How is OFDM symbol duration calculated?
Table of Contents
- 1 How is OFDM symbol duration calculated?
- 2 When the symbol duration of OFDM symbol is 3.2 microseconds the used subcarrier frequencies are?
- 3 How many OFDM symbols are present in a slot with extended cyclic prefix?
- 4 How many OFDM symbols are in a slot for normal cyclic prefix?
- 5 What is the symbol duration of 1/15000?
- 6 What are the examples of OFDM spectrum?
How is OFDM symbol duration calculated?
The sub-carrier frequency spacing delta_f =1/Ts= 1/(Td * N), Ts is the OFDM symbol duration,Td is the sampling symbol duration and equal to the smapling time interval。 Thus Td=1/fs, fs is the DAC sampling rate. Then we can calculate the bandwidth of the fignal.
When the symbol duration of OFDM symbol is 3.2 microseconds the used subcarrier frequencies are?
Each OFDM subcarrier is 312.5 KHz. 802.11ax introduces a longer OFDM symbol time of 12.8 μs, which is four times longer than the legacy symbol time of 3.2 μs. Subcarrier spacing is equal to the reciprocal of the symbol time.
What is the symbol rate of 256 QAM?
Reliable Carrier Lock
| Digital Modulation Format | Minimum Result Length (0 Hz frequency offset) | Maximum frequency offset (Result Length = 1000 symbols) |
|---|---|---|
| 64-QAM | 150 symbols | 4.65\% symbol rate |
| 128-QAM | 250 symbols | 0.3\% symbol rate |
| 256-QAM | 400 symbols | 0.3\% symbol rate |
| 512-QAM | 1000 symbols | 0.15\% symbol rate |
Why does the symbol duration reduce with the increasing subcarrier spacing?
Since the FFT size is fixed, the subcarrier spacing varies with channel bandwidth. When larger bandwidths are used, the subcarrier spacing increases, and the symbol time decreases. Decreasing symbol time implies that a larger fraction needs to be allocated as guard time to overcome delay spread.
How many OFDM symbols are present in a slot with extended cyclic prefix?
For an extended cyclic prefix, where there are six OFDM symbols per slot, the same structure is used but with one reference-signal symbol per slot instead of two.
How many OFDM symbols are in a slot for normal cyclic prefix?
seven
There are seven OFDM symbols per slot for a normal cyclic prefix (six in the case of an extended cyclic prefix). In each of those seven OFDM symbols, a length-12 sequence, obtained by phase rotation of the cell-specific sequence as described earlier, is transmitted.
What is the OFDM symbol?
However, OFDM symbol consists of (N) information symbols modulated over (N) subcarriers , which are all sent simultaneously , giving what is named as multicarrier transmission or modulation.
What is the spectrum of QAM and OFDM symbols?
Here is the spectrum of QAM symbol occupying all bandwidth for 1 information symbol. And this the spectrum of 1 OFDM symbol consisting of ( N ) information symbols , where N is the number of subcarriers. 8 clever moves when you have $1,000 in the bank.
What is the symbol duration of 1/15000?
The symbol duration is simply 1/subcarrier and hence 1/15000 = 66.66us. We then add a cyclic prefix and stack up 14 symbols into a 1ms Transmission Time Interval (TTI). The actual cyclic prefix length is not the same for all symbols to fit into 1ms but we can ignore that for now.
What are the examples of OFDM spectrum?
Fig. 4 Examples of OFDM spectrum (a) a single subchannel, (b) 5 carriers At the central frequency of each subchannel, there is no crosstalk from other subchannels. Mathematically, each carrier can be described as a complex wave: (1) The real signal is the real part of sc(t).