Wireless MAN Neil Tang 10/03/2008 CS440 Computer Networks

Outline Basic Architecture Physical Properties MAC Protocol CS440 Computer Networks

WMAN Basic Architecture: Point-to-Multipoint (PMP) mode and mesh mode MAC Protocol: TDMA/FDMA(OFDMA) CS440 Computer Networks

Basic Architecture CS440 Computer Networks

Physical Properties Encoding & Modulation: OFDM (Orthogonal Frequency Division Multiplexing). Spectrum: 2-11GHz (Licensed, non-LOS), 11-66GHz (Free, LOS). Maximum Data Rate: 131Mbps. Transmission Range: 30 miles. Several miles in practice. CS440 Computer Networks

MAC Protocol Control sub-frames are partitioned into slots of fixed duration (control slots). Data sub-frames consist of a fixed number of data mini-slots. The control slot is accessed in a contention-based fashion. A WiMAX-based mesh network can employ up to 16 multiple non-overlapping channels for data transmission. CS440 Computer Networks

MAC Protocol Centralized scheduling using the MSH-CSCH message. Distributed scheduling using the MSH-DSCH message. CS440 Computer Networks

MAC Protocol Collision-Free Scheduling CS440 Computer Networks

MAC Protocol A general framework for link scheduling: In the first phase, the links are labeled, and in the second phase, the links are scheduled one by one based on their labels. The scheduling problem is equivalent to the problem of finding a valid node coloring in the contention graph. The hidden and exposed terminal problems are resolved. CS440 Computer Networks