doc.: ieee coex-02/004r0 submission 23 january, 2001 james p. k. gilb, appairent technologies...
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doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Interoperability enables low-cost dual-mode radios that could support and serially –Same symbol (chip) rate and accuracy –Essentially same channels and frequency accuracy –Same modulation (DQPSK) for base rate –Similar TX PSD and RX bandwidthTRANSCRIPT
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)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:[[email protected]]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.
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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 (?)
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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 24422462 2461
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.”
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.)
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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:
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.”
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.”
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.”
23 January, 2001
James P. K. Gilb, Appairent Technologies
doc.: IEEE COEX-02/004r0
Submission
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.”