CTN Issue: November 2015

A note from the editor:

Continuing the theme of the next billion users and how 5G might affect them, this month we have an article coming out of Sweden by Mats Eriksson and Jaap van de Beek that considers the impact of 5G on rural users. Even as Google touts “Project Loon” [11], stating " two-thirds of the world’s population does not yet have Internet access", 5G seems to be solidly focused on the most dense of urban environments. In these authors' words, "5G is becoming an urban system". Mats and Jaap have worked with both Ericsson and Huawei on wireless system development;  Jaap is now a professor in signal processing at Luleå University of Technology; and for a while now they have been asking the question, "what about rural access?". In this article they provide some thoughtful answers. Hope you enjoy it. As always, comments are welcome.

Alan Gatherer, Editor-in-Chief

Rural 5G: Oxymoron or Opportunity?

Mats Eriksson, CEO, Arctos Labs Scandinavia AB
Jaap van de Beek, Luleå University of Technology

Today, most telecom players are ramping up their activities on "5G"; and, as for previous generations of cellular systems,  there is an ongoing vibrant discussion about its critical, most important services and use-cases. New 5G-capabilities include radically higher bandwidths and lower latencies which its designers  hope will enable virtual-reality, tactile internet, and control of moving things in real time.  The industry generally focuses on capacity as the most crucial issue. This is technically supported by proposals based on more spectrum and dense deployment of base stations. All of this is  extremely challenging and will keep the industry busy for another decade.

But are these focal points the most important telecom issues for the world as a whole? Are these issues what we should be focusing on  as a long-term global perspective?

With the ITU estimating that 3G covers 69% of the world’s population [1] a staggering two billion people still have no coverage, most of them in rural areas. On a global scale, Internet connectivity is generally urban in nature. The digital divide is widening and is arguably of much larger concern than a local tenfold capacity increase in downtown Manhattan or in the streets of Tokyo.

Recent initiatives by Google [11] and Facebook [12] are rooted in a deep recognition of the above situation and both initiatives adopt a revolutionary aerial network topology. But how do traditional stakeholders act? What are the answers provided by the traditional telecom industry, its vendors, operators, service providers? How could the reigning terrestrial solutions and 5G evolve to connect rural areas to the Internet? Can we see contours of how to tackle the widening digital divide?

The silence is remarkable. The authoritative 5G white paper by the Next Generation Mobile Networks Alliance (NGMN), published earlier this year [2], sketches many scenarios and use-cases for the urban citizens of the coming decades. For the majority of the world's population, 5G has seemingly little to offer. Rural connectivity is limited to 400-person villages and to low Average Revenue Per User (ARPU) regions, with focus on the residential patterns, ignoring nuances in regional mobility. An important plea for low-cost 5G solutions comes with a list of technologies and services that could be stripped off in order to reduce costs. But most worrying is that the "Coverage Everywhere" regime in the document is restricted to a "service area", those places where operators will choose to roll out their networks. Target data rates are "indicative, depending upon the 5G technology evolution to support these figures economically".

Rural regions suffer the same fate in the recently closed European FP7 flagship project METIS where the larger vendors and operators joined forces. Here, rural 5G coverage is found under Test Case 7 ("Blind Spots"), in a scenario with 100 users/vehicles per squared kilometer. This is  disappointingly associated with a disclaimer: "high data rate coverage is expected at every location of the service area even in remote rural areas" [3] (our italics). No ambitious targets with respect to areal coverage as for other KPIs in the document, no concrete coverage figures – indeed, no further mentioning at all.

Mainstream telecom business, to a large extent, ignores the issue.  This silence should not come as a surprise. Not only is it well known that the building cost of a network is related to the area to be covered, but more importantly, as recognized in [4], "the real barrier to rural deployment is the lack of potential revenue per square mile. The revenue potential for a wireless carrier in a major urban center is $248,000 per square mile of service. By contrast, in the least densely populated areas, the potential revenue per square mile drops as low as $262 per square mile." There simply is no good commercial reason today to connect the un-connected part of the world's population, and hence little substantial and necessary research is carried out.

While spectrum scarcity is not a problem [5] there appears to be a growing need for regulatory and societal 5G-initiatives to achieve progress. Like water, electricity and sewage systems, mobile broadband, too, is rapidly become a basic human need and comes with associated structural transformations for society and policy makers.

Regulation of coverage is not new. Initial cellular generations were rolled out under tight regulatory requirements. Although these have been relaxed in 3G and 4G, recent 3GPP standardization for mission-critical communication in LTE-A (proximity-based services and network-assisted D2D [6]) are influenced by new societal and regulatory demands for improved public safety (not really the high revenue regime many an operator would wish to address).

There are compelling societal arguments for improved 5G rural coverage: counteract urbanization, improve public safety, develop e-health and entertainment services that make these regions attractive places to reside. In a near future, regulations with respect to rural coverage may well come back to influence research, standardization and network operation. The public sector may become involved in the development of networks and we cannot even preclude new unlicensed types of operation, where users, villages, society or companies would contribute to the network, on voluntary basis.

While, on one hand, appropriate (low-frequency) spectrum bands must be assigned, equipment, on the other, must be cheap and energy-efficient. Only through standardization of key aspects (de facto or 3GPP) is this cost-efficiency possible. But extensive dedicated research is needed.

Fortunately, academia has been devoting some efforts to the issue — there appear to be a number of promising technologies and innovations where dedicated research could anchor. Base stations equipped with a large number of antennas when researched for multiplexing and capacity also hold a beamforming promise and potential coverage-extension in thermal-noise dominated regimes [7]. Cheap, energy-efficient battery-powered relay stations with intelligent sleeping modes that support the critical uplink channel have been studied for rural coverage [8], while [9] contains a study on base station switching approach for energy efficiency. New, simple control and scheduling mechanisms for TDD-mode in an (ultra-)low capacity regime can improve cost- and energy-efficiency. A joint operation with TV broadcast services [10] has recently been studied to provide for a highly needed cost-efficiency.

In summary, we believe 5G research efforts are alarmingly disproportionate: 5G is becoming an urban system. We expect that in a near future the public sector in many countries will show a highly needed tighter engagement. The research community should take self-initiated, change-oriented and anticipatory steps to support such engagement, for which references to this post provide some good examples.

References

1. International Telecommunication Union (ITU), "ICT Facts & Figures – the world in 2015", 2015. Available from http://www.itu.int/en/ITU-D/Statistics/Pages/facts/
2. NGMN Alliance, “5G White Paper”, Editors: Rachid El Hattachi,  Javan Erfanian, 17 February 2015. Available from http://www.ngmn.org
3. METIS, "Requirement analysis and design approaches for 5G air interface", Deliverable D1.1, Doc nr ICT-317669-METIS/D2.1, 29 April 2013, available from https://www.metis2020.com/documents/
4. A.-M. Kovacs, "Regulation in Financial Translation: Will the Incentive Auction Increase Mobile-Broadband Competition in Rural America?", May 2014.
5. D. Smith, "The Truth about Spectrum Deployment in Rural America", 16 March 2015. Available from http://mobilefuture.org/resources/
6. X. Lin, J.G. Andrews, A. Ghosh and R. Ratasuk, "An Overview of 3GPP Device-to-Device Proximity Services", IEEE Communications Magazine, April 2014, pp. 40-48.
7. F. Rusek, D. Persson, B. K. Lau, E. G. Larsson, T. L. Marzetta, O. Edfors, and F. Tufvesson, "Scaling up MIMO: Opportunities and Challenges with Large Arrays", IEEE Signal Processing Magazine, January 2013, pp. 40-60.
8. S. Jangsher, H. Zhou, V.O.K. Li, and K.-C. Leung, " Joint Allocation of Resource Blocks, Power, and Energy-Harvesting Relays in Cellular Networks ", IEEE Journal on Selected Areas in Communications, Vol. 33, no.3, pp.482-495, March 2015.
9. A. Kumar and C. Rosenberg, "Energy and Throughput Trade-offs in Cellular Networks using Base Station Switching", IEEE Transactions on Mobile Computing, DOI 10.1109/TMC.2015.2416181, in press.
10. L. Shi, K.W. Sung and J. Zander, "Future TV Content Delivery over Cellular Networks from Urban to Rural Environments", IEEE Transactions on Wireless Communications, DOI 10.1109/TWC.2015.2449841, in press.
11. www.google.com/loon
12. www.internet.org

Statements and opinions given in a work published by the IEEE or the IEEE Communications Society are the expressions of the author(s). Responsibility for the content of published articles rests upon the authors(s), not IEEE nor the IEEE Communications Society.