Howtosignalprocessing
OFDM Parameters in WiMAX
| Parameter | Fixed WiMAX OFDM-PHY | Mobile WiMAX Scalable OFDMA-PHY |
|---|---|---|
| Subcarrier frequency spacing (kHz) | 15.625 | 10.94 |
| Useful symbol time (μs) | 64 | 91.4 |
| Guard time assuming 12.5% (μs) | 8 | 11.4 |
| OFDM symbol duration (μs) | 72 | 102.9 |
- What is symbol duration in OFDM?
- What is the channel spacing used for OFDM subcarriers?
- Why subcarrier spacing is 15 kHz in LTE?
- How many symbols are in a subcarrier?
What is symbol duration in OFDM?
Each OFDM subcarrier is 312.5 KHz. Figure 1: 802.11n/ac 20 MHz channel—OFDM subcarriers. 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.
What is the channel spacing used for OFDM subcarriers?
Subcarriers in Wi-Fi
OFDM and subcarriers allow Wi-Fi to be more fault tolerant and carry data more reliably. Older Wi-Fi standards, such as 802.11ab/g/n/ac, use 64 subcarriers. Each Wi-Fi channel is 20 MHz. Therefore, each subcarrier is spaced 312.5 kHz apart.
Why subcarrier spacing is 15 kHz in LTE?
Simply, It is because 3G and LTE have the same clock timing for multi technology handsets.
How many symbols are in a subcarrier?
For normal 15kHz subcarrier spacing, the normal CP is 7 OFDM symbols per slot, which works well in typical urban multipath (Tu = 66.
