Page 122 - ITU Kaleidoscope 2016

Service and Network
RRH-Balloon
Orchestration

UAVs Network RRH-UAV SP-Node
RRH-UAV SP-LC

50 km
SP-Node

DTN SP-Node Optical Transport
Network
Radio Link SP-Node
Optical Link SP-Node

Fig. 1. Vision of a 5G network for rural and low-income zones. (SP = solar powered, LC = Large Cell, RRH = Remote Radio
Head, UAV = Unmanned Aerial Vehicle, DTN = Delay Tolerant Network, NODE = Flexible component that can act as micro
server, BBU, SDN switch and optical router).

the deployment of radio elements covering ultra-large cell gies. Specifically, for rural zones with a limited number
sizes (over 50 km). It is widely acknowledged in academia of users, coverage and capacity may be provided by RRH
and industry that deployment of very large antenna arrays mounted on top of UAV (RRH-UAV). These devices can
at the base station side will form a key component of the provide flexible coverage over a territory, by considering
5G radio standards that very recently have started to be ad- only the zones where the users are located. Moreover, RRH-
dressed by 3GPP. Technologies in academia referred to as UAVs can be exploited when the capacity of the network
massive MIMO are in the heart of the urban, capacity-driven is needed (e.g., during the day). Each RRH-UAV establish
5G use cases and scenarios. Moreover, the energy-efficiency communication with the other RRH-UAVs flying in the same
of these very large antenna arrays is also promising for the zone. The goal is then to compute the UAV trajectories in or-
noise-limited, low-load rural and remote coverage scenar- der to optimize the coverage of the zone where the users are
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ios. The large arrays can accomplish a beamforming gain located. In addition, the RRH-UAV will establish a radio link
that will beneficially affect the link budgets of large macro- with a BBU mounted in selected Solar-Powered (SP) Nodes
cells. The pencil-sharp radiobeams produced by these base 7 . The challenge here will be to develop smart solutions to
stations allow to increase the cell radius without compro- reduce the amount of information exchanged between the
mising implementation complexity, cost-efficiency or energy RRH-UAVs and the SP-Node with the BBU. Notice also that
consumption. Finally, we foresee the exploitation of new he UAVs can be recharged by power stations fed by solar
ultra-lean radio-protocols, which will be developed with the panels. In addition to this, RRHs are also mounted on top of
explicit goal in reducing the transmission overhead of the ra- balloons. These elements are continuously flying in the at-
dio nodes and improving their energy efficiency [38]. mosphere in order to provide basic coverage and emergency
services. Finally, each community connected to such an in-
frastructure may develop Delay Tolerant Networks (DTNs)
4.2. Overall Architecture
to further spread the information by means of low-velocity
Our vision aims to develop a comprehensive low-cost con- vehicles (i.e., mainly bicycles). As second alternative to pro-
nectivity architecture that can efficiently support a wide- vide wireless access connectivity, we foresee the exploitation
range of services and applications. Fig. 1 reports the pro- of Large Cells (LCs), with coverage radius in the order of 50
posed architecture. Focusing first on the access part of the km. Such cells can be spread in low-income areas where the
network, we foresee the exploitation of different technolo- users requirements are low in terms of bandwidth and delays.
LCs are also powered by Solar Panels (SPs), since the power
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We refer the reader to the Facebook project ARIES: https:
//code.facebook.com/posts/1072680049445290/ 7 This solution has to be evaluated w.r.t. the LTE UL-HARQ latency
,lastaccessedon1stJuly2016. constraint.