OpenAir Specifications and Reference Implementations OpenAir targets two network topologies, namely -
Cellular Networks : These networks are comprised of a higher-level network of basestations and mobile terminals. The basestations form a network whose interconnections make use of different physical resources (a combination of fixed and wireless) than those shared with the mobile terminals. If this network interface is wireless, it could be another instantiation of OpenAirInterface typically using the mesh network topologies. Mobile terminals do not dialog directly with each other, although they may potentially dialog with more than one basestation at a given instant in time. -
Clustered Mesh Networks: These are networks which are comprised of several clusterheads (light basestations) responsible for MAC and PHY layer resource allocation as well as providing local synchronization references for network synchronization. The mesh topology provides a means for rapidly deployable infrastructure for interconnection of secondary air interfaces, for example, OpenAirInterface Cellular ;-), WIFI, WiMAX, Tetra, etc.
Layer 1 Development The different modes of operation are reflected by the Layer 2 protocol stack which is attached to a particular configuration of the OpenAirInterface PHY. The basic configuration defines the physical layer structure (bandwidth, framing and modulation paramters, control channels, etc.) OpenAirInterface PHY resembles parts of the ongoing 3GPP LTE and 802.16e/m efforts. In contrast , however, the PHY is meant to be completely reconfigurable in order to be adapted to the different Layer 2 network topologies. The current PHY development focuses on reconfigurable low-latency MIMO/OFDMA (Orthogonal Frequency Division Multiple-Access) with rapid dynamic physical resource scheduling (time, frequency and spatial dimensions) controlled at the physical and medium-access layer interface. The PHY layer was adapted from the OFDMA PHY developped in the WIDENS (IST FP6) EU Project and Lao Tseu ANR (2004) French Project. OpenAirInterface PHY is bundled with our hardware device drivers on our SVN server under openair1. Documentation for the PHY specifications and reference implementation can be found here. Layer 2 Development The broadband mesh network Layer 2 development is a continuation of the work begun in the context of WIDENS. It is used in the CHORIST (ICT FP6) EU (www.chorist.eu) project as well as the AIRNET ANR (2006) projects. It will be used in the future HNPS (Celtic) project. The broadband cellular Layer 2 development is a continuation of the work begun in the context of the French ANR projects Lao Tseu (2004) and OPUS (2005). It is currently being used in the APOGEE ANR Project (2007). OpenAirInterface Layer 2 is bundled with our drivers for real-time emulation on ethernet networks Linux networking devices and PHY interfaces for openair1 on our SVN server under openair2. Documentation for the MAC specifications and reference implementation can be found here. Layer 3 Development The network interface rely on IP-based protocols for managing mobility and radio resources as well as packet-switched data at all protocol layers. For mesh networks we also make use of the MPLS (multi-packet label switching) protocol for QoS-aware relaying. The reference implementation is based on the open-source initiative MPLS-Linux. Proxy Mobile IPv6 is in charge of the Mobile Node management. | 
