Wireless Network Design: Optimization Models and Solution ...

15 Major Trends in Cellular Networks and Corresponding Optimization Issues 357
For low income populations, affordability is key. The relevant metric is user
TCO, which is the total cost to buy and use a mobile device. This includes the price
of the mobile device and the price of the service. An analysis of global income [25]
shows that 2.7bn people earn 2 USD or less per day, and have a budget of 3 USD
per month or less to spend on Information and Communications Technology (ICT).
Slightly higher up the income scale, we find that 2.8bn people have an income of
between 4 USD and 40 USD per month. Yet today the average TCO for the lower
income consumer is about 13 USD [21]. Clearly, the operators need to lower their
own TCO to be in a position to offer lower-priced services and still be profitable.
Innovation in the business model and cost structure is called for.
15.3 Overview of Solution Approaches
This section provides an overview of the most significant solution approaches, but
is not intended to be exhaustive. Subsequent sections provide more details on a
selected subset of solutions. In general, solutions attempt to reduce costs and/or
increase revenues.
The first challenge is the explosive growth in data traffic. As mobile data traffic
is expected to grow from 1.3 Exabytes in 2008 to 19.2 Exabytes in 2014 [11], and
users expect higher throughput and lower latency, an incremental upgrade will not
be enough. Operators will have to acquire new spectrum and overhaul the network
infrastructure from the base station all the way to the core network, including the
transport infrastructure. Furthermore, new technologies such as LTE (Long Term
Evolution) will be needed to achieve a quantum jump in the throughput and latency
compared to 3G [3].
A near term solution to alleviate the spectrum capacity problem is to use femtocells.
Femtocells are miniature cellular base stations, with relatively short radio
range, deployed in the home to provide regular cellular service to the users in the
household. Traffic to/from the femtocell is backhauled through the home’s fixed
broadband connection (xDSL, cable, etc.) to the cellular core network [16]. It
should be noted that femtocells offer other benefits such as better radio quality for
the user, and lower power drain on the mobile terminal. To take the U.S. as an example,
operators such as AT&T [10] and Verizon [36] are starting to offer femtocells.
Unlicensed mobile access (UMA) is another near term approach to alleviate the
spectrum capacity problem by offloading the cellular traffic to a WiFi access point
in the home [2]. As with Femtocells, UMA traffic is backhauled on the home’s fixed
broadband connection to the cellular core network. UMA-based service is currently
offered in the U.S. by T-Mobile.
A generalization of Femtocells and UMA is Smart Connectivity (SC). SC enables
seamless access to services in heterogeneous networks across a variety of access
systems (2G, 3G, LTE, WIMAX, WiFi, xDSL, PON, etc.). As the user roams,
Smart Connectivity determines what accesses are available and provides the ability
to select the optimal one for the best user experience and most efficient use