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m-Hop: Multi-Hop Cellular Communications in Heterogeneous Beyond 3G Wireless Systems

Cellular communications have shown over the past decades their potential to provide ubiquituous mobile communications services with increasing data rates and multimedia capabilities. To cope with the increase demand for higher bit rates necessary to provide richer and more diverse multimedia services, several 4G research trends can be identified. Although novel radio interfaces with higher spectral efficiency are necessary due to the spectrum scarcity, there is also a common view in that future 4G systems will not correspond to a single radio system, but rather to a group of radio technologies that complement each other. In this context, heterogenous Beyond 3G wireless systems are aimed at seamlessly exploiting the capabilities of current and future mobile and wireless systems by allowing to dynamically change the serving Radio Access Technology (RAT) without the need for user intervention. To achieve this objective, it is of paramount importance to design and optimise adequate Common Radio Resource Management (CRRM) policies that will coordinate each RAT's radio resources use.

Despite these research efforts, the fundamental limits of communication technologies and radio propagation result in that data rates in a traditional cellular architecture, and independently of the 3.5G or 4G radio interfaces being employed, decrease with the distance to the serving base station. Providing homogeneous high bit rates, as requested by the ITU recommendations for the future 4G systems, would require to considerably increase the transmission powers, or to limit the link to short distances, which will in turn increase the number of base stations to be deployed and consequently the network's roll out and operational cost. These constraints question the economical feasibility of the current cellular architecture to cater for the requirements of future mobile communication services. In parallel to the continuous development of mobile cellular communications systems, ad-hoc wireless networking has emerged as an alternative technology enabling nodes to form an infraestructureless network by communicating via multi-hop links. Their capacity to enable high bit rates over various reduced multi-hop communication distances has fueled the emergence of a novel but promising field, combining cellular and ad-hoc networking technologies, referred to as Multihop Cellular Networks (MCN). MCN preserves the benefit of using a communications infrastructure while overcoming the limitations of cellular networks to provide homogeneous high bit rates over large areas through the use of multi-hop transmissions over short distances.

In this context, this project is aimed at investigating multi-hop cellular communications for heterogeneous Beyond 3G systems with a special interest on mobile relaying solutions. In particular, the project will address three key factors to ensure the viability and performance of MCN solutions. At first, the project will analyse the possibility to establish multi-hop links under various operating conditions, including node's density, speed, propagating conditions and use of opportunistic networking solutions. The conducted research will not only be based on theoretical and simulation analysis, but most importantly on real-time hardware testbeds. Given that MRS-MCN's operation depends on the user terminal's cooperation, the project will also investigate how to foster mobile node's cooperation through various policies. The third novel contribution of this project will be the study of MCN networks as an integral part of heterogeneous Beyond 3G systems. To this end, the project will use the previous multi-hop connectivity studies to design CRRM policies that adequately consider and quantify the multi-hop's connectivity probability, and reduces both the inter-relay and vertical RAT handover requests.

To achieve its objectives, the m-Hop project is organized around the following technical workpackages.

  • WP1: Multi-hop connectivity characterisation.
  • WP2: Cooperation and routing in MCN networks.
  • WP3: Multi-hop CRRM policies.
  • WP4: Hardware and simulation testbeds

The project is funded by the Spanish Ministry of Science and Innovation and FEDER funds.
MICINN-Ministerio de Ciencia e Innovación
Ministerio de Ciencia e Innovación
Fondo de Desarrollo Regional FEDER
FEDER-Fondo Europeo de Desarrollo Regional