Spectrum Etiquette Rules for Shared and Unlicensed Bands

1. Spectrum Etiquette Rules for Shared and Unlicensed Bands Amer Hassan, Microsoft Jan Kruys, Cisco Jim Raab, Dell Stefan Mangold, Philips

2. Purpose • IEEE 802.18 SG1 is approaching the FCC with recommendations regarding the unlicensed use ofTV-bands and other fallow spectrum • A task group was formed in summer 2003 in the Wi-Fi Alliance to address spectrum sharing • Ensure license exempt spectrum usable with good user experience with the rapid increase of licensed exempt devices across all market segments & products • It is very important that such recommendations have a solid basis in research and modeling • Industry should provide the right direction to international regulators in this early stage of discussion • Simple sharing rules are discussed in the following

3. Space/Power Time Wireless LAN UWB Time beacon UMTS CDMA LW bdcst Frequency Information Solutions in Four Domains • Frequency, Space, Time, Information

4. Improving Receivers Filtering Modulation and Coding Antenna Diversity, MIMO Improving Transmitter Modulation & Coding Power Constraints Antenna Pattern Listen-before Talk (LBT) Sample spectrum etiquette rulesare discussed in the following … Improving Wireless System Power/Time constraints Frequency selection Feedback from the receiver Hybrid Methods Possible Solutions to Spectrum Etiquette

5. “Be Nice and Efficient” • Non-Greedy Occupancy • No user may occupy the channel with rate 0 (no data to send): RULE#1: A device shall only transmit when it has data to send • Channel Selection • A channel is deemed accessible at a node if the aggregate interference power at the intended receiver is less than ITH: RULE#2: A device shall only transmit on a channel if the aggregate interference power for that channel as measured at the intended receiver is less than ITH

6. RULE#1 Simulation Results (Out/Indoor) • average number of blocked nodes, as function of number of greedy nodes even 1 greedy node blocks the channel at an average of 4 nodes outdoors and 24 nodes indoors 10 of the nodes greedy blocks an average of 41% of the nodes outdoors and 98% indoors • number of nodes blocked at least 90% in time, as function of number of greedy nodes 10 of the nodes greedy blocks 33% of the nodes outdoors and 93% indoors at least 90% of the time a small fraction of greedy nodes can block channel access for the majority indoor outdoor indoor outdoor

7. With RULE#2 W/O RULE#2 RULE#2 Simulation Results  a new active link with RULE#2 results in a slight reduction in clear links compared to the background case a new active link w/o RULE#2 results in a more significant reduction in clear links compared to both the background and the RULE#2 cases • average number of clear (not blocked) links for four scenarios • Outdoor propagation model with low background interference • Outdoor propagation with high background interference • Indoor propagation with low background interference • Indoor propagation with high background interference For each scenario the average number of clear links is shown with background interference only, with new active link, with and w/o channel check (RULE#2)

8. Left: without etiquette, right: with etiquette Apparently, it would be beneficial to the broadband radio systems if the narrowband radio systems would select channels according to the etiquette Frequency Selection

9. Conclusions • It is important that we work together as industry to improve the usage of unlicensed spectrum • We demonstrated simple rules that significantly improve the usage of such spectrum • Thorough evaluation is already under way at 802.18 SG1 and Wi-Fi Alliance • Such evaluation is needed prior to approaching regulators