NOT APPLICABLE
NOT APPLICABLE
This invention relates to radio telecommunication networks. More particularly, and not by way of limitation, the invention is directed to a system, node, and method for efficiently supporting mobile terminals and core network (CN) nodes that are not compliant with the latest technical specifications governing the operation of radio telecommunication networks and mobile terminals.
Today, service nodes in radio telecommunication core networks, such as Serving GPRS Service Nodes (SGSNs) are increasingly having to solve problems created by non-compliant mobile terminals such as User Equipments (UEs) and Mobile Stations (MSs). From the viewpoint of operators and handset vendors, it is easier and more cost efficient to make updates and changes in one place (the SGSN) instead of in millions of places (all UE/MSs).
The problem for SGSN vendors is that the efforts to solve these problems for the non-compliant UE/MSs negatively affect the performance of the SGSN. In many cases, features added to the SGSN for the benefit of compliant UE/MSs must be turned off in order to serve the non-compliant UE/MSs. This problem makes it extremely difficult to evolve the standards. Two known examples of UE/MS non-compliant performance are:
Thus, the existing solution is for the SGSN to drop the optional IE's that cause problems for non-compliant UE/MSs. While this solution enables the maximum number of UE/MSs to be served, it causes other problems when the IEs are dropped for all UE/MSs. For example, when removing the PDP Context Status IE, there is a risk of getting a Serving Radio Network Subsystem (SRNS) feature that is not as efficient as it is meant to be. There is also greater risk of a mismatch between the perception of which contexts are really active between the UE/MS and the SGSN.
In the future, as additional features are added to radio telecommunication networks, this problem will continue to get worse. Many enhanced features will simply not work if the optional IEs are excluded by the core network.
Similar problems occur when the SGSN has to support other CN nodes that are not compliant with the latest software version. This may occur because the operator and CN vendors decide not to update “faulty” CN nodes because the nodes are scheduled for replacement. There are also interoperability issues between home networks and visited networks which may cause software level differences between the SGSN and other CN nodes.
The problem may be exemplified by considering an SGSN-GGSN communication. If the SGSN sends a Create PDP Context Request message to the GGSN and includes an AACE parameter (implicitly using the GPRS Tunneling Protocol version 1. GTPv1) and the GGSN doesn't understand the “new” optional information element Radio Access Technology (RAT), then the GGSN will either send back a protocol error or will not respond at all. This causes the SGSN to switch to GTPv0, and the GGSN looses a lot of important information since GTPv0 does not contain all the fields needed. The SGSN-GGSN communication is then also “marked” as GTPv0 and this will cause additional problems when performing an SGSN Routing Area Update (ISRAU).
What is needed in the art is a system, node, and method for efficiently supporting non-compliant mobile terminals and CN nodes without negatively affecting the features that are available to compliant mobile terminals and nodes. The present invention provides such a system, node, and method.
The present invention is directed to a system, node, and method for efficiently supporting non-compliant mobile terminals and CN nodes without negatively affecting the features that are available to compliant mobile terminals and nodes. Compliant mobile terminals and nodes enjoy all the features offered by messages containing optional and conditional IEs, while non-compliant mobile terminals and nodes are also provided with an opportunity to respond to an altered message in which the optional and conditional IEs have been excluded. The invention does this without increasing the signaling load in the network.
In one aspect, the present invention is directed to method of serving mobile terminals in a radio telecommunication network. The method includes the steps of attempting to obtain a response from a mobile terminal by sending a standardized message from a network node to the mobile terminal, and if a response is not received, attempting to obtain a response from the mobile terminal by sending an altered message from the network node to the mobile terminal. In one embodiment, the standardized message is sent a maximum of three times while awaiting a response from the mobile terminal, and the altered message is sent a maximum of two times while awaiting a response from the mobile terminal. The altered message may be created by removing optional and conditional IEs from the standardized message.
In another aspect, the present invention is directed to a network node for serving mobile terminals in a radio telecommunication network. The node includes means for sending a standardized message to a mobile terminal; means for determining whether a response is received from the mobile terminal in response to the standardized message; and means responsive to a determination that a response is not received, for sending an altered message to the mobile terminal. In one embodiment, the node may store an ID of the mobile terminal in a list of non-compliant mobile terminals if the mobile terminal responds to the altered message. Thereafter, in a future session with the same mobile terminal, the node may send only the altered message to the mobile terminal a maximum of five times while awaiting a response from the mobile terminal.
In another aspect, the present invention is directed to a system in a radio telecommunication network for serving a plurality of mobile terminals, wherein a first portion of the mobile terminals is compliant with network specifications and a second portion of the mobile terminals is not compliant with the network specifications. The system includes means for identifying a non-compliant mobile terminal- and means for providing the non-compliant mobile terminal a reduced feature set while providing compliant mobile terminals with a full feature set. The means for identifying a non-compliant mobile terminal may include means for determining whether the given mobile terminal responds to a standardized message or an altered message in which information elements likely to cause a non-compliant mobile terminal to not respond have been removed. The system, which may be implemented in an SGSN in one embodiment, is adapted to send the standardized message a maximum of three times and to send the altered message a maximum of two times while awaiting a response from the given mobile terminal.
In another aspect, the present invention is directed to a method in a core network (CN) service node for supporting other CN nodes. The method includes the steps of attempting to obtain a predefined response from a supported CN node by sending a standardized message from the service node to the supported CN node; and if the predefined response is not received, attempting to obtain a response from the supported CN node by sending an altered message from the service node to the supported CN node.
In the following, the essential features of the invention will be described in detail by showing preferred embodiments, with reference to the attached figures in which:
The present invention is directed to a system, node, and method for efficiently serving non-compliant mobile terminals and CN nodes without negatively affecting the features that are available to compliant mobile terminals and nodes. In the embodiments described herein, the term SGSN is utilized generically to refer to any present or future generation of network service node. For example, the 3GPP Evolved Packet System (EPS), which includes an Evolved Packet Core (EPC) network and an Evolved UTRAN radio access network (EU-TRAN), includes a Mobility Management Entity (MME) and a User Plane Entity (UPE) which provide services to UE/MSs and other CN nodes. The MME is similar to the control plane of a SGSN, and performs user authentication, terminates Non-Access Stratum (NAS) signaling security, and the like. The functions of the MME currently reside in the SGSN. The UPE is similar to the user plane of a RNC and SGSN, and terminates UP (User Plane) security. The functions of the UPE currently reside in an enhanced Node-B (e-NB). All of these service functions are included in the generic term SGSN for purposes of the present invention.
Under existing 3GPP technical specifications such as 3GPP TS 24.008, the SGSN may send certain standardized messages to UE/MSs a maximum of five times if a proper response (as defined in the technical specifications) is not received from the target UE/MS. This procedure is changed in the present invention so that the SGSN sends the identical standardized message a reduced number of times (for example only three times), and then alters the message for subsequent attempts (for example the last two attempts). The message is altered to exclude “known problem” optional and/or conditional IEs in the last two attempts. In this way, a compliant UE/MS is given three chances to receive the standardized message and respond, thereby enjoying all the features offered by the optional and conditional IEs. A compliant UE/MS may also respond to one of the last two attempts and receive service with a reduced set of features. A non-compliant UE/MS may be unable to respond to the first three message attempts, but has two chances to respond after the SGSN alters the message to exclude the problem IEs.
The “known problem” IEs may be those for which it has been demonstrated that they cannot be processed by a significant number or percentage of non-compliant UE/MSs. The problem IEs may be stored in a memory associated with the SGSN or elsewhere in the network.
In one embodiment, the SGSN or other network node may also store an ID of the non-compliant UE/MS in memory so that the next time the SGSN serves the same UE/MS, network logic will recognize that the UE/MS is non-compliant, and cause the SGSN to send the only altered message up to a maximum of five times. In this way, network resources are not wasted by first sending the standardized message, which will not be properly answered. In the description herein, the network logic is implemented in the SGSN, although it may also be implemented in other network nodes or in a stand-alone node in communication with the SGSN.
Referring now to
However, if it is determined at step 15 that this is the fourth message attempt, the method moves to step 16 where the SGSN alters the mobility management message by excluding “known problem” optional and conditional IEs. At step 17, the SGSN sends the altered mobility management message to the UE/MS. At step 18, it is determined whether a proper response is received from the UE/MS. If not, the method moves to step 19 where the response timer expires. At step 20, it is determined whether this is the fifth or last message attempt. If not, the method returns to step 17 where the SGSN again sends the altered mobility management message to the UE/MS. Alternatively, if this was the fifth or last message attempt, the method moves to step 21 where the SGSN excludes the UE/MS.
If it is determined at step 18 that a proper response is received to the altered mobility management message, the method moves to step 22 where the SGSN continues to service the UE/MS with a reduced feature set. The method may then proceed to
Table 2 below shows modifications to “Table 11.4/3GPP TS 24.008: GPRS mobility management timers—network side” in accordance with the present invention. As shown, the GPRS mobility management messages are transmitted with all optional and conditional IEs up to a maximum of three times (i.e., second expiry of the retransmission timer) while awaiting a proper response from the UE/MS. For the fourth and fifth message attempts (i.e., after the third and fourth expiry of the retransmission timer) the SGSN excludes “known problem” optional and conditional IEs from the retransmitted messages in order to adapt the messages for non-compliant UE/MSs.
Referring now to
It is possible, however, that a compliant UE/MS may not receive the first three message attempts, but may then receive and respond to one of the altered message attempts. In this case, the UE/MS may be falsely placed on the list of non-compliant UE/MSs. Therefore, if the SGSN repeatedly serves the same UE/MS, the SGSN may periodically revert to first sending the standardized message to the UE/MS in order to provide the UE/MS the opportunity to respond. If the UE/MS properly responds to the standardized message, the SGSN then removes the UE/MS's ID from the list of non-compliant UE/MSs.
Thus, at step 31, a UE/MS that was placed on the list of non-compliant UE/MSs accesses the SGSN at a future time. At step 32, the SGSN sends the standardized mobility management message to the UE/MS a maximum of three times, and then sends the altered message a maximum of two times if the UE/MS has not properly responded. At step 33, it is determined whether or not the UE/MS properly responds to the standardized message. If so, the method moves to step 34 where the SGSN removes the ID of the UE/MS from the list of non-compliant UE/MSs. However, if the UE/MS does not respond to the standardized message, but again responds to the altered message, the method moves to step 35 where the SGSN retains the ID of the UE/MS on the list of non-compliant UE/MSs.
If the UE/MS 42 responds to the altered message 46, the compliant/non-compliant UE/MS logic 45 stores the UE/MSID in a non-compliant UE/MS memory 47. Thereafter, if the same UE/MS accesses the SGSN 41, the compliant/non-compliant UE/MS logic queries the memory 47 to determine whether the UE/MSID is stored. If not, the logic causes the SGSN to send the standardized message 44 to the UE/MS in accordance with the process shown in
As noted above, it is possible that a compliant UE/MS 42 may not receive the first three message attempts, but may then receive and respond to one of the altered message attempts. In this case, the UE/MS may be falsely placed on the list of non-compliant UE/MSs. Therefore, if the SGSN repeatedly serves the same UE/MS, the SGSN may periodically revert to first sending the standardized message to the UE/MS in order to provide the UE/MS the opportunity to respond. If the UE/MS properly responds to the standardized message, the compliant/non-compliant UE/MS logic 45 removes the UE/MSID from the list of non-compliant UE/MSs stored in the non-compliant UE/MS memory 47.
When the SGSN is supporting another CN node rather than a UE/MS, the invention performs similar functions. The existing procedure in 3GPP 29.060 regarding retransmission of certain messages states that the SGSN will send the same identical message to the other CN node up to N3 times. The present invention changes this process and specifies that the SGSN will send the identical message a reduced number of times (for example N3-1 times), and will then alter the message and exclude “known problem” optional IEs in subsequent attempts (for example the last attempt). The SGSN may also store the CN-Id of the CN node in a list of non-compliant CN nodes. Thereafter, for future messages, the SGSN may send the altered message from the start. Optionally, the CN-Id may be periodically reset (for example every 24 hours) so that the CN-Id is removed from the list of non-compliant CN nodes. This enables CN nodes that have been upgraded or CN nodes that have been wrongly placed on the non-compliant list to once again take advantage of the full set of features offered by compliant signaling.
The SGSN 41 then sends an altered Create PDP Context Request message 56, without AACE parameters, to the GGSN 51. The non-compliant GGSN then responds by returning a Create PDP Context Response message 57. The SGSN then sends an Activate PDP Context Accept message 58 to the UE/MS 42.
At 59, the SGSN 41 may also store the GGSN-Id in a list of non-compliant CN nodes. Thereafter, for future messages, the SGSN may send only altered messages to the GGSN 51. Optionally, at 60, the SGSN may periodically reset the GGSN-Id (for example every 24 hours) so that the GGSN-Id is removed from the list of non-compliant CN nodes. If the GGSN has been upgraded or if the GGSN was wrongly placed on the non-compliant list, the GGSN can once again take advantage of the full set of features offered by compliant signaling.
In this manner, the SGSN can support non-compliant CN nodes without adversely affecting the full-featured support provided to compliant CN nodes.
Although preferred embodiments of the present invention have been illustrated in the accompanying drawings and described in the foregoing Detailed Description, it is understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the scope of the invention. The specification contemplates any all modifications that fall within the scope of the invention defined by the following claims.
This application claims the benefit of U.S. Provisional Application No. 60/863,042 filed Oct. 26, 2006, the disclosure of which is incorporated herein by reference.
Number | Date | Country | |
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60863042 | Oct 2006 | US |