A cluster-chain-based context transfer mechanism for fast basic service set transition in the centralized wireless LAN architecture

The emergence of centralized WLAN architectures is proposed to solve the problems of large scale deployment of WLANs. In the centralized WLAN, access point (AP) is split into two pieces: wireless termination point (WTP), and access controller (AC). An AC is the centralized controller for a large number of WTPs. A station (STA) has the demand to move from one WTP to another within the same extended service set (ESS). Such behavior is called a basic service set (BSS) transition. In this paper, we propose the cluster-chain-based context (C3T) mechanism with a cluster member selection (CMS) algorithm to reduce the BSS transition delay in the centralized WLAN architecture. The proposed mechanism can have lower signaling cost for context transfer and does not have the ping-pong problem comparing with the existing context transfer schemes in terms of BSS transition, such as the proactive neighbor caching (PNC) scheme, the configuration and provisioning for wireless APs handoff protocol (CAPWAPHP), and so on. Furthermore, since the original 802.11r fast BSS transition does not specify how to work in the centralized WLAN architecture, we incorporate the C3T mechanism into IEEE 802.11r that works in the centralized WLAN architecture.