1. Context

The growing demand for mobile multimedia applications has led to a dramatic increase in the flow of data exchanged between wireless communication systems. In particular, the use of "smart phones" has contributed to a shift from traditional communications to high-speed multimedia communications, anywhere, anytime. As a result, user expectations are also evolving in the direction of continuous interconnection, both at home and on the move. However, due to the growing penetration of smart phones, current networks [14.4 Mbit/s downlink per cell with HSPA (High Speed Packet Access ), 100 Mbit/s with LTE (Long Term Evolution ) in the short term, i.e. efficiencies of 2.9 bit/(s · Hz) and 5 bit/(s · Hz) respectively] are already reaching their capacity limits when demand is high. Indeed, congestion problems arise both in the wireless link and in the wired physical network.

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