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Broadband over power line

Broadband over power line can be looked upon as among the best options to enhance broadband penetration in India. For this to happen, collaboration between Internet Service Providers and power companies is essential. By Kushal Shah

In 2004, the US Federal government had shown interest in having an alternative for delivering Internet access, and now there are reports that the Government of India is thinking along the same lines. Both governments had focused on the same concept—Broadband over Power Line (BPL)—which is an old idea, but has not been exploited commercially. To put it in simple terms, BPL is nothing but being able to access the Internet using your power sockets rather than a phone line or coaxial cable.

This technology can open fresh scenarios, for both power companies and consumers, but before peeking into the nitty-gritty of BPL, the present Internet scenario in the country is worth evaluating. According to a recent report by the Internet and Mobile Association of India and IMRB International, the number of Internet users in India in the ‘claimed user category’ had touched 46 million in September 2007 up from 32.2 million in September 2006, which is a high 40% year-on-year growth. The statistics seem impressive but discouraging when weighed against approximately 250 million urban population and 1.1 billion national population. We need a technology that can spread deep across the length and breadth of the country with the help of existing systems.

Broadband connections can be deployed using many diverse technologies, for example, fiber optics, satellite, wireless radio (Wi-Max/Wi-Fi), coaxial cable, and telephone twisted-pair (DSL). “All these technologies available for broadband implementation require extensive capital investments in order to reach all homes and business in any geography, whereas broadband over power lines is the technology that allows the use of existent power line or cables as a transmission medium, not only for energy but also for telecommunication signals, which saves a lot in terms of infrastructure cost,” said Dr Vishal Verma, Assistant Professor and the principal investigator of the BPL project at Delhi College of Engineering, which has been selected along with North Delhi Power Limited by the Department of Information Technology, Ministry of Communication and Information Technology for carrying out investigation on deployment issues, interference studies, and other R&D on the subject of BPL. If all of its shortcomings are rectified, BPL can be an effective means of spreading Internet even in rural areas and can buttress the number of Internet users outside the metropolitan centers.

An old concept

“BPL is a last mile technology with an old concept. It puts communication signals over the power line, which comes to your house,” said Subodh Vardhan, Director-Sales and Country Head for Government & Public Safety business, Motorola India.

BPL can be broadly categorized into two types—Access BPL and In-House BPL. The Access BPL network belongs to broadband service providers. In this, the service provider with the help of some injection devices injects data signals into the medium and low voltage power distribution power network in order to provide Internet access. BPL signals may be injected onto power lines in several ways on or between different conductors. Since BPL signals cannot usually pass through an electric distribution transformer, additional equipment is usually required to allow the data signal to bypass distribution transformers, or to regenerate data, in order to get the data signal into a consumer’s home. Access BPL equipment is primarily of three types, namely, injectors, repeaters, and extractors (Consumer Premises Equipment {CPE}). Both repeaters and extractors extract the data signal from power lines using a suitable method. Repeaters amplify the signal strength to carry the data signals seamlessly over the power lines for farther distances.

A typical BPL signal will only propagate along a power line for 1,000 to 3,000 feet before it becomes weak or distorted to be useful. “Though power lines can carry higher voltage levels for the data signals for avoiding or minimizing the use of repeaters, but with such strength of signals the power lines would act as antennas and interfere with wireless networks and radio signals in the vicinity,” said Verma. After the transfer of communication signal, at the consumer premises, customer premise equipment (CPE) extracts the data signals from the lines for its connectivity to computers or any other IP enabled electronic devices. The only thing that the user has to do is plug the modem into the socket and connect it to the computer.

In-House BPL makes use of indoor adapters to transmit data signals over existing interior electric wires within a home, and to connect the data signals to various appliances. In-house BPL systems use the electrical outlets available within a building to transfer information between computers and other home electronic devices and appliances which eliminate the need to install additional wires among devices.

BPL technology can even make use of Orthogonal Frequency Division Multiplexing (OFDM) to distribute the BPL signal over a wide bandwidth using many narrowband sub-carriers. At the BPL injector, data from the Internet backbone is converted into the OFDM signal format and is then coupled onto one phase of the power line. In order to minimize contention for the channel, Carrier Sense Multiple Access (CSMA) is used with Collision Avoidance (CA) extensions. The BPL signal may be sufficiently tolerant of co-channel BPL interference to enable implementation of two or three of these systems independently on adjacent power lines. If one wishes to use Wi-Fi at home, the architecture extracts data signal with CPE and then converts it into an IEEE 802.11b Wi-Fi signal for a wireless interface in the home network.

This system uses different radio frequency bands to separate upstream and downstream BPL signals, and to minimize co-channel interference with other nearby access BPL devices.

Advantage BPL

The biggest advantage of BPL is its ease of use. It can be deployed in a fast and cost-effective manner at the place suitable for its implementation. Giving an example, Naresh Ajwani, President-Consumer division, Sify said, “This technology can be very useful for deployment in multiple dwelling units wherein electricity comes in at one point and from there it goes to other parts. You do not need to put any cable or wiring [specifically] for the Internet. Secondly, if you have a laptop, you can use it wherever you want without a Wi-Fi network.” The technology is cost-effective when compared to other technologies if the number of consumers per transformer is sufficiently large and contacts on power lines are thoroughly coupled. “The technology should be highly cost-effective for rural areas for the last mile distribution through BPL. Further, the technology can even be instrumental in e-governance,” felt Verma.

This technology is even considered as being secure. In BPL, the QoS mechanism guarantees different bandwidth and latency to different users and different traffic flows. It is easier to intrude on information being sent through commonly used GSM phones than it would be to tamper with data transferred over the power lines as the exact modulation used must be known to demodulate a message addressed from one user to another, which is further dependent on Signal to Noise Ratio, which changes dynamically in real time. Thus, it makes the communication more secured. Unlike Wi-Fi systems, each node is identified by its MAC address. Both consumers and operators draw benefit from the advanced network isolation features, which offer a far higher level of security than that provided by most wireless technologies.

Apart from these consumer-based advantages, BPL can be used by power companies to solve their problems in the line with the help of communication signals flowing over the power signals. Other opportunities offered by the technology include automatic energy meter Reading (AMR), real-time system monitoring, preventative maintenance, voltage control, outage detection and restoration, load management on the power grid, load scheduling, load forecasting, capacitor bank control, and development of smart grids, which could add to conservation of energy and its control for the optimized use and offer more transparency in the system and would improve system reliability, service, and safety for electricity customers. So it is not only consumers who will be benefited, the service providers themselves will be more efficient and be able to provide better support.

The roadblocks

Every technology has to go through some roadblocks and disadvantages through its life cycle. Some of these handicaps prove to be so daunting that the technology cannot spread its wings in commercial space. For BPL, the problems are varied—technical, business as well as infrastructure-related.

First of all, for business, Internet providers and power companies have not yet been able to break the ice in terms of partnership. In India, they are finding it rather difficult to join hands with each other owing to several reasons. “Power companies want to implement this, but are asking for money. One thing, which they are not able to understand is that they will be one of the prime beneficiaries when the technology is stable and only then they should ask for a share,” pointed out Ajwani. He added that the industry has a ready infrastructure and only synergy needs to be exploited, which should be done in a proper manner.

In terms of infrastructure, BPL is facing problems from the side of electricity boards and their quality of wiring. In a country like India, where we have had unorganized growth of utility and infrastructure, we often find wires of sub-standard quality. Running broadband on these wires is not a wise option. “The quality of wiring is a huge problem in this country. We have to be dependable on the electric board for it. This technology can be successful in newly developed cities like Gurgaon but it is very difficult to get the best out of BPL in old South Mumbai,” explained Vardhan.

On the technology side, in India for example, several dozen residences are served from a single low voltage (LV) cable line operating at 230–400V which can cause problems such as radiated interference, which is typically confined to the immediate vicinity of the BPL wire and is governed primarily by two parameters—signal power and electrical balance of system excitation. Both these factors are a cause for concern in India because of the non-uniform nature of the supply network. Further, typical latency is below 3 ms. latency is dependent on traffic load and number of users, so this number may increase if the network is heavily loaded which may affect VoIP applications.

Getting ready for prime time

We have more or less everything in place for this technology to take off commercially. The major difficulties are seen in old infrastructure and partnerships which are certainly matters of management and which can be sorted out with some smart

decisions. Companies such as Sify and many other communication providers have realized this fact and have already begun their pilots to test technology feasibility and have started assessing business risks in it. With the help of institutions such as Delhi College of Engineering and others, which are part of research initiatives taken by the government, we can actually understand the on ground scenario for India and make best use of it. Due to our poor wiring infrastructure and other technical hiccups, at least for sometime, we might not see this as a technology for mass implementation, but it can be implemented in parts wherever feasible. A few industry experts are optimistic that if all goes well, we can see some commercial implementations within a year’s time.

kushal.shah@expressindia.com