upon between the first AP STA and the second AP STA; or based upon planning and decisions made by the first and second AP STAs without any explicit related agreement and being based on PS schedule information shared between the first and second AP STAs.

7. The first AP STA of any one of Claims 1-6, wherein the first AP STA is further configured to: set up a backup AP agreement with the second AP STA, the backup AP agreement comprising a rule usable by the second AP STA to act as a stand-in backup AP for serving non-AP STAs (16) associated with the first AP STA during one or more OFF time periods of the first AP STA.

8. The first AP STA of Claim 7, wherein the backup AP agreement involves communication constraints regarding any potential communication between a backup AP STA and the non-AP STAs (16) associated with the first AP STA, the communication constraints being associated with one or more of: an allowed direction of data communication; an allowed type of data; an allowed type of communication; and allowed communication parameters.

9. The first AP STA of any one of Claims 7 and 8, wherein the first AP STA is further configured to: set up multiple backup AP agreements with different AP STAs corresponding to different OFF time periods.

10. The first AP STA of any one of Claims 7-9, wherein the first AP STA is configured to: set up additional multiple backup AP agreements involving different backup AP STAs serving different sets of associated non-AP STAs during the same one or more OFF time periods.

11. The first AP STA of any one of Claims 7-10, wherein selection of a backup AP STA is at least partly based on one or more out of the following: the quality of service (QoS) requirements corresponding to one or more key non-AP STAs associated with the first AP STA; measurement reports or information collected by the first AP STA from the one or more non-AP STAs associated with it; positioning information available at the first AP STA; and other measurement reports or other information collected by the first AP STA from its neighboring AP STAs.

12. The first AP STA of any one of Claims 7-11, wherein the first AP STA is configured to: share information with its associated non-AP STAs via signaling, the shared information including: the final planned PS schedule of the first AP STA; the identity of the one or more backup AP STAs; and the communication constraints corresponding to the one or more backup AP STAs.

13. The first AP STA of any one of Claims 7-12, wherein primary 20 MHz sub-channels of the one or more backup AP STAs are within an operating channel and/or bandwidth of the first AP STA.

14. The first AP STA of any one of Claims 1-13, wherein the first AP STA is further configured to: request or instruct a currently associated non-AP STA (16) to handover to a neighboring AP STA or one among a group of neighboring AP STAs and share with the non-AP STAs the planned PS schedule of the neighboring one or more AP STAs to which the non-AP STAis enabled to associate with.

15. The first AP STA of any one of Claims 1-14, wherein if the first AP STA is communicating with two or more of the at least second AP STA and at least two of the at least second AP STA send the second message, the second message is transmitted based on a frequency division multiple access (FDMA) process or a time division multiple access (TDMA) process.

16. A method in a first access point (AP) station (STA) configured for a coordination process among a group of AP STAs, the group of AP STAs comprising the first AP STA and at least a second AP STA, the method comprising: transmitting a first message to the second AP STA, the first message including information indicating the first AP STA’s preliminary planned power saving (PS) schedule aimed for reducing power consumption of the first AP STA, the PS schedule including upcoming ON and OFF time periods of the first AP STA when the first AP STA is available or unavailable, respectively, for communicating with other devices (SI 34); and receiving, from the second AP STA, a second message, the second message at least acknowledging receipt of the first message (S136).

17. The method of Claim 16, wherein the second message further includes: an acknowledgment of the first AP STA’s preliminary planned PS schedule, the first AP STA’s preliminary planned PS schedule becoming a final planned PS schedule of the first AP STA; or a suggested modification to the first AP STA’s preliminary planned PS schedule, the first AP STA’s final planned PS schedule being different than the first AP STA’s preliminary planned PS schedule.

18. The method of Claim 17, wherein the method further includes: transmitting a third message to the second AP STA indicating the final planned PS schedule.

19. The method of any one of Claims 16-18, wherein the second AP STA is configured to set up its own PS schedule at least in part based on the planned PS schedule of the first AP STA.

20. The method of Claim 19, wherein the first AP STA and the second AP STA are configured to align their respective PS schedules, to have at least one of the first AP STA and the second AP STA turned ON and available for communicating with other devices during one or more time periods.

21. The method of Claim 20, wherein the alignment is: explicitly and mutually agreed upon between the first AP STA and the second AP STA; or based upon planning and decisions made by the first and second AP STAs without any explicit related agreement and being based on PS schedule information shared between the first and second AP STAs.

22. The method of any one of Claims 16-21, wherein the method further includes: setting up a backup AP agreement with the second AP STA, the backup AP agreement comprising a rule usable by the second AP STA to act as a stand-in backup AP for serving non-AP STAs associated with the first AP STA during one or more OFF time periods of the first AP STA.

23. The method of Claim 22, wherein the backup AP agreement involves communication constraints regarding any potential communication between a backup AP STA and the non-AP STAs associated with the first AP STA, the communication constraints being associated with one or more of: an allowed direction of data communication; an allowed type of data; an allowed type of communication; and allowed communication parameters.

24. The method of any one of Claims 22 and 23, wherein the method further includes: setting up multiple backup AP agreements with different AP STAs corresponding to different OFF time periods.

25. The method of any one of Claims 22-24, wherein the method further includes: setting up additional multiple backup AP agreements involving different backup AP STAs serving different sets of associated non-AP STAs during the same one or more OFF time periods.

26. The method of any one of Claims 22-25, wherein selection of a backup AP STA is at least partly based on one or more out of the following: the quality of service (QoS) requirements corresponding to one or more key non-AP STAs associated with the first AP STA; measurement reports or information collected by the first AP STA from the one or more non-AP STAs associated with it; positioning information available at the first AP STA; and other measurement reports or other information collected by the first AP STA from its neighboring AP STAs.

27. The method of any one of Claims 22-26, wherein the method further includes: sharing information with its associated non-AP STAs via signaling, the shared information including: the final planned PS schedule of the first AP STA; the identity of the one or more backup AP STAs; and the communication constraints corresponding to the one or more backup AP STAs.

28. The method of any one of Claims 22-27, wherein primary 20 MHz subchannels of the one or more backup AP STAs are within an operating channel and/or bandwidth of the first AP STA.

29. The method of any one of Claims 16-28, wherein the first AP STA is further configured to: request or instruct a currently associated non-AP STA to handover to a neighboring AP STA or one among a group of neighboring AP STAs and share with the non-AP STAs the planned PS schedule of the neighboring one or more AP STAs to which the non-AP STA is enabled to associate with.

30. The method of any one of Claims 16-29, wherein if the first AP STA is communicating with two or more of the at least second AP STA and at least two of the at least second AP STA send the second message, the second message is transmitted based on a frequency division multiple access (FDMA) process or a time division multiple access (TDMA) process.