Method and mechanism for managing packet data links in a packet data switched network

PRIORITY STATEMENT UNDER 35 U.S.C S.119(e) & 37 C.F.R. S.1.78

0001This non-provisional patent application claims priority based upon the prior U.S provisional patent application entitled “Policy and measurement-based admission control and management for the packet-switched domain of the UMTS core network”, application number 60/659,400, filed Mar. 9, 2005, in the names of Melissa Georges and Yves Lemieux.

BACKGROUND OF THE INVENTION

00021. Field of the invention

0003The invention relates to a method and node for providing Quality-of-Service (QoS) level in a packet data switched network

00042. Description of the Related Art

0005An Universal Mobile Telecommunications System (UMTS) network architecture such as a UMTS architecture <b>10</b> depicted in <figref idref="DRAWINGS">FIG. 1</figref>, which is a schematic diagram illustrating an UMTS architecture <b>10</b> in accordance to the prior art, based on an Internet Protocol (IP) network, and also a suite of new services. UMTS offers services such as voice or Short Messaging Service (SMS) and bearer services, which provide the capability for packet data routing between access points or Mobile Terminals (MTs). It is possible to negotiate and renegotiate the characteristics of a bearer service at session or connection establishment and during ongoing session or connection. The UMTS network architecture <b>10</b> comprises an originating Mobile Terminal (MT) <b>1</b>, a radio interface UMTS Terrestrial Radio Access Network (UTRAN) <b>15</b> for providing radio access to a Core Network (CN) <b>20</b> for the MT <b>12</b>. The CN <b>20</b> is constituted of a packet-switched (PS) domain <b>30</b> and a circuit-switched (CS) domain <b>25</b>. The CN <b>20</b> provides switching and routing for packet data. The CN <b>20</b> also contains the databases and network management functions.

0006Some of the circuit switched network elements are Mobile Services Switching Centre (MSC), a Visitor location register (VLR) and Gateway MSC. Some of the Packet switched network elements are Serving General Packet Radio Services (GPRS) Support Node (SGSN) and Gateway GPRS Support Node (GGSN). Both domains share some network elements such as a Home Location Register (HLR).

0007In order to meet Quality-of-service (QoS) requirements of emerging services and applications through the PS <b>30</b> of the UMTS CN <b>20</b>, the UMTS network architecture <b>10</b> adds an IP Multimedia Sub-system (IMS) <b>35</b>. The IMS <b>35</b> facilitates the tasks of network configuration for admission control and resource management based on policies. The IMS <b>35</b> enables applications such as Voice over IP (VoIP) and multimedia applications. The IMS <b>35</b> is supported by the Common Open Policy Service (COPS) protocol Usage for Policy Provisioning (COPS-PR), Request For Comments (RFC) 3084, 34 pages, published in March 2001 by the Engineering Task Force (IETF).

0008The UMTS network architecture <b>10</b> also contains a Policy Repository, a Policy Management Tool, a policy client such as a Policy Enforcement Point (PEP) <b>31</b> and a policy server such as Policy Decision Point (PDP) <b>32</b>. Policies are articulated around conditions and configuration actions. So Policy-based networking is a rather promising approach that can work for the interests of a variety of domains, such as QoS and security such as in Third Generation Partnership Project (3GPP) Technical Specification Group Services and System Aspects, IP Multimedia Subsystem (IMS), Stage 2, 3GPP TS 23.228 v 5.9.0 (2003-06), 127 pages, published in 2003 by the IETF.

0009Resources are defined as being value in a network infrastructure to which rules or policy criteria are first applied before access is granted. Examples of resources may include buffers in a router and bandwidth on an interface. Resources are defined as path established and reserved for receiving and sending packet data from and to a MT in the UMTS network architecture <b>10</b>. The resources considered may be Label Switching Paths (LSPs). For example, the policy-based admission control may be a condition like allowing a LSP if a traffic bandwidth is below 380 kbps. Another example can be to allow a LSP or resource for the MT <b>1</b> if the traffic is above a certain threshold.

0010An IP-in-IP tunnel of Mobile IP Network can be provided by the one or multiple LSPs through a Multiprotocol Label Switching (MPLS) architecture. MPLS may support Large scale Mobile-IP. For example, Label Distribution Protocol (LDP) may be used for establishing LSPs between a mobile agent such as between a Home Agent (HA) (not shown) an anchor point (not shown) and ultimately to the roaming MT <b>1</b>. When the MT <b>1</b> is moving to a foreign area, the existing LSPs may be extended without service interrupt. The short-cut LSPs between source and destination MTs may be recalculated to avoid the long cascaded connections.

0011With regard to the policy aspect, the 3GPP policy specifications are globally conformant with the IETF specifications on policy-based networking and policy-based admission control. In the management scheme, the policy approach serves IMS services and applications. The mandatory policy nodes are generally located outside the IMS <b>35</b> such as the Policy Enforcement Point (PEP) <b>31</b> that may be incorporated into a peripheral node of the CN <b>20</b> such as a GGSN in a General Packet Radio Service (GPRS) network.

0012The phases of the end-to-end session establishment process between the MT <b>1</b> and another MT <b>2</b> or another server from which the MT <b>1</b> may receive IMS services in the UMTS network <b>10</b> are: authorization of resources, reservation of resources, commitment of resources and billing. Besides, policy-based admission control is executed for each IMS user request. This traffic engineering application relies upon the resources' availability and the operator-defined policies.

0013As for the resources' availability aspect, the 3GPP specifications simply mandate a vendor/operator-specific admission control mechanism that is internal to the two peripheral server nodes of the packet-switched domain. It also suggests the use of the MPLS and Differentiated Services (DiffServ) technologies. Diffserv is an architecture for providing different types or levels of service for network traffic. However, UMTS network architecture exhibits properties that exacerbate the problem of congestion control—hence of admission control. The properties are those of long range dependence and self-similarity that cause fluctuations, which are large in amplitude and persistent over many timescales. They are ascribable with the various behaviors of the users and the unstable character of the applications themselves.

0014As of today, applications are likely to be conveyed solely over the packet-switched domain of the CN <b>20</b>. In order to satisfy QoS requirements of the IMS services, a policy-based management approach can be applied. IMS services also rely upon a policy-based admission control algorithm. Both the mechanism and the global approach define the aspects of policy and resources' availability.

0015The aspects of policy and resources' availability are covered 3GPP specifications. However, the 3GPP specifications are prone to improvements. Indeed, the gaps linked to the policy aspect include the limited policies, the small number of policy clients and the exclusive use of the management approach for the multimedia and VoIP applications. The weak elements of the resources' availability aspect are essentially due to the fact that it is almost not covered in 3GPP specifications in spite of the revealed challenging traffic properties of long range dependence (LDR) and self-similarity.

0016For example, MPLS and DiffServ are two technologies that are not sufficient for providing real QoS offering for applications and services with QoS requirements in a packet data switched network such as the network <b>10</b>. More particularly, there is no linkage between policy-based admission control and resources' availability in the UMTS network architecture <b>10</b> using the IMS <b>35</b>. For that reason, there is a need to improve the cooperation between policy and resources' availability and for providing an efficient traffic engineering system. The invention provides a solution to that problem.

SUMMARY OF THE INVENTION

0017It is a broad object of the present invention to provide a method for establishing a packet data session for a Mobile Terminal (MT) in packet data switched network, the method comprising steps of:

0018receiving at a Bandwidth Broker (BB) node from an aggregation node, Quality-of-Service (QoS) measurements for a path assigned to the MT, the path being assigned for transmission of packet data for the MT;

0019storing at the BB node the received QoS measurements from the aggregation node;

0020extracting QoS measurements stored at the BB node, based on reception of a request message from the aggregation node for admitting the path; and

0021admitting at the BB node the assigned path based on the extracted QoS measurements and on policies stored at the BB node.

0022It is another broad object of the present invention to provide a Bandwidth Broker (BB) node for admitting an assigned path for a Mobile Terminal in a packet data network, the BB node comprising

0023a manager for receiving Quality-of-Service (QoS) measurements from an aggregation node, wherein the measurements related to a path assigned to the MT and storing the received QoS measurements in a first internal database;

0024a Policy Control Function (PCF) for extracting QoS measurements from the first internal database, based on reception of a request message from the aggregation node for admitting the path; and

0025a measurement-based admission control mechanism for admitting the assigned path based on the extracted QoS measurements and on policies stored in a second internal database.

BRIEF DESCRIPTION OF THE DRAWINGS

0026For a more detailed understanding of the invention, for further objects and advantages thereof, reference can now be made to the following description, taken in conjunction with the accompanying drawings, in which:

0027<figref idref="DRAWINGS">FIG. 1</figref> depicts a schematic diagram illustrating an UMTS architecture <b>10</b> for bloc in accordance to the prior art; and

0028<figref idref="DRAWINGS">FIG. 2</figref> is a nodal operation and signal flow diagrams illustrating a flow of messages and steps of a method for managing Quality-of-Service (QoS) measurements and session admission for a Mobile Terminal (MT) in a packet data switched network.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0029Reference is now made to <figref idref="DRAWINGS">FIG. 2</figref>, which is a nodal operation and signal flow diagrams illustrating a flow of messages and steps of a method for managing Quality-of-Service (QoS) measurements and session admission for a Mobile Terminal (MT) <b>12</b> in a packet data network <b>100</b>.

0030The packet data network <b>100</b> allows establishment of a packet data session for transmitting packet data between the originating MT <b>12</b> and a destination MT or Service Application <b>22</b>. The MT <b>12</b> may be any mobile equipment that is registered in the packet data network <b>100</b> and that can operate in the packet data switched network <b>100</b>. The MT <b>12</b> may roam in the packet data network <b>100</b> and also receive packet data services from different locations namely service areas in the packet data network <b>100</b>. The SA <b>22</b> may be an application server that can provide Internet services or VoIP to the MT <b>12</b>. The packet data network <b>100</b> comprises an Application Function (AF) <b>101</b>, a first aggregation node <b>102</b>, a Bandwidth Broker (BB) node <b>106</b> and a second aggregation node <b>111</b>.

0031The AF <b>101</b> ensures that messages from and to the MT <b>12</b> are transmitted to and from the packet data switched network <b>100</b>. The first aggregation node <b>102</b> and the second aggregation node <b>111</b> include agents <b>103</b> and <b>112</b> respectively. The agents <b>103</b> and <b>112</b> periodically collect packet data connection utilization measurements and communicate these measurements to the BB node <b>104</b>. The agents <b>103</b> and <b>112</b> may use a network management protocol such as Simple Network Management Protocol (SNMP), which is an application layer protocol that facilitates the exchange of management information between network elements.

0032Common Open Policy Service (COPS) protocol is a simple query and response protocol that can be used to exchange policy information (request and response messages) between network elements in the packet data network. References to SNMP and COPS may be used for supporting QoS measurements process and convey the resources' availability related data.

0033The first aggregation node <b>102</b> processes uplink requests from the MT <b>12</b> and the second aggregation node <b>111</b> processes downlink requests to the MT <b>12</b>. However, both aggregation nodes <b>102</b> and <b>111</b> are concerned for bidirectional requests. The two nodes <b>102</b> and <b>111</b> collect measurements periodically and associate the measurements to the appropriate path on which packet data are sent to the MT <b>12</b>. Both the first and second aggregation nodes <b>102</b> and <b>111</b> store them locally in databases <b>104</b> and <b>113</b> respectively. The first aggregation node <b>102</b> and the second aggregation node <b>111</b> provide the necessary information about the available resources to the BB node <b>106</b>. The first aggregation node <b>102</b> and the second aggregation node <b>111</b> may be collocated with link <b>115</b> or use as standalone network elements as shown in <figref idref="DRAWINGS">FIG. 2</figref>. The first and second aggregation nodes <b>102</b> and <b>111</b> also comprise local PDPs (LPDP <b>105</b> and LPDP <b>114</b>) for local treatment of decisions of policies. The PCF <b>109</b> manages the LPDP <b>105</b> and LPDP <b>114</b> for local application of policy-based admission control.

0034The BB node <b>106</b> comprises a manager <b>107</b>, a Policy Control Function (PCF) <b>109</b> and a Measurement-Based Admission Control mechanism (MBAC) <b>206</b> that may use an AC-MVEv2/AC-KQv2 algorithm along with QoS measurements for determining if transmissions of packet data are admitted or not on an assigned path for the MT <b>12</b>. The manager <b>107</b> supports measurements and stores received results from agents <b>103</b> and <b>112</b> in a database <b>108</b>. The PCF <b>109</b> provides a set of policies used in conjunction with the MBAC mechanism <b>206</b>. As a consequence, the BB node <b>106</b> optimizes the bandwidth resources and supports admission control in the packet data network <b>100</b>. The agents <b>103</b> and <b>112</b>, the manager <b>107</b>, the MBAC mechanism <b>206</b> and the PCF <b>109</b> may be software, hardware or any combination thereof. The manager <b>107</b> comprises a database for storing measurements and path identifier and the PCF <b>109</b> comprises a database for storing policies for admission control and binding with path states and available resources. The database <b>110</b> may be a policy information database (PIB) for storing policy-based control admission, which is a set of rules to be applied to an assigned path for admitting resource to the MT <b>12</b> that requests packet data services.

0035The present invention can preferably be described with reference made to a General Packet Radio Services (GPRS) network but may be applied to any packet data telecommunications network. More particularly, the packet data network <b>100</b> may be any 2 G network such as in a Time Division Multiple Access (TDMA) network or a Code Division Multiple Access (CDMA), 2.5 G networks such as a General Packet Radio Service (GPRS) any 3 G Universal Mobile Telecommunications Systems (3 G UMTS) network such as a CDMA2000 network a Wideband Code Division Multiple Access (WCDMA) network, a Global System for Mobile Communications/Enhanced Data for GSM Evolution (GSM/EDGE) or a High Speed Packet Data Access (HSPDA) network. The present invention may also be applicable to Institute of Electrical and Electronics Engineers (IEEE) 802.11, WiMAX IEEE 802.16, and NGN Functional Architecture: Resource and Admission Control Subsystem (RACS), European Telecommunications Standards Institute (ETSI) ES 201 v 1.6.2.

0036For example, a second aggregation node may be a Gateway GPRS Service Node (GGSN), a first aggregation node may be a Serving GPRS Service Node (SGSN) in a GPRS network and a AF may be a Proxy-Call Session Control Function (P-CSCF) for forwarding of messages received from a MT. Furthermore, if there is a common core network between the MT <b>12</b> and the first or second aggregation nodes <b>102</b> and <b>111</b> or a collocated node combining the function of both nodes <b>102</b> and <b>111</b>.

0037In the present invention, the method and the BB node <b>106</b> are based on policies and measurements-based admission control. The invention may use pseudo-static L-LSPs as a path for transmitting packet data to the MT <b>12</b>. L-LSPs are said pseudo-static because they are predefined for each class of traffic offline by a Traffic Engineering-Configuration Management System (TE-CMS) entity for requesting a path set up for a new LSP in the service. The TE-CMS is responsible for reading the network topology and based on this it calculates a path to be assigned to the MT <b>12</b>. The path, may be terminated, created or modified dynamically in the packet data network <b>100</b>. Their duration exceeds that of a single flow but it is not perpetual. The creation/modification/termination of the path is commanded by the PCF <b>109</b> decisions in response to time or event-related policies such as time of day or network state. The resources or paths in the packet data switched network <b>100</b> may alternatively be based on MPLS, Virtual protocol label Switching (VPLS) or Ethernet over optical while not being limited to.

0038Whenever the MT <b>12</b> wishes to receive packet data services from the packet data switched network <b>100</b> or wishes to send packet data to the MT or SA <b>22</b> of the packet data switched network <b>100</b>, the MT <b>12</b> sends a packet data session request <b>120</b> to the first aggregation node <b>102</b> for establishing a packet data session. The request <b>120</b> includes parameters for identifying and authenticating the MT <b>12</b> in the packet data network <b>100</b>.

0039The packet data session may be a Session Initiation Protocol (SIP) session as defined in 3GPP Technical Specification Group Services and System Aspects, end-to-end quality of QoS concept and architecture, 3GPP TS 23.207 v 5.8.0 (2003-06), 47 pages, published in 2003 by 3GPP. The packet data session may alternatively be an Extensible Authentication Protocol (EAP) session as defined in RFC 3748, published by the IETF, June 2004.

0040Upon reception of the session requests <b>120</b> the first aggregation node <b>102</b> starts the QoS authorization phase for authorizing the packet data session between the MT <b>12</b> and another MT or SA <b>22</b> (step <b>124</b>). During phase <b>124</b>, the MT <b>12</b> receives a token <b>122</b> from the first aggregation node <b>102</b>. The token is later used for authentication by the network <b>100</b> and for authorizing the MT <b>12</b> to receive and sends packet data during the packet data session. Alternatively, the packet data session may be established by any protocol that provides authentication of an MT. In some protocols the MT <b>12</b> does not need to provide a token. Therefore, the network <b>100</b> may alternatively authenticate the MT <b>12</b> without the need of a token provided by the MT <b>12</b> and therefore the sending of some messages for authenticating the MT <b>12</b> may be rendered not necessary.

0041After completion of the authorization phase, the MT <b>12</b> sends a Request message <b>126</b> for initiating a resource reservation of path such as LSPs. At step <b>128</b>, reservation phase is established between the MT <b>12</b> and the MT or a SA <b>22</b> for providing packet data services to the MT <b>12</b>. Next, a node such as a Traffic Engineering-Configuration Management System (TE-CMS) entity (not shown) in the packet data network <b>100</b> assigns a path set up for a new path <b>231</b> for the MT <b>12</b>. The path <b>231</b> is assigned for transmitting packet data for the MT <b>12</b> (step <b>129</b>). The path is defined towards the MT <b>12</b>, the AF <b>101</b>, first aggregation node <b>102</b>, the second aggregation node <b>111</b> and ultimately the MT/SA <b>22</b>.

0042Following this, the first aggregation node <b>102</b> periodically collects by the agent <b>103</b> QoS measurements <b>131</b> for the path <b>231</b> assigned to the MT <b>12</b> (step <b>130</b>). The QoS measurements <b>131</b> are stored in the database <b>104</b> by the agent <b>103</b> and are sent to the PCF <b>109</b>, at step <b>133</b>. The database <b>104</b> may be a Management Information Base (MIB), which is a collection of information that is organized hierarchically. A MIB is accessed using a network-management protocol such as SNMP. They are comprised of managed objects and are identified by object identifiers. In the database <b>104</b>, the managed objects are path identifiers for identifying path assigned to the MT <b>12</b> and QoS measurements data measured in the packet data switched network <b>100</b>.

0043In parallel to step <b>133</b>, the first aggregation node sends a request <b>135</b> for policy decision based admission control. Upon reception of the request <b>135</b> the PCF <b>109</b> verifies that an authorization state of the MT <b>12</b> is valid by looking in the database <b>110</b> and by applying the stored policies in the database <b>110</b>, that the authorization state is valid (step <b>137</b>).

0044If the authorization state is not valid the BB node <b>106</b> sends a rejection message <b>140</b> to the MT <b>12</b>. However, if the authorization state is valid at step <b>139</b>, the PCF <b>109</b> extracts the QoS measurements form the database <b>110</b> (step <b>141</b>). Following this, the MBAC mechanism <b>206</b> decides on admission of path <b>231</b> based on policies stored in database <b>110</b> and the extracted QoS measurements <b>131</b> and executes MBAC on the assigned paths (step <b>142</b>).

0045Based on a determination by the TE-CMS that the assigned path <b>231</b> is currently optimal and based on defined constraints the BB node <b>106</b> determines resource allocation: creation, modification or release of the path <b>231</b> (step <b>143</b>). Following this, the BB node <b>106</b> sends a response message <b>144</b> for responding to the message <b>135</b> sent from the first aggregation <b>102</b>. The response message <b>144</b> includes a path identifier <b>145</b> for identifying the path <b>231</b> that is created, modified or released.

0046Upon reception of the response message <b>144</b> the first aggregation node <b>102</b>, sends a policy request message <b>147</b> for resource reservation to the second aggregation node <b>111</b>. The request message <b>147</b> includes parameters for opening the packet data session in the packet data switched network <b>100</b>. Following the reception of message <b>147</b>, the second aggregation node <b>111</b> executes the reservation of resource for the MT <b>12</b> (step <b>148</b>). The second aggregation node <b>111</b> sends a policy response message <b>150</b> to the first aggregation node <b>102</b> for responding to the request message <b>147</b> and more particularly for acknowledging that resource reservation has been accepted for the packet data session.

0047Following the reception of the response message <b>150</b>, the first aggregation node <b>102</b> determines if the packet data session is accepted based on the response message <b>150</b> indicating that the reservation of resources has been made at the second aggregation node <b>111</b> (step <b>154</b>). If the packet data session is not accepted at step <b>154</b> the first aggregation node <b>102</b> sends a rejection message <b>158</b> to the MT <b>12</b>.

0048If the packet data session is accepted, the first aggregation node <b>102</b> forwards the response request <b>150</b> to the MT <b>12</b> for acknowledging that resource reservation has been accepted for the packet data session. A commitment phase <b>168</b> is then established for opening a gate and using path or resource allocation for transmitting packet data during the packet data session requested by the MT <b>12</b>. Afterwards, the packet data session is established between the MT <b>12</b> and the MT or SA <b>22</b> in the packet data switched network <b>100</b> (step <b>170</b>).

0049More particularly, the MBAC mechanism <b>206</b> provides admission control (algorithms and gating at commitment <b>168</b>) and signaling. Admission control ensures based on measurements that sufficient network resources are available for each new path assigned, and the signaling is performed by using messages <b>144</b>, <b>147</b> and <b>150</b> for providing such resource allocation demands to each nodes along the path <b>231</b>.

0050The management of QoS relies upon mechanisms that are local to the domains traversed by the connection and upon mechanisms dedicated to the inter-functioning of the UMTS network with external networks. Various protocols such as Resource Reservation Protocol (RSVP) and LDP can be used for signaling on the assigned paths for a MT, appropriate marking/labeling of the packets such as DiffServ, MPLS, interaction between policy control and/or resource management elements and, finally, SLA (expand acronym) agreements between operators. MPLS and DiffServ technologies may be used for policies' setup.

0051If a path is assigned to the MT <b>12</b> while the MT <b>12</b> is roaming in the network <b>100</b>. The second aggregation node <b>111</b> or any node that acts as a gateway node for the MT <b>12</b> switches a traffic of packet data from a first assigned path in a first service area to a second assigned path in a second service area in the packet data network <b>100</b> when the MT <b>12</b> moves and consequently handoffs to the second service area in the packet data network <b>100</b>.

0052Therefore, the present invention defines the aspect of resources' availability and makes modifications to the one of policy. Moreover, it offers a fairer compromise between the constraints of resources' utilization and QoS, thereby enabling the respect of the requirements of the stringent QoS requirements. Finally, it leads to a greater cooperation between policies and resources availability. In particular, the method and BB node <b>106</b> of the present invention manages high QoS for multimedia applications such as VoIP, Video on demand and Interactive TV and users application such as mission critical services including <b>911</b> and telemedicine sessions based on EISS with the addition of the present invention. As a consequence, the present invention may manage the QoS for high scalable services and not only for VoIP and multimedia such as for the IMS.

0053It can be understood that some messages and therefore some parameters sent from the MT <b>12</b> to the packet data network <b>100</b> and vice versa are not mentioned nor described for clarity reasons. Also some messages and therefore some parameters sent between network elements in the packet data network <b>100</b> are omitted for clarity reasons. More particularly, it should also be understood that Figures depict a simplified packet data network <b>100</b>, and that many other network elements have been omitted for clarity reasons only. Furthermore, <figref idref="DRAWINGS">FIG. 2</figref> shows that only one path <b>231</b> is assigned to the MT <b>12</b>, but it can be understood that more that one path may simultaneously be assigned to the MT <b>12</b> and therefore a plurality of packet data services may simultaneously be provided to the MT <b>12</b> on different assigned paths. The method establishes a packet data session for a MT, but it can be appreciated that the BB node <b>106</b> may simultaneously admit paths based on policies for a plurality of MTs.

0054Although several preferred embodiments of the method and the Bandwidth Broker node of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the present invention as set forth and defined by the following claims.