Evolution of Mobile Backhaul

In the last quarter of a century, wireless networks have dramatically transformed and redefined our lives. At first, cellular networks provided mobile telephone service; currently, they also offer mobile internet access. This technology has been evolving at an astonishing pace to provide ever-higher network capacities, increasing mobile internet data rates, and lower latency access. While radio access networks have drawn the most attention, the fixed network providing connectivity to the base stations - the backhaul network - has evolved at a similar pace. As innovations on the radio interface have continued to create issues for the backhaul, in turn, this has led to innovations on the backhaul network. This dissertation investigates six challenges for the backhaul network; it presents solutions to these challenges and evaluates their performance through simulations.One such challenge was the femtocell concept, which appeared with 3.5G systems. Femtocells are small cells that are backhauled by an arbitrary wired internet connection. Another challenge is the shift to Voice over Internet Protocol (VoIP). VoIP has led to very inefficient transportation of small and frequent voice packets, which are burdened by excessive packet overhead. This overhead can be reduced if the small packets are bundled or multiplexed together in order for multiple packets to share a single overhead. Adaptive multiplexing algorithms are proposed that further improve efficiency. A further issue is the backhaul requirement for Coordinated Multipoint (CoMP), which is a feature of 4G that increases radio interface efficiency. Its applicability is restricted by backhaul latency requirements. This dissertation describes a method that decreases these backhaul requirements, and allows its employment in more scenarios.Furthermore, a cognitive radio system concept is presented where the difference between the radio interface and backhaul is blurred.To provide the data rates promised by 5G, wireless networks have to turn to far higher frequencies, such as millimetre wavelengths; however, this implies very small maximum cell sizes. For providing backhaul for such dense deployments, a cost efficient technology candidate is multi-hop, millimetre-wave, in-band backhaul; the performance of which is also evaluated in this dissertation.Finally, the effect of rain fading on millimetre-wave multi-hop backhaul is also quantized.The results presented in this dissertation show that the individual backhaul challenges of each generation of wireless networks can be overcome with corresponding backhaul solutions.