n Spread Spectrum LANs use RF bands that are allocated to wireless nets by FCC, signal is spread by transmitting a chirp pattern, receiver accepts signals it can decode. RF-noisy environment.
 nWireless LANs topologies - see Figure 6.5 
 n1. Peer Level System: Each
 unit communicated with every
 other unit. Low cost and no master control needed.  Breaks
 down as traffic grows.
 n2. Centrally Controlled
 System (client-server): Central
 controller is linked to a wired LAN. Control
 unit handles all communications, and has centralized network management and access control.