Cross-layer protocol interactions (also known as interlayer protocol interactions), when used appropriately, can lead to increased network efficiency and better QoS support. In MANETs, cross-layer protocol interactions can be used to improve the routing mechanism or to provide service discovery support. Cross-layer design is particularly important for any network using wireless technologies, since the state of the physical medium can significantly vary over time. Layers can exchange information to make more optimal usage of the network.

In order to achieve interlayer protocol interaction, we modified the 802.11 MAC layer so that it provides various information about the state of the medium to higher layers. The modified MAC provides radio idle time, the links bandwidth, and the last rate used to transmit to neighbor nodes. The changes are implemented in the MADWIFI Linux driver of 802.11g cards based on Atheros 5212 chipset. The changes could be eventually ported to any other open-source 802.11 Linux driver. These modifications to the MAC will be used to perform cost-based routing.

Software:

• Modified MADWIFI driver for interlayer interaction

Papers:

• Y.Ge, T.Kunz, L.Lamont, "Quality of Service routing in ad-hoc networks using OLSR", The 36th Hawaii International Conference on System Sciences (HICSS-36), Hawaii, USA, January 2003.
  
  
• Y.Ge, T.Kunz, L.Lamont ,"Proactive QoS Routing in Ad-Hoc Networks", 2nd International Conference on Ad-Hoc Networks and Wireless, Montreal, Canada, October 8-10, 2003.