OFDMA in LTE:

 OFDMA in LTE:

Orthogonal Frequency Division Multiple Access, is a key technology used in LTE to enable efficient digital data transmission. By splitting a signal into multiple carrier frequencies (subcarriers), OFDMA allows multiple users to transmit simultaneously on different subcarriers within the same OFDM symbol.

-Key Characteristics of an OFDMA System in LTE:
1️⃣ LTE Radio Frame Duration= 10 ms
2️⃣ Sub-frame Duration= 1 ms
3️⃣ Time Slot Duration= 0.5 ms
4️⃣ Symbol Duration= 0.5 ms / 7 or 0.5 ms / 6
5️⃣ Symbol Count= 7 in normal CP, 6 in extended CP
6️⃣ Subcarrier Bandwidth= 15 KHz
7️⃣ Subcarrier Count in One PRB= 12

-An LTE Radio Frame consists of:
👉🏾 10 Subframes 👉🏾20 Time Slots 👉🏾140 Symbols

-Physical Resource Block (PRB), A PRB consists of:
👉🏾12 subcarriers 👉🏾7 symbols in normal CP
👉🏾Resource elements and lasts for one 0.5 ms time slot

-PRBs can be visualized as boxes where user data, signals, and control data are allocated. The number of PRBs and subcarriers depends on the frequency bandwidth:

⭐ 20 MHz: 100 PRB, 1200 subcarriers
⭐15 MHz: 75 PRB, 900 subcarriers
⭐10 MHz: 50 PRB, 600 subcarriers
⭐ 5 MHz: 25 PRB, 300 subcarriers
⭐ 3 MHz: 15 PRB, 180 subcarriers
⭐ 1.4 MHz: 6 PRB, 72 subcarriers

Transmission Time Interval (TTI):
⚡Equals 1 ms and is the minimum scheduling unit in LTE.
⚡Two PRBs are scheduled for the user at a time.

Resource Element (RE):
👌🏾 The smallest unit in an OFDMA system, used to carry user data, signals, and control data.

OFDMA's efficiency and flexibility make it a cornerstone of modern LTE networks, ensuring robust and scalable data transmission for multiple users simultaneously.