Range & Rate of CCK-OFDM November 2001 Range & Rate of CCK-OFDM Steve Halford Jim Zyren Mark Webster Intersil Corporation Palm Bay, FL S.Halford, Intersil Corporation

Does PBCC-22 add value to CCK-OFDM? November 2001 Does PBCC-22 add value to CCK-OFDM? NO! Incomplete comparisons made in 11-01-477r1 Ignores optional modes of CCK-OFDM (18 Mbps) Uses unexplained modes of PBCC (49 & 66 Mbps) Incorrect noise bandwidth values used in 11-01-286r1 11-01-286r1: Penalized OFDM by > 7 dB Corrected in 11-01-286r2 but never presented S.Halford, Intersil Corporation

May 2000 doc.: IEEE 802.11-00/xxx November 2001 Range Calculations Note that PBCC and CCK/Barker use a single carrier so the number of subcarriers is equal to one. For comparison -- only these values will differ between CCK, OFDM, and PBCC S.Halford, Intersil Corporation M. Webster and K. Halford, Intersil Corp

Path Loss Model Selected ITU-RP.1238 model Model May 2000 doc.: IEEE 802.11-00/xxx November 2001 Path Loss Model Selected ITU-RP.1238 model See 802.15.2 Doc. 00-294r1 or 802.11 Doc. 11-01-339r0 Model used by 11-01-286r2 assumes 8m of free space propagation Seems unreasonable for W-LAN environment Model selection has minor impact on conclusions Model The loss exponent of 3.6 (36) was selected to make CCK-11 range match the Intersil measured range of 120 feet (36 meters) at 5 % PER. S.Halford, Intersil Corporation M. Webster and K. Halford, Intersil Corp

Range Equation Simplified November 2001 Range Equation Simplified Distance (in m) as a function of SNR required to meet a given packet error rate S.Halford, Intersil Corporation

SNR per subcarrier (at MF output) May 2000 doc.: IEEE 802.11-00/xxx November 2001 SNR as a function of PER Waveform Data Rate (Mbps) SNR per subcarrier (at MF output) in dB SNR(.01) 1% PER SNR(.05) 5% PER SNR(.10) 10% PER Barker 1 11.1 10.5 10.25 2 15.9 15.3 14.7 CCK 5.5 5.7 5.0 4.8 11 8.6 8.0 7.0 PBCC 1.9 1.5 1.2 4.4 4.1 22 9.0 8.5 8.3 OFDM 6 0.8 0.6 9 3.8 3.4 3.1 12 3.5 18 6.4 6.1 24 10.1 9.4 9.1 36 13.1 12.7 12.4 48 17.7 16.9 16.5 54 19.0 18.3 18..0 S.Halford, Intersil Corporation M. Webster and K. Halford, Intersil Corp

Throughput Calculations November 2001 Throughput Calculations Use Maximum Sustainable Throughput (Rmax) as basis Defined by 11-01-007 (see also 11-01-059) Consider the following case IEEE 802.11b short preamble with 1000 byte packets Acknowledgement packets of 14 bytes at same rate as data No access backoff (DIFS only between ACK & subsequent packets) Modify the throughput to account for re-transmissions Same procedure as followed by 11-01-286r2 Adjusts the throughput based on average # of retransmissions for a given Same formula for all waveforms S.Halford, Intersil Corporation

Throughput with Re-transmission May 2000 doc.: IEEE 802.11-00/xxx November 2001 Throughput with Re-transmission Waveform Data Rate (Mbps) Throughput (Mbps) Rmax R(0) 1% PER R(.01) 5% PER R(.05) 10% PER R(.10) Barker 1 0.96 0.95 0.91 0.86 2 1.86 1.84 1.76 1.67 CCK/PBCC 5.5 4.63 4.59 4.40 4.17 11 8.09 8.00 7.68 7.28 PBCC 22 12.89 12.76 12.24 11.60 OFDM 6 4.87 4.82 4.62 4.38 9 6.69 6.62 6.35 6.02 12 8.26 8.18 7.85 7.44 18 10.75 10.65 10.22 9.68 24 12.66 12.53 12.03 11.39 36 15.50 15.35 14.73 13.95 48 17.39 17.22 16.52 15.65 54 18.02 17.84 17.11 16.22 Sources: IEEE Document 802.11-01-059r0 S.Halford, Intersil Corporation M. Webster and K. Halford, Intersil Corp

TGg Range & Rate for PER = 0.05 May 2000 doc.: IEEE 802.11-00/xxx November 2001 TGg Range & Rate for PER = 0.05 Waveform Rate Range (meters) Throughput (Mbps) CCK 11 35 7.5 PBCC 22 34 12.0 OFDM 18 10.0 24 29 36 23 14.5 48 16.5 54 16 17.0 Sources: IEEE Document 802.11-01-059r0 S.Halford, Intersil Corporation M. Webster and K. Halford, Intersil Corp

TGg Range & Rate for PER = 0.05 May 2000 doc.: IEEE 802.11-00/xxx November 2001 TGg Range & Rate for PER = 0.05 In theory, a W-LAN system with PBCC-22 might get 2 Mbps higher throughput for this 5 meter region. For all other regions, CCK-OFDM has equivalent or superior throughput Sources: IEEE Document 802.11-01-059r0 S.Halford, Intersil Corporation M. Webster and K. Halford, Intersil Corp

Conclusions from Range vs. Rate November 2001 Conclusions from Range vs. Rate CCK-OFDM offers superior throughput for nearly all ranges PBCC proposal offers a small throughput advantage over a very limited range under ideal conditions Optional 802.11a mode offers vastly superior throughput for the 2.4 GHz band Much better than the extended (>22 Mbps) PBCC This is undisputed! See 11-01-339r0 & 11-01-286r2 PBCC team recognized this advantage & added the same optional mode S.Halford, Intersil Corporation

Would adding PBCC-22 as Tx-only requirement make sense? November 2001 Would adding PBCC-22 as Tx-only requirement make sense? No! MAC issues How to handle broadcast? Market confusion due to adding a third waveform Violates the spirit of the PAR req’ment for single high rate waveform No real throughput improvement in PBCC-22 mode Burden the standard with unnecessary IP Scramble sequence has no demonstrated value Questions remain about other codes with same performance Increased complexity to any TGg product Add gates (& IP) in order to transmit PBCC-22 More modes to test and debug S.Halford, Intersil Corporation