Abstract:
A communications system is capable of knowing presence status of mobile communications devices such as cellular transceivers. An access gateway such as, for example, a PDSN access gateway or home agent access gateway, manages access to a mobile communications device. The access gateway knows the presence status of the mobile communications device and reports it to a presence server. The access gateway can know the presence status using attributes obtained during management of system operation by the access gateway.

Description:
BACKGROUND OF THE INVENTIONS  
       [0001]     1. Technical Field  
         [0002]     The present inventions relate to presence communications and, more particularly, relate to communications systems having presence awareness.  
         [0003]     2. Description of the Related Art  
         [0004]     Presence, availability and location (PAL) services require that a networked presence entity such as a presence server, is informed with information about the status of a device, application, or user. This information can be queried, polled, or pushed to watcher devices in order for the watchers to make intelligent decisions about when, where, and how to deliver information to the presence entity.  
         [0005]     Presence and availability services are implemented in a basic form in some of the instant messaging applications available today. These programs allow a user to establish a “buddy list” of other users. When the user turns on the instant messaging application, he becomes “present”. If he has configured his client to do so, he is also indicated as “available”. However, he may change his presence and availability status depending if he goes off line, or becomes busy. If he has been idle for a period of time, the instant messaging client may automatically mark the user as idle.  
         [0006]     The Internet Engineering Taskforce (IETF) as published some Requests for Comments (RFC) and an internet draft on presence used in Instant Messaging (IM) and the Session Initiation Protocol (SIP). M. Day, et. al. published “A Model for Presence and Instant Messaging,” Internet RFC 2778, in February 2000. M. Day, et. al. also published “Instant Messaging/Presence Protocol Requirements,” Internet RFC 2779, in February 2000. J. Rosenberg published “A Presence Event Package for the Session Initiation Protocol (SIP),” Internet draft draft-ietf-simple-presence-10.txt, on Jan. 31, 2003.  
         [0007]     Currently presence, availability and location (PAL) services are mostly used to notify other users of a user&#39;s status. However, these capabilities are being enhanced to include device and application presence, as well as location services. For mobile users, location is a potentially beneficial enhancement.  
         [0008]     The presence entity currently sends out messages to publish its presence status to the presence servers and watchers. What is needed is a more efficient way for a presence entity to make its presence status known.  
       SUMMARY OF THE INVENTIONS  
       [0009]     An object of the present inventions is to provide amore efficient way for a presence entity to make its presence status known.  
         [0010]     Another object of the present inventions is to provide a way for a presence entity to publish its presence status without creating additional network traffic.  
         [0011]     A further object of the present inventions is to utilize knowledge already existing in network equipment and reduce presence demands on a presence entity.  
         [0012]     An additional object of the present inventions is to utilize an access gateway to handle presence communications with a presence entity and a presence server.  
         [0013]     A communications system is capable of knowing presence status of mobile communications devices such as cellular transceivers. An access gateway such as, for example, a PDSN access gateway or home agent access gateway, manages access to a mobile communications device. The access gateway knows the presence status of the mobile communications device and reports it to a presence server. For mobile IP the access gateway is either the PDSN or the home agent.  
         [0014]     The access gateway can know the presence status using attributes obtained during management of system operation by the access gateway. The presence server receives the presence status for the mobile communications device without querying the mobile communications device. The access gateway may query the mobile communications device on a predetermined schedule to obtain presence status of the mobile communications device. The presence server can alternatively initiate a query of the access gateway for presence status of the mobile communications device, perhaps on a predetermined schedule. The access gateway knows the presence status of the mobile communications device by storing attributes from the mobile communications device. The access gateway can obtain presence data from a radio access network. The presence server receives the presence status for the mobile communications device by obtaining some of the attributes from the mobile communications device from the access gateway. The access gateway at a home network, known as a home agent, can hold attributes.  
         [0015]     The details of the preferred embodiments and these and other objects and features of the inventions will be more readily understood from the following detailed description when read in conjunction with the accompanying drawings wherein: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  illustrates a schematic block diagram of a presence entity, a presence aggregator, a presence server and one or more watchers according to the present inventions;  
         [0017]      FIG. 2  illustrates a schematic block diagram of a mobile communications system having presence awareness according to the present inventions;  
         [0018]      FIG. 3  illustrates flow diagrams of three exemplary call flows for presence reporting from a home agent access gateway in the communications system of the present inventions; and  
         [0019]      FIG. 4  illustrates flow diagrams of three exemplary of call flows for presence reporting from a PDSN access gateway in the communications system of the present inventions. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]      FIG. 1  illustrates a schematic block diagram of a presence entity  110 , a presence aggregator  120 , a presence server  130  and one or more watchers  140  according to the present inventions. These components simply make-up the presence architecture. The presence entity  110  is the entity whose presence is being monitored. The presence entity  110 , can be any device, application, or user, and is represented by a mobile transceiver according to the preferred embodiment. The mobile transceiver can be a mobile cellular radio or radiotelephone.  
         [0021]     The presence entity  110  communicates over an access protocol  150  with the presence aggregator  120 , which according to the preferred embodiments is an access gateway. In the preferred embodiments, the presence aggregator  120  is an access device, such as a PDSN or a HA or a GGSN, but its function is not limited to these roles. A PDSN is a Packet Data Serving Node PDSN, a HA is a Home Agent and a GGSN is a GPRS (General Pack Data Service) Serving Node. The presence aggregator  120  may collect and publish presence status multiple presence servers  130 .  
         [0022]     By presence status in the present inventions, applicant means the status of one or more of the statuses selected from the group consisting of presence, availability and location (PAL). The presence, availability and location (PAL) statuses, with respect to a presence entity such as a mobile transceiver, can be defined as follows: 
        Presence identifies whether or not the presence entity such as a mobile transceiver is on the network, and if it is, its preferred methods of contact, such as email addresses, phone numbers, URL&#39;s, etc. Presence is a set of attributes characterizing current properties of presence entities such as status, an optional communication address and other optional attributes etc.     Availability identifies whether the presence entity is available for a particular type of session. For example, it identifies, if a presence entity is on a phone call, it may be available for instant messaging, but not telephony services. Availability is a property of a presence entity denoting its ability and willingness to communicate based on factors such as the identity or properties of the watcher and the preferences and/or policies that are associated with the presence entity.     Location identifies the physical or location of the presence entity such as a mobile transceiver. Location is a representation of the physical or virtual location of a presence entity.        
 
         [0026]     Note that the presence entity  110  may have control over which watcher  140  sees any of this information. For example, a presence entity  110  may allow only certain groups of watchers  140  to know its availability.  
         [0027]     The presence aggregator  120  may also be a third party that publishes PAL information of the presence entity on its behalf.  
         [0028]     The presence server  130  receives published information  160  from the presence aggregator  120 , and stores this information in a local database. The presence server  130  can receive published information  160  from more than one presence aggregator  120 . The presence server  130  also allows watchers  140  to request presence status of one or more presence entities  110 . In other words, a watcher  140  can subscribe to the presence status of a device and the presence server  130  may notify the watcher when this status changes.  
         [0029]     The presence server  130  may allow the presence entity  110  or the presence aggregator  120  to determine the privacy level of its PAL information. For example a presence entity  110  may be able to indicate to the presence server  130  that its entire presence status, or parts of its presence status, can be seen by only certain watchers  140 . Then the presence server  130  must authenticate watchers  140  that request this presence status.  
         [0030]     Watchers  140  can subscribe to the presence status of a presence entity  110  via the presence server  130 . Several types of watchers  140  may exist. Subscribing watchers  140  subscribe  170  to the presence status of a presence entity  110  and then waits to be notified  180  of events by the presence server  130 . Polling watchers  140 , on the other hand, periodically request an update of the presence status of a presence entity  110 . Polling watchers  140  are more efficient on wireless networks where bandwidth is limited and the watcher  140  wants some control over the volume of information sent.  
         [0031]     Presence and availability services are considered for third generation cellular systems such as CDMA2000. The CDMA2000 system contains an access gateway known as the Packet Data Serving Node (PDSN) and defined in the CDMA2000 Wireless IP Standard, TIA/EIA IS-835-B, of September 2002.  
         [0032]      FIG. 2  illustrates a schematic block diagram of a mobile communications system having presence awareness according to the present inventions. A CDMA2000 communications system architecture is illustrated in the preferred embodiment of  FIG. 2 . Voice and data mobile devices  210  connect through a wireless channel  220  and a radio access network (RAN)  230  to an access gateway such as a packet data serving node (PDSN) access gateway  240  in a visited network  250 . A mobile user session is encapsulated in PPP, and then tunneled over an A10/A11 interface  260 , which uses GRE encapsulation.  
         [0033]     There are two types of calls, simple IP and mobile IP. Simple IP calls follow path  280  and provide basic IP network access, with the mobile being assigned an IP address from the visited network. If a mobile using simple IP roams to a new RAN, it is likely to be assigned a different PDSN access gateway  240  and therefore assigned a new IP address, breaking any data transfer in progress. Mobile IP calls follow path  285  and allow an IP address to be assigned by a home network  290  and kept by a mobile device  210  as it roams across RANs. A mobile IP call will maintain application state and data transfer between handoffs, enhancing the overall user experience. Mobile IP calls are tunneled between the PDSN access gateway  240  and a home agent access gateway  291  using either IP-in-IP, GRE, or Ipsec.  
         [0034]     Both simple IP and mobile IP types of calls are authenticated by the authentication, authorization and accounting (AAA) infrastructure, which consists of a foreign AAA (RADIUS FAAA)  252  and a home AM (RADIUS HAAA)  292 . The user&#39;s profile and associated information resides in the RADIUS HAAA  292 , so the RADIUS FAAA  252  proxies requests and responses between the PDSN access gateway  240  and the RADIUS HAAA  292 . The home agent access gateway  291  may also communicate with the RADIUS HAAA  292  directly for a further round of authentication, if necessary, or to acquire an IP address for the mobile device  210 .  
         [0035]     Both simple IP and mobile IP calls connect to the internet  283 . This is where a presence server  287  connects to obtain the presence information for either the simple IP or mobile IP access gateways. In the case of simple IP, the access gateway is the PDSN access gateway  240 . In the case of mobile IP, the access gateway is made up of both the home agent  291  and the access gateway PDSN  240  acting together on the two sides of the mobile IP tunnel  285 . Watchers  288  obtain presence status from the presence server  287  over the internet as well. The presence server  287  and the watchers  288  can alternatively be connected more directly to the simple IP or mobile IP data behind their respective PDSN access gateway  240  or home agent access gateway  291  for security or other reasons. An alternate connection is over the wide area network of the internet  283  as illustrated in the embodiment of  FIG. 2 .  
         [0036]     In the CDMA2000 network, a presence server  287  may exist either behind the PDSN access gateway  240 , for simple IP, or behind the home agent access gateway  291 , for mobile IP. Being in the core network would allow it to receive input from a number of presence entities as well as access gateways, such as the PDSN access gateway  240  and home agent access gateway  291 . Presence capability is thus facilitated in the communications system of the present inventions by these access gateways. The presence status of a mobile device  210  is thus provided to the presence server  287  by facilitation of an access gateway thus improving network utilization.  
         [0037]     While the embodiment of  FIG. 2  exemplifies a general CDMA2000 network, there are many variations that can be deployed commercially. In fact, every service provider their own unique architecture based on their technical and business requirements. Some networks are simple IP only, while others support both simple IP and mobile IP. Some network architectures are centralized, with PDSNs and home agents co-located in one or more points of presence, while others employ a distributed architecture. Furthermore, the visited and home networks may be the same network, may be different networks operated by the same service provider, or may be different networks operated by different service providers.  
         [0038]     Reporting of presence status in a CDMA2000 network may occur on the home agent access gateway  291  or the PDSN access gateway  240 . We will discuss each case in detail. In CDMA2000, it may be useful to track presence status on behalf of a mobile device not only to enable communications to and from the mobile device, but to also gather detailed network usage statistics and track mobile node behavior for purposes of lawful electronic surveillance.  
         [0039]     In the case of the home agent access gateway  291 , the home agent access gateway may report presence status to the presence server  287  on behalf of a mobile device  210 . The following attributes of presence status can be published at the presence server  287 : 
        Network Access Identifier (NAI): The email address of the mobile device,     assigned IP address(es) of the mobile device,     the total duration of the mobile device&#39;s registration at the home agent access gateway,     the remaining duration of the mobile device&#39;s registration at the home agent access gateway,     the IP address of the PDSN access gateway by which the mobile device is current being served,     the number of PDSN access gateway handoffs that the mobile device has experienced in this session,     whether or not the mobile device is using an IPsec tunnel that is either terminating at or passing through the home agent access gateway, and     additional attributes as become available in future access gateway architectures.        
 
         [0048]     In general, the home agent access gateway may provide presence information on behalf of a mobile device based on any information that the home agent access gateway stores with respect to that mobile device. This includes the mobile IP mobility binding record (MBR), the AAA profile, and other information. We refer to the aggregate of information that the home agent access gateway can report to the presence server as the home agent access gateway (HA) Presence Data Record, or HA-PDR.  
         [0049]     The home agent access gateway may update the presence server using at least two different methods: triggered updates and timer-based updates. Triggered updates are sent when the presence status of a presence entity such as a mobile device changes, for example, when a mobile device registers with the home agent access gateway. Timer based updates are sent periodically, and only include the changes in the presence status of all of the presence entities served by the home agent access gateway since the same update. Some combination of triggered and timer-based updates may be used.  
         [0050]     The home agent access gateway may determine whether or not to transmit presence information on behalf of the mobile device depending on local configuration, or on attributes returned from the RADIUS HAAA.  
         [0051]     In the case of the PDSN access gateway, the PDSN access gateway  240  may report the presence status to the presence server  287  on behalf of a mobile device  210 . The following attributes of presence status can be published at the presence server  287 : 
        dormancy status (dormant or active),     length of dormancy, if dormant,     Network Access Identifier (NAI): The email address of the mobile device,     assigned IP address(es) of the mobile device,     whether or not the mobile device is using mobile IP instead of simple IP,     the number of simple IP and mobile IP sessions in use by the mobile device,     the amount of time that the mobile device has been logged on,     the International Mobile Subscriber Identifier (IMSI) of the mobile device,     the signal strength of the mobile device,     the Electronic Serial Number (ESN) of the mobile device,     Serving Packet Control Function (PCF) that the mobile device is attached to,     base station ID from the serving base station that the mobile is attached to, and sector ID &amp; cell ID,     service option(s) associated with this mobile&#39;s session(s)     serving home agent (if applicable),     whether or not a P-P session is being used,     whether or not IPsec is being used,     geographical coordinates,     Network Access Server (NAS) ID of PDSN to determine carrier, and     additional attributes as become available in future access gateway architectures.        
 
         [0071]     In general, the PDSN access gateway  240  may provide presence status on behalf of a mobile device based on any information that the PDSN stores with respect to that mobile device. This includes any information received from the radio access network  230  over an A10/A11 interface, the AAA profile, and other information. Thus the access gateway efficiently provides presence status information to a presence server using the attributes already managed by the access gateway without additional network burden querying for or deriving that status information. We refer to the aggregate of information that the PDSN access gateway can report to the presence server as the PDSN Presence Data Record, or PDSN-PDR.  
         [0072]     The PDSN access gateway may update the presence server using at least two different methods: triggered updates and timer-based updates. Triggered updates are sent when the presence status of a presence entity such as a mobile device changes, for example, when a mobile device registers with the PDSN. Timer based updates are sent periodically, and only include the changes in the presence status of all of the presence entities served by the PDSN since the same update.  
         [0073]     The PDSN may determine whether or not to transmit presence information on behalf of the mobile depending on local configuration, or on attributes returned from the home AAA server.  
         [0074]     When an access gateway  240  or  291  obtains the presence status of a mobile device  210 , it will typically not need to query the mobile device  210 . The presence status can be obtained by the access gateway from attributes within the access gateway or obtained from the Radio Access Network (RAN)  230 .  
         [0075]     Although the presence server receives the presence status for the mobile communications device without querying, the access gateway can query the mobile communications device on a predetermined schedule to obtain its presence status. This query can be initiated by the presence server or by the presence server in response to a request from a watcher. Alternatively this query of the access gateway for presence status of the mobile communications device can occur on a predetermined schedule.  
         [0076]     Because the presence status of a user and the presence status of an application reside on a mobile communications device, the presence status of a mobile communications device can represent the status of the user using the device or the application on the device. The mobile communications device is the presence entity for devices, as well as users and applications.  
         [0077]      FIG. 3  illustrates flow diagrams of three exemplary call flows for presence reporting from a home agent access gateway in the communications system of the present inventions. In a first call flow, the home agent access gateway receives a mobile IP registration request  310  that is either a new registration or a renewal of an old registration for a particular user. This may trigger the home agent access gateway to send  320  the user&#39;s HA-PDR to the presence server. The presence server may then send a presence update  330  to any of the appropriate watchers. In a second call flow, the presence update timer expires  335 , triggering the home agent access gateway to send  340  one or more mobile device&#39;s HA-PDRs to the presence server. The presence server may then send a presence update  350  to any of the appropriate watchers. In a third call flow, the home agent access gateway receives a mobile IP de-registration request  360  (or the call terminates for a different reason) for a particular mobile device. This triggers the home agent access gateway to send  370  the user&#39;s HA-PDR to the presence server. The presence server may then send a presence status update  380  to any of the appropriate watchers.  
         [0078]      FIG. 4  illustrates flow diagrams of three exemplary call flows for presence reporting from a PDSN access gateway in the communications system of the present inventions. In a first call flow, the PDSN access gateway receives an A11 registration request  410  that is either a new registration or a renewal of an old registration for a particular mobile device. This may trigger the PDSN access gateway to send  420  the mobile device&#39;s PDSN-PDR to the presence server. The presence server may then send a presence update  430  to any of the appropriate watchers. In a second call flow, the presence status update timer expires  435 , triggering the PDSN access gateway to send  440  one or more mobile device&#39;s PDSN-PDRs to the presence server. The presence server may then send a presence update  450  to any of the appropriate watchers. In a third call flow, the PDSN access gateway receives an A11 de-registration request (or the call terminates  460  for a different reason) for a particular mobile device. This triggers the PDSN access gateway to send  470  the mobile device&#39;s PDSN-PDR to the presence server. The presence server may then send a presence update  480  to any of the appropriate watchers.  
         [0079]     Although the inventions have been described and illustrated in the above description and drawings, it is understood that this description is by example only, and that numerous changes and modifications can be made by those skilled in the art without departing from the true spirit and scope of the inventions. Although the examples in the drawings depict only example constructions and embodiments, alternate embodiments are available given the teachings of the present patent disclosure. For example, the inventions are applicable to wireless LAN or also wireline communications.