U.S. patent application number 12/059208 was filed with the patent office on 2009-10-01 for broadcast/multicast based network discovery.
This patent application is currently assigned to Intel Corporation. Invention is credited to Necati Canpolat, Vivek Gupta.
Application Number | 20090245133 12/059208 |
Document ID | / |
Family ID | 41117063 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090245133 |
Kind Code |
A1 |
Gupta; Vivek ; et
al. |
October 1, 2009 |
BROADCAST/MULTICAST BASED NETWORK DISCOVERY
Abstract
Embodiments of the invention relate to apparatus, system and
method for use of WLAN access enabled mobile devices such as
notebooks and handheld communication devices. In particular,
embodiments of the invention relate to methodology whereby WiFi
enabled devices can automatically select the appropriate service
provider, in a power efficient manner, thereby taking advantage of
different services offered by different service providers.
Inventors: |
Gupta; Vivek; (Portland,
OR) ; Canpolat; Necati; (Beaverton, OR) |
Correspondence
Address: |
Client 21058;c/o DARBY & DARBY P.C.
P.O. BOX 770, CHURCH STREET STATION
NEW YORK
NY
10008-0770
US
|
Assignee: |
Intel Corporation
Santa Clara
CA
|
Family ID: |
41117063 |
Appl. No.: |
12/059208 |
Filed: |
March 31, 2008 |
Current U.S.
Class: |
370/254 |
Current CPC
Class: |
H04W 48/14 20130101;
Y02D 70/146 20180101; H04W 8/005 20130101; H04W 88/08 20130101;
Y02D 30/70 20200801; H04W 48/16 20130101; H04W 84/12 20130101; Y02D
70/142 20180101; Y02D 70/23 20180101 |
Class at
Publication: |
370/254 |
International
Class: |
H04W 48/16 20090101
H04W048/16 |
Claims
1. A method for wireless discovery of network services, comprising:
transmitting a probe request from a first networking client to a
network access point, wherein the first networking client has a
wireless communication capability; and receiving a probe response,
from the network access point, by the first networking client,
wherein the probe response includes an indication of network
services available to the first networking client.
2. The method of claim 1, further comprising: calculating service
availability from the probe response.
3. The method of claim 1, further comprising: ranking service
provider preference based on the probe response.
4. The method of claim 1, further comprising: using a beacon to
formulate the probe request.
5. The method of claim 1, further comprising: using the probe
response to formulate a second probe request.
6. The method of claim 1, wherein the probe request is created
using a specific device configuration information of the first
networking client.
7. The method of claim 1, wherein the wireless communication
capability is operating using a wireless network protocol selected
from the group consisting of IEEE 802.11, IEEE 802.16 and
WiMAX.
8. A method for wireless discovery of network services by a first
networking client, comprising: receiving a probe response from the
network access point, by the first networking client, wherein the
probe response was transmitted in broadcast mode in response to a
probe request from a second networking client, wherein the probe
response includes an indication of network services available to
the second networking client; and using data from the probe
response to configure communication access by the first networking
client.
9. The method of claim 7, further comprising: calculating service
availability from the probe response; and ranking service provider
preference based on the probe response.
10. An apparatus to perform wireless discovery of network services
comprising: a processor configured to create a probe request; a
wireless transmitter in communication contact with the processor,
the wireless transmitter configured to transmit the probe request;
a wireless receiver in communication contact with the processor,
the wireless receiver configured to receive a probe response,
wherein the probe response includes an indication of network
services available to the apparatus.
11. The apparatus of claim 10, wherein the wireless transmitter
operates with a communications protocol selected from the group
consisting of IEEE 802.11, IEEE 802.16 and WiMAX.
12. A system for wireless discovery of network services comprising:
a network access point, having a first processor, configured to
receive a probe request from a first networking client, wherein the
first processor creates a primary advertisement query from the
probe request; a Network Advertising Provider Advertising Server,
in communication contact with the network access point, configured
to receive the primary advertisement query from the network access
point; a second processor, within the Network Advertising Provider
Advertising Server, wherein the second processor is configured to
determine a primary advertisement response, wherein the primary
advertisement response is communicated from the Network Advertising
Provider Advertising Server to the network access point, wherein
the first processor creates a query response for transmission to
the first networking client, using information from the primary
advertisement response.
13. The system of claim 12, further comprising: a Subscription
Service Provider Network advertising server in communication
contact with the Network Advertising Provider Advertising Server,
the Network Advertising Provider Advertising Server configured to
transmit a secondary advertisement query to the Subscription
Service Provider Network advertising server; a third processor,
within the Subscription Service Provider Network advertising
server, wherein the third processor is configured to determine a
secondary advertisement response, wherein the secondary
advertisement response is communicated from the Subscription
Service Provider Network advertising server to the Network
Advertising Provider Advertising Server, wherein the second
processor creates the primary advertisement response for
transmission to the network access point, using information from
the secondary advertisement response.
14. The system of claim 12, further comprising: a plurality of
network elements, wherein at least one of the plurality does not
transmit a probe request, but can receive and act upon a probe
response.
15. A method for wireless discovery of network services,
comprising: receiving a probe request from a first networking
client, by a network access point; creating a primary advertisement
query from the probe request by the network access point;
transmitting the primary advertisement query from the network
access point to a Network Advertising Provider Advertising Server
in communication contact with the network access point; creating a
primary advertisement response by the Network Advertising Provider
Advertising Server; transmitting the primary advertisement response
from the Network Advertising Provider Advertising Server to the
network access point; and using information from the primary
advertisement response to create a composite query response for
transmission to the first networking client.
16. The method of claim 15, further comprising: transmitting a
secondary advertisement query from the Network Advertising Provider
Advertising Server to the Subscription Service Provider Network
advertising server; determining a secondary advertisement response,
by the Subscription Service Provider Network advertising server,
using the secondary advertisement query; transmitting the secondary
advertisement response from the Subscription Service Provider
Network advertising server to the Network Advertising Provider
Advertising Server; and using information from the secondary
advertisement response to create the primary advertisement response
for transmission to the network access point.
17. The method of claim 15, wherein the query response is
transmitted in broadcast mode, suitable for reception by a
networking client different than the first networking client.
18. The method of claim 15, wherein the secondary advertisement
response is formed by analyzing system capability by the
Subscription Service Provider Network advertising server.
19. The method of claim 15, wherein the composite query response is
queued in the network access point.
20. The method of claim 15, wherein transmitting the composite
query response further comprises: forming a plurality of sections
of the composite query response; transmitting a plurality of
messages, wherein each message includes at least one section of the
composite query response.
21. The method of claim 15, wherein the composite query response is
transmitted as at least one multicast message.
Description
RELATED APPLICATION
[0001] None.
FIELD OF INVENTION
[0002] Embodiments of the invention relate to apparatus, system and
method for use of WLAN access enabled mobile devices such as
notebooks and handheld communication devices.
BACKGROUND
[0003] WiFi hotspots provide pubic WLAN access in many locations
such as airports, hotels, coffee shops, etc. Multiple hotspot
providers may provide overlapping service coverage in these areas.
Roaming agreements may exist between different service providers.
End users need to be aware of these roaming agreements and other
available services to select the appropriate service provider and
take advantage of different services offered.
[0004] The embodiments of the invention relate to methodology
whereby WiFi enabled devices can automatically select the
appropriate service provider, thereby taking advantage of different
services offered by different service providers.
[0005] Related art for WLAN network/service discovery relies on
manual user intervention to identify capabilities or services
offered at any hotspot. In the absence of any advertisement
mechanism, users will have to first associate with the hotspot, if
they can, and determine the capabilities through manual exploration
and manual entry, which is error prone and very difficult to do
from small form factor devices (apart from battery drain and longer
times to connect). Embodiments of the invention provide mechanisms
for making the capability and service advertisement available
during pre-association phase to WLAN hotspot which a mobile station
("STA") can use when discovering the service and selecting the
network that offers the preferred capabilities.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 shows an IEEE 802.11 based Reference Network;
[0007] FIG. 2 shows an example flow of advertisement mechanism;
[0008] FIG. 3 shows multicasting service discovery information in
chunks at regular intervals.
DETAILED DESCRIPTION
[0009] In the following description, numerous specific details are
set forth. However, embodiments of the invention may be practiced
without these specific details. In other instances, well-known
circuits, structures and techniques have not been shown in detail
in order not to obscure the understanding of this description.
[0010] The following glossary defines terms used herein unless a
different meaning is assigned within the context of usage. The
Authoritative Dictionary of IEEE Standards Terms, Seventh Edition,
should be referenced for terms not otherwise defined herein.
TABLE-US-00001 Acronym Definition 3GPP 3.sup.rd generation
Partnership Project 3GPP2 3.sup.rd generation Partnership Project 2
AAA Authentication, Authorization Accounting AdvS Advertising
Server AP Access Points AR IE Access Request Information Element BC
Broadcast DoS Denial of Service B-SNA Beacon-Start of Network
Advertising BWA Broadband wireless access DTI Delivery Traffic
Indication DTIM Delivery Traffic Indication Message IEEE Institute
of Electrical and Electronic Engineers IMS IP Multimedia Subsystem
IPTV Internet protocol television L2 Level 2 of the OSI networking
model LAN Local area network MAC Medium Access Control MC Multicast
MCA Multicast address MIH Media independent handover NAI Network
Access Identifier NA Network Advertising NAP Network Access
Provider OFDM Orthogonal frequency-division multiplexing OFDMA
Orthogonal frequency-division multiple access OSI Open Systems
Interconnection OTA Over The Air PHY Physical Layer QoS Quality of
Service SNA Start of Network Advertising SSID Service set
identifier SSPN Subscription Service Provider Network STA Station
TBTT Target Beacon Transmission Time TSF Time synchronization
function TU Time unit WiMAX World Interoperability for Microwave
Access WLAN Wireless Local Area Network
[0011] WiFi refers to wireless communication technology usable by
both mobile and fixed communication devices. Mobile wireless
technology may be specified in IEEE Standard 802.11, "Wireless LAN
Medium Access Control (MAC) and Physical Layer (PHY)
specifications" and amendments thereto (hereinafter "IEEE 802.11"
or "802.11"). In particular, 802.11 Amendment 7, "Interworking with
External Networks" may be referred to as "IEEE 802.11u" or
"802.11u." Wireless technology used by fixed wireless communication
devices may be specified in IEEE Standard 802.16, "Air Interface
for Fixed Broadband Wireless Systems" and amendments thereto
(hereinafter "IEEE 802.16" or "802.16"). It will be understood as
used herein that "wireless," "wireless technology," and similar
terms may refer to either 802.11 or 802.16 unless expressly limited
otherwise.
[0012] The purpose of IEEE 802.11 is to provide wireless
connectivity to automatic machinery, equipment, or stations that
require rapid deployment, which may be portable or hand-held, or
which may be mounted on moving vehicles within a local area. This
standard also offers regulatory bodies a means of standardizing
access to one or more frequency bands for the purpose of local area
communication. IEEE 802.11u specifies enhancements to 802.11 that
support WLAN Interworking with External Networks, facilitating
higher layer functionalities. IEEE 802.11u improves information
transfer from external networks, aiding network selection, and
enabling emergency services. IEEE 802.11 and amendments are hereby
incorporated by reference in their entirety.
[0013] The purpose of IEEE 802.16 is to specify the air interface
of fixed broadband wireless access (BWA) systems supporting
multimedia services. The medium access control layer (MAC) supports
a primarily point-to-multipoint architecture, with an optional mesh
topology. The MAC is structured to support multiple physical layer
(PHY) specifications, each suited to a particular operational
environment. For operational frequencies from 10-66 GHz, the PHY is
based on single-carrier modulation. For frequencies below 11 GHz,
where propagation without a direct line of sight must be
accommodated, three alternatives are provided: orthogonal
frequency-division multiplexing (i.e., WirelessMAN-OFDM or "OFDM");
orthogonal frequency-division multiple access (i.e.,
WirelessMAN-OFDMA or "OFDMA"); and orthogonal frequency-division
using single-carrier modulation (i.e., WirelessMAN-SCa or
"single-carrier modulation"). IEEE 802.16 and amendments are hereby
incorporated by reference in their entirety.
[0014] WiFi hotspots provide pubic WLAN access in many locations
such as airports, hotels, coffee shops, etc. and may provide
various services such as internet access, streaming video (e.g., IP
TV), IMS, and online games. Multiple hotspot providers may provide
overlapping service coverage in these areas. A roaming mobile
device that is enabled for wireless communication may be within the
coverage area of more than one network access point. The ability of
a mobile device to choose from among the available network access
points in the past has been limited. The mobile device may not be
able to connect to the network at all required levels of the
networking mode. (e.g., at L2, but not at the network layer).
Another shortcoming is that if several networks are available to
choose among, one network may be preferred but the mobile device
may also connect to a different network based on signal strength
criteria alone. This problem could extend to multiple interfaces as
the number of interfaces on the mobile device increases.
[0015] A roaming mobile device that is enabled for wireless
communication may enter and exit the coverage area of various
network access points. The process of transitioning network access
from one network access point to another is referred to as
"handover." Handover may be a homogeneous ("horizontal") event
within a single network, and used primary for localized or limited
mobility, for instance multiple 802.11 access points within a
single LAN. Handover may also be a heterogeneous ("vertical") event
in which the handover occurs across different types of networks,
and is used primarily for more global mobility. Vertical handover
offers more opportunities for optimizing the handover process.
[0016] Standardized handover protocols have been proposed in draft
IEEE Standard 802.21, "Media Independent Handover Services" and
amendments thereto (hereinafter "IEEE 802.21" or "802.21"). IEEE
802.21 and amendments are hereby incorporated by reference in their
entirety. IEEE 802.21 defines a common media independent handover
(MIH) function between Layer 2 and Layer 3 of the Open Systems
Interconnection ("OSI") network stack, which enables mobility
across heterogeneous networks. By allowing client devices and
networks to work cooperatively during these network transitions,
IEEE 802.21 provides mechanisms for optimizing handovers across
Wi-Fi, WiMAX and cellular radios that will dramatically enhance the
user's mobile experience. The intended application of IEEE 802.21
is primarily for vertical handovers, but it can also be used for
homogeneous handovers. IEEE 802.21 enables co-operative handover
decision making between clients and network. Media specific changes
closely follow the base 802.21 media independent handover ("MIH")
protocol.
[0017] IEEE 802.21 can provide a way for end users to select the
most appropriate provider, and this selection may change with time,
location, or type of service. Benefits of 802.21 include optimum
network selection, seamless roaming to maintain connections, and
lower power operation for multi-radio devices.
[0018] Supporting concurrent multiple radios presents unique
mobility-related and platform-related challenges. Client devices
must be capable of automatically detecting and selecting the best
wireless network and providing a seamless transition from one
network to another. Emerging mobility standards are needed to
enable handovers and also to enable terminal mobility across
multiple points of attachment as changes in user environments make
one network more attractive than another.
[0019] The standards address two kinds of handover: homogeneous
handovers and heterogeneous handovers. Homogeneous handovers across
similar points of attachment such as Wi-Fi Access Points ("APs"),
and WiMAX base stations within a single network, are handled by the
technology standards of the respective access networks. IEEE
802.11k and 802.11r address mobility in WLAN networks. IEEE 802.16e
augments mobility in WiMAX (802.16), and mobility in cellular
networks is enabled by 3GPP and 3GPP2 standards. Heterogeneous
handovers are defined as handovers across different networks and
are applicable to multiradio client platforms. The emerging IEEE
802.21 standard addresses mobility across heterogeneous
networks.
[0020] The embodiments of the present invention include a method
for wireless discovery of network services by one or more wireless
clients. The method includes transmitting a probe request from a
first networking client to a network access point, wherein the
first networking client has a wireless communication capability;
then
[0021] receiving a probe response, from the network access point,
by the first networking client, wherein the probe response includes
an indication of network services available to the first networking
client.
[0022] Optionally, this method by the wireless networking client
may further include calculating service availability from the probe
response.
[0023] Optionally, this method by the wireless networking client
may further include ranking service provider preference based on
the probe response.
[0024] Optionally, this method by the wireless networking client
may further include using a beacon to formulate the probe
request.
[0025] Optionally, this method by the wireless networking client
may further include using the probe response to formulate a second
probe request.
[0026] Optionally, this method by the wireless networking client
may be characterized by probe request being created using specific
device configuration information of the wireless networking
client.
[0027] Optionally, this method by the wireless networking client
may further include operating using a wireless network protocol
selected from the group consisting of IEEE 802.11, IEEE 802.16 and
WiMAX.
[0028] Embodiments of the present invention also include a method
for wireless discovery of network services by a first wireless
client. The method includes receiving a probe response from the
network access point, by the first wireless networking client, in
which the probe response had been transmitted in broadcast mode in
response to a probe request from a second wireless networking
client; furthermore, the probe response includes an indication of
network services available to the second wireless networking
client. The first wireless networking client then uses data from
the probe response to configure communication access by the first
wireless networking client.
[0029] Optionally, this method by the first wireless networking
client may further include calculating service availability from
the probe response, and ranking service provider preference based
on the probe response.
[0030] Embodiments of the present invention also include an
apparatus to perform wireless discovery of network services. The
apparatus includes a processor configured to create a probe
request; a wireless transmitter in communication contact with the
processor, with the wireless transmitter configured to transmit the
probe request; a wireless receiver in communication contact with
the processor, with the wireless receiver configured to receive a
probe response. The probe response includes an indication of
wireless network services available to the apparatus.
[0031] Optionally, this apparatus to perform wireless discovery of
network services may operate with the IEEE 802.11, IEEE 802.16 or
WiMAX communications protocol.
[0032] Embodiments of the present invention also include a system
for wireless discovery of network services, including a network
access point, having a first processor, configured to receive a
probe request from a first networking client, in which the first
processor creates a primary advertisement query from the probe
request. The system also includes a Network Advertising Provider
Advertising Server ("NAP AdvS"), in communication contact with the
network access point, configured to receive the primary
advertisement query from the network access point. The system also
includes a second processor, within the NAP AdvS, in which the
second processor is configured to determine a primary advertisement
response, wherein the primary advertisement response is
communicated from the NAP AdvS to the network access point. The
first processor creates a query response for transmission to the
first networking client, using information from the primary
advertisement response.
[0033] Optionally, this system for wireless discovery of network
services may include a Subscription Service Provider Network
advertising server ("SSPN AdvS") in communication contact with the
NAP AdvS. The NAP AdvS is configured to transmit a secondary
advertisement query to the SSPN AdvS. A third processor is located
within the SSPN AdvS, wherein the third processor is configured to
determine a secondary advertisement response, wherein the secondary
advertisement response is communicated from the SSPN AdvS to the
NAP AdvS. The second processor then creates the primary
advertisement response for transmission to the network access
point, using information from the secondary advertisement
response.
[0034] Optionally, this system for wireless discovery of network
services further includes a plurality of wireless networking
clients, in which at least one of the plurality of wireless
networking clients does not transmit a probe request, but can
receive and act upon a probe response.
[0035] Embodiments of the present invention also include a method
for wireless discovery of network services, by a server of wireless
networking, including receiving a probe request from a first
networking client, by a network access point; creating a primary
advertisement query from the probe request by the network access
point; transmitting the primary advertisement query from the
network access point to a NAP AdvS in communication contact with
the network access point; creating a primary advertisement response
by the NAP AdvS; transmitting the primary advertisement response
from the NAP AdvS to the network access point; and using
information from the primary advertisement response to create a
composite query response for transmission to the first networking
client.
[0036] Optionally, the method for wireless discovery of network
services, by a server of wireless networking, may further include
transmitting a secondary advertisement query from the NAP AdvS to
the SSPN AdvS; determining a secondary advertisement response, by
the SSPN AdvS, using the secondary advertisement query;
transmitting the secondary advertisement response from the SSPN
AdvS to the NAP AdvS; and using information from the secondary
advertisement response to create the primary advertisement response
for transmission to the network access point.
[0037] Optionally, the method for wireless discovery of network
services, by a server of wireless networking, may be further
characterized by the query response being transmitted in broadcast
mode, suitable for reception by a networking client different than
the first networking client.
[0038] Optionally, the method for wireless discovery of network
services, by a server of wireless networking, may be further
characterized by the secondary advertisement response being formed
by analyzing system capability by the SSPN AdvS.
[0039] Optionally, the method for wireless discovery of network
services, by a server of wireless networking, may be further
characterized by the composite query response being queued in the
network access point.
[0040] Optionally, the method for wireless discovery of network
services, by a server of wireless networking, further includes
transmitting the composite query response such that it includes
forming a plurality of sections of the composite query response;
transmitting a plurality of messages, wherein each message includes
at least one section of the composite query response.
[0041] Optionally, the method for wireless discovery of network
services, by a server of wireless networking, is further
characterized by the composite query response being transmitted as
at least one multicast message.
[0042] FIG. 1 provides exemplary reference configurations of an
802.11 reference network. Hot spots 1 and 2 could be using a common
Network Access Provider ("NAP") that provides a broadcast of the
communication capability of the hot spot and a broadcast or
advertisement of the services offered and AAA services. The
hotspots may also obtain these advertised services from different
Subscription Service Provider Network ("SSPN") providers through
the NAP core network. The advertisement information may include
SSPN name, service set identifier ("SSID"), inter-working services,
enrollment information, etc. The NAP AAA server authenticates
customers of the NAP onto their network. The NAP AAA also acts as a
proxy server to relay client authentication information requests to
the SSPN AAA servers, and routes the authentication requests based
on Network Access Identifier (NAI).
[0043] For seamless handovers between different networks and for
optimum selection of different networks, clients need to be able to
find back-end networks with favorable roaming agreements. Clients
need to be able to receive the advertised capabilities from SSPNs
and roaming partners, and be able to request more information about
available services, so that clients can make use of the information
during its network selection. This process is referred to as the
service discovery process.
[0044] There are at least three issues in the service discovery
process. First, clients may request information based on their
specific device configuration, and the requests may require the
clients to use multiple protocols to query the information. Second,
multiple clients may query for the same information and hence
information needs to be provided in a manner that provides an
efficient usage of power and bandwidth, while minimizing adverse
impact to other clients. Third, because a client may not know in
advance which networks the client can connect to, the client may
query this information when not associated with a particular public
WLAN. The client will scan and retrieve information from multiple
networks, which can lead to large power consumption depending on
the number of available networks, thereby draining battery power.
Therefore clients need to retrieve this information in a power
efficient manner.
[0045] FIG. 2 presents an embodiment of the present invention
providing a method that has improved service discovery. Prior to
performing the method, the AP may periodically transmit a beacon 1
("advertising beacon 1") that advertises capabilities of the AP,
such as the advertising protocol that the AP supports.
[0046] Prior to performing the method, the client has completed
network entry and an initial attach procedure. The client is able
to send and receive frames from the AP, but the client has not been
authenticated with the network and hence the client cannot access
network services. The method of FIG. 2 is performed by: First, the
client makes a probe request 10 which includes a query of services
available through the AP. The probe request 10 is made using a
protocol determined by the client after monitoring the advertising
beacon 1 from the AP. The probe request 10 includes a request
identifier Access Request Information Element ("AR IE"), which
uniquely identifies the probe request 10. The AP may use the probe
request 10 to formulate an advertisement query 20 to request
advertisement information from an advertising server. The probe
request 10 is more fully described in IEEE 802.11u.
[0047] When the AP receives a probe request 10 from a client, the
AP confirms receipt of request by returning to the client a probe
response 15, which includes the pass/fail status of the request;
the AR IE request identifier; and the multicast address ("MCA") to
which the response is sent. Including the AR IE in the response
from the AP allows the client to match a response from the AP with
a request sent by the client by matching the AR IE returned by the
AP with the AR IE sent by the client.
[0048] In some cases the AP can prepare a probe response 15,
responding to the probe request 10, based on information cached
within the AP. In other cases, the AP may have to query the NAP
server and get a response from the NAP server to respond to the
probe request 10. The Access Point ("AP") will form an
advertisement query 20 to relay the probe request 10 to a NAP
Advertising Server ("AdvS"). If the NAP AdvS is not able to satisfy
the query, the NAP AdvS will relay the advertisement query 20 to an
SSPN AdvS using a secondary advertisement query message 21 shown in
FIG. 2. The connection between the AP AdvS and the NAP AdvS may be
implemented at either L3 (i.e., the IP layer of communication), or
at L2 (i.e., the data link layer of communication), therefore the
advertisement query 20 can be transmitted at either L3 using an IP
frame, or L2.
[0049] The NAP and SSPN Advertising Servers store information about
the capabilities of network and the services they provide, and can
help the client determine whether or not it is possible or feasible
to connect to these NAP and SSPN Advertising Servers. For instance,
if the client needs VoIP/IPTV or gaming services and if the network
does not provide these services, then it would not be feasible for
the client to connect to the network. The procedure begins by
having the client request what services are provided by the
network. The NAP and SSPN AdvS analyze system capability and
respond back appropriately with the services provided by the
network. In some cases a NAP may have all the information, whereas
in other cases the NAP may have to redirect the requests to
specific operators that may maintain their own SSPN AdvS and
generate the appropriate response based on the query from the
client.
[0050] Any response to the advertisement query (i.e., an
advertisement response) from the NAP AdvS or SSPN AdvS is sent to
the AP via one or more Advertising Response 25 messages. The AP
then transmits back to the client a plurality of multicast Action
Frames in response to the probe request 10 from the client,
containing an encapsulated query response 30 (i.e. "MC (Query
Response)"), wherein a multicast frame is a frame that is addressed
to a plurality of recipients. The first MC (Query Response) message
is included with the B-SNA beacon. The query response 30 includes
action frames transmitted in clear text, wherein in a further
embodiment the reliability of the transmission is improved by, for
example, transmitting each advertising frame several times. If any
additional advertisement responses 25 have been received from the
NAP AdvS, or secondary advertisement responses 24 from the SSPN
AdvS, those responses are passed to the client using additional MC
(Query Response) messages 30. Details of the structure of these
messages are provided in IEEE 802.11u.
[0051] Action Frames that follow the beacon are used to relay the
Query Response 30, the Action Frame being a message format defined
by 802.11 that provides a mechanism for specifying management
actions. An embodiment of the invention includes that the Query
Response 30 may be divided into portions called "chunks," and then
be transmitted to the client in chunks having a size determined by
the AP based on the size of the response message and based on how
much time it would take to send a chunk based on network speed. The
chunks are sent at regular intervals as part of every "Nth"
periodic beacon messages, wherein "N" is denoted by the DTIM
interval.
[0052] Although a single client may have transmitted the probe
request 10, multiple clients may be interested in the response.
This situation may arise when there is a surge of clients
attempting to access services on a network, for instance in an
airport lounge when passengers exit an arriving airplane. In such
situations, the clients will all need the same type of information,
and network efficiency would be improved if all clients could
receive the Query Response 30, sent as a multicast in response to
the first Probe Request 10. Embodiments of the present invention
make the response from the AP available to multiple clients,
including silent clients, by using broadcast and/or multicast
messages to transmit the advertising response from the AP. These
silent clients ignore the AR IE field. Embodiments of the present
invention provide improved use of radio frequency (RF) spectrum and
the bandwidth. System throughput is improved because the silent
clients avoid the need to transmit a Probe Request 10, resulting in
less message traffic contending for bandwidth over the air, and
removing from the AP the burden of responding to duplicative Probe
Requests 10. The silent clients are able to monitor the
availability of services, and are able to improve their connections
at a later time with any changes in available services, link
conditions, or the silent client's service requirements.
[0053] By having the AP send the query response 30 in a
broadcast/multicast manner, the silent clients can determine
network capability without having to transmit an advertisement
query 10, thereby conserving power in the client, reducing usage of
transmission bandwidth, and increasing MAC efficiency. Because the
information is sent in small chunks, the beacon message containing
this information is relatively short, thereby reducing the
disruption to other routine network operations.
[0054] FIG. 3 presents an example of a sequence of beacon
transmissions, with a DTIM interval of 3, wherein the DTIM interval
indicates the proportion of the total number of beacons to the
number of beacons containing the DTIM information chunks 45. For
instance, a DTIM interval of "3" indicates that every third beacon
contains an information chunk 45. Each of the beacon transmissions
having a DTIM information chunk 45 is referred to as a "DTIM beacon
40." Because beacon messages are transmitted at fixed times known
in advance, the DTIM beacons 40 can be spaced out, thereby reducing
the distortion in the duration and relative timing of each beacon.
Information chunks 45 are transmitted in broadcast and multicast
format, commencing immediately after the DTIM beacon 40. B-SNA 50
is the Beacon-Start of Network Advertising.
[0055] Beacons are sent at regular intervals and are usually of a
fixed number of bits, as shown in FIG. 3 by the hollow bars,
bearing various fields of information that may be received by any
client, or any mobile terminal attempting to become a client. DTIM
beacons 40 are a subset of normal beacons, wherein DTIM beacons 40
occur periodically after a predetermined number of normal beacons
have elapsed. DTIM beacons 40 contain a special flag denoting that
beacon as the start of a DTIM frame. After each DTIM beacon 40,
additional information is sent in additional chunks 45 as indicated
by the shaded bars. FIG. 3 illustrates the DTIM 40 beacon and
additional chunk 45 transmitted in place of every third normal
beacon. One field within a DTIM beacon 40 is the DTIM interval.
Clients, knowing which beacons are DTIM beacons 40 from monitoring
the flag, can extract the DTIM interval from the DTIM beacon
40.
[0056] B-SNA 50 is an otherwise normal, non-DTIM beacon that
signals the Start of Network Advertising. The B-SNA interval is "N"
times the DTIM interval with offset of +1, wherein the offset
refers to the location of the query response 30 with respect to the
next B-SNA beacon 50; "N" is configurable and an offset of +1 helps
ensure that the B-SNA beacon 50 does not collide with the DTIM
beacon 40. Typical values of N produces B-SNA every 1-2
seconds.
[0057] Immediately after a B-SNA beacon 50 is sent, a Network
Advertising (NA) frame begins. NA frames are transmitted as clear
text (i.e., not encrypted), in multicast action frames. However,
unlike a BC/MC information chunk 45, in which a chunk 45 of the
Query Response 30 is broadcast/multicast after a DTIM beacon 40, NA
frames can have other intervening in time unicast frames (i.e., a
frame intended for only one host), for instance QoS frames. Since
information is sent in small chunks that are spread out over time,
the change to the starting time of the next B-SNA beacon 50 is
minimized, producing a small shift in time, thereby minimizing the
jitter of the beacon. The B-SNA beacon 50 contains the B-SNA count
and the data buffered bit so that the client can predict the TSF
time when network advertisements will start and whether any
advertisements will be sent after the B-SNA beacon 50.
[0058] B-SNA also includes a configured "Time to Suspend" field,
which is the amount of time in TUs that an AP will schedule NA
frames for transmission after the Target Beacon Transmission Time
("TBTT") for B-SNA. After expiration of this time, no more NA
frames will be transmitted until the next B-SNA beacon 50.
[0059] If additional advertising frames are queued in the AP, then
a "MORE" data bit in the multicast action frame is set to indicate
that additional advertising frames are queued.
[0060] Embodiments of the present invention offer solutions
providing much better system operation and improved user
experiences. Other key advantages include: Susceptibility to a
Denial of Service ("DoS") attack is minimized because the network
manages bandwidth consumption over the air; More efficient
utilization of bandwidth and spectrum by multicasting the responses
based on specific user query, and by the AP limiting probe requests
10 if needed; Network efficiency is improved because an
un-associated client never gets its frames passed into network; and
less power is required by clients, because clients wake up only at
predetermined points in time.
[0061] This application may disclose several numerical range
limitations that support any range within the disclosed numerical
ranges even though a precise range limitation is not stated
verbatim in the specification because the embodiments of the
invention could be practiced throughout the disclosed numerical
ranges. Finally, the entire disclosure of the patents and
publications referred in this application, if any, are hereby
incorporated herein in entirety by reference.
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