On 06/01/2011 06:15, Mark Borgerson wrote:> In article<J-SdnVz2Csvyr7jQnZ2dnUVZ_jqdnZ2d@giganews.com>, > nospam@nowhere.com says... >> >> There is a network of ~100 wireless sensors, communicating to a single >> host. All sensors are located within ~50..100m from the host in the >> typical urban environment. Ideally, it would be desirable to poll each >> sensor at least 10 times/sec. When polling the sensors, we have to get >> just several bits of the status information from each sensor. > > > 100 sensors at 10Hz means 1,000 samples per second. If they occupy > the same bandwith, each sensor has to power up, sync, and transmit > in 1mSec. If it is really a polled network, you have to subtract > from the millisecond, the time for the polling signal. > >> >> Problem: as sensors are battery powered, the average power consumption >> of the entire communication part of a sensor is limited to ~ 10mW max. > > At 3.3V, that's only 3.3mA. That seems hardly enough to keep a receiver > running all the time and to transmit occasionally at 10 to 50mA. >>I agree here - the aim should be to keep the receiver powered-down most of the time. If you can keep the receiver active time to under 10% duty cycle, that gives you 33 mA when active, which should be plenty. Transmission costs should be low using short, high-speed bursts of data.>> Is there a wireless technology/modules on the market that would allow >> such power budget? >> >> Would it be possible to develop such technology using existing >> transceiver ICs or modules? >> >> (Cost, operating band, compliance, acceptance, etc. are outside of >> consideration at this point). > > Are there any time-division systems where the host sends a > broadcast polling command and each sensor transmits at a defined > time slot offset from the polling? That means that after the > polling command is received, both transmitter and receiver could > shut down until time to send, then wake up the receiver until > just before the next polling signal. > > > Does the system really respond to the sensors in 100mSec? If not, > would it be possible to poll each sensor every 10 seconds and have > it return 100 readings? With a lower transmit duty cycle, you might > meet the power constraints. The host could then assemble a continuous > record with 10 seconds of delay. >This is definitely the way to do it, if that suits the application. For short messages, it is the protocol and message overhead that is the real power-drain - wake-up, synchronisation, preambles, acknowledge messages, etc., are all much power power-consuming than the actual few bytes of sensor data.
Feasibility of the VERY low power wireless network?
Started by ●January 5, 2011
Reply by ●January 6, 20112011-01-06
Reply by ●January 6, 20112011-01-06
Le 06/01/2011 04:09, Vladimir Vassilevsky a �crit :> > There is a network of ~100 wireless sensors, communicating to a single > host. All sensors are located within ~50..100m from the host in the > typical urban environment. Ideally, it would be desirable to poll each > sensor at least 10 times/sec. When polling the sensors, we have to get > just several bits of the status information from each sensor. > > Problem: as sensors are battery powered, the average power consumption > of the entire communication part of a sensor is limited to ~ 10mW max.Assuming wireless sensors wake up from "idle-state" (few hundred nA) to "run state" (20-30mA) ten times per seconds, you have to compute the total time of run-state during 1s to achieve 10mW. i.e : ---- idle for 90ms ---- run for 10ms ---- idle for 90ms ---- run for 10ms --- .... BTW i'm not sure that nowadays wireless transceivers can reach such time budget, especially i think 10ms is too short to exit from the idle state to run-state (clocks time stabilisation ...etc.) Is that correct Vlad ?> > Is there a wireless technology/modules on the market that would allow > such power budget? > > Would it be possible to develop such technology using existing > transceiver ICs or modules? > > (Cost, operating band, compliance, acceptance, etc. are outside of > consideration at this point). > > Vladimir Vassilevsky > DSP and Mixed Signal Design Consultant > http://www.abvolt.com >
Reply by ●January 6, 20112011-01-06
On Wed, 05 Jan 2011 21:09:34 -0600, Vladimir Vassilevsky <nospam@nowhere.com> wrote:> >There is a network of ~100 wireless sensors, communicating to a single >host. All sensors are located within ~50..100m from the host in the >typical urban environment. Ideally, it would be desirable to poll each >sensor at least 10 times/sec. When polling the sensors, we have to get >just several bits of the status information from each sensor.What does several bits mean ? 10 ? 100 ? or what amount of bits. With 100 sensors, the receiver bandwidth would have to be several kHz i.e. in the same order of magnitude as two way handheld radios, which require at least -120 dBm for reliable reception in quiet areas. The free space loss is inversely proportional to the square of distance, so with omnidirectional antennas at 433 MHz, the path loss is about 65 dB at 100 m, thus a peak transmitter power of -55 dBm would be sufficient. However, in real world urban environment, the signal drop is more like inversely proportional of the fourth power of distance, thus the signal drops about 12 dB with each doubling of distance. Thus, using multiple receiving antennas on the master at different locations in order to halving the RF path from each sensor, will drop the Tx power requirement well below 1/10 compared to a single antenna..>Problem: as sensors are battery powered, the average power consumption >of the entire communication part of a sensor is limited to ~ 10mW max.Keeping the sensor receiver active only during the expected synchronization time will also help in saving power.
Reply by ●January 6, 20112011-01-06
Vladimir Vassilevsky wrote:>There is a network of ~100 wireless sensors, communicating to a single >host. All sensors are located within ~50..100m from the host in the >typical urban environment. Ideally, it would be desirable to poll each >sensor at least 10 times/sec. When polling the sensors, we have to get >just several bits of the status information from each sensor. > >Problem: as sensors are battery powered, the average power consumptionWhy do they need to be battery powered? Although I'm not a friend of it, technology exists to transmit enough power over this distance. Oliver -- Oliver Betz, Muenchen (oliverbetz.de)
Reply by ●January 6, 20112011-01-06
On 6 Jan., 05:10, linnix <m...@linnix.info-for.us> wrote:> On Jan 5, 7:48=A0pm, Mostafa Kassem <m.kassem...@gmail.com> wrote: > > > > > On 1/5/2011 10:09 PM, Vladimir Vassilevsky wrote: > > > > There is a network of ~100 wireless sensors, communicating to a singl=e> > > host. All sensors are located within ~50..100m from the host in the > > > typical urban environment. Ideally, it would be desirable to poll eac=h> > > sensor at least 10 times/sec. When polling the sensors, we have to ge=t> > > just several bits of the status information from each sensor. > > > > Problem: as sensors are battery powered, the average power consumptio=n> > > of the entire communication part of a sensor is limited to ~ 10mW max=.> > > > Is there a wireless technology/modules on the market that would allow > > > such power budget? > > > > Would it be possible to develop such technology using existing > > > transceiver ICs or modules? > > > > (Cost, operating band, compliance, acceptance, etc. are outside of > > > consideration at this point). > > > > Vladimir Vassilevsky > > > DSP and Mixed Signal Design Consultant > > >http://www.abvolt.com > > > Zigbee? > > Anything but low power.it of course depends on how you use it but if zigbee isn't low power what is then? -Lasse
Reply by ●January 6, 20112011-01-06
On Jan 6, 11:25=A0am, "langw...@fonz.dk" <langw...@fonz.dk> wrote:> On 6 Jan., 05:10, linnix <m...@linnix.info-for.us> wrote: > > > > > On Jan 5, 7:48=A0pm, Mostafa Kassem <m.kassem...@gmail.com> wrote: > > > > On 1/5/2011 10:09 PM, Vladimir Vassilevsky wrote: > > > > > There is a network of ~100 wireless sensors, communicating to a sin=gle> > > > host. All sensors are located within ~50..100m from the host in the > > > > typical urban environment. Ideally, it would be desirable to poll e=ach> > > > sensor at least 10 times/sec. When polling the sensors, we have to =get> > > > just several bits of the status information from each sensor. > > > > > Problem: as sensors are battery powered, the average power consumpt=ion> > > > of the entire communication part of a sensor is limited to ~ 10mW m=ax.> > > > > Is there a wireless technology/modules on the market that would all=ow> > > > such power budget? > > > > > Would it be possible to develop such technology using existing > > > > transceiver ICs or modules? > > > > > (Cost, operating band, compliance, acceptance, etc. are outside of > > > > consideration at this point). > > > > > Vladimir Vassilevsky > > > > DSP and Mixed Signal Design Consultant > > > >http://www.abvolt.com > > > > Zigbee? > > > Anything but low power. > > it of course depends on how you use it but if zigbee isn't low power > what is then?ZigBee takes around 50mW to 100mW, so it won't be low power by itself. If OP can limit RF duty to less than 10%, then it might be possible.
Reply by ●January 6, 20112011-01-06
On Jan 5, 11:58=A0pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:> hamilton wrote: > > On 1/5/2011 8:09 PM, Vladimir Vassilevsky wrote: > > >> There is a network of ~100 wireless sensors, communicating to a single > >> host. All sensors are located within ~50..100m from the host in the > >> typical urban environment. Ideally, it would be desirable to poll each > >> sensor at least 10 times/sec. When polling the sensors, we have to get > >> just several bits of the status information from each sensor. > > >> Problem: as sensors are battery powered, the average power consumption > >> of the entire communication part of a sensor is limited to ~ 10mW max. > > >> Is there a wireless technology/modules on the market that would allow > >> such power budget? > > >> Would it be possible to develop such technology using existing > >> transceiver ICs or modules? > > >> (Cost, operating band, compliance, acceptance, etc. are outside of > >> consideration at this point). > > >> Vladimir Vassilevsky > >> DSP and Mixed Signal Design Consultant > >>http://www.abvolt.com > > > What is the real time requirement ? > > > TinyOS maybe what your looking for. > > > A google search for "wireless sensor networks" found this: > >https://secure.wikimedia.org/wikipedia/en/wiki/Wireless_sensor_network > > > as well as almost 1 million others. > > > hamilton > > IdiotWhy does anyone respond to this guy? When others ask questions rather than give even the least answer or any encouragement he derides them. When he asks questions and others respond, if he doesn't like the response, he derides them rather than thanking them and moving on or even just ignoring them. Why does anyone think this guy deserves any sort of response when he is asking for help? Rick
Reply by ●January 7, 20112011-01-07
On Jan 6, 8:21=A0pm, rickman <gnu...@gmail.com> wrote:> On Jan 5, 11:58=A0pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote: > > > > > > > hamilton wrote: > > > On 1/5/2011 8:09 PM, Vladimir Vassilevsky wrote: > > > >> There is a network of ~100 wireless sensors, communicating to a sing=le> > >> host. All sensors are located within ~50..100m from the host in the > > >> typical urban environment. Ideally, it would be desirable to poll ea=ch> > >> sensor at least 10 times/sec. When polling the sensors, we have to g=et> > >> just several bits of the status information from each sensor. > > > >> Problem: as sensors are battery powered, the average power consumpti=on> > >> of the entire communication part of a sensor is limited to ~ 10mW ma=x.> > > >> Is there a wireless technology/modules on the market that would allo=w> > >> such power budget? > > > >> Would it be possible to develop such technology using existing > > >> transceiver ICs or modules? > > > >> (Cost, operating band, compliance, acceptance, etc. are outside of > > >> consideration at this point). > > > >> Vladimir Vassilevsky > > >> DSP and Mixed Signal Design Consultant > > >>http://www.abvolt.com > > > > What is the real time requirement ? > > > > TinyOS maybe what your looking for. > > > > A google search for "wireless sensor networks" found this: > > >https://secure.wikimedia.org/wikipedia/en/wiki/Wireless_sensor_network > > > > as well as almost 1 million others. > > > > hamilton > > > Idiot > > Why does anyone respond to this guy? =A0When others ask questions rather > than give even the least answer or any encouragement he derides them. > When he asks questions and others respond, if he doesn't like the > response, he derides them rather than thanking them and moving on or > even just ignoring them. > > Why does anyone think this guy deserves any sort of response when he > is asking for help? > > Rick- Hide quoted text - > > - Show quoted text -Actually, even though the OP is a bit surly, his point-of-view and statements are often very valuable to me. Secondarily, I also thought the "1 million google responses" thing was small-brained since the post started out looking for very low power wireless and not wireless in general.
Reply by ●January 7, 20112011-01-07
linnix skrev 2011-01-06 21:51:> On Jan 6, 11:25 am, "langw...@fonz.dk"<langw...@fonz.dk> wrote: >> On 6 Jan., 05:10, linnix<m...@linnix.info-for.us> wrote: >> >> >> >>> On Jan 5, 7:48 pm, Mostafa Kassem<m.kassem...@gmail.com> wrote: >> >>>> On 1/5/2011 10:09 PM, Vladimir Vassilevsky wrote: >> >>>>> There is a network of ~100 wireless sensors, communicating to a single >>>>> host. All sensors are located within ~50..100m from the host in the >>>>> typical urban environment. Ideally, it would be desirable to poll each >>>>> sensor at least 10 times/sec. When polling the sensors, we have to get >>>>> just several bits of the status information from each sensor. >> >>>>> Problem: as sensors are battery powered, the average power consumption >>>>> of the entire communication part of a sensor is limited to ~ 10mW max. >> >>>>> Is there a wireless technology/modules on the market that would allow >>>>> such power budget? >> >>>>> Would it be possible to develop such technology using existing >>>>> transceiver ICs or modules? >> >>>>> (Cost, operating band, compliance, acceptance, etc. are outside of >>>>> consideration at this point). >> >>>>> Vladimir Vassilevsky >>>>> DSP and Mixed Signal Design Consultant >>>>> http://www.abvolt.com >> >>>> Zigbee? >> >>> Anything but low power. >> >> it of course depends on how you use it but if zigbee isn't low power >> what is then? > > ZigBee takes around 50mW to 100mW, so it won't be low power by > itself. If OP can limit RF duty to less than 10%, then it might be > possible. >The ATmega128RFA1 (ZigBee + 128kB Flash AVR) uses about 26 mW during transmission and a little bit lower during reception. -- Best Regards Ulf Samuelsson These are my own personal opinions, which may or may not be shared by my employer Atmel Nordic AB
Reply by ●January 7, 20112011-01-07
On Jan 7, 10:07=A0am, Ulf Samuelsson <u...@invalid.atmel.com> wrote:> linnix skrev 2011-01-06 21:51: > > > > > On Jan 6, 11:25 am, "langw...@fonz.dk"<langw...@fonz.dk> =A0wrote: > >> On 6 Jan., 05:10, linnix<m...@linnix.info-for.us> =A0wrote: > > >>> On Jan 5, 7:48 pm, Mostafa Kassem<m.kassem...@gmail.com> =A0wrote: > > >>>> On 1/5/2011 10:09 PM, Vladimir Vassilevsky wrote: > > >>>>> There is a network of ~100 wireless sensors, communicating to a sin=gle> >>>>> host. All sensors are located within ~50..100m from the host in the > >>>>> typical urban environment. Ideally, it would be desirable to poll e=ach> >>>>> sensor at least 10 times/sec. When polling the sensors, we have to =get> >>>>> just several bits of the status information from each sensor. > > >>>>> Problem: as sensors are battery powered, the average power consumpt=ion> >>>>> of the entire communication part of a sensor is limited to ~ 10mW m=ax.> > >>>>> Is there a wireless technology/modules on the market that would all=ow> >>>>> such power budget? > > >>>>> Would it be possible to develop such technology using existing > >>>>> transceiver ICs or modules? > > >>>>> (Cost, operating band, compliance, acceptance, etc. are outside of > >>>>> consideration at this point). > > >>>>> Vladimir Vassilevsky > >>>>> DSP and Mixed Signal Design Consultant > >>>>>http://www.abvolt.com > > >>>> Zigbee? > > >>> Anything but low power. > > >> it of course depends on how you use it but if zigbee isn't low power > >> what is then? > > > ZigBee takes around 50mW to 100mW, so it won't be low power by > > itself. =A0If OP can limit RF duty to less than 10%, then it might be > > possible. > > The ATmega128RFA1 (ZigBee + 128kB Flash AVR) uses about 26 mW during > transmission and a little bit lower during reception. >Atmega128RF runs at 8MHz with 30mW and 16MHz with 50mW. EM351 (128K ARM M3) runs at 24MHz with 50mW. But Atmega128RF is not available on Digikey yet.
