The present invention is enclosed in the area of mesh networks. Particularly, the present invention relates to a method and system for managing the operation of wireless mesh networks. More particularly, the present invention describes a method and system for enhanced steering and traffic load balancing in wireless mesh networks.
Home wireless networks, a particular scenario of Wireless Local Area Networks (WLANs), target indoor environments with several radio propagation obstacles, such as walls and furniture to name a few. These obstacles reduce the signal quality emitted by an access point (AP), therefore reducing the coverage of such equipment. Due to the regulatory bodies, as well as the different transmission characteristics of both APs and stations (STA)/client devices, increasing the transmission power is not a valid solution to improve the wireless coverage. A more effective way to solve this problem is to bring additional APs to the network, forming a wireless mesh network. In a home wireless network, the main AP is denoted as Root AP, responsible to communicate with the outside world (e.g. Internet), and the remaining APs are denoted as Extenders and, if used, they establish the connection between the Root AP and the STA devices. Extenders can be connected to the Root AP and/or between themselves through wireless links or through cable, depending on the configuration of the scenario, thus creating backhaul links.
From the several challenges associated with the operation of wireless mesh networks, one of the most critical is the steering of the STA device, i.e., how to manage the connections of the several STAs among the available APs (Root AP and Extenders). However, choosing between the Root AP and one of the Extenders is not the only choice available. With the latest generation of Wi-Fi APs, two wireless bands can be used, 2.4 and 5 GHz, each one with distinguished characteristics: the first one typically enables higher coverage while the second one offers higher throughput. In a conventional Wi-Fi mesh network, a STA device remains associated with an AP if the link quality, given by the Received Signal Strength Indicator (RSSI), is better than any other link with any other AP in the network. However, the AP with the best link quality may not provide the best Quality of Service, and consequently, Quality of Experience. For example, the number of STAs connected to a specific AP can be too high that, although the link quality is considered of high quality, the resulting airtime for each STA device is considerably small.
Traditional steering methods are independently-based, i.e., the STA device usually selects the AP that provides the highest signal strength in comparison to the signal strength provided by other APs without considering the effects of an eventual steering in the performance of the new AP, and consequently, on the network. More recently, several works have proposed alternative STA steering mechanisms whose decision takes place in the AP. For that, the STA sends its neighbouring information to the AP in response to a beaconing message sent by the AP to the STA. Such approach is not transparent to the STA device in the sense that he is the one to provide the required information to the AP of interest. Finally, other approaches admit that all the APs in the network are allowed to exchange STA's information using the backhaul links. Following this approach, the steering decision may occur in any of the AP, Extender or Root AP.
All the aforementioned solutions, although providing different levels of steering decisions, they lack on finding a steering criterion that takes into consideration not only the link quality, but also the network topology, the bandwidth, the capabilities of each element, AP and STA device, and other important parameters, and proactively steer the STAs in an integrated way from the network's point of view.
The present solution intends to innovatively overcome such issues, providing an efficient method and system for steering clients of a Wi-Fi mesh network to the best AP and wireless band.
It is therefore an object of the present invention to produce a method and system for optimizing the link quality of clients connected to a wireless mesh network, either through band steering (2.4 GHz or 5 GHz) or AP steering (Root AP or Extenders).
In order to achieve that, the present solution makes use of two logical entities, a centralized controller that acts as a master and has the vision of the entire network, and distributed agent entities that act as slaves and exchange information with the controller, to build a mesh architecture. In this configuration, the Root AP typically contains the controller and may also contain an agent entity, while the Extenders are always comprised by agent entities.
The present invention provides a method and system for managing the connections of multiple STAs in a Wi-Fi mesh network, using STA steering to optimize the overall throughput of the network. The STAs are proactively steered depending on the, link quality, the network topology and wireless medium occupation, as well as the different equipment capabilities, to ultimately provide the best available throughput. This invention also aims to detect crowded APs or frequency bands, and steer STAs accordingly towards an efficient load control and traffic management between APs and improved quality of experience.
The Root AP will then use the values computed in S104 to decide which action can and should be taken regarding Link Optimization (S105) and Load Balance (S106) processes.
In step S206, the link optimization routine S200 checks if there is any steer required, following the evaluation in step S205. If required, a steer is requested for the pair {STA, target BSS}with the highest score. The link optimization assessment ends in step S208.
To estimate the maximum throughput that a STA will achieve when connected to a different AP, the following inputs are used:
The estimation of maximum theoretical physical data rate uses the following formula:
where Ephy represents the estimation, s represents the STA, bt represents the target BSS, Mphy(s, bt) represents the maximum theoretical physical data rate that can be obtained on the link between the STA s and the target BSS bt, according to each other's capabilities. H(bt) represents the distance of the AP that advertises the 855 in relation to the Root AP, in hops. IFH(bt)refers to the interface that is used to advertise the target BSS (fronthaul), IBH(bt) represents the interface used for backhaul communications. This model is valid for equipment with a shared radio interface for fronthaul and backhaul communications. These inputs are combined and define a curve through a fitting function, which results in a formula that is capable of estimating the maximum throughput that a STA will be able to achieve when connected to a set AP, in the described conditions.
The Link Optimization routine is also programmed to detect weak STAs (S700) by means of the process described in
Weak STAs rely on the Link Optimization routine to maintain connectivity. In order for the Link Optimization process to provide a faster response to the weak STAs' fading link, the Link Optimization routine score computing (S704) and assessment (S705) is performed when the STAs' metrics are received.
To provide a quicker response, weak STAs' metric requests are not handled by the base algorithm routine (S103) as regular STAs are; instead a separate entity, named Monitor Entity, is responsible for requesting metrics for these associated STAs, in a higher frequency in relation to the base algorithm routine.
Weak STAs are only subject to the Link Optimization routine and the Load balance routine will not act or consider them.
The load balance routine is comprised of two different subprocesses:
This subprocess is depicted on
The detection itself takes into account a wide range of inputs, which not only includes metrics from the STA under evaluation, but also from other STAs in the network.
From the STA under evaluation:
From other STAs connected to the same AP:
Using all this information, some of these metrics are combined to derive the following:
The decision is accomplished using a classification tree with two classes: saturated or not saturated STAs. This is modelled in a conservative manner, as it is tuned to reduce false positives in detriment of true positives. The outcome of this approach is a slower identification of overloaded STAs, but also a more trustworthy overall classification.
In step S406, the process S400 checks if there is any steer required, following the evaluation in step S405. If required, a steer is requested for the pair of STA and target AP where the throughput gain is the highest. The link optimization routine then ends its execution in step S407.
This process combines the estimation of the maximum throughput from the link optimization process S200 with metrics that characterize the medium occupation.
As such, the considered inputs are as follows:
In order to manage the steering of STA devices and also the hierarchy between Link Optimization and Load Balance routines' actions and steer requests, the Root AP comprises a Steer Manager entity. Such entity acts base on the current priorities:
This entity is also responsible for allowing or denying the Link Optimization and Load Balance modules' actions on a particular STA, based on the STA's previous behaviour.
To perform these tasks, the Steer Manager entity maintains a queue of steer requests. For each request, a state is assigned accordingly. The following table describes these states:
In
After the request is received, the Steer Manager checks if there is no current time penalty on the STA (S502). If a time penalty is in effect, the request will be rejected (S504). Otherwise, the Steer Manager will check if there are no conflicting requests (S503).
A new request will be rejected if an old similar request (same STA, same source BSS, same target BSS) with equal or higher priority in a pending or processing state exists. If the old request, as described previously, with a lower priority exists, the new request will be rejected if the old request is in the processing state (S504). If the old request is in the pending state, the old request will be deleted and the new request will be accepted (S505).
If a STA did not respond as expected to a steer request, this STA will be marked as misbehaved, for a predefined period of time. The steering type can be classified as:
Following a steer request, the behaviour or the STA device is not completely deterministic and in some cases, it can have an unexpected behaviour. To prevent unnecessary disconnects, every steer response is classified as one of the following:
Using the steer response classification above, penalties are given accordingly:
The more general and advantageous configurations of the present invention are described in the Summary of the invention. Such configurations are detailed below in accordance with other advantageous and/or preferred embodiments of implementation of the present invention.
In a preferred embodiment of the method for enhanced steering and traffic load balancing in wireless mesh networks of the invention, it is comprised by the following steps:
In another embodiment of the method of the present invention, combinable with the above described, the message status send by the Extenders AP to the Root AP includes metrics related to the connected STAs or the status of the wireless medium in which the Root AP is located.
In another embodiment of the method of the present invention, combinable with any above described, the Link Optimization routine is programmed to execute a link optimization process comprising the following steps:
In another embodiment of the method of the present invention, combinable with any above described, the maximum throughput is estimated considering:
where Ephy represents the Estimation, s represents the STA, bt represents the target BSS, Mphy(s,bt) represents the maximum theoretical physical data rate that can be obtained on the link between the STA s and the target BSS bt, according to each other's capabilities; H(bt) represents the distance of the AP that advertises the BSS in relation to the Root AP, in hops; IFH(bt) refers to the interface that is used to advertise the target BSS (fronthaul), IBH(bt) represents the interface used for backhaul communications.
In another embodiment of the method of the present invention, combinable with any above described, the Link Optimization routine is further programmed to detect weak STAs based on the STA's metrics contained in the message status; said detection being based on the RSSI of the STA's link.
in another embodiment of the method of the present invention, combinable with any above described, weak STA's links are flagged and are handled by a Monitor Entity of the Link Optimization routine; said Monitor Entity being configured to:
In another embodiment of the method of the present invention, combinable with any above described, weak STAs are not considered by the Load Balance routine.
In another embodiment of the method of the present invention, combinable with any above described, the Load Balance routine is programmed to execute a load balance process comprised by two sequential stages:
In another embodiment of the method of the present invention, combinable with any above described, the saturated STA detection stage is executed for all connected STAs' links and comprises the following steps:
In another embodiment of the method of the present invention, combinable with any above described, the evaluation of the saturation level takes into account inputs including metrics from the STA under evaluation, such as
and metrics from other STAs in the network, such as
in order to determine:
which are the inputs of a classification tree with two classes: saturated or not saturated STAs.
In another embodiment of the method of the present invention, combinable with any above described, the throughput prediction stage comprises the following steps:
In another embodiment of the method of the present invention, combinable with any above described, the estimation of the highest score of a saturated STA combines the estimation of the maximum throughput, of the link optimization routine, with metrics that characterize the medium occupation such as transmission opportunity, available airtime and retransmission rate.
In another embodiment of the method of the present invention, combinable with any above described, the Root AP comprises a Steer Manager entity adapted to steering STAs and managing the hierarchy between Link Optimization and Load Balance routines' actions and steer requests, according to the priorities as follows:
In another embodiment of the method of the present invention, combinable with any above described, the Steer Manager is further configured to allow or deny the Link Optimization and Load Balance routines' actions on a particular STA based on the respective STA's previous behaviour.
In another embodiment of the method of the present invention, combinable with any above described, the Steer Manager maintains a queue of steer requests; for each request, a steering state is assigned accordingly such as:
In another embodiment of the method of the present invention, combinable with any above described, the Steering Manager is configured to execute procedure for managing steering requests, such requests being generated in the Link Optimization or in the Load Balance routines; said procedure comprising the following steps:
In another embodiment of the method of the present invention, combinable with any above described, if the STA does not respond to the steer request as expected, the Steering Manager is configured to mark such STA as ‘misbehaved’ for a predefined period of time, according to a following steer type:
In another embodiment of the method of the present invention, combinable with any above described, the steer response to a steer request is classified as one of the following:
The present invention also relates to a system for enhanced steering and traffic load balancing in wireless mesh networks. In a preferred embodiment of said system it is comprised by:
wherein,
As will be dear to one skilled in the art, the present invention, should not be limited to the embodiments described herein, and a number of changes are possible which remain within the scope of the present invention.
Of course, the preferred embodiments shown above are combinable, in the different possible forms, being herein avoided the repetition all such combinations.
Filing Document | Filing Date | Country | Kind |
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PCT/PT2019/000006 | 9/3/2019 | WO |