Thursday, November 12, 2015

The Buzz Around TV White Space

There's a war brewing around wireless broadband trials using TV white space in India

Shyam Ponappa  |  November 5, 2015

Large blocks of underused spectrum lie tantalizingly out of reach, waiting for enabling regulation, administration, and to some extent technology, to accelerate our move towards Digital India. One such category is unused/underused TV spectrum or "TV White Space" (TVWS). Despite growing demand, operators face bleak prospects as they struggle to deliver, starved of spectrum and infrastructure. Their dilemma is how to extend delivery capability without choking on buying spectrum so precious it's like an albatross around their necks, leaving little capital for densifying and extending their networks.

There's a war brewing around wireless broadband trials using TVWS in India, years after completion in other countries. These frequencies are most effective for long-range broadband. Mobile operators are watchful of developments such as Microsoft getting preferential access, triggered by announcements of its partnership with the Education and Research Network (ERNET) for countrywide rural broadband. Equipment suppliers also seem apprehensive of developments that could lead to swathes of spectrum being "unlicensed", reducing markets for their established products for licensed spectrum.

This article aims to clear some of the misinformation to facilitate policies for Digital India.

What is "TV White Space"?

There's confusion and disinformation about what TVWS is. Quite simply, TVWS is unused TV spectrum, or TV bands devoid of TV signals. The meaning derives from the areas on a page without print or pictures. Microsoft calls [the technology developed for] it "White-Fi", while some call [the technology developed for] it "super Wi-Fi".

Even bands broadcasting TV programs can have underutilised sections that can carry broadband, as pioneered by researchers at Rice University in Houston, Texas. Rice has a system that uses TV bands for both broadcasting as well as broadband.1 According to researchers, although the 400 to 700MHz band is used for broadcasting TV in many US cities, its capacity is largely underutilised because of alternative ways of accessing TV signals, such as through cable, satellite, or Internet TV. Therefore, incorporating Rice's technology in TV sets or remote equipment could significantly expand the urban reach of "super Wi-Fi", and not restrict it to rural areas.

Is there any TVWS in India? Some say there isn't!

Studies across the country show that over most of it, unused TV spectrum (white space) amounts to 85 to 95 per cent of TV spectrum.2,3,4 Studies excluding northern India show that in over a third of the area, a large band -- 470 to 585 MHz -- is available for alternate use.2,4

An odd controversy has been created about whether this is "white space" or not, precisely because the spectrum is largely unused.5 The convoluted semantics are mystifying, because white space is by definition unused broadcast spectrum. The National Frequency Allocation Plan already designates this band for fixed or mobile wireless, in addition to TV. In other words, without changes in allocation, operators can share TV spectrum on a secondary basis, as in the USA, the UK, and Singapore.

Regarding spectrum usage charges, as with any infrastructure, it is much more beneficial in the public interest to provide affordable services first and to collect government fees and taxes later, than to front-load auction fees and have no services at all (imagine road systems if up-front charges had to be paid for the right to build them). Overall benefits from Digital India, which is impossible in the foreseeable future without low-cost wireless broadband connections to the NOFN and other backbone networks like ERNET, will far exceed cash collections from auctions.

Proponents of auctions suggest that TVWS be reallocated as cellular spectrum and auctioned. Their reasons: (a) The transfer of public property to private operators; (b) Transparency and fairness; and (c) Government collections. This reasoning is false and misleading, because: (a) No transfer is required, as all operators can get secondary access equitably through a consortium approach; (b) This ensures transparency and fairness; and (c) Government collections from productive use will far exceed any auction collections, as evidenced by licence fees: in 2005, estimated auction fees lost until March 2007 were Rs 20,000 crore, whereas actual collections were double, at Rs 40,000 crore; collections by March 2010 were Rs 80,000 crore, in addition to the public benefits of better services.

Should TVWS be used only for 3G & 4G?

Another negative argument is the insistence that TVWS should be auctioned for 3G and 4G. Whereas Digital India needs low-cost wireless broadband, especially for long-distance links in rural India, because of the high cost and difficulty of building and maintaining fibre or wired networks in difficult terrain, and/or in sparsely populated areas. Therefore, access to TVWS needs to be bundled with the National Optic Fibre Network/BharatNet, and other shared backbone networks like ERNET. Policies should permit different network design scenarios including transmission power and purpose. Point-to-point links are needed over long distances in place of fibre or microwave, and broad coverage is needed for contiguous areas like industrial developments, campuses, commercial complexes, or rural communities. At the user end, TVWS could interface through cellular (3G or 4G) or Wi-Fi transceivers.

TVWS does need tight radio filters (unlike Wi-Fi) to minimise interference, the underlying consideration that drives spectrum management. There's also need for varying power specifications depending on the network design and purpose as described above, and policies for unlicensed sharing using geolocation databases, as defined by the US FCC (Federal Communications Commission).

To be most beneficial, it is not important to extract the maximum carrying capacity from TVWS in every location, as in the misplaced number-of-subscribers-linked spectrum policy some years ago. Rather, the objective for Digital India is to use this technology in combination with others for the purposes people need, namely, for affordable broadband wherever they are, while mitigating radiation hazards. This is essential for India to get its basic communications infrastructure.




Shyam (no space) Ponappa at gmail dot com

1. http://news.rice.edu/2015/07/13/rice-tests-wireless-data-delivery-over-active-tv-channels-2/, Jade Boyd, September 5, 2014.
2. IIT-Hyderabad studied TVWS in southern India from 2009, shared findings with the government/other IITs from 2011, and published in 2014:http://link.springer.com/chapter/10.1007/978-3-319-08747-4_3#, Kalpana Naidu et al.
3. http://www.cse.iitd.ernet.in/~vinay/papers/coral13.pdf, Pradeep Kumar et al, June 2013, IIT-Delhi.
4. arXiv:1310.8540v1 [cs.IT], Gaurang Naik et al, 31 October 2013, IIT-Bombay.
5. https://www.linkedin.com/pulse/tv-whitespaces-how-white-spaces-parag-kar;http://www.financialexpress.com/article/fe-columnist/editorial-beware-the-white-spaces/146355/



COMMENTS

DEBASHISH

I think this whole issue of TV White Space is being clouded with needless convoluted semantics . The author also does not do much to ' clear the air '.Some basic facts have to be placed on the table and understood clearly. 

1. TV White Space ( TVWS )is not an access technology. Hence the comparison with 3G/4G/cellular technologies is infructuous. 

2. TV White Space is and is being positioned as a " Middle Mile " or a " Mobile Backhaul " technology. This means that it is supposed to compete/susbtitute with fiber or microwave. Indirectly, it is in direct competition to the Optical Fiber which is required to be laid between the Block and the Gram Panchayat ( GP )as a part of the NOFN/Bharat Net Project ! 

3. Going by the Expert Committee Report on NOFN, BBNL shall lay fiber at only 80% of the locations as it is not feasible to do so in the balance 20% locations. They have advocated the mixed use of UBR Backhaul technology (which works in the unlicensed bands ) and satellite technology for the technically non-feasible areas ! 

4. So , if at all there is a use case in the revamped NOFN project ( now called Bharat Net ) for such 'special technologies ' like TVWS, it is only in these 20% GPs only ( unless of course Govt. decides to abandon the fiber project and decide to opt for alternate long-distance wireless backhaul technologies ). 

5. TVWS is being touted as a " technology for providing Rural broadband ". However before we join the bandwagon, it may be good to step back and find out what are we talking about . The moot question is that is this truly a broadband technology ? What are the bandwidths that TVWS is capable of providing ? . In the classical NOFN architecture, each GP was to be equipped with 100Mbps bandwidth which was meant to be used by different Telcos/Internet Service Providers/Cable TV providers etc to provide broadband enabled services to the 640,000 ( and not 500,000 ! ) villages . The early results of the trials with TVWS technologies have indicated a throughput of ~10Mbps against a spectrum requirement of 10Mhz ( under ideal conditions ). By simple extrapolation, this means that to provide 100Mbps, it would need a minimum of 100Mhz spectrum ! Surely, this cannot be a very efficient way of using the spectrum , when the entire " White Space " available is of that order only ( Refer IIT Mumbai study report ). Also, it is quite clear that in GPs which have higher bandwidth requirements due to presence of co-located schools, hospitals , government offices etc , TVWS technology may not be appropriate for such higher bandwidth requirements. 

6. Digital India ensures provision of guaranteed broadband transmission bandwidths everywhere with guaranteed SLAs and not on ' best effort ' basis. We have yet to come across a single commercial network being run on TVWS technology anywhere in the world offering highly reliable ( five 9s grade ) and assured quality of broadband service. 

7. It may be prudent to point out that ' field proven' High Capacity Wireless backhaul technologies do exist ( which provide scalable capacities of upto 1-2Gbps ) at distances of upto 10-13 kms , which are in licensed spectrum bands. These are extremely low cost, highly efficient, interference free, Point to Point links which can meet the requirements and complement the government's fibre roll-out in a more cost effective manner than ' special technologies ' viz. TVWS , treated in a special manner ! 

8. Besides, the issue of auction vs free/unlicensed spectrum remains as another moot point where the business case of TVWS hinges on keeping it unlicensed and thereby leading to frittering away of ' precious ' natural resource viz. spectrum , in contravention to the SC guidelines. Given the hype and buzz , it may suffice to state that TVWS has not yet passed the peak of inflated expectations ! I think it would be prudent for the government to let the dust settle down, before making the next move ahead.
November 05, 2015

The author responDS 


Comments 1-5: A “comparison that is infructuous”: The article asks: “Should TVWS be used only for 3G & 4G?” The implied question: “or for other technologies including TVWS-specific ones?” The article also states: “…the objective for Digital India is to use this technology [TVWS technology, as against the spectral medium] in combination with others…” Yes, the term “TVWS” is applied to both the medium – the spectrum – and TVWS technologies, for the (new) technologies developed for that medium, namely, 802.22 and 802.11af. 

The commentator must surely know this, as also the TRAI’s recommendations on the next comment: 
“…direct competition to the Optical Fiber”: 
This perhaps reflects genuine confusion and/or lack of awareness of the complementary role of wireless backhaul (including TVWS). The article clearly mentions supplementing the backbone where laying fibre is too expensive or infeasible. The TRAI’s recommendations on microwave for backhaul discuss this in detail (see: http://www.trai.gov.in/WriteReadData/Recommendation/Documents/MW%20Reco%20Final29082014.pdf – “Recommendations on Allocation and Pricing of Microwave Access (MWA) and Microwave Backbone (MWB) RF carriers”, Telecom Regulatory Authority of India, August 29, 2014. 

The more fibre, the better. The question is to what extent it can be deployed cost-effectively. For the rest, other technologies and mediums are needed for the intermediate mile. 

“By simple extrapolation, this means that to provide 100Mbps, it would need a minimum of 100Mhz spectrum ! Surely, this cannot be a very efficient way of using the spectrum , when the entire " White Space " available is of that order only…” 

Comments like this appear to be misleading, especially when made by a commentator who seems to understand the technological implications: if there are more cost-effective ways, those are the ones to use. If not, use less perfect methods, including TVWS. The objective is connectivity at reasonable cost, not designing or deploying the most appropriate technology. Why should TVWS be used in any other way than to provide a 100Mbps link to a node to which it is infeasible for cost or other reasons to lay a fibre connection? What could be more desirable in the public interest? Surely not the optimization of some academic measure of TVWS usage. This is where the best is the enemy of the good. 

Comments 6-8

"6. …We have yet to come across a single commercial network being run on TVWS technology anywhere in the world offering highly reliable ( five 9s grade ) and assured quality of broadband service." 

Response
In the author’s surmise, this may be because the pioneers of TVWS-use and technologies (devices), namely, the USA, the UK, Singapore, already have good fibre and cable networks over most of their geographies. It is only on the fringes that they lack adequate connectivity. These are insufficient markets to provide the level of demand that could have otherwise led to proliferation, and therefore lower-cost devices and success. For instance, device makers are relatively small companies. So it’s a chicken-or-egg situation. The markets that are large enough are China and India, and both have started considering TVWS. Huawei has even acquired one of the early manufacturers, Neul, which was involved in the UK trials. The latter may be an indicator of possibly higher volume production and deployment, assuming Huawei knows what it’s doing (and it certainly seems to). 

"7. It may be prudent to point out that ' field proven' High Capacity Wireless backhaul technologies do exist ( which provide scalable capacities of upto 1-2Gbps ) at distances of upto 10-13 kms , which are in licensed spectrum bands. These are extremely low cost, highly efficient, interference free, Point to Point links which can meet the requirements and complement the government's fibre roll-out in a more cost effective manner than ' special technologies ' viz. TVWS , treated in a special manner !"

Response
This is partly true, but leaves out the rest of the relevant facts; else, if they were really low-cost (and unrestricted), such links would have been deployed extensively in India. Instead, the high cost (and restrictive regulations) make it impractical. This has resulted in the matter being taken to the Supreme Court [Supreme Court civil appeal No. D29714 of 2010]. All this is given in detail in the TRAI recommendations referred to above. 

"8. Besides, the issue of auction vs free/unlicensed spectrum remains as another moot point where the business case of TVWS hinges on keeping it unlicensed and thereby leading to frittering away of ' precious ' natural resource viz. spectrum , in contravention to the SC guidelines."

Response
Consider this: the objective is digital connectivity, in the sense of ubiquitous affordable access. It has not been achieved, and appears infeasible without lower cost access across rural India. If there are better, less expensive ways of providing it, suggest them by all means. If you can’t, think about (a) the objective (ubiquitous affordable access) and (b) constructive alternatives, and try to suggest practical solutions, and avoid misleading or ill-informed comments.  As for the Supreme Court guidelines, if the government formulates sound policies in the public interest, the court's aims will be well served.

9. "Given the hype and buzz , it may suffice to state that TVWS has not yet passed the peak of inflated expectations ! I think it would be prudent for the government to let the dust settle down, before making the next move ahead." 

Response
TVWS use with TVWS devices is not proven. That’s what the trials (mentioned in the article) are about. 

November 10, 2015