This section deals with ATM layer issues. Address resolution is discussed in Section 5. This section is concerned with a static wireless environment, i.e. assuming no handoffs take place. ATM signaling, routing, and maintaining cell order are some of the critical areas that will be affected by mobility. All of these issues are related to the mechanism used for handoff of an RN from one EN to another which is considered in Section 10. The protocol on the ES will remove ATM cells from the HDLC-like frames and switch them to the proper port. It will also pack ATM cells into an HDLC-like frame to send to the radio. Figure 9 shows the Linux environment on the RN. Note that dashed boxes represent code that has not yet been developed. The ATM Device Driver API and HDLC-like Driver are detailed in Figures 5 and 6.
A detailed view of the proposed software archecture for the ES is shown in Figure 10. There is one Packet Radio driver for the antenna with multple ES Adaptive drivers, one per RN. The ATM Microswitch is shown in the middle of the ES. The Microswitch performs software ATM cell switching. Note that an ES connecting a wireless EN-EN will only have a single ES Adaptive driver and will contain a special version of the ATM Microswitch which will simply pass through ATM cells. In this case the ES-ES link would require a directly connected ATM switch.
Figure 9: RN Linux ATM Protocol Stack.
Figure 10: Detailed view of Edge Switch Connection to Remote Node.