Dear Jon & Geoff, Thank you very much for such a nice and detail mail.... It helped me a lot. I want to add few comments regarding this issues, after my little research in this field.
1. Even thr are some free channels available for different region, but still creating problem for IEEE802.15.4 traffic. Actually, high power of wifi is killing ieee802.15.4 traffic (testbed results). 2. The current research on this issue is interestingly biased, some are saying its not a big problem (e.g ZigBee Alliance) and others (e.g. Z-Wave Alliance) are saying its a big issue. 3. Distance between ieee802.15.4 and ieee802.11x is a big problem in this case. If I summarize all the research efforts (ieee802.19 coexistence assurance documents, white paper(ZigBee, Z-Wave) and many research papers), its not possible that 15.4 & 11x stay together in a distance of <2 meters (even tried with offset 20MHz). 4. thr are many potential application require this distance to be in few centimeters. May be some technique in upper layers can give little bit reliability... but is it enough??? I am looking for some help, comments and suggestion, how coexistence problem can be solved for very short distance scenario... Thank you....... Regards M. Hasan On Mon, Jul 14, 2008 at 5:54 PM, Adams Jon <[EMAIL PROTECTED]> wrote: > Good afternoon, Hasan (and Geoff) > > Appendix e does discuss a number of mitigation factors designed into > 802.15.4 to improve its ability to coexist with other 802 as well as a > narrow class of known interferers. Two important features are the > non-alignment of of 802.11 channels with that of 802.15.4 channels in > the 2400MHz band. This in theory allows an 802.15.4 station to operate > away from a given 802.11 station in the immediate vicinity and even > provides (in many regulatory domains) a few 15.4 channels that are > completely clear of 802.11 channels. The other is the temporal agility > of the 15.4 radio and the brevity of conversations (low duty cycle)- the > fact that clear channel assessment and an entire 802.15.4 conversation > (data transmission and acknowledgement) can occur in a few milliseconds. > This means that 802.15.4 transceivers can take advantage of small gaps > in conversations taking place between 802.11 equipment, the off times > for consumer microwave ovens, etc. > > There is a real issue with 802.11n in 40MHz channels, one that was not > perceived long ago. As it is described right now, the expectation by a > number of 802.11 voters is to allow 2 channels of non-overlapping > 40MHz-wide operation in the US 2400-2483.5MHz band (and likely in other > regions/countries as well). If there is agreement on this, there will be > locations (likely many) where both 40MHz channels are occupied and used > intensively. With two heavily loaded 11n channels and a number of hidden > transmitters, it may prove difficult for 802.15.4 stations to compete > successfully as there will be NO clear channels and only the temporal > agility of the 15.4 radio gives it a chance to communicate. > > Sincerely, Jon > > Jon Adams > Business Development, Wireless Connectivity Operation > Freescale Semiconductor > 2100 E Elliot Rd MD EL 542 > Tempe, AZ 85284 > +1 480.628.6686 mobile > +1 480.413.3439 office > [EMAIL PROTECTED] > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Geoff Mulligan > Sent: Monday, July 07, 2008 8:31 AM > To: Mustafa Hasan > Cc: [email protected] > Subject: Re: [6lowpan] Regarding coexistence with 802.11n > > Appendix E of the 802.15.4 standard goes into detail on co-existence. > > On Fri, 2008-07-04 at 09:04 -0700, Mustafa Hasan wrote: >> Dear 6lowpaner, >> >> I need little help regarding the coexistence issue of ISM Band with >> other ISM, especially with the 802.11n, 802.11b. >> >> I want to know what are the factor is going to save the 802.15.4 >> fighting with others frequency. >> >> >> Thanks in Advance... >> >> >> Regards >> >> M. Hasan >> _______________________________________________ >> 6lowpan mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/6lowpan > > _______________________________________________ > 6lowpan mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/6lowpan > _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
