1. Coexistence Analysis for the 2.4 GHz ISM band Srikanth Gummadi, Sean Coffey, Chris Heegard Home and Office Networking Group, Santa Rosa, CA Kofi Anim-Appiah, Anuj Batra, Matthew B. Shoemake DSP Solutions R&D, Dallas, TX Oren Eliezer Short Distance Wireless Group, Israel Texas Instruments Incorporated Gummadi, et al; Texas Instruments

2. Outline • Introduction • Simulation Parameters • SIR requirements for coexistence • Performance loss due to interference in AWGN • Conclusions Gummadi, et al; Texas Instruments

3. Introduction • Coexistence • “To exist together, at the same time, or in the same place” • “To live in peace with another or others despite differences, especially as a matter of policy” • Study of coexistence naturally suggests the following questions: • Q1: How much interference can you withstand? • Q2: How much interference do you cause? Gummadi, et al; Texas Instruments

4. Time of Arrival for Interferer • Either, the interferer is on the air before a packet is transmitted: • Receiver has knowledge of interference • Interference cancellation techniques can be used • Or, the interferer starts during the payload section of packet • Receiver has no knowledge of interference • Worst case scenario Gummadi, et al; Texas Instruments

5. Interference Only • Simulation parameters: • Receiver has no knowledge of the interferer • No multipath • No noise • Packet Length • 802.11 systems: 1000 bytes • Bluetooth: DM1/DH1 packet (366 bits) • Performance criteria: • SIR (in dB) required to achieve a PER of 10-2 Gummadi, et al; Texas Instruments

6. Comparison Matrix – No Noise Comparison Matrix – No Noise Comparison Matrix – No Noise Table shows Signal to Interferer ratio (SIR) in decibels (dB) required for the signal to meet the performance criteria. Gummadi, et al; Texas Instruments

7. Peak-to-Average Dominates • Interference from PBCC-22 and current Wi-Fi systems have similar effect • OFDM-24 is similar to that of AWGN, which is the worse • PBCC-22 outperforms OFDM-24 in all conditions Gummadi, et al; Texas Instruments

8. Interference on Bluetooth • Interference from PBCC-22 and current Wi-Fi systems have similar effect • OFDM-24 is a worse interferer on Bluetooth, since it very much resembles AWGN Gummadi, et al; Texas Instruments

9. Interference on current Wi-Fi Systems • PBCC-22 causes similar interference as current Wi-Fi systems • OFDM-24 is a worse interferer on current Wi-Fi systems Gummadi, et al; Texas Instruments

10. Interference With Noise • Simulation conditions: • Receiver has no knowledge of the interferer • No multipath • SIR is fixed • Packet Length • 802.11 systems: 1000 bytes • BT: DM1/DH1 (366 bits) • Loss in SNR (in dB) from the AWGN case to achieve a PER of 10-2 • Loss in SNR = SNRfixed SIR - SNRAWGN Gummadi, et al; Texas Instruments

11. Loss in SNR with SIR = 15 dB Gummadi, et al; Texas Instruments

12. Loss in SNR with SIR = 10 dB Gummadi, et al; Texas Instruments

13. Interference From BT • Bluetooth signal has a 20dB bandwidth of 1MHz. • Bluetooth hops over 79 1-MHz wide channels in the 2.4GHz band. Gummadi, et al; Texas Instruments

14. Interference From BT • Bandwidth required to capture 90% Power: • PBCC22: 12.0 MHz • OFDM24: 15.1 MHz  OFDM gets hits 25% more Gummadi, et al; Texas Instruments

15. Conclusion • PBCC is more robust than OFDM: • Withstands 6 dB more interference from BT • Withstands 2 dB more interference from current Wi-Fi systems • PBCC causes the same interference as 802.11b: • Coexists with current Wi-Fi systems • Same effect on BT as current systems • OFDM is a worse interferer: Similar to AWGN Gummadi, et al; Texas Instruments