Hello, everyone!
Today, I would like to share with you an article on DSL technology and its comparison.
Table 1. Comparison of DSL systems in use or being introduced.
Figure 1. Typical reach vs. bit rate in DSL systems using twisted pairs in telephone cables.
Bandwidth and bit rate data in Table 1 are maximum values set in standards. Reach achieved in service depends on cable design and its technical condition; data in Table 1 and Figure 1 are only indicative.
Performance of DSL link can be improved by pair bonding: the use of two or more copper pairs for parallel transmission, most effective when combined with vectoring.
Figure 2. Top download rates offered to residential customers
Comparison of Figures 1 and 2 suggests that further upgrades of legacy copper networks are not feasible, as system reach becomes too short for most purposes, barring exceptional situations like historical buildings in Europe, where installation of new cables is strongly opposed.
This has been already experienced with gigabit version of G.fast system. Despite issuance of standards in 2014, large-scale deployments began only in 2017, and operators prefer 250 Mb/s products with reach of approx. 200 m.
However, development continues—a prototype XG-FAST system transmitting 10 Gb/s at a distance of 30 m over one or two pairs, using 500 MHz bandwidth.
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