doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Overview of Draft Standard ] Date Submitted: [14 November 2001] Source: [James P. K. Gilb] Company: [Appairent Technologies] Address: [9921 Carmel Mountain Rd. #247, San Diego, 92129] Voice:[ ], FAX: [ ], 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 P 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 P

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Interoperability The standard had a goal of a level interoperability or coexistence with other standards – interoperability is not mandated –Evaluated as less than 50% cost increase to include compatibility.

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 bandwidth

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Interoperability (cont.) Differences –Different MAC –Different coding (TCM vs. Barker/CCK/PBCC) –Different channel center frequencies –Higher transmit power –In the US different regulations, vs

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Coexistence Potential for reduced throughput – DSSS and b – FHSS – No reduction in throughput –802.11a – IR – (?)

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Coexistence methods in 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

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Passive Scanning DEVs required to passively scan to join ACs required to passively scan for other piconets ACs will get a rated list of channels to choose from to start a piconet based on interference

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Dynamic Channel Selection The draft standard has procedure for changing piconet channels The PNC changes channels when conditions deteriorate This allows the piconet to detect and avoid other fixed-frequency networks and avoid them

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Channel plan TG3 asked for 4 simultaneous piconets However, each of the 2 center channels overlaps with b channels Thus, there is an b coexistence plan where the channels are aligned, so overlap is only one channel at a time (all in MHz)

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Lower transmit power operates under 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 rules –1 W, but is +14 to +18 dBm –Allows 6 dB antenna gain with no reduction in 1 W limit. Allows up to 36 dBm EIRP –Most APs have at > +3 dB gain antennas

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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.

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies Neighbor Piconet Capability Allows another DEV that supports a small subset of to request quiet time on the channel –Other network must be able to keep quiet as well b 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 as well. –Master would need to schedule transmissions –Some of this has been proposed to TG2.

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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.”

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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.)

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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 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 piconet, four of the methods that it may use to mitigate the interference between the two piconets are:

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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.”

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies 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.”

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies PHY Enhancement 1 Add to PHY section “A DEV may, in the course of a scan, change to an b channel for the purpose of detecting the presence of b 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.”

doc.: IEEE COEX-02/004r0 Submission 23 January, 2001 James P. K. Gilb, Appairent Technologies SCAN/START Enhancement, cont. 2 Add to PHY section “If a DEV is capable of identifying an b network and it does identify an b network while scanning, it should use the b coexistence channel set. It should also rate the channels where b networks were identified as the worst channels. If multiple b networks are detected, the DEV should order them based on an estimate of the amount of traffic and the power level in the channel.”