Hi Srdjan.<div><br></div><div><div>Thank you for reply.</div><div><div>Our potential customer asked us about TDD with 43dBm at antenna port and with as šmany 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.</div>
<div>So, now we have to understand real LMS performances for LTE anyway.</div><div>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.</div>
</div></div><div>Please suggest us something to answer.</div><div><br></div><div>Best regards,<div>Andrey Sviyazov.</div><br>
<br><br><div class="gmail_quote">2012/10/15 Srdjan Milenkovic <span dir="ltr"><<a href="mailto:s.milenkovic@limemicro.com" target="_blank">s.milenkovic@limemicro.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>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?<div><div class="h5"><br>
<br>
On 15/10/2012 09:13, Andrey Sviyazov wrote:<br>
</div></div></div><div><div class="h5">
<blockquote type="cite">
<div>Since we decided to make version 3 (due to additions of šLMS
thermosensors) then we can also add external Fref prescaler for
PLL, no problems here.</div>
<div>I think ICPR is more important restriction.</div>
<div>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).</div>
<div>So, we can't use LMS for LTE without DPD or additional
filtration (2nd Tx IF).</div>
<div>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.</div>
<div><br clear="all">
Best regards,
<div>Andrey Sviyazov.</div>
<br>
<br>
<br>
<div class="gmail_quote">2012/10/14 Alexander Chemeris <span dir="ltr"><<a href="mailto:alexander.chemeris@gmail.com" target="_blank">alexander.chemeris@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Srdjan, thanks for the answers. This is enough for us at the
moment.<br>
<div>
<div><br>
On Sun, Oct 14, 2012 at 3:50 PM, Srdjan Milenkovic<br>
<<a href="mailto:s.milenkovic@limemicro.com" target="_blank">s.milenkovic@limemicro.com</a>>
wrote:<br>
> Hi Alexander,<br>
> Remaining questions are addressed below.<br>
><br>
><br>
> On 13/10/2012 21:47, Alexander Chemeris wrote:<br>
><br>
> Hi Srdjan,<br>
><br>
> We're looking into re-purposing UmTRX for LTE and
there a few things which<br>
> we need to understand better.<br>
><br>
> 1. Is it possible to support 15MHz and 20MHz LTE
channel bandwidths? To<br>
> achieve this we at least need to sample at
23.04Msps and 30.72Msps<br>
> respectively. LMS6002D datasheet specifies the
maximum I/Q samplerate of<br>
> 14Msps, which is not enough. But at the same time,
datasheet claims that ADC<br>
> and DAC are specified up to 50Msps. How does this
fits together?<br>
><br>
> 2. Do you have any experience what maximum output
power we could achieve<br>
> with LMS and proper amplifiers, while still staying
in the bounds of the LTE<br>
> Standard? What would be the limiting factor for the
further power increase?<br>
><br>
> The limiting factor here would be absolute specs on
ACPR, out of band spurs<br>
> ... i.e. TX spectrum mask, expressed in dBm not in
dBc. For example, you may<br>
> meet <= -45dBc ACPR but on the other hand you
can not inject noise into<br>
> adjacent channel more than xdBm. LMS device is OK
for 20-25dBm modulated<br>
> output power. We can probably push it more however
this is šnot tested so<br>
> far.<br>
><br>
><br>
><br>
> 3. Is there any issues using TDD mode in LMS6002D?
We've been using onnly<br>
> FDD mode so far and it would be great to know what
issues could we expect<br>
> when switching to TDD mode.<br>
><br>
> TDD mode should be just fine. We measured around
20us TX<->RX switching<br>
> time. We will probably need to reconfigure VCO
supplies on UmTRX board to<br>
> simplify switching control while keeping switching
time at 20us. Lat us know<br>
> when you are ready for such experiment.<br>
><br>
><br>
><br>
> --<br>
> Regards,<br>
> Alexander Chemeris.<br>
> CEO, Fairwaves LLC / ïïï õÍòÁÄÉÏ<br>
> <a href="http://fairwaves.ru" target="_blank">http://fairwaves.ru</a><br>
><br>
><br>
<br>
<br>
<br>
--<br>
Regards,<br>
Alexander Chemeris.<br>
CEO, Fairwaves LLC / ïïï õÍòÁÄÉÏ<br>
<a href="http://fairwaves.ru" target="_blank">http://fairwaves.ru</a><br>
<br>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</blockquote>
<br>
</div></div></div>
</blockquote></div><br></div>