WLAN Roaming Handover via Access Controller Mobility Information
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current WLAN roaming technologies, such as IAPP and MIP, face challenges in enabling seamless mobility across different ESSes and subnets, leading to handover delays and packet loss, especially in centralized network architectures where Layer 3 isolation hampers effective mobile agent discovery.
Innovation Solution
A method and system that determine whether roaming is inter-IP subnet or intra-IP subnet roaming based on mobility information, performing MIP-based handovers for inter-subnet roaming and IAPP-based handovers for intra-subnet roaming, with an Access Controller and Access Point device configuration that manages mobility information and handovers efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MIP technology is used for inter-network roaming between different ESSes, then mobile terminal can roam between different IP segments, but handover delay and packet loss increase
Solution Approach 1:
The patent performs preliminary actions by establishing tunnel connections between access controllers in advance before handover occurs. The mobility information is pre-collected and stored, including IP addresses of access controllers and AP devices. When handover is needed, the tunnel is already in place, eliminating the time-consuming process of establishing connections during actual handover, thus reducing handover delay while maintaining roaming capability between different ESSes
2Adaptability or versatility
If MIP technology is used for inter-network roaming, then mobile terminal can roam between different IP segments, but packet loss increases
Solution Approach 1:
The patent introduces tunnel connections as intermediary channels between access controllers for different ESSes. Instead of direct communication that may cause packet loss during handover, the tunnel acts as a stable intermediary pathway that forwards packets reliably. The tunnel encapsulates and transports data packets between the mobile terminal's previous and new access points, ensuring no packet loss during the handover process while enabling roaming between different IP segments
3Productivity
If IAPP protocol is used for intra-network roaming within one ESS, then handover is efficient, but mobile terminal cannot roam between different ESSes
Solution Approach 1:
The patent creates a universal handover mechanism that combines the efficiency of IAPP protocol for intra-ESS roaming with the inter-ESS roaming capability of MIP technology. The system determines whether roaming is within the same ESS or across different ESSes, and applies the appropriate protocol: IAPP for efficient intra-ESS handovers and MIP with tunnel establishment for inter-ESS roaming. This multi-functional approach maintains high handover efficiency while extending roaming capability to different ESSes
4Ease of operation
If centralized WLAN architecture is used with AC controlling WTP devices, then network management is improved, but Layer 3 isolation hampers mobile agent discovery
Solution Approach 1:
The patent uses the access controller as an intermediary that bridges the Layer 3 isolation in centralized WLAN architecture. The AC collects mobility information from WTP devices and maintains a unified view of mobile terminal locations across different ESSes. This intermediary role allows mobile agent discovery to function effectively despite Layer 3 isolation, as the AC can query and share mobility information between different network segments while maintaining centralized network management
Data Source
AI summary
A roaming method for a mobile terminal in a wireless local area network is disclosed. In the method, a target access point (AP) device receives an access request for roaming from the mobile terminal, and a target access controller (AC) obtains mobility information of the mobile terminal in an original extended service set based on the access request, wherein the mobility information include information of an AP device, an AC and a mobile agent server associated with the mobile terminal. Then the target AC determines whether the roaming for the mobile terminal is an inter-IP subnet roaming or an intra-IP subnet roaming based on the obtained mobility information. The target AC performs mobile IP based handover when the roaming is determined as the inter-IP subnet roaming and performs Inter Access Point Protocol based handover when the roaming is determined as the intra-IP subnet roaming.