Abstract
The deployment of Next Generation Access networks (NGAs) is likely to have a significant impact on the telecommunications’ value chain and, consequently, on the necessary regulatory remedies. In particular, unlike existing telephone networks, NGAs present regulators with a dilemma, in so far as the possibility of regulatory intervention after network deployment (negatively) affects investment incentives for such a deployment. We review the current discussion surrounding NGAs and discuss some of the main regulatory challenges it presents.
TopWhat Is A Next Generation Access Network?
An access network, commonly referred to as the local loop, is the part of the telecommunications network which connects the subscriber to the local exchange, where switching equipment is installed. Traditionally, access networks consisted of copper wire connections used solely for telephone services. Recently, these copper wire connections have proved to be good carriers for additional services such as broadband connections.
Most broadband connections provided by telephone operators are xDSL connections. xDSL is a broadband technology which uses existing copper wired telephone networks to carry data traffic. The provision of xDSL services requires the network operator to install additional equipment in an exchange, so that voice traffic is separated from data traffic (they travel together along the copper-based access network). Data traffic is sent to the DSLAM (Digital Subscriber Line Access Multiplexer), the entry point in the IP network, which concentrates subscriber lines and their respective traffic.
By far the most popular type of xDSL is ADSL, which provides more capacity downstream (from the network to the subscriber) than it does upstream (from the subscriber to the network). The problem with xDSL is that not all existing copper wired subscribers can benefit from it in the same way. The analysis of several xDSL products, such as ADSL2, ADSL2+, VDSL, HDSL1 or SDSL2, highlights a trade-off between maximum download speed and local loop length. For some types of xDSL (e.g. VDSL), that length is very small (up to 1.5Km), but can deliver maximum download (52Mbps) and upload (16Mbps) speeds which are much faster than ADSL. These speeds make the provision of triple play services – three communications services (voice, data and television) over a single broadband connection – a real possibility. For instance, OFCOM (2007) suggests that 25Mbps would be sufficient to carry simultaneous multiple HDTV3 channels, broadband internet and voice services.
Copper-based networks are investing in ADSL2+ deployment, which allows speeds up to 24Mbps. However, several factors such as the length, quality and dimensions of the copper cable and various other noise-contributing factors limit the overall availability of such speeds4. This suggests that offering triple play services through ADSL2+ may face significant limitations.
Key Terms in this Chapter
NGA Layers: The basic and media layers comprise the transmission infrastructure and the contents layer encompasses the communication and media services that can offered on such an infrastructure.
Triple Play: Provision of three communications services (voice, data and television) over a single broadband connection.
FTTCab: FTTCab (Fibre-to-the-Cabinet) is a network architecture where optical fibre replaces copper in the access network connection between the local exchange and street cabinets.
ADSL: ADSL (Asymmetric Digital Subscriber Line) allows voice and data to be sent simultaneously over the existing copper-based telephone line (ITU-T Recommendation G.992.1), with speeds up to 6Mbps downstream and 640Kbps upstream. In July 2002, the ITU completed G.992.3 and G.992.4, two new standards for ADSL technology collectively called “ADSL2”, allowing for a maximum 12Mbps downstream speed and 1.3Mbps upstream. In January 2003, a new standard called ADSL2+ (ITU G.992.5) doubled the bandwidth used for downstream data transmission, achieving rates of 20 Mbps on phone lines as long at 1,5Km.
Next Generation Access Network (NGA): Not fully copper-based access network, capable of providing broadband access services with sustained bandwidths clearly higher than those available with fully copper-based access networks.
FTTH: FTTH (Fibre-to-the-Home) is a network architecture which makes use of optical fibre to connect to the subscriber’s homes.
VDSL: VDSL (very high speed digital subscriber line) download speeds are in the 13-55 Mbps range, over short distances, usually between 300 and 1500 meters, using twisted pair copper wire. The shorter is the distance, the faster the connection rate. VDSL2 (ITU-T G.993.2) allows speeds up to 100Mbps each way, but depends crucially on the length and quality of the copper loop. For loops longer than approximately 1.6Km it no longer provides a faster bit rate than ADSL2+.
IPTV: IPTV (Internet Protocol Television) is a digital television service delivered through a broadband connection.
Ladder of Investment Principle: Regulatory principle with the objective of encouraging investment by both incumbents and new entrants and ultimately promoting network competition. It is based on the idea that investments by new entrants are gradual as their customer base increases, but until this happens several complementary services (provided by incumbents) are needed.
Next Generation Network (NGN): A multi-service (voice, data, video, etc) packet-based network in which service-related functions are independent from the underlying transport-related technologies.