The disclosed embodiments relate generally to local wireless area network (WLAN) communications, and, more particularly, to direct finding and positioning in wireless local area networks (WLANs).
IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specification for implementing wireless local area network (WLAN) communication, in the unlicensed (2.4, 5, and 60 GHz) frequency bands. The standards and amendments provide the basis for wireless network products using the IEEE 802.11 frequency bands. IEEE 802.11 plays an important role in the growing application of Indoor/Outdoor Location. The key applicable technology is that of ranging using time-of-flight (TOF) ranging measurements defined in IEEE 802.11v. Once the distance between devices is measured, the information can be used to determine device location.
In IEEE 802.11-REVmc, Fine Timing Measurement (FTM) protocol is proposed for Indoor Location. Based on FTM, an initiating station exchanges FTM frames during an FTM session with a responding station to measure the time-of-flight (TOF) or the Round Trip Delay (RTD/2). The initiating station then computes its range to the responding station after receiving timing measurements (i.e., timestamps corresponding to the departure time and arrival time of the FTM frames) from the responding station. To calculate a station position, the station performs ranging measurements with multiple access points (APs) via FTM frame exchange and obtains AP's positions. FTM positioning requires the initiating station to exchange FTM frames with multiple responding APs for TOF measurements in order to determine its absolute location. For 3D positioning, the station needs to exchange FTM frames with four or more APs in order to determine its absolute location.
However, for managed/controlled environments like airports, enterprise, or department stores, it is common to have many Basic Service Sets (BSSs) or Service Set Identifiers (SSIDs) at close locations, i.e. co-located, as shown in Fig. 1. Therefore, it is no benefit for a station (STA) to initiate FTMs with co-located BSSs, because the STA will get the same location and round trip time (RTT). The APs might as well get overloaded with the FTMs. Ideally, STAs would identify co-located BSSs and avoid doing FTM with co-located BSSs. The STA should consider whether co-located BSSs of different capability can provide different level of location information, such as security, accuracy, etc, and whether there are more than one set of location information with respect to the same AP with different accuracy through different BSSs.
One of the conventional method is using multiple BSSID (mBSSID) to signal in beacons which BSSIDs are co-located. The MAC addresses for the co-located BSSs have to be contiguous, otherwise the feature cannot be used. However, the co-located BSSs may be administered by different entities, thus it is not possible to perform coordination between the co-located BSSs.
Another known method is when multiple BSSs are co-located, only one of the BSSs can advertise FTM capability. But this method requires co-ordination between the BSSs. If a STA is associated with one of the BSSs which does not advertise FTM support, it may need to go off the channel to do FTM with the BSS that indicates the support for it. Besides, this method does not allow the BSSs to provide FTM with different resolutions, add-on features, etc. Moreover, if the BSSs belong to different operators, it would be hard to agree which one to advertise FTM support.
Hence, there's a need for a solution for simplified FTM advertising.
Besides, BRIAN HART (CISCO SYSTEMS) in "Location related CIDs; 11-13-1509-06-000m-location-related-cids" introduces a Fine Timing Measurement procedure in which the ranges between the requested STA and some nearby Aps are reported by a responding STA to a requesting STA.
US 2014/112325 A1
discloses an extension to the Access Network Query Protocol (ANQP) protocol that allows stations (STAs) to discover multiple APs via a single ANQP request/response exchange. The response message may include a plurality of AP identifiers, e.g., basic service set identifiers (BSSIDs), to identify the multiple APs for which information is sought. In particular, the requested information may be specific to a set of APs operating in or near a common geographical location.
The invention is defined by independent claim 1. Preferred embodiments are set out in the dependent claims.
It is therefore an object of the present invention to provide a method for a multiple BSSID environment. In this method, a first wireless device obtains basic service set (BSS) information of a plurality of BSSs. The first wireless device then sends a fine time measurement (FTM) frame containing the BSS information to a second wireless device.
In one aspect, the BSS information is co-located BSS information.
In another aspect, the FTM frame is an unicast frame.
In yet another aspect, the second wireless device wirelessly joins to one of the plurality of BSS according to the BSS information.
Other embodiments and advantages are described in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates the geometry of AP positions.
Figure 2 illustrates a frame in accordance with one novel aspect.
Reference will now be made in detail to some examples illustrated in the accompanying drawings.
According to an aspect, the co-located BSSs can advertise freely and independently about the FTM support that each BSS has. Therefore, a first wireless device such as the access points (APs) in each of the BSS, can receive the co-located BSS information. The AP can then send FTM frames that includes mBBSID or MAC addresses of the co-located BSSs, such as the frame shown in Fig. 2. The FTM frame 200 includes the BSSID 201 of co-located BSS#1 until the BSSID 202 of co-located BSS#n.
Compared to sending mBSSID in beacon that used in prior arts, the present embodiment does not overload the beacon, and the FTM frame can indicate a list of BSSIDs as it is unicast. Therefore, when a second wireless device, such as a station (STA), receives the FTM frame that contains the mBBSID or MAC addresses of the co-located BSSs, the STA can select one of the BSSs to join and to perform FTM function.
In another example, the FTM frame can contain multiple mBSSID elements instead of a list of BSSIDs. This embodiment does not require coordination between the co-located BSSs. It only needs the MAC addresses information of co-located BSSs. And the BSSs can learn this information from each other.
According to another example, an indication can be added to the beacon to show that this BSS is co-located with other BSSs. The indication may be only one bit in size. In other words, the beacon provides the capability for a STA to obtain the list of co-located BSSs' MAC addresses when the STA receives such beacons from different BSSs. According to an embodiment of the present invention, a new Access Network Query Protocol (ANQP) element can be defined to ask the BSS about the MAC addresses of the co-located BSSs. Therefore, the STA can do FTM with only one BSSID from the list received. Similarly, this embodiment does not require coordination between the co-located BSSs. It only needs the MAC addresses information of co-located BSSs. And this information can be learned or shared from each other.
According to yet another example, an indication can be added to the beacon to show that this BSS is co-located with other BSSs. The indication may be only one bit in size. In other words, the beacon provides the capability for a STA to obtain the list of co-located BSSs' MAC addresses when the STA receives such beacons from different BSSs. According to an example, the STA can send a FTM Request Frame including one bit that is used to request the list of BBSIDs of the co-located BSSs. So an AP provides a FTM Frame to contain the list of co-located BSSIDs when requested in the FTM Request Frame.
Although the present invention has been described in connection with certain specific examples for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features can be practiced without departing from the scope of the invention as set forth in the claims.
A method for use in a multiple BSSID environment, the method comprising:
obtaining by a first wireless device information of a plurality of co-located basic service sets, BSSs, which are co-located with each other; and
sending by the first wireless device a fine timing measurement, FTM, frame (200) to a second wireless device,
wherein the FTM frame (200) contains the information of the plurality of co-located BSSs.
2. The method of claim 1, wherein the FTM frame (200) is a unicast frame.
3. The method of claim 1, further comprising
the second wireless device joining at least one of the plurality of co-located BSSs according to the information of the plurality of co-located BBSs in the FTM frame (200).
4. The method of claim 1, wherein the information of the plurality of co-located BSSs comprise MAC addresses of the plurality of co-located BSSs.
5. The method of claim 1, wherein the information of the plurality of co-located BSSs comprise multiple BSSIDs (201, 202) of the plurality of co-located BSSs.
Verfahren zur Verwendung in einer Multi-BSSID-Umgebung, wobei das Verfahren umfasst:
Erhalten, durch eine erste Funkvorrichtung, von Informationen einer Mehrzahl von gemeinsam angeordneten Basisdienstsätzen, BSSs, welche miteinander gemeinsam angeordnet sind; und
Senden, durch die erste Funkvorrichtung, eines Feinzeitmessungs-, FTM-, Rahmens (200) an eine zweite Funkvorrichtung,
wobei der FTM-Rahmen (200) die Informationen der Mehrzahl von gemeinsam angeordneten BSSs umfasst.
2. Verfahren gemäß Anspruch 1, wobei der FTM-Rahmen (200) ein Unicast-Rahmen ist.
3. Verfahren gemäß Anspruch 1, weiter umfassend:
die zweite Funkvorrichtung tritt gemäß den Informationen der Mehrzahl von gemeinsam angeordneten BSSs in dem FTM-Rahmen (200) mindestens einem der Mehrzahl von gemeinsam angeordneten BSSs bei.
4. Verfahren gemäß Anspruch 1, wobei die Informationen der Mehrzahl von gemeinsam angeordneten BSSs MAC-Adressen der Mehrzahl von gemeinsam angeordneten BSSs umfassen.
5. Verfahren gemäß Anspruch 1, wobei die Informationen der Mehrzahl von gemeinsam angeordneten BSSs mehrere BSSIDs (201, 202) der Mehrzahl von gemeinsame angeordneten BSSs umfassen.
Procédé pour une utilisation dans un environnement à multiples BSSID, le procédé comprenant le fait :
d'obtenir, par un premier dispositif sans fil, des informations d'une pluralité d'ensembles de services de base colocalisés, BSS, qui sont colocalisés les uns avec les autres ; et
d'envoyer, par le premier dispositif sans fil, une trame de mesure précise de temporisation, FTM, (200) à un deuxième dispositif sans fil,
dans lequel la trame FTM (200) contient les informations de la pluralité de BSS colocalisés.
2. Procédé de la revendication 1, dans lequel la trame FTM (200) est une trame en unidiffusion.
3. Procédé de la revendication 1, comprenant en outre le fait
de rejoindre, par le biais du deuxième dispositif sans fil, au moins l'un de la pluralité de BSS colocalisés en fonction des informations de la pluralité de BBS colocalisés dans la trame FTM (200).
4. Procédé de la revendication 1, dans lequel les informations de la pluralité de BSS colocalisés comprennent des adresses MAC de la pluralité de BSS colocalisés.
5. Procédé de la revendication 1, dans lequel les informations de la pluralité de BSS colocalisés comprennent de multiples BSSID (201, 202) de la pluralité de BSS colocalisés.