Thanks to the raging debates on spectrum allocation over the past few years, it is fairly well known that spectrum, which is the veritable oxygen of mobile service, is basically a finite and limited resource. And the mobile industry in India has a total spectrum of less than half of what given to industry in other countries. Regrettably, this handicap right at the start is considerably worsened by the fact that we, in India, have 3-4 times the level of competition available elsewhere; obviously, therefore, spectrum per operator in India is far less than elsewhere. Not only is the allocated spectrum considerably less and fragmented, but also not contiguous, i.e, given in separate chunks.
One would tend to think that the less spectrum per operator is more than compensated by the fact that there are more operators and so more subscribers can be served. However, such thinking would be wrong, because this is where spectrum physics weighs in with a significant difference. Due to a spectrum technology characteristic called trunking efficiency, the overall network capacity increases disproportionately with more spectrum. Simply put, in spectrum physics, 2+2 is not 4, but much more.
The number and the size of spectrum fragments allocated affect the utility of the spectrum. For each individual fragment to be useful, it must be used in such a way that it does not harm users operating on frequencies adjacent to each spectrum fragment, thus necessitating use of ‘guard bands’. For large blocks of spectrum, such as for 3G services, this does not present a significant problem, as it is only the extreme edges of the assigned blocks that are constrained by the need to protect adjacent users. The more the fragments, the more such extreme edges, and consequently, wastage due to guard bands and reduced efficiency.
The accompanying graph shows the increase of capacity and spectrum efficiency with spectrum allocation. Here, the graph is plotted between the frequency (MHz) and traffic density (Erlangs) and shows the exponentially increased capacity and the spectrum efficiency. While 6 MHz frequency delivers 40 erlangs capacity, 12 MHz delivers not 80 but 110 erlangs!
Looking at it another way, increasing fragmentation with a given amount of spectrum actually destroys part of the network capacity!
The accompanying graph shows that, for a given amount of spectrum (50/60/70 MHz), the more the number of operators, the sharper the drop in network capacity. For example, 4 operators deliver more than twice as much capacity as twelve! Hence, to maximise network capacity for the benefit of the nation, one needs to optimise the number of operators by balancing between competition and spectrum efficiency.
It is of critical importance for mobile network operators to be able to quickly and efficiently upgrade their networks to 3G, 4G and higher technologies to be able to deliver higher bandwidth services and thus provide customers with the benefits of such services. However, higher technologies require bigger blocks of spectrum and can not work with smaller fragments or chunks. They need at least 5MHz, preferably 10 or 20 MHz.
Mobile technology works on the basis of reuse of frequencies in cells distanced from each other. However, if the spectrum is less, the same frequency will obviously have to be reused in closer cells, which means higher investment in infrastructure. Such increased reuse, would surely increase the probability of interference, causing call drops and other unwanted effects that make the customer experience poor. Thus, in a bizarre manner, more investment results in more interference and call drops!
As explained above, if spectrum is fragmented and not provided in bigger blocks, then more cells are needed, i.e., more towers and network equipment, etc. This sharply increases the cost of network and service provision. Consequently, user tariffs would also be higher. China has less operators and less sites, but higher network capacity! China achieves double the capacity of India with less operators and one quarter of the towers/ cell sites. Of course, it provides per operator spectrum that is several fold ours.
India could have done without such a large number of telecom towers if only the spectrum had not been fragmented. It is estimated that with spectrum blocks as in China, India could have saved at least 30% of its towers with many consequential benefits. The more the towers, the more the diesel consumption via the backup generator for each tower. The nearly 4.5 lakh towers in the country are estimated to consume over 3 billion litres of diesel per year. The energy savings due to less towers would therefore be a huge number—equivalent to possibly one or two large power stations’ output. India can ill afford such wastage.
Apart from the serious energy losses caused, increased number of towers /cell sites represent huge environmental challenges due to public concerns regarding aesthetics, radiation hazards, etc.
Fragmented spectrum has less value for the operator. Hence, if the government were to auction larger blocks of spectrum, it could hope to garner more revenue apart from reaping the various other benefits detailed above.
Thus, fragmented and inadequate spectrum harms all—the consumer, the economy and the nation. India needs to urgently align itself with international best practices to exploit the full benefits of available spectrum.
The author is honorary fellow of the Institution of Engineering and Technology, London, and is a telecom consultant. Views are personal