Hello, I'm trying to compute the Zigbee capacity between two nodes. Is there a physical layer Shannon capacity representation for a Zigbee? Doing a search, I don't see any meaningful results for Zigbee Shannon Capacity or Zigbee Capacity which seems strange. Is there something I'm missing? Thanks, Omar
Zigbee capacity?
Started by ●August 7, 2008
Reply by ●August 7, 20082008-08-07
On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheikh81@gmail.com> wrote:>Hello, > >I'm trying to compute the Zigbee capacity between two nodes. Is there >a physical layer Shannon capacity representation for a Zigbee? Doing a >search, I don't see any meaningful results for Zigbee Shannon Capacity >or Zigbee Capacity which seems strange. Is there something I'm >missing? > >Thanks, >OmarComputing channel capacity doesn't mean much when one is using a standardized implementation. Do you mean you're looking for the maximum data rates achievable with a Zigbee system? Or do you mean you're looking for performance curves for a Zigbee system? If the latter, you're not likely to find such things. Performance for any wireless system varies among implementations, but varies hugely across environments. It doesn't make much sense for manufacturers to publish performance curves when practical channel conditions are not controlled or predictable. Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
Reply by ●August 7, 20082008-08-07
Eric Jacobsen <eric.jacobsen@ieee.org> writes:> On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheikh81@gmail.com> > wrote: > >>Hello, >> >>I'm trying to compute the Zigbee capacity between two nodes. Is there >>a physical layer Shannon capacity representation for a Zigbee? Doing a >>search, I don't see any meaningful results for Zigbee Shannon Capacity >>or Zigbee Capacity which seems strange. Is there something I'm >>missing? >> >>Thanks, >>Omar > > Computing channel capacity doesn't mean much when one is using a > standardized implementation. Do you mean you're looking for the > maximum data rates achievable with a Zigbee system? Or do you mean > you're looking for performance curves for a Zigbee system? > > If the latter, you're not likely to find such things. Performance > for any wireless system varies among implementations, but varies > hugely across environments. It doesn't make much sense for > manufacturers to publish performance curves when practical channel > conditions are not controlled or predictable.Surely there must be some assumptiong on channel conditions, otherwise how could you plan a system? -- % Randy Yates % "My Shangri-la has gone away, fading like %% Fuquay-Varina, NC % the Beatles on 'Hey Jude'" %%% 919-577-9882 % %%%% <yates@ieee.org> % 'Shangri-La', *A New World Record*, ELO http://www.digitalsignallabs.com
Reply by ●August 7, 20082008-08-07
On Aug 8, 7:47�am, Randy Yates <ya...@ieee.org> wrote:> Eric Jacobsen <eric.jacob...@ieee.org> writes: > > On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheik...@gmail.com> > > wrote: > > >>Hello, > > >>I'm trying to compute the Zigbee capacity between two nodes. Is there > >>a physical layer Shannon capacity representation for a Zigbee? Doing a > >>search, I don't see any meaningful results for Zigbee Shannon Capacity > >>or Zigbee Capacity which seems strange. Is there something I'm > >>missing? > > >>Thanks, > >>Omar > > > Computing channel capacity doesn't mean much when one is using a > > standardized implementation. � Do you mean you're looking for the > > maximum data rates achievable with a Zigbee system? � Or do you mean > > you're looking for performance curves for a Zigbee system? > > > If the latter, you're not likely to find such things. � Performance > > for any wireless system varies among implementations, but varies > > hugely across environments. � It doesn't make much sense for > > manufacturers to publish performance curves when practical channel > > conditions are not controlled or predictable. > > Surely there must be some assumptiong on channel conditions, > otherwise how could you plan a system?ZigBee uses the same band as 802.11. When you use 802.11 indoors do you have any clue in advance how well its going to work? Its easy to produce performance curves for open air operation. However, if you ask its developers how well ZigBee is going to work in a real house or office they shrug their shoulders and say "let's see". I don't think anyone has yet planned a ZigBee system. Regards, Steve
Reply by ●August 7, 20082008-08-07
steveu@coppice.org writes:> On Aug 8, 7:47�am, Randy Yates <ya...@ieee.org> wrote: >> Eric Jacobsen <eric.jacob...@ieee.org> writes: >> > On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheik...@gmail.com> >> > wrote: >> >> >>Hello, >> >> >>I'm trying to compute the Zigbee capacity between two nodes. Is there >> >>a physical layer Shannon capacity representation for a Zigbee? Doing a >> >>search, I don't see any meaningful results for Zigbee Shannon Capacity >> >>or Zigbee Capacity which seems strange. Is there something I'm >> >>missing? >> >> >>Thanks, >> >>Omar >> >> > Computing channel capacity doesn't mean much when one is using a >> > standardized implementation. � Do you mean you're looking for the >> > maximum data rates achievable with a Zigbee system? � Or do you mean >> > you're looking for performance curves for a Zigbee system? >> >> > If the latter, you're not likely to find such things. � Performance >> > for any wireless system varies among implementations, but varies >> > hugely across environments. � It doesn't make much sense for >> > manufacturers to publish performance curves when practical channel >> > conditions are not controlled or predictable. >> >> Surely there must be some assumptiong on channel conditions, >> otherwise how could you plan a system? > > ZigBee uses the same band as 802.11. When you use 802.11 indoors do > you have any clue in advance how well its going to work?You have a pretty good idea what the ranges will be.> Its easy to produce performance curves for open air > operation. However, if you ask its developers how well ZigBee is going > to work in a real house or office they shrug their shoulders and say > "let's see". > > I don't think anyone has yet planned a ZigBee system.Surely someone has. I think TI has parts based on the standard. (Their site seems to be down right now). -- % Randy Yates % "I met someone who looks alot like you, %% Fuquay-Varina, NC % she does the things you do, %%% 919-577-9882 % but she is an IBM." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com
Reply by ●August 7, 20082008-08-07
steveu@coppice.org writes:> On Aug 8, 7:47�am, Randy Yates <ya...@ieee.org> wrote: >> Eric Jacobsen <eric.jacob...@ieee.org> writes: >> > On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheik...@gmail.com> >> > wrote: >> >> >>Hello, >> >> >>I'm trying to compute the Zigbee capacity between two nodes. Is there >> >>a physical layer Shannon capacity representation for a Zigbee? Doing a >> >>search, I don't see any meaningful results for Zigbee Shannon Capacity >> >>or Zigbee Capacity which seems strange. Is there something I'm >> >>missing? >> >> >>Thanks, >> >>Omar >> >> > Computing channel capacity doesn't mean much when one is using a >> > standardized implementation. � Do you mean you're looking for the >> > maximum data rates achievable with a Zigbee system? � Or do you mean >> > you're looking for performance curves for a Zigbee system? >> >> > If the latter, you're not likely to find such things. � Performance >> > for any wireless system varies among implementations, but varies >> > hugely across environments. � It doesn't make much sense for >> > manufacturers to publish performance curves when practical channel >> > conditions are not controlled or predictable. >> >> Surely there must be some assumptiong on channel conditions, >> otherwise how could you plan a system? > > ZigBee uses the same band as 802.11. When you use 802.11 indoors do > you have any clue in advance how well its going to work?You have a pretty good idea what the ranges will be.> Its easy to produce performance curves for open air > operation. However, if you ask its developers how well ZigBee is going > to work in a real house or office they shrug their shoulders and say > "let's see". > > I don't think anyone has yet planned a ZigBee system.Surely someone has. I think TI has parts based on the standard. (Their site seems to be down right now). -- % Randy Yates % "I met someone who looks alot like you, %% Fuquay-Varina, NC % she does the things you do, %%% 919-577-9882 % but she is an IBM." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com
Reply by ●August 7, 20082008-08-07
steveu@coppice.org writes:> On Aug 8, 7:47�am, Randy Yates <ya...@ieee.org> wrote: >> Eric Jacobsen <eric.jacob...@ieee.org> writes: >> > On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheik...@gmail.com> >> > wrote: >> >> >>Hello, >> >> >>I'm trying to compute the Zigbee capacity between two nodes. Is there >> >>a physical layer Shannon capacity representation for a Zigbee? Doing a >> >>search, I don't see any meaningful results for Zigbee Shannon Capacity >> >>or Zigbee Capacity which seems strange. Is there something I'm >> >>missing? >> >> >>Thanks, >> >>Omar >> >> > Computing channel capacity doesn't mean much when one is using a >> > standardized implementation. � Do you mean you're looking for the >> > maximum data rates achievable with a Zigbee system? � Or do you mean >> > you're looking for performance curves for a Zigbee system? >> >> > If the latter, you're not likely to find such things. � Performance >> > for any wireless system varies among implementations, but varies >> > hugely across environments. � It doesn't make much sense for >> > manufacturers to publish performance curves when practical channel >> > conditions are not controlled or predictable. >> >> Surely there must be some assumptiong on channel conditions, >> otherwise how could you plan a system? > > ZigBee uses the same band as 802.11. When you use 802.11 indoors do > you have any clue in advance how well its going to work?You have a pretty good idea what the ranges will be.> Its easy to produce performance curves for open air > operation. However, if you ask its developers how well ZigBee is going > to work in a real house or office they shrug their shoulders and say > "let's see". > > I don't think anyone has yet planned a ZigBee system.Surely someone has. I think TI has parts based on the standard. (Their site seems to be down right now). -- % Randy Yates % "I met someone who looks alot like you, %% Fuquay-Varina, NC % she does the things you do, %%% 919-577-9882 % but she is an IBM." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com
Reply by ●August 8, 20082008-08-08
On Thu, 07 Aug 2008 22:02:08 -0400, Randy Yates <yates@ieee.org> wrote:>steveu@coppice.org writes: > >> On Aug 8, 7:47�am, Randy Yates <ya...@ieee.org> wrote: >>> Eric Jacobsen <eric.jacob...@ieee.org> writes: >>> > On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheik...@gmail.com> >>> > wrote: >>> >>> >>Hello, >>> >>> >>I'm trying to compute the Zigbee capacity between two nodes. Is there >>> >>a physical layer Shannon capacity representation for a Zigbee? Doing a >>> >>search, I don't see any meaningful results for Zigbee Shannon Capacity >>> >>or Zigbee Capacity which seems strange. Is there something I'm >>> >>missing? >>> >>> >>Thanks, >>> >>Omar >>> >>> > Computing channel capacity doesn't mean much when one is using a >>> > standardized implementation. � Do you mean you're looking for the >>> > maximum data rates achievable with a Zigbee system? � Or do you mean >>> > you're looking for performance curves for a Zigbee system? >>> >>> > If the latter, you're not likely to find such things. � Performance >>> > for any wireless system varies among implementations, but varies >>> > hugely across environments. � It doesn't make much sense for >>> > manufacturers to publish performance curves when practical channel >>> > conditions are not controlled or predictable. >>> >>> Surely there must be some assumptiong on channel conditions, >>> otherwise how could you plan a system? >> >> ZigBee uses the same band as 802.11. When you use 802.11 indoors do >> you have any clue in advance how well its going to work? > >You have a pretty good idea what the ranges will be.Yes, but not the channel conditions. The variation in fading in PAN/LAN environments is very broad, and it's anybody's bet what sort of throughput/performance one will get for a given link at whatever expected range. e.g., basic low-power Zigbee is only really expected to work for ranges of about 3ft to maybe 10m. Whether one gets the 3ft or the 10m just depends on the environment. Likewise with 802.11; how many walls, how close are they, what's the reflective environment, etc., etc. It all makes a big difference from one link to the next.>> Its easy to produce performance curves for open air >> operation. However, if you ask its developers how well ZigBee is going >> to work in a real house or office they shrug their shoulders and say >> "let's see". >> >> I don't think anyone has yet planned a ZigBee system. > >Surely someone has. I think TI has parts based on the standard. (Their >site seems to be down right now).Yes, there are Zigbee products on the market. They basically work, but performance seems to be all over the place. You can get them with 100mW PAs (or more) and try to make them do long range, too. No guarantees, though. ;) Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
Reply by ●August 12, 20082008-08-12
On Aug 8, 12:54�am, Eric Jacobsen <eric.jacob...@ieee.org> wrote:> On Thu, 07 Aug 2008 22:02:08 -0400, Randy Yates <ya...@ieee.org> > wrote: > > > > > > >ste...@coppice.org writes: > > >> On Aug 8, 7:47�am, Randy Yates <ya...@ieee.org> wrote: > >>> Eric Jacobsen <eric.jacob...@ieee.org> writes: > >>> > On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheik...@gmail.com> > >>> > wrote: > > >>> >>Hello, > > >>> >>I'm trying to compute the Zigbee capacity between two nodes. Is there > >>> >>a physical layer Shannon capacity representation for a Zigbee? Doing a > >>> >>search, I don't see any meaningful results for Zigbee Shannon Capacity > >>> >>or Zigbee Capacity which seems strange. Is there something I'm > >>> >>missing? > > >>> >>Thanks, > >>> >>Omar > > >>> > Computing channel capacity doesn't mean much when one is using a > >>> > standardized implementation. � Do you mean you're looking for the > >>> > maximum data rates achievable with a Zigbee system? � Or do you mean > >>> > you're looking for performance curves for a Zigbee system? > > >>> > If the latter, you're not likely to find such things. � Performance > >>> > for any wireless system varies among implementations, but varies > >>> > hugely across environments. � It doesn't make much sense for > >>> > manufacturers to publish performance curves when practical channel > >>> > conditions are not controlled or predictable. > > >>> Surely there must be some assumptiong on channel conditions, > >>> otherwise how could you plan a system? > > >> ZigBee uses the same band as 802.11. When you use 802.11 indoors do > >> you have any clue in advance how well its going to work? > > >You have a pretty good idea what the ranges will be. > > Yes, but not the channel conditions. � The variation in fading in > PAN/LAN environments is very broad, and it's anybody's bet what sort > of throughput/performance one will get for a given link at whatever > expected range. � e.g., basic low-power Zigbee is only really expected > to work for ranges of about 3ft to maybe 10m. � Whether one gets the > 3ft or the 10m just depends on the environment. �Likewise with 802.11; > how many walls, how close are they, what's the reflective environment, > etc., etc. � It all makes a big difference from one link to the next. > > >> Its easy to produce performance curves for open air > >> operation. However, if you ask its developers how well ZigBee is going > >> to work in a real house or office they shrug their shoulders and say > >> "let's see". > > >> I don't think anyone has yet planned a ZigBee system. > > >Surely someone has. I think TI has parts based on the standard. (Their > >site seems to be down right now). > > Yes, there are Zigbee products on the market. � They basically work, > but performance seems to be all over the place. � You can get them > with 100mW PAs (or more) and try to make them do long range, too. � No > guarantees, though. �;) > > Eric Jacobsen > Minister of Algorithms > Abineau Communicationshttp://www.ericjacobsen.org > > Blog:http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php- Hide quoted text - > > - Show quoted text -Well, by Shannon Capacity of Zigbee networks, I mean the maximum achievable data rate for the Zigbee standard. Zigbee has rates up to 250 kbps. Surely there's a physical layer representation of the maximum achievable date rate for Zigbee considering it's a wireless technology, uses power and bandwidth. Would it use the common R = w * log2 ( 1 + P*G/(w*N + I)) bits/sec formula? For the maximum possible transmit power of 1 mW for the Zigbee standard, distances of say 50 metres, I'm getting astonishingly high rates in the order of 10^6, not 10^3.
Reply by ●August 12, 20082008-08-12
On Tue, 12 Aug 2008 10:49:38 -0700 (PDT), Ginu <osheikh81@gmail.com> wrote:>On Aug 8, 12:54�am, Eric Jacobsen <eric.jacob...@ieee.org> wrote: >> On Thu, 07 Aug 2008 22:02:08 -0400, Randy Yates <ya...@ieee.org> >> wrote: >> >> >> >> >> >> >ste...@coppice.org writes: >> >> >> On Aug 8, 7:47�am, Randy Yates <ya...@ieee.org> wrote: >> >>> Eric Jacobsen <eric.jacob...@ieee.org> writes: >> >>> > On Thu, 7 Aug 2008 14:17:10 -0700 (PDT), Ginu <osheik...@gmail.com> >> >>> > wrote: >> >> >>> >>Hello, >> >> >>> >>I'm trying to compute the Zigbee capacity between two nodes. Is there >> >>> >>a physical layer Shannon capacity representation for a Zigbee? Doing a >> >>> >>search, I don't see any meaningful results for Zigbee Shannon Capacity >> >>> >>or Zigbee Capacity which seems strange. Is there something I'm >> >>> >>missing? >> >> >>> >>Thanks, >> >>> >>Omar >> >> >>> > Computing channel capacity doesn't mean much when one is using a >> >>> > standardized implementation. � Do you mean you're looking for the >> >>> > maximum data rates achievable with a Zigbee system? � Or do you mean >> >>> > you're looking for performance curves for a Zigbee system? >> >> >>> > If the latter, you're not likely to find such things. � Performance >> >>> > for any wireless system varies among implementations, but varies >> >>> > hugely across environments. � It doesn't make much sense for >> >>> > manufacturers to publish performance curves when practical channel >> >>> > conditions are not controlled or predictable. >> >> >>> Surely there must be some assumptiong on channel conditions, >> >>> otherwise how could you plan a system? >> >> >> ZigBee uses the same band as 802.11. When you use 802.11 indoors do >> >> you have any clue in advance how well its going to work? >> >> >You have a pretty good idea what the ranges will be. >> >> Yes, but not the channel conditions. � The variation in fading in >> PAN/LAN environments is very broad, and it's anybody's bet what sort >> of throughput/performance one will get for a given link at whatever >> expected range. � e.g., basic low-power Zigbee is only really expected >> to work for ranges of about 3ft to maybe 10m. � Whether one gets the >> 3ft or the 10m just depends on the environment. �Likewise with 802.11; >> how many walls, how close are they, what's the reflective environment, >> etc., etc. � It all makes a big difference from one link to the next. >> >> >> Its easy to produce performance curves for open air >> >> operation. However, if you ask its developers how well ZigBee is going >> >> to work in a real house or office they shrug their shoulders and say >> >> "let's see". >> >> >> I don't think anyone has yet planned a ZigBee system. >> >> >Surely someone has. I think TI has parts based on the standard. (Their >> >site seems to be down right now). >> >> Yes, there are Zigbee products on the market. � They basically work, >> but performance seems to be all over the place. � You can get them >> with 100mW PAs (or more) and try to make them do long range, too. � No >> guarantees, though. �;) >> >> Eric Jacobsen >> Minister of Algorithms >> Abineau Communicationshttp://www.ericjacobsen.org >> >> Blog:http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php- Hide quoted text - >> >> - Show quoted text - > >Well, by Shannon Capacity of Zigbee networks, I mean the maximum >achievable data rate for the Zigbee standard. Zigbee has rates up to >250 kbps. Surely there's a physical layer representation of the >maximum achievable date rate for Zigbee considering it's a wireless >technology, uses power and bandwidth. Would it use the common R = w * >log2 ( 1 + P*G/(w*N + I)) bits/sec formula? For the maximum possible >transmit power of 1 mW for the Zigbee standard, distances of say 50 >metres, I'm getting astonishingly high rates in the order of 10^6, not >10^3.I still don't think the Shannon capacity has any bearing on a defined standard, unless you're interested in how closely the implementation may be able to approach capacity. A defined maximum data rate of 250kbps sets the max data rate, and the Modulation and Coding Scheme used to achieve that rate sets the performance, less any implementation losses. If a capacity-approaching code is not used (and Zigbee does not use a capacity-approaching code), then it does not achieve Shannon capacity. I don't recall off the top of my head what coding Zigbee uses, but there's probably at least a 3-6dB gap to capacity at typically measured error rates. That would also assume a continuous stream, which Zigbee doesn't do. Bottom line: I don't think Shannon capacity is relevant to a defined standard unless one just cares about how big the gap is to capacity. Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
