DOCSIS Versions Compared: What Changed from 1.0 to 4.0
Trying to decode DOCSIS versions? This guide compares 1.0 through 4.0—downstream and upstream ceilings, modulation (SC-QAM vs. OFDM/OFDMA), spectrum changes, and the new 4.0 options (FDX/ESD)—so you know what actually affects speed and latency on real cable networks.
| DOCSIS | First release | Peak downstream (theoretical) | Peak upstream (theoretical) | Channelization / modulation | Spectrum & PHY notes | Notable features |
|---|---|---|---|---|---|---|
| 1.0 | 1997 | ~40 Mbps per 6 MHz channel | ~10 Mbps per channel | Single-carrier QAM (64/256-QAM) | 6/8 MHz SC-QAM carriers | First interoperable cable modem spec |
| 1.1 | 2001 | ~40 Mbps per 6 MHz channel | ~10 Mbps per channel | SC-QAM | Same as 1.0 | QoS/service flows; VoIP/security refinements |
| 2.0 | 2002 | ~40 Mbps per 6 MHz channel | ~30 Mbps per 6.4 MHz channel | SC-QAM; A-TDMA/S-CDMA upstream | Wider upstream channels (to 6.4 MHz) | Major upstream boost for early VoIP/symmetric needs |
| 3.0 | 2006 | ~1 Gbps+ with 32× bonding | ~200 Mbps+ with 8× bonding | SC-QAM with channel bonding | 6/8 MHz per bonded SC-QAM channel | Channel bonding; native IPv6; big capacity jump |
| 3.1 | 2013 | Up to ~10 Gbps | ~1–2 Gbps | OFDM/OFDMA blocks + SC-QAM; up to 4096-QAM | OFDM 24–192 MHz (DS), OFDMA 6.4–96 MHz (US) | High spectral efficiency; higher QAM; better latency options |
| 4.0 (FDX/ESD) | 2017 (spec) | Up to ~10 Gbps | Up to ~6 Gbps | OFDM/OFDMA + full-duplex options | ESD to 1.8 GHz DS / 684 MHz US; FDX within ~108–1218 MHz | Massive upstream headroom; FDX for simultaneous two-way; ESD for extended spectrum |
Notes & caveats: Throughput figures are theoretical PHY capacities under ideal modulation. Real-world service tiers are lower and depend on ISP profiles, node density/splits, and signal quality. DOCSIS 3.0+ aggregate rates rely on how many channels/blocks are actually allocated on your local plant.
Key Takeaways
- 3.0 vs. 3.1: DOCSIS 3.1 introduces OFDM/OFDMA, higher QAM (up to 4096-QAM), better efficiency, and multi-gig downstream with higher uploads—making it the present-day sweet spot for owned retail modems.
- 4.0 = upload leap: Targets up to ~6 Gbps upstream and ~10 Gbps downstream via FDX or ESD with expanded spectrum to 1.8 GHz (downstream) and 684 MHz (upstream). Retail 4.0 modems aren’t broadly available yet; early access is via ISP-supplied gateways.
