By Nader Foroughi, Shaw Communications
The majority of MSOs outside plant architecture (OSP) consists of N+X. As time goes on the demand for capacity and speed in both upstream and downstream grows. Along with that, the era of symmetrical services is approaching as competitive pressure arises.
Fibre to the premises (FTTP) can help to meet this capacity demand but it is extremely costly. Over the past few years, many innovative alternatives and technologies have been proposed to alleviate this challenge. Full-duplex-DOCSIS (FDX) was one of the developed technologies in response to these demands. Although this concept is revolutionary, it requires the MSO to upgrade the OSP to a passive(N+0) state. This is more cost effective than FTTP, but depending on the operator, area of construction and plant type (aerial or underground), it can be quite costly. Moreover, FDX can be challenging from a technology implementation perspective, as it requires overlapping the downstream and upstream spectrum from 108MHz-684MHz.
Knowing that coaxial cable has 6GHz of useable bandwidth (BW) on average, last year the idea of extending the spectrum from 1.2GHz to 1.8GHz and eventually 3GHz was proposed, which gained a lot of traction in the industry. This can present different approaches to upgrading the OSP, to satisfy the future capacity demands.
In this paper an analysis has been carried out to evaluate the achievable capacity in an extended spectrum network. Capacity estimates have been based on the field measurements taken from the acquired 2.7GHztaps. Furthermore, a cost analysis has been carried out based on capacity estimations in a cascade of N+4.
Based on the analysis demonstrated in this paper, 1.8GHz extended-spectrum-DOCSIS (ESD) can be a great alternative to both N+2 and N+0 FDX. It can provide matching through puts as N+0 and N+2 FDX, at a lower cost. This allows an MSO to rapidly deploy this technology throughout their existing cascaded plant, in a cost-effective manner.