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Technology Transition: Innovation in access networks leads to improved speeds

August 01, 2013

The uptake of high speed internet services has picked up over the past few years, though it still lags far behind voice services. The number of broadband subscribers increased from 5.52 million as of December 2008 to 14.98 million as of December 2012. Although the majority of these subscribers are using fixed broadband services, the introduction of 3G and 4G technologies has resulted in an increase in the share of wireless broadband subscribers. As per the Telecom Regulatory Authority of India, the wireless segment’s share in the total broadband subscriber base increased from 1.3 per cent as of December 2008 to 3.11 per cent as of December 2012.

The increase in broadband usage can be attributed to service providers’ ability to offer users higher bandwidth at lower rates. This has been achieved through constant innovation in broadband access technologies, for both the wireline and wireless segments. New technologies have not only facilitated a higher data transmission rate but also reduced latency and attenuation, which, in turn, has enabled service providers to offer bandwidth-intensive services such as video-on-demand, IPTV, file sharing, gaming and VoIP.

Of the several wireline broadband access technologies available in the market, digital subscriber line (DSL) continues to be the preferred medium with 84.82 per cent market share. Ethernet/LAN technology has also witnessed considerable uptake in the recent past. In contrast, the deployment of fibre has been limited due to high upfront costs, but is likely to witness significant growth on account of an expected rise in demand for bandwidth-intensive services going forward. On the wireless front, both 3G and 4G technologies are being increasingly implemented to provide high speed broadband services as the majority of users will access broadband through mobile devices in the future.

tele.net takes a look at some of the competing broadband access technologies in the market…

 Wireline broadband technologies

The most commonly deployed wireline broadband access technology is DSL, which delivers bandwidth over a twisted pair of copper wires. Depending on speed and bandwidth requirements, service providers use different variants of DSL for providing broadband services to end-users. Asymmetric DSL (ADSL) technology, which offers a higher downstream rate than upstream, provides a maximum downlink speed of 12 Mbps. In contrast, symmetric DSL, which offers the same downstream and upstream data transmission rate, provides a maximum speed of 3 Mbps. However, the two technologies suffer from high attenuation, resulting in reduced speed over long distances. For instance, ADSL offers a downstream speed of only 500 kbps at a distance of 5.4 km and therefore, cannot be used for providing IPTV and VoIP services. Newer technologies such as VDSL and VDSL2 offer downstream data transmission rates of up to 50 Mbps and 100 Mbps respectively, which also fall drastically after a distance of 500 metres. Nonetheless, VDSL2 is the most preferred access technology owing to its higher transmission rate and cost advantages over competing technologies such as fibre.

Another access technology is data over cable service interface specifications (DOCSIS), which is widely deployed by cable operators. DOCSIS 2.0 technology allocates higher and lower frequency bands of the 6 MHz carrier for downstream and upstream data transmission rates respectively. It allows cable operators to offer downstream speeds of up to 40 Mbps. However, a typical downstream channel services over 1,000 subscribers, which limits the bandwidth available to the end-user.

With an increase in demand for high speed broadband services, DOCSIS 2.0 is being replaced with DOCSIS 3.0, which overcomes the speed limits associated with the former through a bonding technique. DOCSIS 3.0 bonds multiple carriers resulting in a downstream transmission rate of 400 Mbps. Using DOCSIS 3.0, cable operators can offer high-bandwidth services such as high definition (HD) video, gaming and IPTV, which allows them to compete with internet service providers. However, the number of carriers that can be bonded depends on the quantum of radio frequency spectrum available to cable operators. Following the expected launch of DOCSIS 3.1, cable service providers will be able to offer a minimum speed of 5 Gbps.

Meanwhile, deployment of fibre in access networks is gaining traction owing to its unlimited bandwidth capabilities. Fibre-to-the-home (FTTH) architecture provides full fibre connectivity till the customers’ premises, thus offering maximum bandwidth amongst all wireless access technologies. However, the costs associated with an FTTH connection are the biggest constraint in its implementation.

The two most commonly deployed fibre technologies are gigabit passive optical network (GPON) and point-to-point (P2P) Ethernet. P2P Ethernet offers a dedicated optical fibre connection to the end-user, which ensures availability of maximum bandwidth (100-1,000 Mbps) but at a significant cost. In contrast, GPON technology, with a point-to-multipoint (P2MP) topology, splits the total bandwidth (100-1,000 Mbps) and cost amongst a maximum of 64 end-users, which makes it viable to offer modest broadband speeds at considerably lower prices. Ethernet PON is another technology that uses P2MP. It transmits data using Ethernet protocol instead of the asynchronous transfer mode protocol used by GPON.

 Wireless broadband technologies

Wireless broadband access technologies include P2P microwave, local multipoint delivery systems, GPRS, EDGE, HSPA and long term evolution (LTE). These technologies can operate in licensed or unlicensed spectrum through P2P or P2MP topologies. Fixed wireless broadband technologies such as P2MP microwave, which require line of sight for transmitting signals, are used to provide broadband services, especially in difficult terrain. Local multipoint distribution service (LMDS) and multichannel multipoint distribution service (MMDS) use P2MP architecture to transmit signals in the lower (2.1-2.7 GHz) and higher (27.5-29.5 GHz) bands of ultra high frequency spectrum. While MMDS has bandwidth limitations, LMDS offers high bandwidth only up to a distance of 8 km. Consequently, both LMDS and MMDS have limited application in access networks.

Meanwhile, cellular technologies such as Wi-Fi, EDGE, 3G, Wi-Max and LTE are gaining traction due to the growing demand for on-the-go broadband access. Wi-Fi is the only access technology that uses unlicensed spectrum for data transmission. It uses spectrum in the 2.4 GHz band to provide speeds of up to 54 Mbps within a distance of about 30 metres and therefore, cannot be deployed for wide area coverage. Wi-Max technology, which is based on IEEE 802.16e standards, overcomes the distance limitations of Wi-Fi and can offer speeds of up to 75 Mbps within a distance of 10 km. In the future, Wi-Max is expected to deliver speeds of up to 1 Gbps with the introduction of the new IEEE 802.16m standards.

Another popular cellular technology is GPRS (2.5G), which uses packet switched functionality to transmit data, unlike the circuit switched functionality used by 2G. GPRS gained widespread adoption due to its better downstream and upstream data rates, of 114 kbps and 20 kbps respectively, as compared to those offered by 2G. Subsequently, EDGE was released, which was an improvement over GPRS. The technology provides downstream and upstream speeds of 384 kbps and 60 kbps respectively, by implementing a modulation technique – 8 phase shift keying. Mobile operators use EDGE to offer various value-added services including music applications and low resolution online games. EDGE is, however, not capable of supporting HDTV and videoconferencing services.

Innovation in mobile access technologies has resulted in the development of next-generation technologies such as HSPA, HSPA+ and LTE, which offer maximum download speeds of 14.4 Mbps, 56 Mbps and 100 Mbps respectively. In addition, latency is less than 50 milliseconds (ms) with HSPA+ while that with LTE is less than 5 ms. Lower latency enhances a mobile network’s ability to deliver videos with reduced lag. Consequently, several operators have upgraded/shifted to these technologies to cater to the demand of their customers. In order to push data transmission rates, 3GPPP is working on developing standards for LTE-Advanced, which has the capability to offer download speeds of up to 1 Gbps.

 Conclusion

With a host of options available in the market, selecting the right access technology has become a challenge for service providers. In the wireline segment, operators have the option of deploying fibre or DOCSIS. While fibre offers unlimited bandwidth potential, right-of-way (RoW) and high capex requirements impact its implementation. In contrast, DOCSIS does not involve RoW issues as it can be deployed over the existing copper cables, but it is yet to match the speeds offered by fibre. In the wireless segment, LTE and Wi-Max are the frontrunners. Although most telecom operators are deploying LTE networks to offer high speed broadband, Wi-Max is also gaining traction in certain regions as it is expected to provide enhanced bandwidth in the future. Above all, a key consideration for service providers while making a technology choice would be the data usage patterns of their customers as well as the return on investments.

 
 

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