Home Base Station NATed Address Detection and Provisioning
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Solution Overview
Problem
Home base stations (HNBs) in mobile telecommunication networks often encounter issues with Network Address Translation (NAT) devices, which change local IP addresses and UDP ports, making it difficult for HNBs to provide necessary address information to the core network, leading to interoperability problems and resource reservation challenges.
Innovation Solution
The solution involves mechanisms for HNBs to obtain and provide 'NATed' address information during setup procedures, using methods such as extending IKEv2, implementing the STUN Protocol, or defining a new interface between the Security Gateway and HNB management entities, to ensure accurate IP tunnel address and UDP port information is shared with the core network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HNB provides local IP address to core network, then resource reservation can be performed, but NAT devices will change the IP address and UDP port making the information inaccurate
Solution Approach 1:
The system performs preliminary detection of NAT devices during the IKEv2 setup phase before actual resource reservation. The HNB detects NAT traversal requirements and obtains public IP address and UDP port information in advance, so that when resource reservation is needed, the correct public addressing information is already available without requiring changes to the resource reservation process itself.
Solution Approach 2:
The core network acts as an intermediary that receives both the local IP address from HNB and the public IP address/UDP port information from the HNB or access network. This intermediary approach allows the system to maintain multiple address representations and use the appropriate one (public or local) depending on the communication direction and NAT presence, resolving the conflict between accuracy and simplicity.
2Loss of information
If HNB detects NAT devices using IKEv2 extension, then accurate public address information can be obtained, but the protocol complexity increases
Solution Approach 1:
The IKEv2 protocol extension is designed to serve multiple functions: it not only performs the traditional key exchange and security association establishment but also simultaneously detects NAT devices and exchanges public IP address and UDP port information. This multi-functionality reduces the need for separate detection mechanisms and consolidates address information gathering within the existing IKEv2 framework.
3Reliability
If new interface is defined between Security Gateway and HNB management entities, then NATed address information can be shared accurately, but system complexity increases
Solution Approach 1:
The new interface merges multiple information exchange functions into a single standardized communication path between the Security Gateway and HNB management entities. Instead of defining separate interfaces for address information, control signaling, and management data, the solution combines these functions into one integrated interface that handles NATed address information sharing along with other management operations.
Data Source
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Figure 3~4b
AI summary
A communication system is described in which a NATed IP address of a home base station is communicated to the home base station by a home base station gateway or a mobility management entity. In one embodiment, the gateway or the mobility management entity receives the NATed IP address from a security gateway that is used to establish a secure tunnel with the home base station through an IP network.