Hi guys, is there a way to measure the the power (which will later convert to distance) from an USRP to a cellular phone? the cell will work on LTE or 3g network. it doesn't have to be very accurate. any ideas? Thanks, Meny

Hi Meny, you're not the first one to ask this question, but: No. To estimate distance based on power, you would 1. need to know how much power was emitted, 2. need to know how much power was lost on the way between the transmitter and the receiver. Neither condition is applicable: 3G and 4G phones definitely scale their TX power based on the quality of their connection to the base station, so they don't have a fixed TX power. Then, you don't know the antenna pattern of the cell phone, nor its orientation, so even if you knew how much power the transmitter used, you wouldn't know how much was emitted in your direction. Then, the thing about the typical mobile phone channel is that it is neither necessarily line-of-sight nor multipath-free, so there's only stochastic measures (if any) to tell you how much power got lost underway. And of course, being heavily used bands, it'll be hard to discern power coming from a single handset from other handsets. I mean, UMTS/FDD (which AFAIK is the mode in most widespread use), if I'm not totally mistaken, uses code division multiple access, which means that at one time, you receive the superposition of all active transmitters, and will need to know the correct sequence to extract the power of a single handset, and of course correct things like the interference of other users still present in the despread rx signal at the point of reception (partly, due to signal runtime that is not the same for your antenna and the basestation antenna, so that spreading sequences that are synchronous for the base station aren't in sync for you, and because doppler will be completely different, but all that greatly depends on the codes actually used and isn't that easy to model). So basically, you'd be writing something to at least discern different subscribers; that's pretty close to an IMSI catcher, which probably is illegal for you to own… Furthermore, you're getting the "hard" version of the near-far problem, because the handsets will adjust their TX power to minimize necessary dynamic range for the base station, and not for you. This will be even harder because of the fading properties of mobile channels especially in urban areas. So: physics of your channel, technology of the transceivers, topology of the network and on top at least conceptual security of the standards are working against you. Physics alone is a show-stopper here. Best regards, Marcus On 11.12.2015 14:18, Meny Sidar via USRP-users wrote: > Hi guys, > > is there a way to measure the the power (which will later convert to > distance) from an USRP to a cellular phone? the cell will work on LTE > or 3g network. > it doesn't have to be very accurate. > any ideas? > > Thanks, > Meny > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

1. need to know how much power was emitted,
2. need to know how much power was lost on the way between the
transmitter and the receiver.

Thank you for that detailed response. Really sad to know that what i need is impossible, my project is counting on it. Last thing i can think of, is creating a base station (lets say in 3G) and make communications with mobile phones nearby. But the catch is, i need them to connect to my network without any registration or even touching the mobile phone. an automatic registration to my network. lets say that it is the only network available. Is it possible? or am i just aiming to high? Thanks a lot, Regards, Meny 2015-12-11 16:15 GMT+02:00 Marcus Müller <usrp-users@lists.ettus.com>: > Hi Meny, > > you're not the first one to ask this question, but: > > No. To estimate distance based on power, you would > > 1. need to know how much power was emitted, > 2. need to know how much power was lost on the way between the > transmitter and the receiver. > > Neither condition is applicable: 3G and 4G phones definitely scale their > TX power based on the quality of their connection to the base station, so > they don't have a fixed TX power. Then, you don't know the antenna pattern > of the cell phone, nor its orientation, so even if you knew how much power > the transmitter used, you wouldn't know how much was emitted in your > direction. > Then, the thing about the typical mobile phone channel is that it is > neither necessarily line-of-sight nor multipath-free, so there's only > stochastic measures (if any) to tell you how much power got lost underway. > And of course, being heavily used bands, it'll be hard to discern power > coming from a single handset from other handsets. I mean, UMTS/FDD (which > AFAIK is the mode in most widespread use), if I'm not totally mistaken, > uses code division multiple access, which means that at one time, you > receive the superposition of all active transmitters, and will need to know > the correct sequence to extract the power of a single handset, and of > course correct things like the interference of other users still present in > the despread rx signal at the point of reception (partly, due to signal > runtime that is not the same for your antenna and the basestation antenna, > so that spreading sequences that are synchronous for the base station > aren't in sync for you, and because doppler will be completely different, > but all that greatly depends on the codes actually used and isn't that easy > to model). So basically, you'd be writing something to at least discern > different subscribers; that's pretty close to an IMSI catcher, which > probably is illegal for you to own… > > Furthermore, you're getting the "hard" version of the near-far problem, > because the handsets will adjust their TX power to minimize necessary > dynamic range for the base station, and not for you. This will be even > harder because of the fading properties of mobile channels especially in > urban areas. > > So: physics of your channel, technology of the transceivers, topology of > the network and on top at least conceptual security of the standards are > working against you. Physics alone is a show-stopper here. > > Best regards, > Marcus > On 11.12.2015 14:18, Meny Sidar via USRP-users wrote: > > Hi guys, > > is there a way to measure the the power (which will later convert to > distance) from an USRP to a cellular phone? the cell will work on LTE or 3g > network. > it doesn't have to be very accurate. > any ideas? > > Thanks, > Meny > > > _______________________________________________ > USRP-users mailing listUSRP-users@lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >

1. need to know how much power was emitted,
2. need to know how much power was lost on the way between the
transmitter and the receiver.

Hi Meny, I've seen some interesting work where the goal was to locate cell-phones in disaster areas for search and rescue. Essentially, they use an interrogator to send a high power pulse into the area of interest. Most cell phones contain a SAW/BAW device for front-end filtering, which will reflect some of the incoming pulse power. The reflecting energy can be used to estimate location and distance to the cell phone. Here is a link to publication, maybe it will give you some good ideas: https://www.researchgate.net/publication/259162956_New_technologies_for_the_search_of_trapped_victims -Trip On Fri, Dec 11, 2015 at 9:36 AM, Meny Sidar via USRP-users < usrp-users@lists.ettus.com> wrote: > Thank you for that detailed response. > Really sad to know that what i need is impossible, my project is counting > on it. > > Last thing i can think of, is creating a base station (lets say in 3G) and > make communications with mobile phones nearby. > But the catch is, i need them to connect to my network without any > registration or even touching the mobile phone. an automatic registration > to my network. lets say that it is the only network available. > > Is it possible? > or am i just aiming to high? > > Thanks a lot, > Regards, > Meny > > 2015-12-11 16:15 GMT+02:00 Marcus Müller <usrp-users@lists.ettus.com>: > >> Hi Meny, >> >> you're not the first one to ask this question, but: >> >> No. To estimate distance based on power, you would >> >> 1. need to know how much power was emitted, >> 2. need to know how much power was lost on the way between the >> transmitter and the receiver. >> >> Neither condition is applicable: 3G and 4G phones definitely scale their >> TX power based on the quality of their connection to the base station, so >> they don't have a fixed TX power. Then, you don't know the antenna pattern >> of the cell phone, nor its orientation, so even if you knew how much power >> the transmitter used, you wouldn't know how much was emitted in your >> direction. >> Then, the thing about the typical mobile phone channel is that it is >> neither necessarily line-of-sight nor multipath-free, so there's only >> stochastic measures (if any) to tell you how much power got lost underway. >> And of course, being heavily used bands, it'll be hard to discern power >> coming from a single handset from other handsets. I mean, UMTS/FDD (which >> AFAIK is the mode in most widespread use), if I'm not totally mistaken, >> uses code division multiple access, which means that at one time, you >> receive the superposition of all active transmitters, and will need to know >> the correct sequence to extract the power of a single handset, and of >> course correct things like the interference of other users still present in >> the despread rx signal at the point of reception (partly, due to signal >> runtime that is not the same for your antenna and the basestation antenna, >> so that spreading sequences that are synchronous for the base station >> aren't in sync for you, and because doppler will be completely different, >> but all that greatly depends on the codes actually used and isn't that easy >> to model). So basically, you'd be writing something to at least discern >> different subscribers; that's pretty close to an IMSI catcher, which >> probably is illegal for you to own… >> >> Furthermore, you're getting the "hard" version of the near-far problem, >> because the handsets will adjust their TX power to minimize necessary >> dynamic range for the base station, and not for you. This will be even >> harder because of the fading properties of mobile channels especially in >> urban areas. >> >> So: physics of your channel, technology of the transceivers, topology of >> the network and on top at least conceptual security of the standards are >> working against you. Physics alone is a show-stopper here. >> >> Best regards, >> Marcus >> On 11.12.2015 14:18, Meny Sidar via USRP-users wrote: >> >> Hi guys, >> >> is there a way to measure the the power (which will later convert to >> distance) from an USRP to a cellular phone? the cell will work on LTE or 3g >> network. >> it doesn't have to be very accurate. >> any ideas? >> >> Thanks, >> Meny >> >> >> _______________________________________________ >> USRP-users mailing listUSRP-users@lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >

1. need to know how much power was emitted,
2. need to know how much power was lost on the way between the
transmitter and the receiver.

I'll be sure to check it out. Thanks! Meny 2015-12-11 16:58 GMT+02:00 James Humphries <james.humphries@ettus.com>: > Hi Meny, > > I've seen some interesting work where the goal was to locate cell-phones > in disaster areas for search and rescue. Essentially, they use an > interrogator to send a high power pulse into the area of interest. Most > cell phones contain a SAW/BAW device for front-end filtering, which will > reflect some of the incoming pulse power. The reflecting energy can be used > to estimate location and distance to the cell phone. > > Here is a link to publication, maybe it will give you some good ideas: > > > https://www.researchgate.net/publication/259162956_New_technologies_for_the_search_of_trapped_victims > > -Trip > > On Fri, Dec 11, 2015 at 9:36 AM, Meny Sidar via USRP-users < > usrp-users@lists.ettus.com> wrote: > >> Thank you for that detailed response. >> Really sad to know that what i need is impossible, my project is counting >> on it. >> >> Last thing i can think of, is creating a base station (lets say in 3G) >> and make communications with mobile phones nearby. >> But the catch is, i need them to connect to my network without any >> registration or even touching the mobile phone. an automatic registration >> to my network. lets say that it is the only network available. >> >> Is it possible? >> or am i just aiming to high? >> >> Thanks a lot, >> Regards, >> Meny >> >> 2015-12-11 16:15 GMT+02:00 Marcus Müller <usrp-users@lists.ettus.com>: >> >>> Hi Meny, >>> >>> you're not the first one to ask this question, but: >>> >>> No. To estimate distance based on power, you would >>> >>> 1. need to know how much power was emitted, >>> 2. need to know how much power was lost on the way between the >>> transmitter and the receiver. >>> >>> Neither condition is applicable: 3G and 4G phones definitely scale their >>> TX power based on the quality of their connection to the base station, so >>> they don't have a fixed TX power. Then, you don't know the antenna pattern >>> of the cell phone, nor its orientation, so even if you knew how much power >>> the transmitter used, you wouldn't know how much was emitted in your >>> direction. >>> Then, the thing about the typical mobile phone channel is that it is >>> neither necessarily line-of-sight nor multipath-free, so there's only >>> stochastic measures (if any) to tell you how much power got lost underway. >>> And of course, being heavily used bands, it'll be hard to discern power >>> coming from a single handset from other handsets. I mean, UMTS/FDD (which >>> AFAIK is the mode in most widespread use), if I'm not totally mistaken, >>> uses code division multiple access, which means that at one time, you >>> receive the superposition of all active transmitters, and will need to know >>> the correct sequence to extract the power of a single handset, and of >>> course correct things like the interference of other users still present in >>> the despread rx signal at the point of reception (partly, due to signal >>> runtime that is not the same for your antenna and the basestation antenna, >>> so that spreading sequences that are synchronous for the base station >>> aren't in sync for you, and because doppler will be completely different, >>> but all that greatly depends on the codes actually used and isn't that easy >>> to model). So basically, you'd be writing something to at least discern >>> different subscribers; that's pretty close to an IMSI catcher, which >>> probably is illegal for you to own… >>> >>> Furthermore, you're getting the "hard" version of the near-far problem, >>> because the handsets will adjust their TX power to minimize necessary >>> dynamic range for the base station, and not for you. This will be even >>> harder because of the fading properties of mobile channels especially in >>> urban areas. >>> >>> So: physics of your channel, technology of the transceivers, topology of >>> the network and on top at least conceptual security of the standards are >>> working against you. Physics alone is a show-stopper here. >>> >>> Best regards, >>> Marcus >>> On 11.12.2015 14:18, Meny Sidar via USRP-users wrote: >>> >>> Hi guys, >>> >>> is there a way to measure the the power (which will later convert to >>> distance) from an USRP to a cellular phone? the cell will work on LTE or 3g >>> network. >>> it doesn't have to be very accurate. >>> any ideas? >>> >>> Thanks, >>> Meny >>> >>> >>> _______________________________________________ >>> USRP-users mailing listUSRP-users@lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> >>> >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >