Jack Zhu, Huawei's chief architect for access network product management, explains why telcos are looking for a mixed copper-fiber approach to keep costs down and speed up rollouts
Broadband Insights: The life of copper seems to keep expanding. What are the main reasons it is now being used along with fiber in mixed broadband deployments?
Zhu: Yes, the life of copper is expanding. One reason is the new innovative technologies such as vectoring and G.fast can bring higher bandwidth over existing copper. Another reason is after the initial roll out of FTTH, many operators found the cost of FTTH is huge for brown-field customers. And the FTTH roll-out speed was also too slow.
Examples include Deutsche Telekom changing from FTTH to FTTC and Australia's NBN also shifting from pure FTTH to FTTH + FTTN + cable access.
There's a great deal of talk about G.fast. What are its key advantages?
G.fast technology demonstrated that it can achieve 1 Gbps over existing copper, which is about 10 times faster than today's DSL technology. G.fast can reuse existing copper to avoid home fiber wiring and achieve fiber-like speeds. This will accelerate the superfast broadband network roll out and reduce the engineering cost.
What about vectoring technology, how is it being used with fiber to improve performance and bring down costs?
Vectoring is noise cancelation technology. Both VDSL2 and G.fast need vectoring to improve performance. But when talking about vectoring today, it usually means VDSL2 vectoring. VDSL2 technology is suitable for FTTC. Due to the crosstalk within the copper bundle, line performance dropped a lot. Vectoring technology can pre-add the anti-phase noise to let the end-user receive a clearer signal, which can improve line performance significantly.
Most existing CPE only needs a software upgrade to support vectoring. Vectoring with FTTC can reuse existing copper and requires no home visit, which can bring down costs.
Why would you recommend one over the other and vice versa - what are the specific market conditions for each?
G.fast, due to its high-frequency band, can only achieve higher access rates within short distances (the standard defined maximum is 250 meters for G.fast). We suggest G.fast be used as the alternative to FTTH through an FTTD (fiber to the door) solution.
Vectoring is more suitable for longer distances such as 500-800 meters through FTTC, and the per user cost will be much lower.