Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [IEEE 802.15.4 Performance In Heavily Loaded Mixed Protocol Environments] Date Submitted: [17 March, 2014] Source: [Tim Harrington] Company [Zebra] Address [2940 North first Street, San Jose, CA 95033] Voice:[408-473-8513], FAX: [], E-Mail:[Timothy.Harrington@verizon.net] Abstract: [IEEE 802.15.4 Performance In Heavily Loaded Mixed Protocol Environments] Purpose: [Informative.] 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. Tim Harrington (Zebra)

2. IEEE 802.15.4 Performance In Heavily Loaded Mixed Protocol Environments Tim Harrington (Zebra)

3. Non-FH Mixed Protocol Environments • Many LBT protocols use CSMA that look for other “like” users • ETSI 300 328 v1.8.1 specifies Energy Detect Instead of Carrier Sense • IEEE 802.11 and other hi-data rate devices appear to have superior access over 802.15.4 when using current LBT CSMA CCA in heavily loaded environments Tim Harrington (Zebra)

4. Studying the Coexistence of Dissimilar and Competing Wireless Networks • The Following Results Are Excerpts From a Study Funded by the Industry Automation Group In EU Using COMB Tool Developed By: • Alessia Autolitano • Massimo Reineri • Riccardo M. Scopigno • From Istituto Superiore Mario Boella, Torino, Italy • The Results are From MAC simulations • A Complete Paper Presenting COMB is to appear in IEEE IWCMC 2014, Cyprus Tim Harrington (Zebra)

5. Protocols Included in Funded Study Tim Harrington (Zebra) Slide 5

6. Interfering Wireless Technologies WiFi Channel 7 selected (2440 MHz) 22MHz BT: 22 overlapping channel over 79 for WiFi 4 over ZigBee ZigBee: 16 5Mhz-spaced and 3,5MHz-wide channels in the 2.4 Ghz. Channel 8 (2440) Tim Harrington (Zebra) Slide 6

7. 5 Significant Conclusions • FH techniques work fine with other FH techniques • BT1.2 AFH & BT1.2 non-AFH (sc.1) • BT1.2 AFH & BT 1.2 non-AFH & BT1.2 with ED (sc.17) • FH techniques work fine with non-FH DAA techniques… • BT1.2 non-AFH/AFH & nonFH-Frame_based_LBT-DAA (sc. 3,7) • BT1.2 non-AFH/AFH/ED & IEEE 802.15.4 (sc. 4,8,10) • BT1.2 non-AFH/AFH/ED & IEEE 802.11b (sc. 5,9,11) • But with a significant exception of FH & non-LBT non-FH DAA • BT1.2 non-AFH/AFH & nonFH-nonLBT-DAA (sc. 2,6) • All the non-FH techniques seem to exhibit mutual coexistence problems • IEEE 802.11b is voracious over slower LBTs (IEEE 802.15.4) (sc.16)… even worse with IEEE 802.11g (results available) • IEEE 802.11b corrupts slotted methods (sc. 15) • nonFH-nonLBT_DAA gets always penalized (sc. 13-14) • When all the MACs are together, it is a mess (sc. 18) Tim Harrington (Zebra) Slide 7

8. All the non-FH techniques seem to meet problems in their mutual coexistence IEEE 802.11b is voracious over slower LBTs (IEEE 802.15.4) (sc.16)… even worse with IEEE 802.11g (results available) Statement 4 – Scenario 16 11b’s occupancy drops from ~65% to 40% 15.4’s one drops from ~70% to less than 25% At 60% traffic 11b almost unaffected. 50% loss at 70% with 15.4 and at 120% with 11b Tim Harrington (Zebra) Slide 8

9. When several different MACs are together, it is a mess (sc. 18) Statement 5 Scenario 18 Tim Harrington (Zebra) Slide 9

10. EN 300 328 v 1.8.1 LBT • Specifies using Energy Detect for LBT • energy detect: mechanism used by an LBT based adaptive equipment to determine the presence of other devices operating on the channel based on detecting the signal level of that other device • Frame Based Equipment shall comply with the following requirements: • 1) Before transmission, the equipment shall perform a Clear Channel Assessment (CCA) check using energy detect. The equipment shall observe the operating channel for the duration of the CCA observation time which shall be not less than 20 µs. The channel shall be considered occupied if the energy level in the channel exceeds the threshold given in step 5) below. If the equipment finds the channel to be clear, it may transmit immediately. • 5) The energy detection threshold for the CCA shall be proportional to the transmit power of the transmitter: for a 20 dBm e.i.r.p. transmitter the CCA threshold level (TL) shall be equal or lower than -70 dBm/MHz at the input to the receiver (assuming a 0 dBi receive antenna). For power levels below 20 dBm e.i.r.p. the CCA threshold level may be relaxed to TL = -70 dBm/MHz + (20 dBm - Pout e.i.r.p.)/1 MHz (Pout in dBm). Tim Harrington (Zebra)

11. There Are Options In 802.15.4-2011: • 8.2.7 Clear channel assessment (CCA)The PHY shall provide the capability to perform CCA according to at least one of the following methods:— CCA Mode 1: Energy above threshold. CCA shall report a busy medium upon detecting any energy above the ED threshold.— CCA Mode 2: Carrier sense only. CCA shall report a busy medium only upon the detection of a signal compliant with this standard with the same modulation and spreading characteristics of the PHY that is currently in use by the device. This signal may be above or below the ED threshold.— CCA Mode 3: Carrier sense with energy above threshold. CCA shall report a busy medium using a logical combination of: — Detection of a signal with the modulation and spreading characteristics of this standard, and — Energy above the ED threshold, where the logical operator may be AND or OR.— CCA Mode 4: ALOHA. CCA shall always report an idle medium.— CCA Modes 5 and 6 address UWB: Not relevant to this discussion. Tim Harrington (Zebra)

12. Additional Excerpt From 802.15.4:2011 • For any of the CCA modes, if a request to perform CCA is received by the PHY during reception of a PPDU, CCA shall report a busy medium. PPDU reception is considered to be in progress following detection of the SFD, and it remains in progress until the number of octets specified by the decoded PHR has been received.The PHY PIB attribute phyCCAMode, as described in 9.3, shall indicate the appropriate operation mode. The CCA parameters are subject to the following criteria:a) The ED threshold shall correspond to a received signal power of at most 10 dB greater than the specified receiver sensitivity for that PHY.b) The CCA detection time shall be equal to 8 symbol periods or hyCCADuration symbol periods for the 950 MHz band PHY.For the 950 MHz band, if channel 14 is supported, CCA shall be performed on channel 13 and channel 14. If channel 17 is supported, CCA shall be performed on channel 16 and channel 17 (English translation ofARIB STD-T96 [B6]). Tim Harrington (Zebra)

13. Possible Next Steps • Update ED mechanism and value during SC-M to optimize performance with regard to FCC, ETSI 300 328 v1.81 (v1.9.1 draft) and ETSI 300 220 • Question: Will Steps In This direction Cause an Unending Technology Race? • No ETSI Regs Provide a Bottom Limit • Create Interest Group (IG) to investigate optimized energy detect protocol Tim Harrington (Zebra)