I read an article from T-Mobile link where they claimed a 3Gbps speedtest with the aggregation of 3 three bands in 5G.
How it is possible to make 3 Gbps with a 210 MHz bandwidth and using 256QAM in 5G?
210e6 x 8 = 1.680e9
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2 Answers
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There must be MIMO. As Samsung S22 5G posseses 4 antenna, I would say, for example, MIMO 4x4 for the two TDD bands and MIMO 2x2 for the FDD band.
The upper bound of rate for the n41 band of 100MHz is $(273 \times 12 \times 28) \times (8) \times (4) \approx 2800\textrm{Mbps}$ where the factors are the number of subcarriers, the number of bit per subcarrier, and the number of spatial multiplexing layers, respectively.
Similarly, the upper bound of rate for the n41 band of 90MHz is $(245 \times 12 \times 28) \times (8) \times (4) \approx 2512\textrm{Mbps}$; for the n25 20MHz $(106 \times 12 \times 14) \times (8) \times (2) \approx 271\textrm{Mbps}$.
The theoretical rate is therefore largely greater than the 3Gbps. There must be overhead induced by signalling, retranmissions, scheduling, device capability, etc.
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$\begingroup$ I am totally new to MIMO. Do you talk about MIMO with multiple beams? $\endgroup$ Commented Dec 2, 2022 at 11:27
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$\begingroup$ @dsp_curious Yes. Spatial Multiplexing. $\endgroup$– AlexTPCommented Dec 2, 2022 at 11:39
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$\begingroup$ another clarification, 273 x 12 x 28 = 91768 is the number of subcarriers in the 100 MHz band of n41? $\endgroup$ Commented Dec 2, 2022 at 12:07
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$\begingroup$ @dsp_curious yes. Check 38.104 and 38.211. $\endgroup$– AlexTPCommented Dec 2, 2022 at 13:10
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Likely with MIMO (Spatial Multiplexing).
