Calculating LTE throughput is crucial for optimizing network performance and ensuring efficient resource utilization. As a telecommunications RF expert engineer, I’ll guide you through the process of calculating LTE throughput under optimal radio conditions, specifically using 16QAM modulation for both downlink and uplink.

## LTE Throughput Calculation.

I shall also demonstrate how to determine the total number of bits in physical resource blocks (PRBs), accounting for overheads such as physical channels and synchronization signals.

### OFDMA/SC-FDMA System Overview.

**LTE Radio Frame Duration:**10 ms**Sub-frame Duration:**1 ms**Time Slot Duration:**0.5 ms**Symbol Duration:**0.5 ms / 7 (assuming normal CP)**Symbols per Sub-frame:**7**Subcarrier Bandwidth:**15 kHz**Subcarrier Count per PRB:**12**Transmission Time Interval:**1 ms (minimum scheduling time for a user, typically 2 PRBs at once).

### Steps to Calculate Downlink Throughput

**Step 1: Bits per PRB Calculation:**

- Number of subcarriers per PRB: 12
- Symbols per sub-frame: 7 (assuming normal CP)
- Bits per RE (Resource Element) for 16QAM modulation: 4
- Bits per PRB: 12 subcarriers × 7 symbols × 4 bits/RE = 336 bits (per 0.5 ms)

**Step 2: Total Bits per ms for 100 PRBs:**

- Total bits per ms: Bits per PRB × Number of PRBs
- Number of PRBs: 100 (for 20 MHz bandwidth)
- Total bits per ms: 336 bits/0.5 ms × 100 PRBs = 67,200 bits/ms

**Step 3: Considering MIMO (2×2) Configuration:**

- Total throughput considering MIMO: Total bits per ms × Number of antennas (transmit or receive, typically the same in LTE).
- Total throughput: 67,200 bits/ms × 2 (for 2T2R MIMO) = 134,400 bits/ms

**Step 4: Net Throughput (Considering Resource Utilization):**

- Assume 75% efficiency due to overheads (e.g., control signaling, channel coding).
- Net throughput: Total throughput × 0.75 = 134,400 bits/ms × 0.75 = 100,800 bits/ms

**Step 5: Convert to Mbps:**

- 1 Mbps = 1,000,000 bits per second
- Net throughput in Mbps: 100,800 bits/ms × 1,000 ms/s / 1,000,000 bits/Mbps = 100.8 Mbps

### Uplink Throughput Calculation.

For the uplink, we follow a similar process but account for different configurations:

1️⃣ Modulation = 16QAM (4 bits per RE, most of the commercial UE support max 16QAM)

2️⃣ Antenna = 1T1R SISO

3️⃣ Bandwidth = 20MHz

**Step 1: Bits per PRB Calculation:**

- Modulation: 16QAM (4 bits per RE)
- Number of subcarriers per PRB: 12
- Symbols per sub-frame: 7 (assuming normal CP)
- Bits per PRB: 12 subcarriers × 7 symbols × 4 bits/RE = 336 bits (per 0.5 ms)

**Step 2: Total Bits per ms for 100 PRBs:**

- Minimum scheduling for user: 336 bits + 336 bits = 672 bits per ms
- Total bits per ms: PRBs × bits = 100 × 672 = 67,200 bits/ms

**Step 3: Net Throughput (Considering Resource Utilization):**

- Assume 75% efficiency due to overheads (e.g., control signaling, channel coding).
- Net throughput: 67,200 bits/ms × 0.75 = 50,400 bits/ms

**Step 4: Convert to Mbps:**

- Net throughput in Mbps: 50,400 bits/ms × 1,000 ms/s / 1,000,000 bits/Mbps = 50.4 Mbps

### Final Thoughts:

By following these steps, you can calculate the LTE throughput for both downlink and uplink under optimal radio conditions. For 16QAM modulation:

**Downlink Net Throughput:**100.8 Mbps**Uplink Net Throughput:**50.4 Mbps

Understanding these calculations helps in optimizing LTE network performance, ensuring efficient resource utilization, and meeting the high data rate demands of modern communication networks.