HSS Location Registration for Unregistered WLAN-GPRS VoIP Calls

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Solution Overview

Problem

In 3G-GPRS based WLAN environments, unregistered mobile nodes (MN) face challenges in location detection and resource occupation, making it difficult to establish VoIP calls efficiently due to the absence of location-based services.

Innovation Solution

A method is introduced where the Home Subscriber Server (HSS) registers the location of unregistered MNs using their MAC addresses, optimizing network resource usage by determining initial registration or movement, and updating databases to facilitate VoIP calls during handoffs between GPRS and WLAN environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If every mobile node (MN) occupies resources for IP connection to make SIP registration in a network, then SIP-based VoIP service can be provided, but network resources are inefficiently occupied

Engineering Contradiction:

ImproveSIP registration capabilityVSAvoidnetwork resource occupation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system performs preliminary location registration using MAC address at the HSS before SIP registration is required. This preliminary action stores the MN's location information in advance, so when a call arrives, the system can quickly retrieve location without requiring the MN to maintain continuous IP connection or perform SIP registration, thus reducing network resource occupation while maintaining service reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism where the HSS uses MAC address as an intermediate identifier to track MN location. Instead of requiring direct SIP registration between MN and network, the HSS acts as an intermediary that maps MAC addresses to location information, enabling call routing without continuous resource occupation by MNs

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a mobile node (MN) must always be connected to IP and complete SIP registration, then calls can be established, but location detection becomes difficult without location based service in WLAN environment

Engineering Contradiction:

Improvecall establishmentVSAvoidlocation detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent extracts the location detection function from the SIP registration process. Instead of relying on SIP registration to obtain location information, the system extracts location detection to a separate mechanism using MAC address tracking at the HSS. This allows location to be detected independently of SIP registration status, solving the difficulty of location detection in WLAN environments where location-based service is absent

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The HSS is given multi-functionality: it not only handles traditional subscriber information but also performs location registration using MAC address. This universal approach allows the same system component to serve both subscriber management and location tracking functions, enabling reliable call establishment through a unified mechanism that works across different network environments

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If mobile nodes use dual mode or are exclusively used for WLAN, then flexibility is improved, but seamless handoff between GPRS and WLAN environments requires efficient location registration

Engineering Contradiction:

Improvedual mode operationVSAvoidhandoff processing

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system performs preliminary location registration at the HSS using MAC address before handoff occurs. When an MN moves between GPRS and WLAN environments, the location is already registered in advance, so handoff processing only requires retrieving existing location information rather than performing complex registration procedures, thus reducing handoff complexity while supporting dual-mode operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The HSS acts as an intermediary that maintains location information across different network environments (GPRS and WLAN). Instead of requiring complex coordination between different network systems during handoff, the HSS intermediary stores and manages location information using MAC address, simplifying the handoff process while enabling flexible dual-mode operation

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7650148B2Method of processing call to unregistered user in WLAN-GPRS network using SIP

Publication Date: 2010.01.19 KT CORP

AI summary

A method of processing a call to an unregistered user in a Wireless Local Area Network (WLAN)-General Packet Radio Service (GPRS) using a Session Initiation Protocol (SIP) is provided. The method of connecting a call to a mobile node present in a GPRS area includes registering location information of the mobile node to be invited in a Home Subscriber Server (HSS); when the mobile node uses a Mobile Internet Protocol (MIP), allocating an Internet Protocol (IP) address to the mobile node and authenticating the mobile node through MIP registration and setting a SIP session; and when the mobile node uses a simple IP, allocating an IP address to the mobile node and authenticating the mobile node through a Dynamic Host Configuration Protocol (DHCP) procedure and setting a SIP session.