Securing Information Exchange

India's First Government Radio Network for Commonwealth Games

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Disasters manmade or otherwise are not new to India. We are continuously facing threats from terrorist outfits both internal and external, in addition to natural calamities like tsunamis and earthquakes. Plus, big events like elections, games, etc put additional burden on disaster response mechanism. In the past, calamities like the serial blasts that rocked Delhi in 2008 left Delhi Police in panic as conventional mechanism of information sharing at that critical juncture simply failed. Now that we have a big-ticket sporting event coming up, the first question that comes to mind is how to tackle emergencies, in case they arise. In this article we explore what kind of technologies are being used to make these games more secure.

Government Radio Network
Secure information sharing is the most important task to mitigate effects of any emergencies. Tackling disasters always needs coordination between different Government agencies. Delhi government has decided to create the first of its kind Radio Network that would help improve coordination amongst Delhi Police, Fire Services, Hospitals, Public Works Department, and the Delhi Transport Corporation during theCommonwealth games. HCL Infosystems and Motorola have signed a Rs 100-crore deal with the Delhi Government to establish this secure communication channel. HCL Infosystems has been involved in projects such as the Emergency Response Center for Police (Dial 100), Ambulance (Dial 102), etc in cities like Delhi, Hyderabad, Chennai, Bangalore, Bhopal, Nagpur, Pune, Bhopal, Dehradun etc in partnership with various state governments. On the other hand Motorola is involved in more than 600 mission critical radio networks all over the globe.

More users per RF channel for a given Grade of Service (GoS) can be achieved using trunking.

Now that we have slight idea about what is going to be implemented and what benefits it has let us look at the technological specifications. The radio network would be based on TETRA (or TErrestrial Trunked RAdio), which is a digital trunked mobile radio standard developed by the European Telecommunications Standards Institute (ETSI). The purpose of the TETRA standard is to meet the needs of traditional Professional Mobile Radio (PMR) user organizations. Benefits of TETRA can be derived by the technologies used in it, namely Digital, Trunking, and Time Division Multiple Access (TDMA).

Digital
To start with let's talk about benefits of digital analog in domains of Voice-quality, Non-voice services, and Security.

Voice-quality is further defined by clarity, distortion, noise and end-to-end transmission delay. In general all codec used in digital transmission would give constant quality, independent of RF signal strength; this is because digital signals either works or doesn't work. In comparison analog transmission would give high quality output at higher signal strength and vice versa.

The other aspect to compare between digital and analog is non-voice services. For the same occupied channel bandwidth, digital systems offer a higher data throughput than analog systems (that are primarily designed to carry voice communications). This is mainly because digital systems are designed only for transmission of digital information, which could be voice and/or data, with no differentiation.

It is much easier to encrypt digital systems when compared with analog systems due to digital nature of common encryption algorithms, which in turn are the best protection against eavesdropping.

Trunking
This technique let's you share the same frequency amongst multiple users, instead of providing different frequencies for each user. Though trunking adds more complexity and is relatively expensive to implement and it provides a lot of benefits, like spectrum efficiency, or more users per RF channel for a given Grade of Service (GoS), etc.

Time Division Multiple Access
TDMA technology used in TETRA provides 4 independent communications channels in a 25 kHz RF bandwidth Channel, making it twice as efficient in occupied bandwidth terms as a traditional 12.5 kHz RF bandwidth FDMA (Frequency Division Multiple Access) channel. Point to note here is that though FDMA technologies tend to have a better carrier to interference ratio performance than TDMA TETRA, the overall spectrum efficiency advantage lies with TETRA. Because trunking is employed to increase network capacity and/or RF spectrum efficiency (for a given Grade of Service) the cost and equipment space at base station site can be significantly reduced compared with traditional FDMA technology trunking solutions. Another benefit is higher data rate and wider channel bandwidth. The higher the data rate and as TDMA uses wider channels than FDMA; the combined data rate on a single RF carrier is greater. Besides higher data rates, TDMA offers better throughput in poor RF conditions due to full duplex nature. If specific application needs more data throughput, then time slots can be combined in TDMA, thus higher bandwidth can be provided on demand. Due to structure of time slots simultaneous transmission of voice and data is possible via single radio terminal.

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