Efficient traffic offloading in advanced wireless networks

With the proliferation of massive smart phones and hand-held devices, user demands for broadband mobile data-intensive services are undergoing an unprecedented rise. Despite the availability, improved spectral efficiencies and data rates of the current networks, effective utilization of wireless resources is still required to keep up with the massive users' demands for mobile contents. Recently, the Third Generation Partnership Project (3GPP) has standardized Long Term Evolution (LTE) and its advanced version LTE-A, with a promising peak data rate up to 1Gbps and 100Mbps in low and high mobility scenarios, aims to provide a tradeoff between high transmission speed and an acceptable QoS for User Equipments (UEs). Besides the conventional human-to-human (H2H) communication, device-to-device (D2D) communication has also been proposed to provide wireless peer-to-peer services and enhance spectrum utilization for the short range communication in the LTE-A networks. In this thesis, efficient solutions through tailoring D2D communications and offloading mechanisms are presented to meet the requirements of seamless high throughput communications in different settings. The proposed solutions aim at providing seamless wireless connectivity in extreme conditions i.e., massive users with data intensive services in high mobility scenarios. This thesis encompasses the following chapters. The Chapter 1 of this thesis introduces the principle of the current wireless technologies. The Chapter 2 explains the state-of-the-art of the current wireless network in extreme conditions and briefly review the related works. The Chapter 3 aims at mining the statistical characteristics of the wireless cellular networks link failure in extreme conditions with frequent handovers (HOs). In this chapter, service discontinuities, service time distributions and also the throughput of wireless networks are extensively modeled and evaluated, via in-lab exhaustive experiments. In the Chapter 4, the statistical characteristics mined in Chapter 3 are used to design efficient scheduling policies by tailoring D2D communications and ad-hoc traffic offloading mechanism, to provide a seamless wireless connectivity in high mobility scenarios, particularly for on-board high speed train (HST) scenario as a realistic example of wireless connectivity in the extreme conditions. In addition, the concept of multi-cell access is proposed to diversify the overhead of frequent HOs (the origin of service discontinuities) over multiple cells. The cost-effective multi-cell access solution is paired to the D2D communication for efficient resource utilization and massive UEs overhead alleviation. It is proved that if multi-cell access is efficiently paired with the ad-hoc traffic offloading mechanism, a considerable UEs' traffic can be managed over the cellular wireless networks specially at the cell edges. The proposed solutions are compared with conventional solutions and their effectiveness is verified. The Chapter 5 introduces new wireless cloud based D2D communications that provide the possibility of Low Latency High Throughput (LLHT) communications for mobile data traffic offloading. An ad-hoc light weight resource allocation mechanism is proposed in Chapter 6. The conclusion and discussion of the proposed schemes for extreme conditions are presented in the last Chapter.