ENHANCED SERVICE DISCOVERY MECHANISM IN WIRELESS
COMMUNICATION SYSTEM
BACKGROUND
This disclosure relates generally to the field of wireless communication, and in
particular to discovering services provided by associated service providers using Layer 2
Service Discovery protocols.
A variety of devices are capable of providing services, for example, printing
service, via wireless communication networks operating in compliance with standardized
technologies such as IEEE 802.11. Conventionally, those devices and/or services are
discovered using Layer 3 Service Discovery (L3SD) protocols, such as Simple Service
Discovery Protocol (SSDP), wherein service consumers are required to establish a layer-3
end-to-end connection with service providers in order to obtain multicast messages
describing services provided by those service providers. These L3SD protocols can result
in a lengthy connection process to discover services.
Layer 2 Service Discovery (L2SD) enables devices to discover desired services
without having to establish layer-3 connection. Efforts have been made to implement
L2SD operable in some wireless communication standards, such as Wi-Fi Protected Setup
(WPS), Peer 2 Peer Special Interest Group (P2P SIG) and Wireless Gigabit Alliance
(WGA).
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates an example network architecture in accordance with various
aspects of the present disclosure.
Figure 2 illustrates a block diagram illustrating an example controller in
accordance with various aspects of the present disclosure.
Figure 3 is a flow diagram illustrating an example process for providing L2SD,
according to an embodiment.
Figure 4 is a flow diagram illustrating another example process for providing
L2SD, according to an embodiment.
DETAILED DESCRIPTION
DEFINITIONS
"Service" can be used interchangeably with "device", or includes device.
Service provider: Any device capable of providing services such as printing via the
wireless medium (WM) for STAs.
Access Point (AP): Any entity that has a station (STA) functionality and provides
access to the distribution services, via the WM for associated STAs.
Mobile Station (MS): A type of STA that uses network communications while in
motion.
Station (STA): Any device that contains an IEEE 802.1 1-conformant medium
access control (MAC) and physical layer (PHY) interface to the wireless medium (WM).
Wireless medium (WM): The medium used to implement the transfer of protocol
data units (PDUs) between peer physical layer (PHY) entities of a wireless local area
network (LAN).
Layer 2 Service Discovery (L2SD) is a protocol which allows communication
devices to discover network services provided by other devices at Layer 2 of the Open
System Interconnection Reference Model (OSI Reference Model).
Layer 3 Service Discovery (L3SD) is a protocol which allows communication
devices to discover network services provided by other devices at Layer 3 of the OSI
Reference Model. An example of L3SD includes Universal Plug and Play (UPnP), Zero
configuration networking (ZeroConf) and Simple Service Discovery Protocol (SSDP).
DESCRIPTION
Various embodiments disclosed herein relate to an apparatus and method that
facilitate an efficient service discovery at Layer 2 in a wireless communication system
where services are provided by one or more service providers to one or more mobile
stations associated with a controller. The wireless communication system is operable
according to standard protocols such as Wi-Fi Protected Setup (WPS), Peer 2 Peer Special
Interest Group (P2P SIG) and Wireless Gigabit Alliance (WGA).
According to various embodiments, an apparatus and method of this disclosure
may be used to transmit, from a controller to associated mobile stations, an advertising
message including an advertising information element indicative of the establishment of
the new association of a new service provider configured to provide at least one particular
service. The advertising message may be configured as one of Layer-2 broadcasting
messages such as a Beacon frame in the IEEE 802. 11 standard. The advertising
information element may be encoded in such a broadcasting message. The advertising
information element may include less bits as compared to that of service information
element that describes services provided by service providers. In some embodiment, the
advertising information element may consist of singly binary bit.
At the receipt of the advertising information element, the mobile stations may
transmit to the controller a discovery request for further information regarding the new
service. In response to the discovery request, the controller may transmit the service
information element associated with the particular service provided by the new service
provider. Using the transmitted service information element, the requesting mobile station
may establish an upper layer connection with the service provider. In this way, the service
information element relating to the new service is transmitted only to the mobile station(s)
transmitting the discovery request in response to the advertising information element.
Because the advertising information element used in this disclosure consists of smaller
number of binary bit(s) as compared to the service information element and the service
information element is not transmitted to all the associated mobile stations, the disclosed
service discovery mechanism can reduce the amount of data used to advertise a new
service. This embodiment may be deemed as "pull model" since the service information
element is provided in response to the discovery request from the requesting mobile
station.
According to various embodiments, an apparatus and method may be used to
transmit a service information element based on a desired service type registered with a
controller. This operation may be deemed as "push model", where a service information
element is transmitted to mobile stations without active solicitation from them. In this
push model, the controller may receive from the associated mobile stations a discovery
request for a service including desired service type and retain the desired service type at a
memory device until a suitable service matching to the discovery request is active. If a
new association is established between the controller and a new service provider
configured to provide a particular service, the controller determines whether the particular
service matches the retained discovery request; and, if any, transmit the matching service
information element to the requesting mobile station.
Figure 1 illustrates an example architecture of a system 100 in accordance with
various aspects of the present disclosure. The system 100 may include a controller 102
configured to wirelessly communicate with associated mobile stations 106a, 106b, and
106c (hereinafter "mobile station 106" or "MS 106"). Controller 102 may be configured
as an Access Point (AP) in the IEEE 802. 11 standard or Private Coordinate Point (PCP) in
Wireless Personal Area Network (WPAN) standards such as 60 GHz WPAN.
Controller 102 may also have wired connections with, for example, service
providers 108a and 108b as well as wireless connections with, for example, a network 104
and a service providerl08c. These service providers 108a, 108b and 108c hereinafter may
be collectively referred to as "service provider 108". Service provider 108 may be
configured to be, for example, PC peripherals such as a printer, monitors and projectors.
Service provider 108 provides the MS 106 with a various kinds of services such as a
printing via the wireless media.
Figure 2 is a block diagram illustrating an example controller 102 in accordance
with various aspects of the present disclosure. Controller 102 may include, among others,
a transceiver 202, an association establishment module 204, service information element
(service IE) registration module 206, a advertising information element (advertising IE)
generation module 208, a service discovery module 210, and a memory module 212.
Transceiver 202 may transmit to and receive communications from MS 106 via the
wireless medium. For example, transceiver 202 may receive a discovery request for a
desired service from MS 106 and transmit to MS 106 various communications, including
an advertising information element (advertising IE) and service information element
(service IE). The advertising IE may be encoded in a Beacon. Transceiver 202 may also
receive, from associated service provider 108, a service registration request including a
service IE. The service IE may include a sub-element, for example, TLVs, in which the
services offered by the requesting service provider 108 and various attributes
corresponding to the service are encoded. For example, the attributes of the service IE
includes the service type, context (location), and user friendly name. These attributes may
be provided by higher level service applications associated with the requesting service
provider 108 or its service. In one embodiment, these attributes may be configured based
on user input.
According to various embodiments, service IE registration module 206 may
receive the service IE included from transceiver 202 and register the received service IE in
Memory module 212. In this manner, the requesting service provider 108 may register its
service IE with controller 102 by sending the service registration request. Upon the
registration of the service IE, advertising IE generation module 208 may generate an
advertising IE. In one embodiment, the advertising IE may be incorporated in a Beacon
frame. For example, the advertising IE may be encoded in a field of the Beacon frame,
wherein the field consists of a single bit. Advertising IE generation module 208 may set
the field, for example, to "1" when the registration of a new service IE is established.
Otherwise, the field remains to be "0". Thus, newly available services may be advertised
using the adverting IE consisting of a single bit indicative of the existence of a new active
service.
According to various embodiments, service discovery module 210 may perform
service discovery process according to a discovery request obtained from MS 106 through
transceiver 202. For example, service discovery module 210 may determine whether any
one of the service types stored in memory module 212 matches the desired service type
based on the discovery request. If one or more matching services are identified,
corresponding service IEs are retrieved from memory module 212 and transmitted to the
requesting MS 106. Upon the receipt of the service IE, the requesting MS 106 may
establish a connection with service provider 108 (e.g., printer) providing the matching
service (e.g., printing service) using L3SD such as UPnP.
Figure 3 is a flow diagram illustrating an example process 300 for providing L2SD,
according to an embodiment. The various processing operations depicted in the flow
diagram of Figure 3 are described in greater detail herein. The described operations for a
flow diagram may be accomplished using some or all of the system components described
in detail above and, in some embodiments, various operations may be performed in
different sequences. In other embodiments, additional operations may be performed along
with some or all of the operations shown in the depicted flow diagrams. In yet other
embodiments, one or more operations may be performed simultaneously. Accordingly,
the operations as illustrated (and described in greater detail below) are examples by nature
and, as such, should not be viewed as limiting.
According to various embodiments, a plurality of service IEs associated with
respective service providers 108 are registered with controller 102. A new service
provider 108, whose service IE has not been registered with controller 102, may be
associated with controller 102 in an operation 302. Service provider 108 may use
Association Request to request a new association with controller 102. In an operation 304,
upon the establishment of the new association, a service IE associated with a particular
service provided by the new service provider 108 may be registered in controller 102. In
one embodiment, the service IE is transmitted from service provider 108 to controller 102
together with a service registration request and, in turn, arranged to be stored in memory
module 212. The service IE may include the service type, context (location), and user
friendly name associated with the new service of the requesting service provider 108.
Thus, information indicative of the service type, context (location), and user friendly name
associated with the new service are stored in memory module 212.
Upon the establishment of the registration of the new service IE, an advertising IE
is generated and transmitted to associated MS 106 in an operation 306. In one
embodiment, the advertising IE may be incorporated in a Beacon frame by setting a value
in a field of the Beacon frame to "1". As such, the single bit field in the Beacon frame
may indicate the existence of a new service. The Beacon frame, in turn, may be broadcast
or multicast to associated MS 106. Thus, instead of forwarding the registered service IE,
the existence of a new service is advertised to associated MS 106 by use of, for example,
the single bit field of the Beacon frame. Ms 106 may receive the transmitted advertising
IE and, in response, transmit a discovery request for further information of the new service
to controller 102 via the wireless medium, if desired. Ms 106 can ignore the advertising
IE if it does not need additional service. In one embodiment, MS 106 may determine
transmission a discovery request based on a user instruction. Alternatively or additionally,
MS 106 may automatically determine whether a discovery request should be transmitted
based on a predetermined settings. The discovery request may include a desired service
type, for example, printing service or monitor service.
In an operation 308, controller 102 receives the discovery request from MS 106.
In an operation 310, the service IE corresponding to the new service is transmitted to the
requesting MS 106 in response to the discovery request. Using the transmitted service
IE(s), MS 106 may establish upper layer connections with the service providers that can
provide the identified services. Thus, because service IEs including various information
about provided service are transmitted only to MS 106 that desires to use additional
services, an efficient service discovery mechanism can be achieved.
Figure 4 is a flow diagram illustrating another example process 400 for providing
L2SD, according to an embodiment. The various processing operations depicted in the
flow diagram of Figure 4 are described in greater detail herein. The described operations
for a flow diagram may also be accomplished using some or all of the system components
described in detail above. In one embodiment, a plurality of service IEs associated with
respective service providers 108 are registered with controller 102. In an operation 402,
MS 106 may transmit a discovery request for a desired service to controller 102 before or
regardless of receiving any advertising IEs. The discovery request may include one or
more device descriptor sub-elements indicative of desired service type or device type.
In an operation 404, upon the receipt of the discovery request at controller 102, it is
determined whether any matching service is available. In one embodiment, the desired
service type included in the discovery request may be compared with the service types
registered in memory module 212. Memory module 212 may include aplurality of service
IEs associated with existing service providers 108. If one or more matching services are
identified as a result of the comparison, the service IEs corresponding to the identified
services are retrieved from memory module 212 and transmitted to the requesting MS 106.
On the other hand, if no matching service is found in memory module 212, a response
indicating absence of matching service is transmitted as a discovery response message to
the requesting MS 106. In parallel with transmitting the discovery response, the desired
service type is retained at controller 102.
If a new service provider 108 that has not registered its service IE(s) becomes
associated with controller 102 in an operation 406, then a new service IE(s) may be
registered with controller 102 at the request of the new service provider 108 in an
operation 408. In an operation 410, upon the registration of the new service, a new
comparison process may be performed to determine whether the newly registered service
IE matches the retained service type. If the new service IE matches the retained desired
service type, the service IE is transmitted to MS 106 that previously registered the desired
service type. Using the transmitted service IE, MS 106 may establish an upper layer
connection with service provider 108 providing the matching service. On the other hand,
in case the new service IE does not match the retained desired service type, controller 102
continues to retain the desired service type. This comparison process can be performed
repeatedly until a service provider capable of providing the desired type of service is
associated with controller 102.
Thus, MS 106 is allowed to register its desired service type with controller 102 and
may receive service IEs matching the registered service type once a service provider 108
configured to provide such a matching service is associated with controller 102 without
any particular request for the new service provider 108.
In addition, various embodiments of this disclosure may be made in hardware,
firmware, software, or any suitable combination thereof. Aspects of this disclosure may
also be implemented as instructions stored on a machine-readable medium, which may be
read and executed by one or more processors. A machine-readable medium may include
any mechanism for storing or transmitting information in a form readable by a machine
(e.g., a computing device). For example, a machine-readable storage medium may include
read only memory, random access memory, magnetic disk storage media, optical storage
media, flash memory devices, and others. Further, firmware, software, routines, or
instructions may be described herein in terms of specific exemplary embodiments that
may perform certain actions. However, it will be apparent that such descriptions are
merely for convenience and that such actions in fact result from computing devices,
processors, controllers, or other devices executing the firmware, software, routines, or
instructions.
Various embodiments herein are described as including a particular feature,
structure, or characteristic, but every aspect or embodiment may not necessarily include
the particular feature, structure, or characteristic. Further, when a particular feature,
structure, or characteristic is described in connection with an embodiment, it will be
understood that such feature, structure, or characteristic may be included in connection
with other embodiments, whether or not explicitly described. Thus, various changes and
modifications may be made to this disclosure without departing from the scope or spirit of
the inventive concept described herein. As such, the specification and drawings should be
regarded as examples only, and the scope of the inventive concept to be determined solely
by the appended claims.

CLAIMS
What is claimed is:
1. An apparatus comprising:
a controller for a wireless network system communicatively coupled to one or
more associated service providers each of which provides at least one service to one or
more associated mobile stations, the controller comprising one or more processors
configured to:
establish a new association between the controller and a new service provider that
provides at least one particular service;
register, upon the establishment of the new association, a service information
element associated with the at least one particular service;
generate, upon the registration of the service information element, an advertising
information element that indicates the establishment of the new association of the new
service provider, wherein the service information element includes larger number of
binary bits than that of the advertising information element;
transmit, from the controller to the one or more associated mobile stations, an
advertising message including the advertising information element.
2. The apparatus of claim 1, wherein the one or more processors are further
configured to:
receive a discovery request for a service, the discovery request being transmitted
from one of the one or more associated mobile stations in response to the advertising
message; and
transmit, in response to the discovery request, to the requesting mobile station, at
least a part of the service information element.
3. The apparatus of claim 2, wherein the service information element is used
by the requesting mobile station to determine whether the at least one particular service is
desired.
4. The apparatus of claim 2, wherein said at least part of the service
information element is transmitted to the requesting mobile station before a connection
between the requesting mobile station and the new service provider is established.
5. The apparatus of claim 1, wherein said advertising information element
consists of a single binary bit.
6. The apparatus of claim 2, wherein the service information element includes
type information indicating at least one type of the at least one particular service; and
wherein the type information is included in said part of the service information element to
be transmitted to the requesting mobile station.
7. The apparatus of claim 2, wherein the discovery request includes type
information indicating desired type of the requested service.
8. The apparatus of claim 7, wherein the one or more processors are further
configured to:
determine whether any one of services provided by the one or more associated
service providers matches the desired type based on the discovery request;
transmit, to the requesting mobile station, one or more service information
elements corresponding to the matching services.
9. The apparatus of claim 1, wherein the advertising message is configured as
one of Layer-2 broadcasting messages that are periodically broadcast.
10. The apparatus of claim 1, wherein the advertising message is configured as
a Beacon frame.
11. A computer-implemented method comprising:
establishing a new association between a controller in a wireless network system,
wherein the wireless network system includes a controller and one or more associated
service providers each of which provides at least one service to one or more associated
mobile stations, and a new service provider, the new service provider providing at least
one particular service;
registering, upon the establishment of the new association, a service information
element associated with the at least one particular service;
generating, upon the registration of the first service information element, an
advertising information element that indicates the establishment of the new association of
the new service provider, wherein the service information element includes larger number
of binary bits than that of the advertising information element; and
transmitting, from the controller to the one or more associated mobile stations, an
advertising message including the advertising information element.
12. The computer-implemented method of claim 11, wherein the computerimplemented
method further comprising:
receiving a discovery request for a service, the discovery request being transmitted
from one of the one or more associated mobile stations in response to the advertising
message; and
transmitting, in response to the discovery request, to the requesting mobile station,
at least a part of the service information element.
13. The computer-implemented method of claim 12, wherein the service
information element is used by the requesting mobile station to determine whether the at
least one particular service is desired.
14. The computer-implemented method of claim 12, wherein said at least part of
the service information element is transmitted to the requesting mobile station before a
connection between the requesting mobile station and the new service provider is
established.
15. The computer-implemented method of claim 11, wherein said advertising
information element consists of a single binary bit.
16. An apparatus comprising: a controller for a wireless network system
communicatively coupled to one or more associated service providers each of which
provides at least one service to one or more associated mobile stations, the controller
comprising one or more processors configured to:
receive, from one of the one or more associated mobile stations, a discovery
request for a service including desired service type;
retain the desired service type at a memory device;
establish a new association between the controller and a new service provider that
provides at least one particular service;
register, upon the establishment of the new association, a service information
element associated with the at least one particular service;
determine, upon the establishment of the new association, whether the at least one
particular service matches the retained discovery request; and
transmit the service information element to the requesting mobile station if the at
least one particular service matches the discovery request.
17. The apparatus of claim 16, wherein the one or more processors are further
configured to:
determine, upon the receipt of the discovery request, whether said at least one
service provided by said one or more associated service providers matches the discovery
request;
transmit, to the requesting mobile station, one or more service information
elements corresponding to the matching services; and
retain the received discovery request at a memory device only if none of said at
least one service matches the discovery request.
18. The apparatus of claim 16, wherein the one or more processors are further
configured to:
update the retained discovery request in response to a update request from the
requesting mobile station.
19. The apparatus of claim 16, wherein the one or more processors are further
configured to remove the retained discovery request if the at least one particular service
matches the retained discovery request.
20. The apparatus of claim 16, wherein the discovery request includes type
information indicating desired type of the requested service; and wherein the one or more
processors are further configured to determine whether the at least one particular service
matches the discovery request by comparing the type information of the requested service
with the service information element corresponding to the at least one particular service.