Developing low-cost Cellular Network Architecture for Remote Areas

October 30th, 2013

Local Cellular Network Services in Remote Areas

Main road into the village of Macha

To help alleviate the problems of high cost and low availability of cellular network access in remote rural areas, researchers at the MOMENT Lab of UC Santa Barbara have developed alternative solutions for high-quality local cellular network services.

Cellular network services have revolutionized the way people live. In developing countries, cellular networks have been used in creative ways to improve banking, healthcare and education. While the need and benefits of cellular network access are well understood, there is still a large discrepancy in affordability and accessibility between developed and developing countries. For example, while residents of developed countries allocate on average 2 percent of their monthly income for cellular services, in developing countries these numbers are typically as high as 12 percent and often higher. 

Furthermore, the accessibility to mobile networks varies largely across regions: while people in the Western world have access to fast-speed 3G and LTE services, those in rural sub-Saharan Africa and Southeast Asia primarily have basic GSM access. The reason for such discrepancy in affordability and accessibility is that "operators find it commercially infeasible to operate in rural areas" (World Bank, 2012).

 

Researchers are solving the problem of high-cost, low-availability cellular network access.

cellular networks
Figure 1. VillageCell architecture

Having recognized these challenges, researchers in the MOMENT Lab at UC Santa Barbara have endeavored to develop cellular network alternatives.  Several Institute for Energy Efficiency members are researchers in the MOMENT Lab, which is part of the Computer Science department.   These researchers have designed a low-cost cellular network architecture called VillageCell that makes use of inexpensive Software-Defined Radio (SDR) hardware, free open-source software, and the generic IP backbone to provide high-quality voice and text messaging services (Figure 1).

In order to field-test VillageCell’s feasibility and performance, they deployed the system in the rural community of Macha, Southern Zambia. The locals dubbed this installation “Kwiizya,” which means “to chat” in their native Tonga language.

Power challenges for the new cellular networks.

One of the challenges the researchers faced in their deployment was related to supplying electricity to the base stations. While some parts of the village are connected to the national power grid, the quality and availability of electricity varies largely. Figure 2 plots the minimum and maximum voltage values measured in 5-minute intervals over the course of two weeks. While the voltage in Macha is supposed to be 220 V, it varies largely over time and follows a diurnal pattern that is indicative of an overloaded power grid. Operation at capacity triggers continuous periods, referred to as brownouts, in which the voltage is lower than the nominal value. This is particularly harmful for computer and communications equipment. Designing a reliable power supply was an iterative process that involved trying out different components and running them continuously in the village to assure that they could operate without failures due to poor electricity.

  

A Base Station and Coverage Tester

Future research and network deployment.

To protect future deployments from damage and downtime, the researchers are transitioning to an off-grid solar power solution. Because each base station draws less than 35W of power, a relatively small and low-cost photovoltaic system can provide ample power. The trial photovoltaic system costs less than $1500 USD and consists of four 100W solar panels, a charge controller, and 300Ah of 12V batteries.

 

Figure 2: Electricity quality and availability in Macha

The field-tests in Macha indicate that VillageCell is capable of providing high-quality, low-cost basic cellular network services and has great technological potential to enable local entrepreneurs and improve the availability of cellular network services in rural communities. UCSB and Institute researchers are continuing their work to provide additional cellular network services with reliable, low-cost power supplies.


Author:  Mariya Zheleva, October 2013
Department of Computer Science, UC Santa Barbara
To read the full paper on this research, click here

References:
MobiSys’13, June 25-28, 2013, Taipei, Taiwan Copyright 2013 ACM 978-1-4503-1672-9/13/06
Authors: Mariya Zheleva, Arghyadip Paul, David L. Johnson and Elizabeth Belding 
Department of Computer Science University of California, Santa Barbara


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