Low-cost Wireless Network Architecture for Developing Countries Yvon Gourhant, Elena Lukashova∗ , Malla Reddy Sama, Sherif Abdel Wahed, Djamal-Eddine Meddour and Daniel Philip Venmani Orange Labs, Lannion, France Emails: {yvon.gourhant, mallareddy.sama, sherif.abdelwahed, djamal.meddour, danielphilip.venmani}@orange.com, ∗
[email protected]
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I. I NTRODUCTION The penetration of Internet is nearly at the beginning in most of the developing countries even if it is increasing day by day in some of these countries; 16% of Africans have access to the Internet whereas 75% in Europe and 61% in America according to 2013 Global Internet Usage [1]. We expect that the arrival of sub-marine cables in developing countries will bridge this gap. However, building mobile access networks in these regions presents radically different challenges than in western countries, considering low ARPU customers [2]. In this paper, we target wireless Internet connectivity in developing countries. The current way is to deploy 4G eNode B or 3G Node B at the same locations than the existing 2G sites, but the question of improving the throughput at the border of cells and extending the broadband coverage beyond those existing sites is still open. In order to go faster than with traditional business models, we propose to share passive infrastructure, tasks of marketing and management operations with infopreneurs rather than between Mobile Network Operators. An infopreneur acts as a local virtual access operator: she/he owns and manages the site, increases the operator customers by bringing more clients within his/her vicinity, taking care of sales, etc. This new business model fits developing countries because it takes roots on existing agents in charge of recharging prepaid cards (and/or mobile money account) who may extend their business. This is also an opportunity for Mobile Network Operators (MNO) thanks to cost savings. The counter part is that the site locations will be chosen by infopreneurs. In this paper, we propose a design of a cost-effective wireless network architecture that calls for deploying spot cells in order to extend 3G/4G coverage in the “some-what-dense”
spots that are out of range of existing sites and increase enduser throughput. A Spot Cell encompasses a Home e/Node-B(HNB) connected to a Home Gateway (HGW) which is connected to the traditional Node-B (NB)/eNode-B (eNB) through a directive antenna that increases the signal strength (see Fig. 1).
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Abstract—The emergence of Internet access and advanced wireless technologies has its limitations across the globe, i.e. today there exist several rural regions, especially in developing countries, that do not afford Internet connectivity. In this paper, we present a design of a cost-effective wireless network architecture that aims at providing Internet in fix-usage within those countries. We claim that with few design changes to the 3GPP architecture, it is possible to extend Internet connectivity within suburban and rural areas by deploying numerous hotspots based on sharing tasks and revenues with local actors. Index Terms—Developing countries, Internet, 3GPP, Small Cells
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Fig. 1. Proposed architecture providing 3G connectivity spots. Green colored links represent the traffic coming from infopreneur’s HNB with a secure tunnel set up between the HGW and the core network; orange colored links represents the traffic of traditional devices connected to the global operator. In the same vein, it applies to LTE/EPC architecture.
Thus, hotspots of connectivity for fix-usage Internet are provided outside coverage of a traditional NB without adding extra back-haul link since access from traditional NB is used for back-hauling the HNB. The motivation to design a new architecture rather than a new algorithm is that in the context of emerging countries we expect major cost savings from reusing mass-market products. Typically, the price of femtocells has critically reduced during the last months due to the high number of units sold in mature markets. Typically the cost of a femtocell is being now roughly equal to the price of a WiFi Access Point. Therefore, we propose a new way of integrating femto cells into the 3GPP 3G/4G architectures and a new business model based on sharing risks and revenues with infopreneurs. The related works are presented in section II. Our proposed architecture is described in section III. Section IV discusses the
practical feasibility of the proposed solution, and performance evaluations are presented in section V. Finally, section VI concludes the paper and gives some perspectives. II. R ELATED W ORKS There exist several ways to improve the throughput at the border of cells and to increase coverage beyond existing sites. Site sharing and/or outsourcing have been widely adopted, especially in rural areas of developing countries. Active network sharing has been set up by mobile network operators but mostly in Europe due to the ease of political/regulatory issues [3]. It has not been adopted in developing countries because the network sharing models defined in 3GPP standards [4] do not allow competition at network flow level. In recent literature ([5], [6]), they have introduced network operator differentiation along with sharing at the network flow level. In fact, serious changes are required on the 3GPP architecture (e.g., impacts on GTP protocol or Node B). 3G/LTE relays ([7], [8]) is a serious option for improving coverage, especially where wired infrastructures are lacking, but the cost saving is not enough for targeting ARPU of developing countries. This is mainly because of the major costs coming from passive infrastructure (tower or site rent, energy, civil works). We propose to reuse the infopreneur house and to share revenues. In that context, current relays implementations do not fit the requirements of our proposed business model due to the following reasons: (1) relays are usually under control of MNO for security issues, but they can’t be trusted in our business model; (2) their location is usually chosen by MNO in order to optimize coverage [9] and to reduce interferences; an update of radio planning is required each time a new site is deployed. Instead of this, spot cells should be plug-and-play in order to ease deployment and their location will be chosen by the infopreneurs. Our business model requires also counting the traffic going through every spot cells in order to share revenues with infopreneurs, and consequently to identify each spot cell.
and the end-users), accounting, backhaul and interconnection connectivity, and end-to-end (e2e) security issues. Spot Cells include outdoor HNB directly connected to the MNO network through HGW equipped with a 3G/LTE interface and passive directive antennas in order to get a better signal strength than simple UE. • Backhaul Connections/Resiliency: a HGW may have two 3G/LTE wireless point-to-point connections with 2 different nearest NB, one as primary link and other as secondary link, for resiliency purpose (Fig. 1). No additional backhaul links is therefore required for the spot cell (as in the case when it would be needed if a new traditional NB is added) thanks to the licensed 3G/4G spectrum provided by the traditional NB acting as the HGW backhaul connection. • AAA Server: the SIM details (e.g., IMSI) are registered in the MNO AAA system (Authentication, Authorization and Accounting). This registration is based on infopreneur slices shown in Fig. 2. The MNO takes care of supplying a bunch of SIM cards to infopreneurs, so its authentication server knows any User Equipment (UE) as well as the infopreneur HGW. The MNO bills all the clients and share revenues with infopreneurs. The HGW authenticates with global operator AAA server. After successful authentication, the AAA server allocates the APN address for the HGW. All HNBs connected to HGW may start SIM authentication process with AAA server which sends the HNB policies to HGW. Then the HGW allocates the local IP address for HNB. The enhanced AAA server detects end-users connected through a HNB in order to avoid charging traffic twice, since the architecture leads to a loop inside the core network. Add New Users Change Users Policies Change User Profile Etc.. Infopreneur_N
Add New Users Change Users Policies Change User Profile Etc..
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III. A RCHITECTURE D ESCRIPTION In the 3GPP standardized femtocell architecture ([10], [11] and [12]), HNB are connected to the mobile core network by a fixed network access through a HNB Gateway (HNBCore-GW). A typical HNB is a residential/entreprise femtocell with limited coverage range radius (
