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Andrey Sviyazov andreysviyaz at gmail.comHi Srdjan. As I understand, I must to re-ask and much simpler and more correctly: Do we need to search another components for LTE BTS with MIMO/20MHz/10-20W or there are chances to use LMS6002? You told about 20-23dBm output power, so please let us know what PA do you use in this case. Best regards, Andrey Sviyazov. P.S. Sorry for my undeveloped english :) 2012/10/15 Andrey Sviyazov <andreysviyaz at gmail.com> > Hi Srdjan. > > Thank you for reply. > Our potential customer asked us about TDD with 43dBm at antenna port and > with as many of MIMO's as it possible (theoreticaly) to realize now to get > higher users density per sector. Of course, for the first look it seems > like an dreams, but it is true real customer dreams. > So, now we have to understand real LMS performances for LTE anyway. > It required to be able to answering customer either something about > 0.1-0.5W and no more or to start good real project with required specs. > Please suggest us something to answer. > > Best regards, > Andrey Sviyazov. > > > > 2012/10/15 Srdjan Milenkovic <s.milenkovic at limemicro.com> > >> DPD will linearize PA, LMS should not be limiting factor in that >> respect. In band spurs should be investigated before we say that LMS can or >> can not be used. What output power are we looking for? >> >> >> On 15/10/2012 09:13, Andrey Sviyazov wrote: >> >> Since we decided to make version 3 (due to additions of LMS >> thermosensors) then we can also add external Fref prescaler for PLL, no >> problems here. >> I think ICPR is more important restriction. >> Srdjan said that it doesn't studied too deeply, but on my opinion, really >> reachable maximum Tx power no more then 25 dBm (without DPD). >> So, we can't use LMS for LTE without DPD or additional filtration (2nd Tx >> IF). >> In other hand, we can implement it similar to UmSEL and with >> upconversion, of course, but high quality SAW filter required (all >> flatness) to keeping EVM as small as possible. >> >> Best regards, >> Andrey Sviyazov. >> >> >> >> 2012/10/14 Alexander Chemeris <alexander.chemeris at gmail.com> >> >>> Srdjan, thanks for the answers. This is enough for us at the moment. >>> >>> On Sun, Oct 14, 2012 at 3:50 PM, Srdjan Milenkovic >>> <s.milenkovic at limemicro.com> wrote: >>> > Hi Alexander, >>> > Remaining questions are addressed below. >>> > >>> > >>> > On 13/10/2012 21:47, Alexander Chemeris wrote: >>> > >>> > Hi Srdjan, >>> > >>> > We're looking into re-purposing UmTRX for LTE and there a few things >>> which >>> > we need to understand better. >>> > >>> > 1. Is it possible to support 15MHz and 20MHz LTE channel bandwidths? To >>> > achieve this we at least need to sample at 23.04Msps and 30.72Msps >>> > respectively. LMS6002D datasheet specifies the maximum I/Q samplerate >>> of >>> > 14Msps, which is not enough. But at the same time, datasheet claims >>> that ADC >>> > and DAC are specified up to 50Msps. How does this fits together? >>> > >>> > 2. Do you have any experience what maximum output power we could >>> achieve >>> > with LMS and proper amplifiers, while still staying in the bounds of >>> the LTE >>> > Standard? What would be the limiting factor for the further power >>> increase? >>> > >>> > The limiting factor here would be absolute specs on ACPR, out of band >>> spurs >>> > ... i.e. TX spectrum mask, expressed in dBm not in dBc. For example, >>> you may >>> > meet <= -45dBc ACPR but on the other hand you can not inject noise into >>> > adjacent channel more than xdBm. LMS device is OK for 20-25dBm >>> modulated >>> > output power. We can probably push it more however this is not tested >>> so >>> > far. >>> > >>> > >>> > >>> > 3. Is there any issues using TDD mode in LMS6002D? We've been using >>> onnly >>> > FDD mode so far and it would be great to know what issues could we >>> expect >>> > when switching to TDD mode. >>> > >>> > TDD mode should be just fine. We measured around 20us TX<->RX switching >>> > time. We will probably need to reconfigure VCO supplies on UmTRX board >>> to >>> > simplify switching control while keeping switching time at 20us. Lat >>> us know >>> > when you are ready for such experiment. >>> > >>> > >>> > >>> > -- >>> > Regards, >>> > Alexander Chemeris. >>> > CEO, Fairwaves LLC / ООО УмРадио >>> > http://fairwaves.ru >>> > >>> > >>> >>> >>> >>> -- >>> Regards, >>> Alexander Chemeris. >>> CEO, Fairwaves LLC / ООО УмРадио >>> http://fairwaves.ru >>> >>> >> >> > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/umtrx/attachments/20121015/57fd9d44/attachment.htm>