Patent Publication Number: US-8526975-B2

Title: Method and system for querying attributes in a cellular communications system

Description:
CLAIM OF PRIORITY UNDER 35 U.S.C. §120 
     The present Application for Patent is a Continuation and claims priority to patent application Ser. No. 09/480,710, entitled “METHOD AND SYSTEM FOR QUERYING ATTRIBUTES IN A CELLULAR COMMUNICATIONS SYSTEM,” filed Jan. 7, 2000, now U.S. Pat. No. 6,850,494; which is a Continuation-in-Part application of U.S. patent application Ser. No. 09/406,452, entitled “METHOD AND SYSTEM FOR QUERYING ATTRIBUTES IN A CELLULAR COMMUNICATIONS SYSTEM,” filed Sep. 27, 1999, now abandoned and assigned to the assignee hereof and hereby expressly incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates to wireless network communications. More specifically, the present invention relates to a novel and improved protocol by which wireless network elements can communicate. 
     2. Background 
     In communications networks many functions performed by individual network elements require knowledge of information from surrounding network elements. Although other techniques such as propagating required information individually to each network element from a central control element are known, the present invention has significant advantages over these other techniques. Attempting to propagate information from a central control element to multiple network elements is time consuming and error prone. In addition, some attributes (such as resource availability) change frequently. 
     In a CDMA communications system, many functions performed by the network elements require information from surrounding network elements. In the present invention, the protocol is described in terms of information propagation between network elements comprising Modem Pool Transceivers and Modem Pool Controllers (MPCs). A Modem Pool Transceiver (MPT) is a communications network element which performs modulation and demodulation of radio frequency network traffic, and is also responsible for scheduling, power control, and overhead message handling tasks. An MPC is another element which provides radio control and signaling services to the MPT elements that include power control synchronization, maintaining modem session state, and network connection control. MPCs generate and process data for the MPTs to transmit and receive. MPTs need air interface attributes of neighboring MPTs in order to construct the correct air interface overhead messages. MPCs need air interface attributes of MPTs in order to perform MPT handoff. MPCs need air interface attributes of MPTs in order to perform Access Terminal paging. An Access Terminal (AT) is a device with a modem and a data interface that allows the user to access an IP network through an Access Network (AN). MPCs need resource availability attributes of surrounding MPCs in order to perform MPC handoff. 
     Presently, there is no ideal method for satisfying the needs of wireless communications network elements to directly exchange information. 
     One problem that arises when network elements cannot directly exchange information is that MPCs do not have an expedient method for discovering information about surrounding MPTs necessary to perform AT Paging. At any given time, an MPC may be responsible for paging one or more dormant ATs. 
     “Dormant” refers to the period of time when an AT and an AN have an established session, but do not have an established connection. Dormant mode allows the AT to maintain the “always on” state while using only limited radio link capacity and limited AT power when sending or receiving data. 
     In order to deliver data to a dormant AT, the MPC must be able to locate the AT. The MPC locates the dormant AT by paging the dormant AT in all the MPTs in which the dormant AT might be located. This collection of MPTs is referred to as the paging area. In order to page the dormant AT, the MPC must know the paging area. 
     Currently, there is no ideal method for satisfying the needs of MPCs to dynamically discover paging area information needed for AT Paging. 
     SUMMARY 
     The present invention is a novel and improved protocol for directly updating attribute information in communications networks. 
     The present invention provides a generic protocol based on the HyperText Transfer Protocol version 1.1 (HTTP/1.1) and Multipurpose Internet Mail Extensions (MIME), which allows individual network elements to query other network elements directly for information without network manager intervention. It greatly reduces system failures caused by propagation errors and stale information, as well as, facilitating additional network element deployment and network element removal. 
     The network elements make their attributes available through the use of HTTP/1.1. Other network elements are able to query for specific attributes using the HTTP GET method. The response is a return HTTP header with a MIME part body containing a list of the attribute name/value pairs. 
     The present invention provides a generic protocol for allowing communication network elements to query other network elements for information. It allows network information to be configured in one location and queried dynamically by other locations. It prevents propagation errors and outdated information errors introduced by propagating required information individually to each network element through network management interfaces by a centralized network manager. 
     Embodiments of the present invention also meet paging information discovery needs by providing a protocol for allowing an MPC to dynamically query information needed for AT Paging from MPTs. The present invention provides a method for determining cellular paging areas of a wireless communication network by exchanging network configuration information directly between network elements, and determining access terminal paging areas from the exchanged network configuration information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters correspond throughout and wherein: 
         FIG. 1  is a functional block diagram of an exemplary embodiment of the present invention corresponding to a traditional, or distributed MPT, wireless communications network topography; 
         FIG. 2A  illustrates a distributed NAS wireless communications network topography; 
         FIG. 2B  illustrates a distributed MPC wireless communications network topography; 
         FIG. 3  is a flowchart illustrating the system parameter update mechanism of the present invention; 
         FIG. 4  is a diagram of an exemplary embodiment of the contents of machine requests and machine responses of the present invention; 
         FIG. 5  is a data structure diagram illustrating the data hierarchy of the present invention; 
         FIG. 6  is an intermediate level flowchart presenting an overview of the system parameter update mechanism; 
         FIG. 7  is a flowchart illustrating the location update procedure of the present invention; 
         FIG. 8  is a flowchart illustrating the antenna attribute update procedure of the present invention; 
         FIG. 9  is a flowchart illustrating the MPT neighbor update procedure of the present invention; 
         FIG. 10  is a flowchart illustrating the MPC update procedure of the present invention; 
         FIG. 11  is a block diagram illustrating the apparatus used to perform the attribute querying operation of the present invention; 
         FIG. 12  is a flowchart illustrating the information caching method of the present invention; 
         FIG. 13  is a block diagram illustrating the apparatus used to perform Paging Information Discovery in a wireless communications system; 
         FIG. 14  is an AT Paging Area Diagram; 
         FIG. 15  is a high level diagram of a method used to perform Paging Information Discovery in a wireless communications system; 
         FIG. 16  is a data structure diagram illustrating the data hierarchy of paging information discovery attributes of an embodiment of the present invention; and 
         FIG. 17  is a block diagram illustrating a paging area determination method. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary telecommunications network system in which the present invention is embodied is illustrated in  FIG. 2A .  FIG. 2A  illustrates wireless communications network access points  100  connected over an Internet Protocol (IP) Network  110 . Access points  100  provide wireless service to subscribers in predefined geographic areas. Sometimes, an access point  100  partitions and independently services portions of the geographic coverage area referred to as sectors. Sectorization of an access point is well known in the art and described in detail in U.S. Pat. No. 5,625,876 entitled “METHOD AND APPARATUS FOR PERFORMING HANDOFF BETWEEN SECTORS OF A COMMON BASE STATION”, which is assigned to the assignee of the present invention and incorporated by reference herein. The MPTs  106  covering the same or RF close areas are referred to as the neighbors of an access point. In wireless communication systems, the MPTs  106  for which given MPTs  106  and MPCs  108  require information is determined by the RF propagation characteristics of the signals transmitted by the network access points. In the exemplary embodiment, access point  100  is a topological element of a communications network comprised by a single hardware platform that contains one or more MPTs (MPT)  106 , one MPC  108 , and one Network Access Server (NAS)  104 . Network Access Server  104  is a device which provides access to services on that network in a controlled fashion, based on the identity of the user of the network services in question and on the policy of the provider of these services. The NAS  104  performs traditional network access server protocol functionality, such as defined by Point-to-Point Protocol (PPP) suite, Remote Authentication Dial-In User Server (RADIUS) protocol suite, and the Layer Two Tunneling Protocol (L2TP) suite. MPT  106  contains a bank of traffic channel modems and is responsible for generating the transmitted waveform, and for receiving transmissions from subscribers in the coverage area of an MPT  106 . MPT  106  generates and receives waveforms by modulation and demodulation of radio frequency network traffic, and also performs scheduling, power control, and system parameter message handling tasks. MPC  108  is a network element which generates and processes data for the MPTs to transmit and receive. MPCs  108  also provide radio control and signaling services to the MPTs  106  elements such as power control synchronization, maintaining modem session state, and network connection control. 
     There are two topological Access Network reference models in addition to the traditional wireless network configuration: the distributed MPC; and the distributed NAS. 
       FIG. 1  is a functional block diagram of an exemplary embodiment of the present invention corresponding to a traditional or distributed MPT  10 , wherein wireless communications network topography MPCs  14  are centralized at a point traditionally identified as a Base Station Controller (BSC)  16 . NAS  18  functionality is located at a point sometimes known as a Packet Data Servicing Node (PDSN)  20 .  FIG. 1  shows a distributed MPT Access Network where the MPTs  10  are distributed and the MPCs  14  and NAS  18  are centralized. A distributed MPT Access Point is formed by grouping together one or more co-located MPTs. The Access Network is formed by connecting one or more distributed MPT Access Points, one or more centralized MPCs and one or more centralized Network Access Servers. 
       FIG. 2A  illustrates a distributed NAS wireless communications network topography. In a distributed NAS Access Network, the MPT  106 , MPC  108  and NAS  104  are distributed.  FIG. 2A  shows Access Points  100  formed by grouping together one or more MPTs, one or more MPCs, and one or more Network Access Servers. The Access Network is formed by connecting one or more distributed Access Points. 
       FIG. 2B  illustrates a distributed MPC wireless communications network topography. In a distributed MPC Access Network, the MPT  206  and MPC  200  are distributed and the NAS  208  is centralized, such as within PDSN  212 . An Access Point is formed by grouping together one or more MPTs and one or more MPCs. The Access Network is formed by connecting one or more distributed Access Points and one or more centralized Network Access Servers. Again, access point components communicate directly with each other over MPT Network  202  using the present invention. In a distributed MPC Access Network, the MPT and MPC are distributed and the NAS is centralized. 
     In CDMA communications networks, operational and network management parameters must be known in multiple places throughout the system. Although the present invention is described in the context of CDMA communications networks, one skilled in the art will understand that the teachings of the present invention are readily extended to other wireless communication systems such as GSM and AMPS communication networks. These parameters include information contained in operational messages such as Handoff Direction messages, Power Control Parameters messages, Page messages and Neighbor List messages. The contents of these messages is well known in the art and described in detail in Telecommunications Industry Association family of standards IS-95 entitled “MOBILE STATION-BASE STATION COMPATIBILITY STANDARD FOR DUAL-MODE WIDEBAND SPREAD SPECTRUM CELLULAR SYSTEM.” These messages are described for illustrative purposes. It will be understood by one skilled in the art that teachings can be extended to other messages necessary to the operation of a wireless communication system. Network configuration parameters must also be known and kept updated in multiple locations. For example, if an MPT  106  is brought on line, brought offline or fails temporarily, other MPTs  106  and MPCs  108  in the system must be informed of the change in resources. The present invention is an improvement over previously known techniques for updating parameters such as propagating required information through the network management interface individually to each network element from a central network manager. Previously known methods require central manager intervention and introduce propagation errors which cause system failures. 
     The present invention allows wireless CDMA network information propagation to resemble Internet information propagation by dispensing with a centralized manager. The Internet does not have a central manager at the top of the Internet pushing new information down to each router on the Internet each time a router is added to or removed from the Internet. Internet routers know their neighboring routers by address configuration and can query information about them directly by wireline connection. The present invention allows MPT  106  elements to query information about its neighbors by being provided with a list of the Fully Qualified Domain Names (FQDN) of neighboring MPTs  106  and providing a protocol to directly communicate with elements of any other sector without wireline connections. MPCs  108  contain lists of MPTs  106  to which they provide service. Thus, the present invention eliminates the need to propagate redundant information through the network management interface individually to each network element from a central location. The present invention allows MPT  106  and MPC  108  network elements to be added to and removed from a wireless communications network in much the same way a router is added to or removed from the Internet. 
     The present invention provides a protocol for allowing network entities to retrieve information from a single network entity where the information is most easily configured. The protocol is a simple and flexible method for discovering information and knowing for how long the information is valid. The present invention allows the attributes in one location to propagate directly to other locations where they are needed. Additionally, because most information changes infrequently, the protocol only returns queried information if the information has changed since the last such query. 
       FIG. 3  illustrates a high level block diagram of the information querying process. In block  300 , a parameter of a network element is changed. In block  302 , a parameter list contained in the network element is updated to indicate the change. In block  304 , a remote network element requests the information in the list. In block  306 , the network element containing the list determines if the list has been updated since the last query from the requesting element. If the list has been updated since the last query, the updated list is sent to the querying device in block  307  in response to the request. If, in block  306 , the network element containing the list determines that no change has occurred, in block  309  the list is not sent, as the requesting element already has this list. If the list has been sent in block  307 , in block  308 , the remote network element updates its parameter list accordingly. 
       FIG. 4  illustrates the machine interfaces employed in block  304  to query information from remote locations and in block  308  to send updated information. In the exemplary embodiment, network elements request attribute information through the use of the HyperText Transfer Protocol (HTTP) GET message  418 . The elements receive information in an HTTP response  420  which contains HTTP header fields  426  and a Multipurpose Internet Mail Extensions (MIME) part  427 . The MIME part  427  is comprised of a MIME header  408 - 414  and a body containing a list of the requested attribute name/value pairs  416 . 
     To be consistent with the HTTP terminology, the network element using the HTTP GET  418  method to request the attributes will be referred to as the client, and the network element providing the response HTTP header  426  and requested attributes  416  in a MIME part response  427  will be referred to as the server. The exemplary embodiment of the present invention employs the formats described in HTTP version 1.1 and MIME version 1.0. The remote clients may now query the updated information from the server location  304 . 
     The client requests the desired attribute values using the HTTP GET method with the attribute names included in the query field of the absolute Universal Resource Identifier&#39;s (URI). In the exemplary embodiment, the URI  418  has the partial form:
         “http://&lt;element&gt;:&lt;port&gt;/get_attributes?&lt;attributes&gt;”
 
wherein element  402  is the Fully Qualified Domain Name of the serving element, port  403  is the port number of the protocol  404 , and attributes  406  are the desired attributes separated by “&amp;”. The HTTP request header may also contain optional fields described in RFC 2068. The present invention always conditions requests on the optional If Modified Since field  421 . The client uses the If Modified Since field  421  to inform the server of when it last updated the information.
       

     The server uses the If Modified Since  421  field of the request  418  to determine if updated information should be sent. If the server has not updated the information since the time specified in the If Modified Since field, the server returns an abbreviated response  420  to the client, containing only HTTP header  426  fields with no MIME part  427  response. 
     If requested information has been updated since the time specified in the If Modified Since field, thus meeting the If Modified Since  418  condition of the request, the server responds with an HTTP header  426  and a MIME part  427  containing a list of attribute name/value pairs  416  for the requested attributes. The server silently discards any unrecognized attributes. The server includes the Last-Modified field  425  in the response header  426 . The server sets the value of the Last-Modified field  425  to the modification time and date of the most recently modified attribute in the response. 
     The response to the attribute query is carried in version 1.0 of the experimental MIME subtype  408  text/x-attribute-list. This MIME subtype is indicated by the Context-Type field  408 . The version parameter  410  indicates the version of the x-attribute-list  408  format. The current value of the version parameter  410  is 1.0. The charset parameter  412  indicates the character set used. In the exemplary embodiment, the only valid value for the character set parameter is “US-ASCII”. The &lt;element&gt;parameter  414  indicates the network element type of the server. For example, “modem-pool-transceiver” and “modem-pool-controller” indicate the server is a communications network MPT and a communications network MPC. The body  416  of the MIME part contains zero or more fields. Each field contains the name and value for one attribute. 
     Some attribute fields  416  are most easily expressed as elements of an array. This MIME part format  427  adopts a uniform method for expressing an array as a set of fields  416 . A multi-dimensional array is treated as an array of arrays. Array elements are indexed from 0 using integers. For an attribute array with the attribute-name “X,” the number of elements in the attribute array is represented by the attribute-name “X#.”For an attribute array with the attribute-name “X,” element K of in the attribute array is represented by the attribute-name “X[K].” 
     If the request contains the attribute name for an attribute array, then the response  420  contains the number of elements in the array and each element in the array, with the number of elements in the array appearing before any of the elements in the array. 
     Some attributes, such as attributes representing characteristics of a MPT neighbor, are most easily expressed as part of a hierarchy. This MIME part format  427  adopts a uniform method for expressing an attribute in a hierarchy as a field. When an attribute within a hierarchy is converted to a field, it is converted to the attribute-name “Y.X”, where “X” is the name of the attribute and Y is the attribute-name of the parent of the attribute. Examples of expressing arrays and hierarchies are described in  FIG. 8  and  FIG. 9 . 
     Network elements make all of their attributes available through the query protocol of the present invention. 
       FIG. 5  is a data tree diagram of an exemplary embodiment of a partial data hierarchy of the present invention, illustrating the MPT data structure. It will be understood by one skilled in the art that the hierarchy is presented for illustrative purposes and does not include all attributes necessary. In addition, other structures may be employed and are within the scope of the presentation. 
     Location  502  is the hierarchical root of all attributes that specify the MPT&#39;s location. 
     Translation  504  is the hierarchical root of all attributes that specify the MPT&#39;s location. Latitude  506  specifies the MPT&#39;s latitude. The latitude is expressed in degrees, minutes and seconds, with a positive number signifies the Northern Hemisphere. The latitude ranges from −90 degrees to +90 degrees. Longitude  510  specifies the MPT&#39;s longitude. The longitude is expressed in degrees, minutes and seconds, with a positive number signifying east longitude. The longitude ranges from −180 degrees to +180 degrees. Altitude  508  specifies the MPT&#39;s altitude. The altitude is expressed in meters, with a positive number indicating above sea level altitude. 
     Rotation  512  is the hierarchical root of all attributes that specify the MPT&#39;s orientation to the Earth. Horizontal  514  specifies the MPT&#39;s horizontal orientation relative to due east. The horizontal orientation is expressed in degrees, minutes and seconds, with a positive number signifying the Northern Hemisphere. Vertical  516  specifies the MPT&#39;s relative vertical orientation. The vertical orientation is expressed in degrees, minutes and seconds. The vertical orientation ranges from −90 degrees to +90 degrees. 
     Temporal  518  specifies the MPT&#39;s local time offset relative to Universal Coordinated Time (UTC). The local time offset is expressed in hours, minutes and seconds. The local time offset ranges from −12 hours to +12 hours. 
     Antenna  520  is the hierarchical root of all attributes that specify the characteristics of the MPT&#39;s antennas. Transmit  522  is an array of the hierarchical root of all attributes that specify the characteristics of the MPT&#39;s transmit antennas. Location  540  is the hierarchical root of all the attributes that specify the location of the transmit antenna relative to the location specified in Location  502 . Beamwidth  542  is the beam width of the transmit antenna. The beam width is expressed in degrees. The beam width ranges from 0 to 360 degrees. Gain  544  is the gain of the transmit antenna. The transmit antenna gain is expressed in decibels. The gain ranges from 0 to 100 decibels. 
     Receive  524  is an array of the hierarchical root of all attributes that specify the characteristics of the MPT&#39;s receive antennas. Location  546  is the hierarchical root of all the attributes that specify the location of the receive antenna relative to the location specified in Location  502 . Beamwidth  548  is the beam width of the receive antenna. The beam width is expressed in degrees. The beam width ranges from 0 to 360 degrees. Gain  550  is the gain of the receive antenna. The receive antenna gain is expressed in decibels. The gain ranges from 0 to 100 decibels. 
     Neighbor  526  is an array of the hierarchical root of all attributes that specify characteristics of the MPT&#39;s neighbors. FQDN  528  contains the Fully Qualified Domain Name (FQDN) of the neighbor. Cost  530  contains the cost of using the neighbor. The lower the cost, the more likely an AT communicating with the MPT is to see this MPT neighbor. The cost is useful pruning neighbor lists that are too large. 
     Controller  532  is an array containing each of the MPCs from which the MPT receives service. FQDN  534  contains the Fully Qualified Domain Name of the controller. 
     Air Interface  536  is the hierarchical root of all of the wireless communications network&#39;s air interface attributes. The Air Interface  536  root is extensible to any air interface protocol. HDR Air Interface Protocol  538  is an example of the extensibility of the Air Interface  536  hierarchical root. HDR  540  is a proposed air interface for providing high rate digital data. The HDR air interface is described in detail in U.S. patent application Ser. No. 08/963,386 entitled “METHOD AND APPARATUS FOR HIGHER RATE PACKET DATA TRANSMISSIONS”, filed Nov. 3, 1997, now U.S. Pat. No. 6,574,211 issued Jun. 3, 2003 to Padovani et al., assigned to the assignee of the present invention and incorporated by reference herein. Other potential air interface extensions may include but are not limited to GSM, IS-95, CDMA2000, and WCDMA. The HDR air interface  538  is defined by a root HDR  540 , including an identifier  542 , Access Network  544 , Access Port  546 , and Access Node  548 . 
       FIG. 6  is a flowchart of an exemplary embodiment of an intermediate level overview of the present invention&#39;s system parameter query and update mechanism. One skilled in the art will understand that ordering of steps illustrated in  FIG. 6  is not limiting. Moreover, the requests for information will logically be integrated as will the responses, and it is contemplated that typically only a subset of the information will be integrated information the requests and responses. Typically, requests will be made in a compound request for complex collections of attributes, not serially for single attributes, as shown for simplicity.  FIG. 6  is an overview of the information exchanged in the exemplary embodiment of the present invention. The information query process starts in block  600 , when a client desires to update information regarding a server. In the exemplary embodiment, the client is updating information regarding the attributes that specify the MPT characteristics of the server. 
     In block  601 , the client conditionally requests Location information  502 . A detailed flowchart of the Location attribute request method is provided in  FIG. 7 . In block  602 , the server determines if the requested Location information has changed in the server since the time specified in the If Modified Since field for this information from this client, as conditioned by the If Modified Since  421  field of the request  418 ; the server sends the new Location attribute information in block  604 ; and the process moves to block  605 . If the requested information has not changed, the server sends header fields  426 , but does not send a MIME part  427  with new Location attribute information, and the process moves directly to block  605 . If new attribute information has been sent in block  604 , the client updates the Location attribute information accordingly. 
     In block  605 , the client conditionally requests Antenna information  520 . A detailed flowchart of the Antenna attribute request method is provided in  FIG. 8 . In block  606 , the server determines if the requested Antenna information has changed in the server since the time specified in the If Modified Since field for this information from this client, as conditioned by the If Modified Since  421  field of the request  418 ; the server sends the new Antenna attribute information in block  608 ; and the process moves to block  609 . If the requested information has not changed, the server sends header fields  426 , but does not send a MIME part  427  with new antenna attribute information, and the process moves directly to block  609 . If new attribute information has been sent in block  608 , the client updates the Antenna attribute information accordingly. 
     In block  609 , the client conditionally requests Neighbor information  526 . A detailed flowchart of the Neighbor attribute request method is provided in  FIG. 9 . In block  610 , the server determines if the requested Neighbor information has changed in the server since the time specified in the If Modified Since field for this information from this client, as conditioned by the If Modified Since  421  field of the request  418 ; the server sends the new. Neighbor attribute information in block  612 ; and the process moves to block  613 . If the requested information has not changed, the server sends header fields  426 , but does not send a MIME part  427  with new Neighbor attribute information, and the process moves directly to block  613 . If new attribute information has been sent in block  612 , the client updates its Neighbor attribute information accordingly. 
     In block  613 , the client conditionally requests Controller information  532 . A detailed flowchart of the Controller attribute request method is provided in  FIG. 10 . In block  614 , the server determines if the requested Controller information has changed in the server since the time specified in the If Modified Since field for this information from this client, as conditioned by the If Modified Since  421  field of the request  418 ; the server sends the new Controller attribute information in block  616 ; and the process moves to block  617 . If the requested information has not changed, the server sends header fields  426 , but does not send a MIME part  427  with new Controller attribute information, and the process moves directly to block  617 . If new attribute information has been sent in block  616 , the client updates its Controller attribute information accordingly. 
     In block  617 , the client conditionally requests Air Interface information  536 . In block  618 , the server determines if the requested Air Interface information has changed in the server since the time specified in the If Modified Since field for this information from this client, as conditioned by the If Modified Since  421  field of the request  418 ; the server sends the new Air Interface attribute information in block  620 ; and the process moves to block  622 . If the requested information has not changed, the server sends header fields  426 , but does not send new Air Interface attribute information and the process moves directly to block  622 . If new attribute information has been sent in block  620 , the client updates its Air Interface attribute information accordingly. 
       FIG. 7  is a flowchart of an exemplary embodiment of the system parameter update method for the Location attributes  502  that specify the location of MPT type network elements. Location attribute  502  is the hierarchical root of all attributes that specify the MPT&#39;s location.  FIG. 7  provides a detailed flowchart of the Location attribute request  601 . MPT location information query process starts in block  700 , when a client desires to update location information of a neighboring MPT server on the wireless communications network. 
     In block  702 , the client requests latitude information. Translation attribute  504  is the hierarchical data structure root of all the attributes that describe an MPT&#39;s physical location on the earth. Latitude attribute  506  specifies the MPT&#39;s latitude expressed in degrees, minutes and seconds, with a positive number signifying the Northern Hemisphere. In block  702 , the client requests Latitude information  506  from, for example, the MPT 0000.mpt.an.net on protocol port 10 by issuing the following URI conditioned on the If Modified since  418  field: 
     “http://0000.mpt.an.net:10/get_attributes?Location.Translation.Latitude” 
     onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of us-ascii, and an element type  414  value of modem-pool-transceiver. If the requested latitude information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server sends a Last Modified field and the new Latitude attribute information in the MIME part response  427  containing the name-attribute name-value field of a Location.Translation.Latitude value expressed as ±dd.mm.ss.f. The latitude ranges from −90 degrees to +90 degrees. 
     In block  704 , the client requests location translation longitude information. The Longitude attribute  510  specifies the MPT&#39;s longitude expressed in degrees, minutes and seconds, with a positive number signifying east longitude. In block  704 , the client requests Longitude information  510  from the example MPT by issuing the following URI conditioned on the If Modified since  418  field: 
     “http://0000.mpt.an.net:10/get_attributes?Location?Translation.Longitude” 
     onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of us-ascii, and an element type  414  value of modem-pool-transceiver. If the requested longitude information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server returns a Last Modified field and the new Longitude attribute information in the MIME part response  427  containing the name-attribute name-value field of a Location.Translation.Longitude value expressed as ±dd.mm.ss.f. The longitude ranges from −180 degrees to +180 degrees. 
     In block  706 , the client requests location translation altitude information. Altitude attribute  508  specifies the MPT&#39;s altitude expressed in meters, with a positive number indicating above sea level altitude. In block  706 , the client requests Altitude information  508  from the example MPT by issuing the following URI conditioned on the If Modified since  418  field: 
     “http://000.mpt.an.net:10/get_attributtes?Location.Translation.Altitude” 
     onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of US-ASCII, and an element type  414  value of modem-pool-transceiver. If the requested altitude information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server sends a Last Modified field and the new Altitude attribute information in the MIME part response  427  containing the name-attribute name-value field of a Location.Translation.Altitude value expressed as +|−m.f. 
     In block  708 , the client requests horizontal orientation information. Rotation attribute  512  is the hierarchical data structure root of all the attributes that describe a MPT&#39;s orientation to the earth. Horizontal attribute  514  specifies the MPT&#39;s horizontal orientation relative to due east. The horizontal orientation is expressed in degrees, minutes and seconds, with a positive number signifying the Northern Hemisphere. In block  708 , the client requests Horizontal  514  information from the example MPT 0000.mpt.an.net on protocol port 10 by issuing the following URI conditioned on the If Modified since  418  field: 
     “http://0000.mpt.an.net:10/get_attributes?Location.Rotation.Horizontal”onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of US-ASCII, and an element type  414  value of modem-pool-transceiver. If the requested horizontal orientation information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server sends a Last Modified field and the new Horizontal attribute information  514  in the MIME part response  427  containing the name-attribute name-value field of a Location.Rotation.Horizontal value expressed as +|−dd.mm.ss.f. 
     The horizontal orientation ranges from −180 degrees to +180 degrees. 
     In block  710 , the client requests vertical orientation information. Vertical attribute  516  specifies the MPT&#39;s vertical orientation relative to a line drawn perpendicular from the center of the earth. The vertical orientation is expressed in degrees, minutes and seconds. In block  710 , the client requests Vertical information  516  from the example MPT by issuing the following URI conditioned on the If Modified since  418  field: 
     “http://0000.mpt.an.net:10/get_attributes?Location.Rotation.Verticle” 
     onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of US-ASCII, and an element type  414  value of modem-pool-transceiver. If the requested vertical orientation information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server sends a Last Modified field and the new Vertical  516  attribute information in the MIME part response  427  containing the name-attirbute name-value field of a Location.Rotation.Horizontal value expressed as +|−dd.mm.ss.f. The vertical orientation ranges from −90 to +90 degrees. 
     In block  712 , the client requests location temporal information. The Temporal attribute  518  is the hierarchical data structure root of all the attributes that describe a MPT&#39;s time offset. The Temporal attribute  518  specifies the MPT&#39;s local time offset relative to Universal Coordinated Time (UTC). The local time offset is expressed in hours, minutes and seconds, with a positive number signifying an added time difference from UTC. In block  712 , the client requests Temporal information  518  from the example MPT by issuing the following URI conditioned on the If Modified since  418  field: 
     “http://0000.mpt.an.net:10/get_attributes?Location.Temporal” 
     onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of us-ascii, and an element type  414  value of modem-pool-transceiver. If the requested temporal information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server sends a Last Modified field and the new Temporal attribute information in the MIME part response  427  containing the name-attirbute name-value field of a Location.Temporal value expressed as ±hh.mm.ss.f. The local time offset ranges from −12 hours to +12 hours. 
     Location information  502  requests terminate, in block  714 , when the client has finished requesting location information. 
       FIG. 8  is a flowchart of an exemplary embodiment of the present invention&#39;s system parameter update method for all of the Antenna attributes  520  that specify the characteristics of the MPT&#39;s antennas.  FIG. 8  provides a detailed flowchart of the Antenna attribute request  605 . An MPT antenna information query process starts, in block  800 , when a client desires to update antenna information from a MPT server of the wireless communications network. 
     In block  802 , the client requests antenna transmit information. The Antenna attribute  520  is the hierarchical data structure root of all the attributes that describe the characteristics of the MPT&#39;s antenna or set of antennas. The Transmit attribute  522  is an array of the hierarchical root of all attributes that specify the characteristics of the MPT&#39;s transmit antennas. Location  540  is the hierarchical root of all the attributes that specify the location of the transmit antenna relative to the location specified in Location  502 . Beamwidth  542  is the beam width of the transmit antenna. The beam width is expressed in degrees. Gain  544  is the gain of the transmit antenna. The transmit antenna gain is expressed in decibels. 
     Some attributes, such as a MPT Transmit  522 , are most easily expressed as an element of an array. This MIME part format adopts a uniform method for expressing an array as a set of fields. A multi-dimensional array is treated as an array of arrays. Array elements are indexed from 0 using integers. For an attribute array with the attribute-name “X”, the number of elements in the attribute array is represented by the attribute-name “X#”. For an attribute array with the attribute-name “X”, element K of in the attribute array is represented by the attribute-name “X[K]”. 
     If the request contains the attribute name for an attribute array, then the response  420  contains the number of elements in the array and each element in the array, with the number of elements in the array appearing before any of the elements in the array. 
     In block  802 , the client requests Transmit array information  522  from the example MPT with  1  transmit antenna by issuing the following URI conditioned on the If Modified since  418  field:
         “http://0000.mpt.an.net:10/get_attributes?Antenna.Transmit.Gain&amp;Antenna. Transmit.Beamwidth”
 
onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of US-ASCII, and an element type  414  value of modem-pool-transceiver. If the requested information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server sends a Last Modified field and the new Antenna Transmit array attribute information in the MIME part response  427  containing the number of elements in the example Antenna.Transmit array expressed as,
       

     Antenna.Transmit#1, 
     the gain of the transmit antenna expressed as 
     Antenna.Transmit[0]. Gain:d.f 
     the beam width of the transmit antenna expressed as 
     Antenna.Transmit[0]. Beamwidth:d.f, 
     The beam width ranges from 0 to 360 degrees. The gain ranges from 0 to 100 decibels. 
     In block  804 , the client requests receive antenna information. The Antenna Receive attribute  524  is an array of the hierarchical data structure root of all the attributes that specify the characteristics of the MPT&#39;s receive antenna or set of receive antennas. Location  546  is the hierarchical root of all the attributes that specify the location of the receive antenna relative to the location specified in Location  502 . Beamwidth  548  is the beam width of the receive antenna. The beam width ranges from 0 to 360 degrees. Gain  550  is the gain of the receive antenna. The receive antenna gain is expressed in decibels 
     In block  804 , the client requests Receive antenna array information  524  from an antenna MPT with one receive antenna by issuing the following URI conditioned on the If Modified since  418  field:
         “http://0000.mpt.an.net:10/get_attributes?Antenna.Receive.Gain&amp;Antenna.Receive.Beamwidth”
 
onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of US-ASCII, and an element type  414  value of modem-pool-transceiver. If the requested information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server returns a Last Modified field and the new Antenna Receive array attribute information in the MIME part response  427  containing the number of elements in the example Antenna.Receive array expressed as
       

     Antenna.Receive#:1 
     the gain of the receive antenna expressed as 
     Antenna.Receive[0]. Gain:d.f 
     the beam width of the receive antenna expressed as 
     Antenna.Receive[0]. Beamwidth:d.f, 
     The beam width ranges from 0 to 360 degrees. The gain ranges from 0 to 100 decibels. 
     Antenna information  520  requests terminate, in block  806 , when the client has finished requesting antenna information. 
       FIG. 9  is a flowchart of an exemplary of the Neighbor attributes  526  which specify the characteristics of MPT&#39;s neighbors.  FIG. 9  provides a detailed flowchart of the Neighbor attribute request  609 . A MPT neighbor information query process starts, in block  900 , when a client desires to update neighbor information from a MPT server on the wireless communications network. 
     In block  902 , the client requests neighbor information. Neighbor attribute  526  is an array of the hierarchical root of all attributes that specify characteristics of the MPT&#39;s neighbors. Neighbor attribute  526  includes FQDN information and Cost information. FQDN attribute  528  contains the Fully Qualified Domain Name (FQDN) of the neighbor. Cost attribute  530  contains information about use of the neighbor. 
     Some attributes, such as attributes representing characteristics of an MPT  106  neighbor, are most easily expressed as part of a hierarchy. This MIME type adopts a uniform method for expressing an attribute in a hierarchy as a field. When an attribute within a hierarchy is converted to a field, it is converted to the attribute-name “Y.X”, where “X” is the name of the attribute and Y is the attribute-name of the parent of the attribute. 
     Neighbor attribute  526  information is both an array and a hierarchy. In block  902 , the client requests Neighbor attribute  526  from an example hierarchy. The example hierarchy contains a wireless communications network  110  with one MPC  108  and three MPTs  106 . The MPC  108  has the FQDN “0000.mpc.an.net”. The MPTs  106 , in the example, have the FQDNs “0000.mpt.an.net”, “0001.mpt.an.net” and “0002.mpt.an.net”. Each MPT  106 , is a neighbor of the other two MPTs  106  and has no routing cost. 
     The MPT  106  stores neighbor attributes in the array Neighbor attribute  526 . The information stored includes the neighbor&#39;s FQDN attribute  528 , and the neighbor&#39;s Cost attribute  530 , corresponding to routing cost. 
     In block  902 , the MPC client 0000.mpc.an.net requests all information about all neighbors of MPT 0000.mpt.an.net by issuing the following URI conditioned on the If Modified since  418  field:
         “http://0000.mpt.an.net:10/get_attributes?Neighbor”
 
onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of US-ASCII, and an element type  414  value of modem-pool-transceiver. If the requested information has changed in the servers since the time specified in the If Modified Since field for this information from this client, the servers responds wtih a Last Modified field and all the new Neighbor array hierarchy information in the MIME part response  427 . Additionally, the body  416  contains the name-attribute name-value fields for the number of neighbors the controller has in the example array expressed as
       

     Neighbor#:2 
     the FQDN of the first neighbor expressed as 
     Neighbor[0].FQDN:0001.mpt.an.net 
     the cost of the first neighbor expressed as 
     Neighbor[0].Cost:0 
     the FQDN of the second neighbor expressed as 
     Neighbor[1].FQDN:0002.mpt.an.net, 
     and the cost of the second neighbor expressed as 
     Neighbor[1].Cost:0 
     Neighbor attribute  526  information requests terminate, in block  904 , when the client has finished requesting neighbor hierarchy information. 
       FIG. 10  is a flowchart of an exemplary embodiment of the present invention&#39;s system parameter update procedure for the attributes that specify the MPC network types from which the MPT network types receive service.  FIG. 10  provides a detailed flowchart of the Controller attribute  613  request. A controller information query process starts, in block  1000 , when a client desires to update controller information from which a MPT server can receive service. 
     In block  1002 , the client requests controller information. The Controller attribute  532  is the hierarchical data structure root of the FQDN attribute  534 , corresponding to the MPCs an MPT can use. 
     In block  1002 , the client requests the FQDN attribute  534 , for example from an MPT with 1 MPC. In block  1002 , the client issues the following URI conditioned on the If Modified since  418  field:
         “http://0000.mpt.an.net:10/get_attributes?Controller”
 
onto the network. The server responds with a header containing a Context-Type  408  of text/x-attribute-list, a version  410  of 1.0, a charset  412  value of US-ASCII, and an element type  414  value of modem-pool-transceiver. If the requested information has changed in the server since the time specified in the If Modified Since field for this information from this client, the server sends a Last Modified field and the new Controller array attribute information in the MIME part response  427  containing the number of elements in the example Controller array expressed as Controller#:1, and the domain name expressed as Controller[0].FQDN:0001.mpc.an.net.
       

       FIG. 11  is a block diagram illustrating the apparatus used to perform the attribute querying operation of the present invention. Access point  1100 A consists of network element  1112 A and a network interface  1104 A, such as an IP router. Network Interface  1104 A is a device that determines the next network point to which a data packet should be forwarded towards its destination, and connects a network element to an IP network over a variety of bearer services. Network element  1112 A can be MPT ( 10 ,  106  or  206 ), MPC ( 14 ,  108  or  200 ) or network access server ( 18 ,  104  or  208 ). For illustrative purposes only the portion of the network elements that are germane to the attribute querying operation are illustrated in network element  1112 A. 
     Network element  1112 A includes a memory device  1110 A which stores the attributes of access point  1100 A wherein the attributes includes a list of FQDNs of other network elements to be queried by the network element  1112 A. Control processor  1106 A receives a signal from request message generator  1102 A indicative of a need for information from another network element. Control processor  1106 A retrieves a FQDN from memory element  1110 A in response to the signal from request message generator  1102 A and in conjunction with this signal and the FQDN generates a query message. Control processor  1106 A provides the message to network interface  1104 A which routes the message to the appropriate network element  1106 B. Network interface  1104 B directs the request message to network element  1112 B. The request message is provided to control processor  1106 B. In response to the request message, control processor  1106 B retrieves information regarding the requested attributes from memory  1110 B. Response message generator  1108 B provides message packaging information to control processor  1106 B. Control processor  1106 B in response to the information from memory  1110 B and response generator  1108 B, generates a response message which it provides to network interface  1104 B. Network interface  1104 B directs the response message to control processor  1106 A in access point  1100 A. 
     If the attribute information in the response message from element  1100 B is new, then control processor  1106 A updates the information in memory element  1110 A. It will be understood by one skilled in the art that the reciprocal operation of querying can be performed from network element  1112 B to network element  1112 A by simply reversing the A&#39;s and B&#39;s. 
       FIG. 12  is a flowchart of an exemplary embodiment of the present invention&#39;s method for requesting and caching attribute information to reduce processing and network traffic. The client request and server caching method illustrated in  FIG. 12  allow the client to request the servers only send information if the information has changed, and prevents the server from repeatedly generating and returning the same response. 
     Block  1222 , illustrates the client side conditional request. In HTTP, the GET method can be conditioned on several different criteria. This allows the client to request that the server only send information if the information has changed. Of particular use in this query protocol is the If-Modified-Since condition. Use of the If-Modified-Since condition reduces network traffic and client processing. In block  1200  the client uses a GET method conditioned on the If-Modified-Since field to request attribute information. In block  1202 , the client determines if the server has responded with updated MIME part  427  attribute information. If the server responds with updated MIME part  427  information, in block  1204 , the client caches the most recent Last-Modified field  425  of the response for each different query to each server for use in future queries. When the client repeats a query to a server, block  1200 , the client sets the If-Modified-Since field  421  to the value of the returned Last-Modified field  425 . 
     Block  1224  illustrates the server side caching method of the present invention. In many instances, protocols using this query protocol will use queries that are always the same. In addition, in many instances, protocols using this query protocol will query for attributes that change infrequently, known as static attributes. As a result, current servers repeatedly generate and return the same response. By caching query responses that contain only static attributes, the present invention reduces server processing. In the present invention, the server tags certain attributes as “static.” Attributes tagged as “static” should be attributes that change infrequently. For example, attributes that are hard coded (such as protocol revisions) and attributes that only change during network build-out and optimization (such as neighbor lists) are good candidates for being tagged as “static.” On the other hand, attributes that change as a function of loading (such as available bandwidth) are bad candidates for being tagged as “static.” In block  1206  the server changes a static attribute. In block  1208 , the server flushes all cached responses whenever one of the attributes tagged as “static” is modified. This will flush some cached pages unnecessarily. However, since “static” attributes change infrequently by definition, the impact of the unnecessary cache flushing is minimal. The server ensures that the cache is flushed when any attribute in the query has been modified. The server gets much of the benefits of caching using a simple conservative cache flushing algorithm. 
     In block  1210 , the server receives an attribute query from a client. In block  1212  the server determines if a cache exists for the queried information. If the cache had previously been flushed due to attribute change, the server builds a new cache in block  1220 , and control proceeds to block  1214 . Otherwise, control proceeds directly to block  1214 . 
     In block  1214 , the server determines if the requested information has changed since the last such request using the If Modified Since field  421  of the query. If the information has not changed, only the HTTP response header  426  is returned, as illustrated by block  1218 . If the requested information has been modified since the time specified in the If Modified Since field, then in block  1216  the server returns the HTTP response header  426  and the MIME part  427  response from the cache. 
       FIG. 13  is a block diagram illustrating the apparatus used to perform Paging Information Discovery with the Access Network Paging Information Protocol. The Access Network Paging Information Protocol allows an MPC  1300  to dynamically determine the paging area  1302  of ATs  1306 A,  1306 B,  1306 C the MPC  1300  controls. 
     When an AT is dormant, or has an active session and no active connection, the AT  1306  provides the Access Network with regular location updates. There are several triggers that cause an AT  1306  to provide the Access Network with a location update. 
     MPC element  1300  provides service to a collection of one or more MPT elements  1308  over IP Network  1304 . An AT  1306  updates, or registers, its location with MPC  1300  by sending its location information to the MPT  1308  in which it is located. The MPT  1308  forwards the location information to the MPC  1300  over the IP Network  1304 . The MPC  1300  locates the AT  1306  by paging AT  1306  in all the MPTs  1302  in which AT  1306  might be located. The collection of MPTs  1302  where an AT could be located is the AT&#39;s paging area  1302 . 
       FIG. 14  illustrates an AT paging area. In one embodiment, a protocol for MPCs to determine paging areas without the intervention of a central network manager is provided. The paging area is determined by AT  1404  location update procedures known as registration. AT  1404  movement through the Access Network may require location registration with MPCs based on different criteria including distance  1406  and zone  1400 A, or both, depending on what types of location registration are enabled in the AT  1404 . A registration area corresponds to the reported MPT  1402  of the location update, plus all other MPTs to which the AT  1404  could move without registering again because no distance or boundary zone has been crossed. In other words, the registration area is the area in which the AT  1404  can be located without the need to re-register. This area is determined by the registration distance and registration zone. If an AT is within registration distance from the last AT in which the AT registered and is within the same registration zone, then the AT is in the same registration area. 
     A paging area is a list of MPTs  1402 ,  1403  in which an AT may be located at any given time. The list comprises the MPTs  1402  located in the registration area of the AT, and all of their neighbors  1403 . The neighbors  1403  of the MPTs  1402  in the registration area are included in the paging area to account for the fact that it takes an AT a non-zero time to detect that a location update must be performed, and to perform the location update. In other words, the AT may have crossed into a neighboring MPT before a location update has occurred at the MPC. 
     If zone-based registration is enabled at the AT  1404 , the AT  1404  must perform a location update if the AT  1401  crosses from one zone  1400   a  to an adjacent zone  1400   b . If distance-based registration is enabled at the AT  1404 , the AT  1404  must perform a location update if the AT  1404  moves farther than distance R  1406  since its last location update. The paging area created is the MPT  1402  where the AT  1404  last reported itself to be located and one ring of neighboring MPTs  1403  around the MPT  1402 . 
     Paging areas depend on the values of the distance and zone location update triggers. While the values of these triggers can differ between MPTs, they are independent of the AT. Registration distances  1406  and zones  1400  are configured by the service provider operator for each MPT to balance the amount of registration traffic against the amount of paging traffic on the network. The paging discovery protocol and paging area algorithm of the presently described embodiments determine where to page an AT moving through the access network based on the configured information and the last registered location. 
     Each MPT has its own paging area. A sector may have one or more MPTs. If a sector has more than one MPT, the MPTs are communicating to ATs on different frequencies. A neighboring MPT in an adjacent sector is known as a horizontal neighbor. A neighboring MPT in the same sector operating on a different frequency is known as a vertical neighbor. 
       FIG. 15  is a high level block diagram of a method in accordance with one embodiment for performing Paging Information Discovery in a wireless communications system. 
     Distance and zone update triggers allow the Access Network to reduce the paging area for an AT. 
     If distance-based location update is enabled, then the AT will perform a location update after moving greater than the location update distance since the AT last performed a location update. If zone-based location update is enabled, then the AT will perform a location update after moving into a location update zone different from the location update zone in which the AT last performed a location update. 
     Blocks  1500 - 1510  illustrate the paging functionality of the AT. In block  1500 , the AT determines if its distance-based location update is enabled. If distance-based location update is enabled, in block  1502  the AT determines if its distance has changed more than its configured registration distance. Otherwise, control proceeds directly to block  1506 . If in block  1502  the AT determined its distance had changed more than the distance trigger, in block  1504  the AT performs a location distance update and control moves to block  1506 . If no distance update is necessary in block  1504 , control moves to block  1506 . 
     In block  1506 , the AT determines if its zone-based location update is enabled. If zone-based location update is enabled, in block  1508  the AT determines if the AT has moved into a location update zone different from the location update zone in which the AT last performed a location update. If zone-based location update is not enabled, AT processing terminates until the next update interval. If in block  1508 , the AT determined its zone had changed, in block  1510  the AT performs a location zone update and AT processing terminates until the next update interval. If no zone update is necessary in block  1510 , AT processing terminates until the next update interval. Update intervals are determined by a state machine that executes every time the AT moves into the coverage of a new MPT. 
     When an AT performs a location update, the location update is forwarded to the MPC that is providing the AT service. If the MPC does not provide service to the MPT that received the location update, then one of two things will happen. If the AN does support MPC handoff, then the AT will be handed off to an MPC that does provide service to the MPT that received the location update. If the Access Network does not support MPC handoff, then the session will be terminated and the AT will need to establish a new session. The new session will be established with an MPC that does provide service to the MPT that received the location update. As a result, the number of paging areas that a particular MPC must have knowledge of and maintain information for can be reduced. 
     Blocks  1512 - 1514  illustrate the individual paging functionality tasks of the MPT. The MPT receives location updates from ATs in task block  1512 . In task block  1514 , the MPT forwards the location updates to the MPC servicing the MPT, and forwards paging messages received from the MPC to ATs. The MPT responds to paging discovery attribute queries from the MPC in task block  1515 . 
     Blocks  1516 - 1520  illustrate the individual paging functionality tasks of the MPC. In task block  1516 , the MPC receives AT location updates forwarded by the MPT and uses the information to determine updated paging areas for the AT in task block  1518 . The MPC sends paging messages to dormant ATs in task block  1520 . The paging area determination and AT paging functionality of the MPC are described in detail with reference to  FIG. 17 . 
       FIG. 16  is a data tree diagram of an exemplary embodiment of a partial data hierarchy of the present invention, illustrating paging information discovery attributes which are an extension of the Air Interface  536  root. It will be understood by one skilled in the art that the hierarchy is presented for illustrative purposes and does not include all attributes necessary. In addition, other structures may be employed and are within the scope of the presentation.
         AirInterface  1600  is the hierarchical root of all air interface attributes.   HDR  1602  is the hierarchical root of all HDR air interface attributes.   Protocol  1603  is the hierarchical root of all HDR air interface attributes organized by protocol type and protocol subtype.   Type — 08  1604  is the hierarchical root of all HDR air interface attributes associated with HDR protocol type 8, the Overhead Protocol.   SubType — 0000  1606  is the hierarchical root of all HDR air interface attributes associated with HDR protocol type 8, the Route Update Protocol and protocol subtype 0, the Default Overhead Protocol.   AccessNetworkID  1608  specifies the Access Network to which the MPT belongs.   SectorID  1610  specifies the Sector to which the MPT belongs.   ChannelFrequency  1612  specifies the channel frequency of the MPT.   Type — 10  1614  is the hierarchical root of all HDR air interface attributes associated with HDR protocol type 10, the Route Update Protocol.   SubType — 0000  1616  is the hierarchical root of all HDR air interface attributes associated with HDR protocol type 0×10, the Route Update Protocol and protocol subtype 0, the Default Route Update Protocol.   Latitude  1618  specifies the AT&#39;s latitude. This attribute is equivalent to the attribute Location.Translation.Latitude  506 .   Longitude  1620  specifies the AT&#39;s longitude. This attribute is equivalent to the attribute Location.Translation.Longitude  510 .   LocationUpdateDistanceEnabled  1622  is a boolean attribute that indicates whether or not distance-based location update is enabled.   LocationUpdateDistance  1624  is the location update distance.   LocationUpdateZoneEnabled  1626  is a boolean that indicates whether or not zone based location update is enabled.   LocationUpdateZone  1626  is the location update zone.       

       FIG. 17  is a block diagram illustrating a paging area determination and AT paging method in accordance with one embodiment. 
     Paging area determination and AT paging are MPC functions. Each MPC builds a database containing the paging area of each AT to which the MPC is providing service. 
     A straightforward implementation of the database might have one paging area entry per AT. Since an MPC may serve as many as one thousand ATs per MPT, this implementation could result in a very large database. In addition, since mobile ATs move frequently, this implementation could result in a large number of database updates. However, the present embodiment implements the database in a more efficient way. 
     Paging areas depend on the values of the distance and zone location update triggers. While the values of these triggers can differ between MPTs, the values are independent of the AT. Therefore, the paging area database of the present embodiment has one paging area entry per MPT rather than one paging area entry per AT. Since multiple ATs are likely to be located in the same MPT, having one entry per MPT reduces the size of the database. 
     When an AT performs a location update, the location update is forwarded to the MPC that is providing the AT service. If this MPC does not provide service to the MPT that received the location update, the present embodiment will provide one of two responses. If the Access Network does support MPC handoff, then the AT will be handed off to an MPC that does provide service to the MPT that received the location update. If the Access Network does not support MPC handoff, then the session will be terminated and the AT will need to establish a new session. The new session will be established with an MPC that does provide service to the MPT that received the location update. As a result, the present embodiment further simplifies the paging area database. 
     Since an MPC will either hand off or release ATs that perform location updates in MPTs that the MPC does not serve, the database of the present embodiment need only contain a paging area entry for each MPT to which the database provides service. In the case where the MPCs are located within the Access Points, the database of the present embodiment will contain entries only for MPTs that are in the same Access Point. 
     The MPC performs initial population of its database in block  1700 . In order to populate the paging area database, each MPC uses the algorithm of the present embodiment to determine the paging area for each MPT to which it provides service. The present embodiment discovers paging area changes every twenty minutes by causing the MPC to re-determine the paging area for each MPT to which it provides service every fifteen minutes. In addition, the MPC re-determines the paging area whenever the MPC is reset, such as after a firmware upgrade or a power outage. Finally, the present embodiment allows the MPC to re-determine the paging area on command from the operator. 
     The first determination of the paging area is performed in block  1702 . When first determining the paging area for an MPT, the MPC does the following. 
     Starting at the root MPT, the MPC recursively follows the neighbor list until one of the stopping criteria is met. The root MPT is the MPT for which the MPC is determining the paging area. If distance-based location update is enabled on the root MPT, then the recursion stops when the distance between the root MPT and the queried MPT exceeds the location update distance of the root MPT. If zone-based location update is enabled on the root MPT, then the recursion stops when the zone of the queried MPT is different than the zone of the root MPT. The MPT paging area is the list of all MPTs that were queried. 
     The paging area includes all the MPTs in which an AT would not perform a location update if the AT had performed a location update in the root MPT. In addition, the paging area includes the neighbors of the aforementioned MPTs. The neighbors are included in order to account for the fact that it takes an AT a non-zero time to detect that a location update must be performed and to perform the location update. 
     The algorithm of the present embodiment prunes the MPTs in which an AT is paged based on location update area. However, the algorithm does not prune MPTs in which an AT is paged based on AT Identifier. An Access Node of the Access Network is a single-coverage, single-frequency point of connection to an Access Network. An Access Node is the basic building block of the Access Network. The Access Node is identified by its sector (SectorId)  1610  and its carrier frequency (ChannelFrequency). A sector of the Access Network is a collection of one or more channels with the same geographical coverage area and SectorED  1610 . 
     When an Access Port contains multiple Access Nodes, a page message for a particular AT need be sent only to the Access Node to which the AT will hash, or successfully match an AT page message address key to the Access Node. Hashing is the transformation of an AT address into a (usually shorter) fixed-length value, or key, that represents the original address. Hashing is used to index and retrieve items in a database because it is faster to find the item using the shorter, hashed key than to find it using the original value. 
     The algorithm could further reduce the MPT paging list by eliminating all Access Nodes in an Access Port to which the AT will not hash, or achieve an address key match. However, the present embodiment does not reduce the MPT paging list by eliminating all Access Nodes in an Access Port to which the AT will not hash for the following reason. If an Access Node within an Access Port fails, some ATs covered by the Access Port will hash to different Access Nodes. If the Access Node paging list had been pruned to include only the Access Nodes to which the AT had originally hashed, then the Access Node paging list would need to be updated whenever such an Access Node failure occurred. The service outage resulting from such Access Node failures is coupled to the MPT paging list update rate. As a result, pruning the Access Node paging list to include only the Access Nodes to which the AT hashes would undesirably increase the MPT paging list update rate. 
     After first determining a paging area, the MPC regularly re-determines the paging area in block  1704 . Re-determination is the same as first determination  1702 , with one exception. In first determination, if a queried MPT does not respond, then the recursion through that MPT stops. However, in re-determination, if a queried MPT does not respond, then the recursion assumes that the configuration is unchanged since the last query and continues. This makes the protocol tolerant of temporary MPT outages. Because the present embodiment is tolerant of outages, lists do not have to be adjusted in every MPT for each occurrence of a temporary outage. The lists dynamically configure themselves, with each cell performing paging information discovery for itself. The present embodiment eliminates the need for paging areas to be reconfigured by a central manager in the event of temporary cell outages. This feature of the present embodiment eliminates paging area information propagation errors and system failures caused by paging failures. Additionally, if carriers change registration distances or zones the lists do not have to be manually changed by a central network manager. Instead, the present embodiment provides a method to automatically update the paging areas using the Paging Information Discovery and Access Network Attribute Query Protocols. 
     Paging area first determination and re-determination requires the MPC to query MPTs for information illustrated in block  1706 . The MPC performs the queries using the Access Network Attribute Query Protocol. The MPC queries the MPT with IF Modified Since conditioned HTTP get requests  418  for the following parameters: “Neighbor.FQDN”  528 , “AirInterface.HDR.Protocol.Type — 08.Subtype — 0000”  1606 , and “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000”  1616 . 
     The MPC may not need all these attributes from a specific MPT. However, rather than creating different queries for the specific attributes that the MPC needs from each MPT, a single query that is the union of all the attributes is created by the protocol of the present embodiment. This is done so that each MPT will receive the same query from every MPC. Therefore, the MPT will only need to cache one query response. However, the MPC will need to discard the attributes that it does not need. 
     The MPC uses the attributes “AirInterface.HDR.Protocol.Type — 08.Subtype — 0000.AccessNetworkID”  1608 , “AirInterface.HDR.Protocol.Type — 08.Subtype — 0000.SectorID”  1610 , and “AirInterface.HDR.Protocol.Type — 08.Subtype — 0000.ChanneFrequency”  1612 , from the query response. 
     If the queried MPT is the root MPT, then the MPC uses the additional attributes, “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.Latitude”  1618 , “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.Longitude”  1620 , “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.LocationUpdateDistanceEnabled” 1622 , “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.LocationUpdateDistance”  1624 , “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.LocationUpdateZoneEnabled”  1626 , and “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.LocationUpdateZone  1628 ” from the query response  420 . 
     If distance-based location update is enabled on the root MPT, then the MPC uses the additional attributes “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.Latitude”  1618 , and “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.Longitude”  1620  from the query response  420 . 
     If zone-based location update is enabled on the root MPT, then the MPC uses the additional, attribute “AirInterface.HDR.Protocol.Type — 10.Subtype — 0000.LocationUpdateZone”  1628  from the query response  420 . 
     In block  1708 , the MPCs page ATs receiving service from the MPCs using the paging protocol of the present embodiment. When paging an AT, the MPC sends a page message to one or more MPTs. 
     Each page message transmitted by the MPC includes the identifier for the AT being paged. This allows an MPT to discard page messages based on whether or not the AT will hash to the MPTs Access Nodes. 
     The MPC sends a copy of the page message to each MPT in the page area. The IP address used by the MPT for its paging resource may be a unicast, multicast or broadcast address. 
     The IP address of the MPT&#39;s paging resource is allowed to be a multicast and broadcast address in order to reduce the number of page message copies that an MPC must send, thus reducing paging traffic on the Access Network. 
     If either distance-based or zone-based location update is enabled, the paging message includes a unique over-the-air identifier comprising the AccessNetworkID  1608  and SectorID  1610  for each MPT in the paging area. This allows an MPT to discard page messages that the MPT is not responsible for transmitting. 
     Preferred embodiments of the present invention have thus been shown and described. It would be apparent to one of ordinary skill in the art, however, that numerous alterations may be made to the embodiments herein disclosed without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited except in accordance with the following claims.