University lecturer & research scientist in Tescom Co,Ltd. Focus on wireless comm testing with a custom platform, built around advansed DSP tools.

Re: CRC field in the middle of a packet

Reply posted 3 months ago (07/28/2021)
Hello!Having CRC field at the end of packet was natural when it was calculated in hardware using shift register. So when you squeezed all the useful data through...

Re: Loop optimization in C6416T Processor

Reply posted 6 months ago (04/14/2021)
Well, mpysp is not operation, but function call. As to complex addition, just take a look at ccs\tools\compiler\c6000_7.4.24\lib\src\xxxcaddcc.h:/* xxxcaddcc.h --...

Re: Loop optimization in C6416T Processor

Reply posted 6 months ago (04/13/2021)
Hi!As it was suggested on e2e, compiler optimization is the most painless and effortless way to improve code performance, it definitely should be used. However,...

Re: Communication between ARM and DSP

Reply posted 10 months ago (12/15/2020)
When it is SoC, shared memory, of course. When it is not, still DMA to dedicated buffer over high speed link like PCIe.

Re: LTE IFFT Sampling and Nyquist Rate

Reply posted 1 year ago (05/14/2020)
HiLTE signal is sampled at 30.72 MHz in time domain. As we use complex baseband signal, is means your whole system bandwidth might be 30.72 MHz exactly. As we produce...
0.3 in ideal conditions means something is very wrong.Once again, I can't see how exactly you compensate your phase. It should be done per each carrier separately....
Well, this is just how equalizer works - it finds compensating factor which turns received signal into expected one. Keep in mind, you can't just blindly rely on...
I'm sorry, could not see anything in the picture, it was compressed too small. From your explanation I can't get, how do you calculate the phase difference. If...
Hello!In simulation model it is possible to get phase delay of the path and compensate it. However, in real life your transmitter and receiver won't be coherent...
Hello!I have no experience with Simulink, but with practical OFDM systems. As you already guessed, channel will introduce delay which would result in constellation...

Re: Few questions on wireless and LTE

Reply posted 2 years ago (09/28/2019)
LTE runs at 30.72 MHz if that was 20 MHz bandwidth . Remaining parts are not used, so there are guard bands at sides.Subcarriers are orthogonal, i.e. make no influence...

Re: Somewhat Off Topic: Manipulating a PDF File.

Reply posted 2 years ago (05/15/2019)
There might be number of ways. One is to print selected pages to PDF printer, which also come in number, like free pdf creator or Foxit reader with export module....

Re: Cyclic prefix concept in LTE

Reply posted 3 years ago (09/29/2018)
 That doesn't contradict nothing of what told before. Although windowing is not mandated by the spec, this step is often added to smooth symbol to symbol transition....

Re: Cyclic prefix concept in LTE

Reply posted 3 years ago (09/29/2018)
IMO you are reading those references too literally. CP removal is no way chopping exactly CP leaving a frame alone, but rather cutting FFT sized block out of received...

Re: Cyclic prefix concept in LTE

Reply posted 3 years ago (09/29/2018)
Hello!Though cutting CP and leaving just original frame looks tempting, it is not practical as it gives no benefits. Because sampling point offset you never sample...

Re: Writing DSP routines in C or assembly?

Reply posted 4 years ago (08/01/2017)
Though I am from TI church, I am pretty impressed so many people suggesting assembly. Guys, are you serious about keeping in mind dozens of registers and trying...
CConsider multiplicative inverse to replace division with multiplications. Two to three Newton iterations will give enough accuracy. There is some reading on wiki,...

Re: OFDM sampling

Reply posted 4 years ago (05/11/2017)
Simply, you may think that for period of one symbol time domain signal is not defined through samples. Instead, the signal is defined in frequency domain, then through...

Re: New Email Notifications System

Reply posted 5 years ago (04/13/2017)
Hello!May I suggest to include original post or at least some excerpt in notification e-mails, so despite vague title the reader could estimate whether the subject...

Re: Cyclic prefix concept in LTE

Reply posted 5 years ago (03/01/2017)
Theoretically, one may eliminate ISI by adding guard interval of silence in front and after every symbol. However, that is hard practically, as would require precise...

Re: Cyclic prefix concept in LTE

Reply posted 5 years ago (03/01/2017)
Yes, exactly, multiple copies of the symbol could step on each other. However, as I have shown with that simple sin(wt) example, that results in some magnitude degradation...

Re: Cyclic prefix concept in LTE

Reply posted 5 years ago (03/01/2017)
Multipath propagation on primitive level makes two things: previous symbol can step on current one; current symbol can step on the next one. Adding CP makes the...

Re: Cyclic prefix concept in LTE

Reply posted 5 years ago (03/01/2017)
Suppose certain carrier transfers signal, which arrives as sin(wt) at receiver through line of sight. Then secondary path through reflection from some obstacle...

Re: Decimation by 2

Reply posted 5 years ago (01/15/2017)
Low pass filtering before decimation is required to limit bandwidth of signal under process and avoid aliasing which may happen during downsampling. Averaging is...

Re: LTE power allocation

Reply posted 5 years ago (01/06/2017)
To my knowledge, design of LTE control channel in downlink is such that power presence means signal presence. No other info may come on place of control channel....

Re: Source coding in WiFi or LTE

Reply posted 5 years ago (12/31/2016)
In LTE several coding schemes are used forddifferent channels. Particularly, Turbo coding in shared channels and convolutional in control ones and that is not full...

Re: Removing DC and low frequency noise from a spectrum

Reply posted 5 years ago (10/18/2016)
DC leakage is often the price for the simplicity of quadrature receiver versus IF. In the real world the leakage would affect not only DC carrier itself, but neighbour...

Re: LTE Downlink TX understanding

Reply posted 5 years ago (09/28/2016)
I gave that simple formula to illustrate where 15kHz subcarrier spacing goes to. Sure, I meant clock period. As duration of the OFDM symbol itself is fixed, one...

Re: LTE Downlink TX understanding

Reply posted 5 years ago (09/25/2016)
(OFDM symbol period) = 1 / (subcarrier spacing * IFFT size) orSampling clock frequency = subcarrier spacing * IFFT size15kHz * 2048 = 30.72 MHz.As pointed above,...

Re: FDATool

Reply posted 5 years ago (05/25/2016)
Since you've used the word "UE" I would assume you're talking about LTE. In this case you might better perform FFT and then pick up the bins matching UE's allocation. As...

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