Due to the wide spread of the installed base of the PSTN physical infrastructure, PSTN has been the basis for fast and efficient development and penetration of the Internet. In the pre broadband phase this was implemented by modulation of data signal in the same frequency spectrum as regular voice in the copper access lines. The data capacity in this frequency bandwidth is small and it can reach the maximum of 56 kbps. The next phase was introduction of ISDN, which improved the capacity and could offer 128 Kbps to residential households.
While dial up PSTN modems and ISDN have had enormous impacts on the development of Internet access, today the Internet connectivity is mainly influenced by different broadband technologies. The new IP broadband infrastructures are in the literature denoted as the New/Next Generation Access technologies (NGAN). NGAN covers both the fixed (wired), wireless and mobile infrastructures, which enable IP connectivity to the households and companies. The terms NGAN and broadband can be used interchangeably, however the important thing is that NGAN is not only characterised by higher capacity networks but also by the two other main characteristics, namely: 1)'always on' provision model, and 2)the flat rate business model.
With regards to the fixed networks the NGAN is mainly dominated by xDSL and cable modems. The advantages of the xDSL and cable modems are the availability of the physical infrastructure and by that the low deployment cost. Other fixed technologies like PLC have been on the market for some time, however it is difficult to see how this technology can compete on the NGAN market other than when it comes to home networking, which is at best peripheral to NGAN. Another fixed network with huge potentials is the fibre access networks.
NGAN is also affected by the development of wireless and mobile technologies. Wi-Fi and WiMAX and their combination seems to have huge potentials. Also satellite, broadcast and new mobile infrastructures are important in development of NGAN.
In this section the most important NGAN are described and organised in two major categories, Fixed and Wireless:
Fixed:
Wireless: