WO2009115991A1

WO2009115991A1 - System and method of providing network status information of a basic service set for selective access point association

Info

Publication number: WO2009115991A1
Application number: PCT/IB2009/051134
Authority: WO
Inventors: Harish Vaidya; Manoj Kamath; Rakesh Raman
Original assignee: Nxp B.V.
Priority date: 2008-03-18
Filing date: 2009-03-17
Publication date: 2009-09-24

Abstract

An access point, wireless communication system, and method of providing network status information of a basic service set for selective access point association uses a management frame that includes network status information of the basic service set supported by the access point so that a receiving client station can use the network status information contained in the management frame to decide whether to associate with the access point. The network status information includes the number of client stations associated with the access point.

Description

SYSTEM AND METHOD OF PROVIDING NETWORK STATUS INFORMATION OF A BASIC SERVICE SET FOR SELECTIVE ACCESS

POINT ASSOCIATION

Wi-Fi is a popular wireless technology that allows Wi-Fi enabled devices to connect to the Internet and allows the Wi-Fi enabled devices to communicate with each other. Wi-Fi is governed by IEEE 802.1 1 standards, such as IEEE 802.1 lb/g/n standards. The number of applications for Wi-Fi is growing rapidly as more devices are Wi-Fi enabled to provide connectivity. Wi-Fi enabled client devices or stations can associate with an access point (AP ), which supports a basic service set (BSS). The BSS includes the AP and one or more client stations supported by the AP. When associated with an AP, a client station can communicate with the other client stations of the BSS.

In some situations, a client station may have only one AP which with the client station can associate. In other situations, a client station may have a choice of different APs with which the client station can associate. However, the quality of connectivity at a particular BSS is unknown by a client station before the client station is associated with the AP of that BSS. Thus, if there is a choice of APs, the client station cannot determine which AP will provide a better connectivity.

Thus, there is a need for a client station to have some information regarding the connectivity in a BSS before association with the AP of that BSS so that the client station can determine whether to associate with that particular AP. An access point, wireless communication system, and method of providing network status information of a basic service set for selective access point association uses a management frame that includes network status information of the basic service set supported by the access point so that a receiving client station can use the network status information contained in the management frame to decide whether to associate with the access point. The network status information includes the number of client stations associated with the access point. The use of the management frame with the network status information allows the client station to associate with an access point that will provide better quality of connectivity for the client station. A method of providing network status information of a basic service set for selective access point association in accordance with an embodiment of the invention comprises generating a management frame at an access point, the management frame including the network status information of the basic service set supported by the access point, the network status information including the number of client stations associated with the access point, and transmitting the management frame from the access point so that a receiving client station can use the network status information contained in the management frame to decide whether to associate with the access point. An access point of a wireless communication system in accordance with an embodiment of the invention comprises at least one antenna for transmitting and receiving signals, a transmitter connected to the at least one antenna to transmit outgoing signals, a receiver connected to the at least one antenna to receive incoming signals, and a control module operatively coupled to the transmitter and the receiver. The control module is configured to generate a management frame that includes network status information of a basic service set supported by the access point. The network status information includes the number of client stations associated with the access point. The control module is further configured to transmit the management frame via the transmitter so that a receiving client station can use the network status information contained in the management frame to decide whether to associate with the access point.

A wireless communication system in accordance with an embodiment of the invention comprises an access point and a client station. The access point is configured to operate in a wireless environment. The access point comprises at least one antenna for transmitting and receiving signals, a transmitter connected to the at least one antenna to transmit outgoing signals, a receiver connected to the at least one antenna to receive incoming signals, and a control module operatively coupled to the transmitter and the receiver. The control module is configured to generate a management frame that includes network status information of a basic service set supported by the access point. The network status information includes the number of client stations associated with the access point. The control module is further configured to transmit the management frame via the transmitter. The client station is configured to operate in the wireless environment. The client station is further configured to receive the management frame and to extract the network status information from the management frame. The client station is further configured to selectively associate with the access point using the network status information. Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the invention.

Fig. 1 is a diagram of a wireless communication system in accordance with an embodiment of the invention.

Fig. 2 is a block diagram showing some of the components of an access point (AP ) and a client station of the wireless communication system in accordance with an embodiment of the invention.

Fig. 3 is a diagram of a management frame transmitted by the AP in accordance with an embodiment of the invention.

Fig. 4 is a process flow diagram of a method of providing network status information of a basic service set for selective access point association in accordance with an embodiment of the invention.

With reference to Fig. 1 , a wireless communication system 100 in accordance with an embodiment of the invention is described. The wireless communication system 100 includes an access point (AP ) 102 and a number of client stations 104 associated with the AP 102. The AP 102 and the client stations 104 are part of a basic service set ( BSS ) 106 supported by the AP 102. The range of the AP 102 is illustrated in Fig. 1 by a dotted circle around the AP 102. The wireless communication system 100 also includes an access point (AP ) 1OS and a number of client stations 1 10 associated with the AP 10S. The AP 1OS and the client stations 1 10 are part of a basic service set ( BSS ) 1 12 supported by the AP 10S. The range of the AP 1OS is illustrated in Fig. 1 by another dotted circle around the AP 10S. The wireless communication system 100 also includes a client station

1 14, which is positioned within the range of both of the APs 102 and 10S. Thus, the client station 1 14 can be associated with the AP 102 as part of the BSS 106 or with the AP 1OS as part of the BSS 1 12. The client station 1 14 may already be associated with the AP 102 or the AP 1OS. Alternatively, the client station 1 14 may not yet be associated with either of the APs 102 and 1OS.

The client stations 104, 1 10 and 1 14 are wireless devices, which may be cellular phones, laptop computers, personal digital assistants (PDAs) or any other wireless devices that can operate in a wireless environment. Each of the APs 102 and 1OS may be any type of wireless central device that can operate in a wireless environment. Although the wireless communication system 100 is illustrated in Fig. 1 as having two APs and seven client stations, the wireless communication system 100 may include any number of APs and client stations. In the illustrated embodiment, the wireless communication system

100 is capable of transmitting data in accordance with one or more IEEE S02.1 1 standards. In this embodiment, the client stations 104, 1 10 and 1 14 may be S02.1 lb/g/n devices, Wi-Fi Multimedia (WMM) devices or Unscheduled Automatic Power Save Delivery (UAPSD) devices. However, in other embodiments, the wireless communication system 100 may be capable of transmitting data in accordance with other standards or protocols. Thus, the client stations 104, 1 10 and 1 14 may be devices that conform to different standards or protocols.

Some of the components of the AP 102 and the client station 1 14 are illustrated in a block diagram of Fig. 2. As shown in Fig. 2, the AP 102 includes at least one antenna 206, a transmitter 20S, a receiver 210, a processor 212 and a control module 214. The transmitter 20S and the receiver 210 are connected to the antenna 206. The transmitter 20S is configured to transmit outgoing signals to the client stations that are within the range of the AP 102, i.e., the client stations 104 and 1 14, using the antenna 206. The receiver 210 is configured to receive incoming signals from the client stations that are within the range of the AP 102, i.e., the client stations 104 and 1 14, using the antenna 206. Although the AP 102 is illustrated with a single antenna 206, the AP 102 may include any number of antennas. In an embodiment, the AP 102 may support Multi-User Multi-Input Multi-Output ( MU-MIMO ) communications.

The control module 214 operates with the processor 212 to perform operations related to transmission of outgoing signals and accepting incoming signals from the client stations that are within the range of the AP 102, i.e., the client stations 104 and 1 14. The control module 214 is configured to periodically transmit a beacon signal in the form of a beacon frame, which is a particular type of a management frame, to announce the presence of the AP 102 and relay information, such as timestamp, service set identifier ( SSID ), and other 5 parameters regarding the AP 102 to the client stations that are within the range of the AP 102. The control module 214 is also configured to transmit a response signal in the form of a probe response frame in response to a request signal in the form of a probe request frame from a client station. The probe request and response frames are also types of management frames.

K) In an embodiment, the control module 214 is configured to generate a beacon frame that includes the current network status information of the BSS 106. The network status information may include:

The number of client stations that are currently associated with the AP 102

15 The number of 802.1 I b client stations that are currently associated with the AP 102

The number of 802.1 I g client stations that are currently associated with the AP 102

The number of 802.1 I n client stations that are currently associated with 20 the AP 102

The number of WMW client stations that are currently associated with the AP 102

The number of UAPSD client stations that are currently associated with the AP 102

25 The different types of traffic (voice, video, best effort and background as defined by 802.1 I e - QoS for 802.1 1 networks ) on the BSS 106 The total load on the BSS 106

The total load is calculated using the following equation: Load °« = ( Bandwidth used by the client stations connected to that AP )* 100/( Available 30 bandwidth on the AP side ). The bandwidth is calculated using known techniques. The network status information may be included in one information element of a beacon frame. In Fig. 3, a beacon frame 302 with an information element 304, which includes the network status information, is shown. In an embodiment, the information element 304 may be one of the currently unused (reserved) information elements of a beacon frame. Currently, element id numbers 51-126 are reserved for future purposes in a beacon frame. Thus, the information element 304 with the network status information may be an information element associated with one of these reserved element id numbers.

The quality of connectivity provided by an AP depends partly on the number and type of client stations associated with that AP, as well as the types of traffic on the BSS supported by the AP and the total load on the BSS. In general, the connectivity is better when fewer the client stations are associated with an AP, in particular, WMM client stations, and when there are less traffic (e.g., video/voice) running in the BSS. Thus, the network status information provided by the AP 102 in the beacon frame 302 can be used by a client station to decide whether to associate with the AP 102 or to associate with another AP. If the client station is already associated with the AP 102, then the client station can use the network status information to switch to another AP or to just disconnect with the AP 102.

In order to reduce the processing burden on the client stations receiving the beacon frames, the "special" beacon frame 302 with the current network status may be transmitted intermittently such that the special beacon frame is not transmitted for eveiy beacon transmission. As an example, the control module 214 of the AP 102 may be configured to transmit the special beacon frame with the current network status for eveiy N'th beacon transmission, where N is user configurable parameter in the AP 102. For other beacon transmissions, the control module 214 of the AP 102 transmits regular beacon frames, i.e., beacon frames without the current network status.

In another embodiment, the control module 214 is configured to generate a probe response frame that includes the current network status information of the BSS 106. A probe response frame is transmitted from an AP to a client station requesting information from the AP using a probe request frame. Similar to the special beacon frame 302, the current network status information may be included in one of the unused (reserved) information elements of a probe response request. The control module 214 may be implemented in the AP 102 as software, hardware and/or firmware. In some embodiments, the control module 214 is a program being executed by the processor 212, and thus, the functions of the control module 214 are performed by the processor 212. The processor 212 may be a general-purpose digital processor such as a microprocessor or microcontroller. In other embodiments, the processor 212 may be a special- purpose processor such as a digital signal processor. In other embodiments, the processor 212 may be another type of controller or a field programmable gate array (FPGA). The AP 102 includes other conventional components commonly found in a wireless AP, which are not described herein so as to not obscure the inventive features of the AP 102.

As shown in Fig. 2, the client station 1 14 includes at least one antenna 216, a transmitter 2 IS, a receiver 220, a processor 222 and an association module 224. The transmitter 2 IS and the receiver 220 are connected to the antenna 216. The transmitter 2 IS is configured to transmit outgoing signals to the APs 102 and 1OS using the antenna 216. The receiver 220 is configured to receive incoming signals from the APs 102 and 1OS using the antenna 21S. Although the client station 1 14 is shown with a single antenna 216, the client station 1 14 may include any number of antennas.

The association module 224 operates with the processor 222 to perform operations related to associating with the AP 102 or the AP 10S. The association module 224 is configured to process or extract the current network status information from the received special beacon frame 302 or the received special probe response signal with the current network status information to determine with which one of the APs 102 and 1OS the client station 1 14 should be associated for better quality of connectivity. In some embodiments, the association module 224 may be configured to automatically connect to the AP that will provide the better quality of connectivity, which in this case is most likely the AP 1OS because there are fewer client stations connected to the AP 1OS than the AP 102. However, if the client stations that are connected to the AP 1OS are WMM devices, then the AP 102 may be a better AP to be connected to with respect to quality of connectivity. In other embodiments, the association module 224 may be configured to inform the user of the client station 1 14 regarding the network status of the BSSs 106 and 1 12 supported by the APs 102 and 1OS, respectively, so that the user can make an informed choice of associating with one of the APs 102 and 1OS. Thus, as used herein, the decision to associate with one of the APs 102 and 1OS by the client station 1 14 means that either the user of the client station 1 14 or the association module 224 is making that decision.

The association module 224 may be implemented in the client station 1 14 as software, hardware and/or firmware. In some embodiments, the association module 224 is a program being executed by the processor 222, and thus, the functions of the association module are performed by the processor 222. The processor 222 may be a general-purpose digital processor such as a microprocessor or microcontroller. In other embodiments, the processor 222 may be a special-purpose processor such as a digital signal processor. In other embodiments, the processor 222 may be another type of controller or a field programmable gate array (FPGA). The client station 1 14 includes other conventional components, which are not described herein so as to not obscure the inventive features of the client station 1 14.

The client station 1 14 is representative of the other client stations 104 and 1 10. Thus, the components of the client stations 104 and 1 10 are not described herein. However, in some embodiments, some of these client stations 104 and 1 10 may not be identical to the client station 1 14. In these embodiments, some of the client stations 104 and 1 10 may not be configured to process or extract the current network status information from the received special beacon frame 302 or the received special probe response signal with the current network status information.

A method of providing network status information of a basic service set for selective access point association in accordance with an embodiment of the invention is now described with reference to a flow diagram of Fig. 4. At block 404, a management frame is generated at an access point. The management frame includes the network status information of the basic service set supported by the access point. The network status information includes the number of client stations associated with the access point. At block 404, the management frame is transmitted from the access point so that a receiving client station can use the network status information contained in the management frame to decide whether to associate with the access point.

Although specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the invention is to be defined by the claims appended hereto and their equivalents.

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Claims

K)What is claimed is:

1. A method υf providing network status information of a basic service set for selective access point association, the method comprising:

5 generating a management frame at an access point, the management frame including the network status information of the basic service set supported by the access point, the network status information including the number of client stations associated with the access point; and transmitting the management frame from the access point so that a K) receiving client station can use the network status information contained in the management frame to decide whether to associate with the access point.

2. The method of claim 1 wherein the network status information of the management frame includes the number of 802.1 lb/g/n client stations that are currently associated with the access point.

15 3. The method of claim 1 wherein the network status information of the management frame includes the number of Wi-Fi Multimedia (WMM) client stations that are currently associated with the access point.

4. The method of claim 1 wherein the network status information of the management frame includes the number of Unscheduled Automatic Power Save

20 Delivery (UAPSD) client stations that are currently associated with the access point.

5. The method of claim 1 wherein the network status information of the management frame indicates different types of traffic on the basic service set supported by the access point.

25 6. The method of claim 1 wherein the network status information of the management frame includes a total load on the basic service set supported by the access point.

7. The method of claim 1 wherein the management frame is a beacon frame.

S. The method of claim 7 wherein the transmitting includes transmitting the 30 beacon frame intermittently such that the beacon frame is not transmitted for every beacon transmission.

9. The method of claim 1 wherein the management frame is a probe response frame.

10. An access point of a wireless communication system comprising: at least one antenna for transmitting and receiving signals; a transmitter connected to the at least one antenna to transmit outgoing signals; 5 a receiver connected to the at least one antenna to receive incoming signals; and a control module operatively coupled to the transmitter and the receiver, the control module being configured to generate a management frame that includes network status information of a basic service set supported by the access K) point, the network status information including the number of client stations associated with the access point, the control module being further configured to transmit the management frame via the transmitter so that a receiving client station can use the network status information contained in the management frame to decide whether to associate with the access point. 15

1 1. The access point of claim 10 wherein the network status information of the management frame includes the number of 802.1 lb/g/n client stations that are currently associated with the access point.

12. The access point of claim 10 wherein the network status information of the management frame includes the number of Wi-Fi Multimedia (WMM) client

20 stations that are currently associated with the access point.

13. The access point of claim 10 wherein the network status information of the management frame includes the number of Unscheduled Automatic Power Save Delivery (UAPSD) client stations that are currently associated with the access point.

25 14. The access point of claim 10 wherein the network status information of the management frame indicates different types of traffic on the basic service set supported by the access point.

15. The access point of claim 10 wherein the network status information of the management frame includes a total load on the basic service set supported by the

30 access point.

16. The access point of claim 10 wherein the management frame is a beacon frame.

17. The access point of claim 10 wherein the control module is configured to transmit the beacon frame intermittently such that the beacon frame is not transmitted for every beacon transmission.

I S. The method of claim 1 wherein the management frame is a probe response 5 frame.

19. A wireless communication system comprising: an access point configured to operate in a wireless environment, the access point comprising: at least one antenna for transmitting and receiving signals;

K) a transmitter connected to the at least one antenna to transmit outgoing signals; a receiver connected to the at least one antenna to receive incoming signals; and a control module operatively coupled to the transmitter and the receiver,

15 the control module being configured to generate a management frame that includes network status information of the basic service set supported by the access point, the network status information including the number of client stations associated with the access point, the control module being further configured to transmit the management frame via the transmitter; and

20 a client station configured to operate in the wireless environment, the client station being further configured to receive the management frame and to extract the network status information from the management frame, the client station being further configured to selectively associate with the access point using the network status information.

25 20. The system of 19 wherein the network status information of the management frame includes the number of Wi-Fi Multimedia ( WMM) client stations that are currently associated with the access point.