OBSS Simulations Date: 2009-04-16 Authors: April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 April 2009 OBSS Simulations Date: 2009-04-16 Authors: Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

April 2009 doc.: IEEE 802.11-09/0474r0 April 2009 Abstract We have performed some OBSS experiments using our 802.11 simulator. This presentation shows some of our results. Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

Simulation Parameters April 2009 doc.: IEEE 802.11-09/0474r0 April 2009 Simulation Parameters Home Detached house 8m x 5.5m x 4.8m, 2 floors, 4 rooms per floor Outer walls: 2 layers of Brick, Plaster Inner Walls: 2 sheets drywall* Floors: Wood, Plaster Distance between homes varied from 300m to 1m 802.11 parameters 1 AP and 5 stations per home, randomly placed 11bg mode, European regulatory channel & power rules, no TPC EDCA, no block ACK, no DLS 11n Channel model B + DARPA building material losses Video 2 x 3Mbps video, streamed using unicast UDP Full simulation from MAC upwards. At PHY, signal reception is simulated, not actual waveforms. *AKA: gypsum board, wallboard, plasterboard, gib, rock lath, Sheetrock, gyproc Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

100 m Overlapping Networks 100m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 April 2009 Overlapping Networks 100m 100 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

100 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 -82 dBm = 6mbps BPSK. CCA = -85 dBm 100 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

100 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 Slice through middle of buildings. Roughly independent networks 100 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

80 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 Start to reach CCA 80 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

60 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 Def CCA. Maybe a few frames receivable 60 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

40 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 Start to be able to pass signals 40 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

20 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 Almost one network. 20 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

1 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 One network Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

Adding More Homes & Channels April 2009 doc.: IEEE 802.11-09/0474r0 April 2009 Adding More Homes & Channels In the real world there is more than one channel (until 11n becomes widespread!). More than two homes. Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

100 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 “Optimal” channel selection that maximises distance between BSS on same channel. 100 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

100 m April 2009 April 2009 doc.: IEEE 802.11-09/0474r0 Not actually any different, just diagonal BSS overlap. 100 m Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

April 2009 80 m Alex Ashley, NDS Ltd

April 2009 60 m Alex Ashley, NDS Ltd

April 2009 40 m Alex Ashley, NDS Ltd

April 2009 20 m Alex Ashley, NDS Ltd

April 2009 1 m Alex Ashley, NDS Ltd

Frequent dropped packets April 2009 doc.: IEEE 802.11-09/0474r0 April 2009 Video Results Roughly 22 lost packets in 30 seconds. 1m Frequent dropped packets 300m No dropped packets Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

April 2009 doc.: IEEE 802.11-09/0474r0 April 2009 Conclusions If max transmit power is used, signals are above CCA threshold for a long range However, BSS need to be reasonably close before reliable information exchange possible Implies OBSS chains are more complex than “nodes with which communication is possible” Video streams take up a lot of air time However good our OBSS solution is, there is still a finite amount of capacity! Solving the ‘n’ overlap problem is probably only useful in theory, because we run out of capacity after 2 or 3 overlaps! Performance is worst in transition zone. Between to be very close or very far apart. Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

April 2009 References Safaai-Jazi A, et al, Ultra-wideband Propagation Measurements and Channel Modelling, DARPA NETEX Program, Report on “Through-the Wall Propagation and Material Characterization”, Virginia Polytechnique Institute and State University, Blacksburg, Virginia, USA, November 18 2002. 11n channel models - 11-03-0940r4 Alex Ashley, NDS Ltd