Baldomero Coll-Perales

Experimental evaluation of multihop cellular networks using mobile relays [Accepted From Open Call]

Future wireless networks are expected to provide high bandwidth multimedia services in extended areas with homogeneous quality of service levels. Conventional cellular architectures might not be able to satisfy these requirements due to the effect of surrounding obstacles and the signal attenuation with distance, in particular under non-line-of-sight propagation conditions. Recent studies have investigated the potential of multihop cellular networks (MCNs) to overcome the traditional cellular architecture limitations through the integration of cellular and ad hoc networking technologies. However, these studies are generally analytical or simulation-based. On the other hand, this article reports the first experimental field tests, which validate and quantify the benefits MCNs using mobile relays can provide over traditional cellular systems.

Empirical performance models for P2P and two hops multi-hop cellular networks with mobile relays

Multi-hop Cellular Networks using Mobile Relays (MCN-MR) are being studied to overcome certain limitations of traditional single hop cellular systems through the integration of cellular and Peer to Peer (P2P) ad-hoc communications. Current MCN-MR research is generally analytical or simulation based, and there is yet the need for studies that empirically demonstrate the potential of MCN-MR and provide valuable models for the research community. In this context, this paper presents the first 2-hop MCN-MR empirical performance models derived from field tests over live networks. The MCN-MR performance is measured for downlink transmissions as the throughput experienced by mobile users. The model parameters are shown to depend on the distance, Line-Of-Sight (LOS) or Non-LOS (NLOS) conditions, and communication settings of the ad-hoc link. As a result, the paper also reports a set of distance-based empirical P2P link level models.

Energy efficient routing protocols for Multi-hop Cellular Networks

Multi-hop Cellular Networks using mobile relays require efficient multi-hop networking protocols that provide a high end-to-end performance and reduce the terminals energy consumption. In this context, this paper proposes a set of novel multi-hop routing protocols that exploit the location of the destination node to reduce their network signalling and overall energy consumption. These two aspects are crucial factors to progress towards the future implementation of Multi-hop Cellular Networks based on mobile relays.

An IEEE 802.11 MAC Software Defined Radio implementation for experimental wireless communications and networking research

Wireless ad-hoc networking will be a fundamental component of emerging technologies such as multi-hop cellular networks, vehicular ad-hoc networks and wireless mesh networks, with most of these technologies based on evolved versions of the 802.11 standard. To achieve their expected benefits, and address their challenges, in terms of energy efficiency, reliability or reconfigurability, advanced cooperative and cross-layer communications and networking techniques need to be investigated. Most of the studies conducted to date are based on analytical and simulation techniques, and the use of commercial hardware equipment usually lacks the flexibility needed to conduct advanced research studies. In this context, this paper presents a fully programmable Software Defined Radio implementation of the IEEE 802.11 MAC that can be used, configured and fully modified, to develop advanced cross-layer communications and networking techniques.

Energy-efficient opportunistic forwarding in multi-hop cellular networks using device-to-device communications

Cellular networks face significant capacity, efficiency and quality challenges because of the exponential growth of cellular data traffic. Multi-hop cellular networks MCNs have been proposed to address these challenges through the integration of cellular and device-to-device communications. This work investigates how the adoption and design of opportunistic store, carry and forward mechanisms in MCNs can help importantly decrease the energy consumption for delay tolerant traffic. To this aim, the study first derives an analytical framework to identify in two-hop scenarios the optimum mobile relay location and the location from which the mobile relay should start forwarding the information to the cellular base station in order to minimise the overall energy consumption. The derived optimum configuration is then used as a benchmark for the proposal and design of a novel context-based opportunistic MCN forwarding scheme that exploits context information provided at low cost by the cellular network. Numerical and simulation results demonstrate that the proposed context-based opportunistic forwarding can achieve a performance close to that obtain with the optimum configuration and reduce the energy consumption by more than 90% compared with traditional single-hop cellular communications. Copyright

Research testbed for field testing of Multi-hop Cellular Networks using Mobile Relays

Multi-hop Cellular Networks have recently emerged as a promising technology to overcome the current limitations of cellular systems through the integration of cellular and ad-hoc networking technologies. Several studies have addressed the challenges of Multi-hop Cellular Networks based on Mobile Relays, and demonstrated their performance and potential to improve the user-perceived Quality of Service. However, most of these studies are based on analytical and simulation techniques, and there is yet the need for field tests that confirm their performance. In this context, this paper introduces a novel testbed to investigate Multi-hop Cellular Networks using Mobile Relays through field testing. In addition, this paper also presents the first field test results that demonstrate the performance improvements that can be achieved with Multi-Hop Cellular Networks over traditional cellular systems.

Empirical models of the communications performance of Multi-hop Cellular Networks using D2D

Multi-hop Cellular Networks (MCNs) can improve the quality of service, capacity and energy-efficiency of traditional infrastructure-centric single-hop cellular systems. MCN systems can exploit Device-to-Device (D2D) communications and utilize the communications and computing capabilities of mobile devices. However, the communications challenges resulting from the use of mobile devices and D2D communications require empirical solid evidences of their performance benefits, and the design of robust communications and networking protocols. In this context, this paper presents a unique set of empirical models of the communications performance of MCN systems that utilize D2D communications. The models take into account the impact of the distance, propagation/visibility conditions, number of hops, and communication settings. The set of derived models can help design, test and optimize communications and networking protocols for MCNs that utilize D2D communications.

Context-aware opportunistic networking in multi-hop cellular networks

5G networks will be required to efficiently support the growth in mobile data traffic. One approach to do so is by exploiting Device-to-Device (D2D) communications and Multi-Hop Cellular Networks (MCNs) in order to enhance the spectrum re-use and offload traffic over underlay networks. This study proposes to further improve the efficiency of transmitting mobile data traffic by integrating opportunistic networking principles into MCNs. Opportunistic networking can exploit the delay tolerance characteristic of relevant data traffic services in order to search for the most efficient transmission conditions in MCNs. The study first presents an analytical framework for two-hop opportunistic MCNs designed to identify their optimum configuration in terms of energy efficiency. Using this reference configuration, the paper then proposes a set of opportunistic forwarding policies that exploit context information provided by the cellular network. Numerical and simulation results demonstrate that opportunistic networking can significantly contribute towards achieving the capacity and energy efficiency gains sought for 5G networks. Under the evaluated conditions, the obtained results show that the proposed schemes can reduce the energy consumption compared to traditional cellular communications by up to 98% for delay tolerant services. In addition, the proposed schemes can increase the cellular capacity by up to 79% compared to traditional cellular communications.

Store, carry and forward for energy efficiency in multi-hop cellular networks with mobile relays

The wide scale adoption of smartphones is boosting cellular data traffic with the consequent capacity constraints of cellular systems and increase in energy consumption. A significant portion of cellular data traffic can be deemed as delay tolerant. Such tolerance offers possibilities for designing novel communications and networking solutions that can accommodate the delay tolerant cellular data traffic while reducing their impact on the overall cellular capacity and energy consumption. In this context, this work studies the use of opportunistic store, carry and forward techniques in Multi-Hop Cellular Networks (MCN) to reduce energy consumption for delay tolerant traffic. The study focuses on two-hop MCN networks using mobile relays (MCN-MR), and identifies the optimum mobile relay location and the location from which the relay should start forwarding the information to the cellular base station in order to minimize the overall energy consumption. The study shows that the use of opportunistic store, carry and forward techniques in MCN-MR can significantly reduce energy consumption compared to other solutions, including traditional single-hop cellular systems or direct contact store, carry and forward solutions.

On the capability of multi-hop cellular networks with mobile relays to improve handover performance

Traditional single-hop cellular architectures fail to provision high and homogeneous quality of service (QoS) levels throughout a cell area. In addition, the performance and optimization of handover mechanisms poses significant challenges due to degraded channel conditions at the cell boundaries. In this context, multi-hop cellular networking technologies have been identified as an attractive solution to overcome traditional cellular limitations and improve the performance in handover areas. This paper discusses a novel handover process using multi-hop cellular networks with mobile relays (MCN-MR), and illustrates the benefits of this approach over traditional cellular handovers through field tests.