Link Adaptation Algorithm for the IEEE 802.11n MIMO System

The employment of Multi-Input Multi-Output (MIMO) technology leads the WLAN to a new stage high throughput (HT) WLAN, recently proposed in IEEE 802.11 TGn. The nature of multiple operation modes of MIMO has fundamentally changed the requirements for the MAC layer link adaptation (LA) process. The LA algorithms currently used in single input single output (SISO) WLANs are hardly effective for HT WLANs. We propose a cross-layer design for a MIMO LA algorithm which requires the MAC and the PHY to work proactively with each other to take full advantage of MIMO technologies adopted in 802.11n. The algorithm employs the channel state information (CSI) and operates in a ‘closed-loop’ manner. Simulations taken under various conditions validate our research. keywords: Link Adaptation, MIMO, 802.11n.