Analytical Modeling of Wireless Communication Systems

5Multi-RAT Algorithms

One of the most challenging issues in the field of communication networks today is coping with the exponential growth of wireless data traffic. The average smartphone is expected to generate 2.6 GB of traffic per month by 2016, with a global mobile data traffic that will increase 18-fold by that time [CIS 12]. To increase the capacity of cellular networks and, thus, accommodate such high data traffic loads, the new long-term evolution (LTE) technology has been introduced, which is deemed to achieve a spectrum efficiency as high as 1.75 bits/s/Hz, a downlink peak throughput of 100 Mb/s and a latency of few milliseconds.

The fast uptake of mobile data services, however, indicates that these solutions are not sufficient to meet the intense user demand in many high-density settings. Thus, a new trend, usually referred to as mobile data offloading, has emerged and will be part of 5G communication networks. This implies that, while the cellular infrastructure will continue to provide high levels of quality of service (QoS), besides the support for high-mobility users, it will be complemented with alternative wireless access technologies such as WiFi hotspots [TRU 10]. Data traffic should therefore be offloaded whenever possible toward such hotspots, at the price of a possible degradation in the QoS experienced by the users [DIM 11, HAN 12].

Such a scenario calls for a new access network architecture, whose distinctive feature is the availability of multiple radio ...