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Overview of IEEE 802.15.3 Coexistence Methods

This submission provides an overview of the coexistence capabilities outlined in the TG3 draft standard, addressing key methods such as passive scanning, dynamic channel selection, and link quality assessment. It examines interoperability with 802.15.1 and 802.11, discussing potential impacts on throughput and power control strategies. The document also delves into neighbor piconet capabilities and channel planning considerations to minimize interference in wireless personal area networks (WPANs).

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Overview of IEEE 802.15.3 Coexistence Methods

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Overview of Draft Standard 802.15.3] Date Submitted: [14 November 2001] Source: [James P. K. Gilb] Company: [Appairent Technologies] Address: [9921 Carmel Mountain Rd. #247, San Diego, 92129] Voice:[1-858-538-3903], FAX: [1-858538-3903], E-Mail:[gilb@ieee.org] Re: [] Abstract: [An overview of the coexistence capabilities of the TG3 draft standard.] Purpose: [To summarize the coexistence methods in the TG3 draft standard.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. James P. K. Gilb, Appairent Technologies

  2. 802.15.1 Interoperability • The 802.15.3 standard had a goal of a level interoperability or coexistence with other 802.15 standards • 802.15.1 interoperability is not mandated • Evaluated as less than 50% cost increase to include 802.15.1 compatibility. James P. K. Gilb, Appairent Technologies

  3. 802.11 Interoperability • 802.15.3 enables low-cost dual-mode radios that could support 802.11and 802.15.3 serially • Same symbol (chip) rate and accuracy • Essentially same channels and frequency accuracy • Same modulation (DQPSK) for base rate • Similar TX PSD and RX bandwidth James P. K. Gilb, Appairent Technologies

  4. 802.11 Interoperability (cont.) • Differences • Different MAC • Different coding (TCM vs. Barker/CCK/PBCC) • Different channel center frequencies • Higher transmit power • In the US different regulations, 15.247 vs. 15.249 James P. K. Gilb, Appairent Technologies

  5. Coexistence • Potential for reduced throughput • 802.11 DSSS and 802.11b • 802.11 FHSS • 802.15.1 • No reduction in throughput • 802.11a • 802.11 IR • 802.16 (?) James P. K. Gilb, Appairent Technologies

  6. Coexistence methods in 802.15.3 • Passive scanning • Dynamic channel selection • The ability to request channel quality information • Link quality and RSSI • A channel plan that minimizes channel overlap • Lower transmit power • Transmit power control • Neighbor piconet capability James P. K. Gilb, Appairent Technologies

  7. Passive Scanning • DEVs required to passively scan to join • ACs required to passively scan for other 802.15.3 piconets • ACs will get a rated list of channels to choose from to start a piconet based on interference James P. K. Gilb, Appairent Technologies

  8. Dynamic Channel Selection • The draft standard has procedure for changing piconet channels • The PNC changes channels when conditions deteriorate • This allows the 802.15.3 piconet to detect and avoid other fixed-frequency networks and avoid them James P. K. Gilb, Appairent Technologies

  9. Channel Status Request • All DEVs can request information on the status of the channel • This includes • TX frames • RX frames • RX frames errors • RX frames loss James P. K. Gilb, Appairent Technologies

  10. Link quality and RSSI • The PHY supports both RSSI and LQI • LQI (link quality indication) indicates the SNR measured at the decision point • Gives estimate of how good the signal is • Combined LQI and RSSI can identify inteference • High RSSI with low LQI indicates interferer James P. K. Gilb, Appairent Technologies

  11. Channel plan • TG3 asked for 4 simultaneous piconets • However, each of the 2 center channels overlaps with 2 802.11b channels • Thus, there is an 802.11b coexistence plan where the channels are aligned, so overlap is only one channel at a time. 802.11 802.15 (all in MHz) 2412 2412 2437 2442 2462 2461 James P. K. Gilb, Appairent Technologies

  12. Lower transmit power • 802.15.3 operates under 15.249 rules • 50 uV/m at 3 m in 1 MHz bandwidth • Roughly +8 dBm maximum power with current PSD. • Power scales directly with antenna gain • 15.247 rules • 1 W, but 802.11 is +14 to +18 dBm • Allows 6 dB antenna gain with no reduction in 1 W limit. Allows up to 36 dBm EIRP • Most 802.11 APs have at > +3 dB gain antennas James P. K. Gilb, Appairent Technologies

  13. Transmit power control • PNC can set the maximum TX power in the CAP and beacon • Down to +4 dBm in current draft • DEVs can control power in a GTS of the remote DEV • Give up/down power control commands • Individual DEVs can choose to change TX power • Channel status, LQI and RSSI help to make these decisions. James P. K. Gilb, Appairent Technologies

  14. Neighbor Piconet Capability • Allows another DEV that supports a small subset of 802.15.3 to request quiet time on the channel • Other network must be able to keep quiet as well. • 802.11b AP has PHY capable of doing this • Would need additions to the MAC • Not currently available, but a dual mode AP would be possible with minor cost impact. • Could be implemented in 802.15.1 as well. • Master would need to schedule transmissions • Some of this has been proposed to TG2. James P. K. Gilb, Appairent Technologies

  15. SCAN/START Enhancement • Add to scan procedure: “If a DEV is looking to start a new piconet, then it should also look for potential interference in the channels that it scans and rate the channels, from best (lowest interference) to worst (highest interference) and return this information in the MLME-SCAN.confirm command via the ChannelRating. The DEV should choose to start the piconet in the channel with the least amount of interference in the channel.” James P. K. Gilb, Appairent Technologies

  16. SCAN/START Enhancement (cont.) • Add to MLME-SCAN a parameter, Channel Rating, type integer, valid range 0-255, that rates channels, 1 through N from “best” to “worst”, 1 is the best channel (i.e. least interference) while N is the worst channel, (i.e. the most interference.) James P. K. Gilb, Appairent Technologies

  17. Add to Dynamic channel selection • 8.12 Add a paragraph “The PNC should periodically listen in the current channel to detect interference, the presence of other 802.15.3 piconets or the presence of other wireless networks. The PNC should also periodically listen to other overlapping channels for the presence of the same types of devices. If the PNC detects the presence of another 802.15.3 piconet, four of the methods that it may use to mitigate the interference between the two piconets are: James P. K. Gilb, Appairent Technologies

  18. Add to Dynamic channel selection, 2 “1. The PNC may join the other piconet to form a child piconet. 2. The PNC may ask the other piconet to form a neighbor network. 3. The PNC may change channels to one that is unoccupied. 4. The PNC may reduce the maximum transmit power in the piconet.” James P. K. Gilb, Appairent Technologies

  19. Add to Dynamic channel selection, 3 “If the PNC determines that there is either an interferer or another wireless network operating in the channel or overlapping with the current channel, two of the methods that the PNC may mitigate the interference are: 1. The PNC may change channels to one that is unoccupied. 2. The PNC may reduce the maximum transmit power in the piconet.” James P. K. Gilb, Appairent Technologies

  20. PHY Enhancement 1 • Add to PHY section 11.2.3 “A DEV may, in the course of a scan, change to an 802.11b channel for the purpose of detecting the presence of 802.11b networks. When a DEV is scanning to start a piconet, it should scan all 5 channels to decrease the probability of chosing an occupied channel.” James P. K. Gilb, Appairent Technologies

  21. SCAN/START Enhancement, cont. 2 • Add to PHY section 11.2.3 “If a DEV is capable of identifying an 802.11b network and it does identify an 802.11b network while scanning, it should use the 802.11b coexistence channel set. It should also rate the channels where 802.11b networks were identified as the worst channels. If multiple 802.11b networks are detected, the DEV should order them based on an estimate of the amount of traffic and the power level in the channel.” James P. K. Gilb, Appairent Technologies

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