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Wireless MAN Neil Tang 10/03/2008. Outline. Basic Architecture Physical Properties MAC Protocol. WMAN. Basic Architecture: Point-to-Multipoint (PMP) mode and mesh mode MAC Protocol: TDMA/FDMA(OFDMA). Basic Architecture. Physical Properties.
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Wireless MANNeil Tang10/03/2008 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