Valdemar Monteiro

Cognitive vehicular communication for 5G

Device-to-device (D2D) is increasingly becoming a prominent technology within the 5G story, portrayed as a means of offloading traffic from the core network. The ever increasing demand for vehicular traffic consumption is providing the impetus for a new architectural design that can harness the benefits of D2D for vehicular users, taking a step toward offloading vehicular traffic from the core network. We propose the notion of extending D2D for vehicular scenarios with the potential to coordinate vehicular traffic using the LTE band. Furthermore, we then extend this approach by investigating cognitive radio in synergy with a geo-location database, to exploit white spaces as a means of further offloading vehicular users. Our simulation results have shown that our approach can outperform the legacy IEEE 802.11p in terms of delay.

Converged wireless networking and optimization for next generation services

The Next Generation Network (NGN) vision is tending towards the convergence of internet and mobile services providing the impetus for new market opportunities in combining the appealing services of internet with the roaming capability of mobile networks. However, this convergence does not go far enough, and with the emergence of new coexistence scenarios, there is a clear need to evolve the current architecture to provide cost-effective end-to-end communication. The LOOP project, a EUREKA-CELTIC driven initiative, is one piece in the jigsaw by helping European industry to sustain a leading role in telecommunications and manufacturing of high-value products and machinery by delivering pioneering converged wireless networking solutions that can be successfully demonstrated. This paper provides an overview of the LOOP project and the key achievements that have been tunneled into first prototypes for showcasing next generation services for operators and process manufacturers.

Positioning for performance enhancement in shared LTE and HSPA networks

Efficient radio resource management in wireless network systems is increasingly becoming a necessity as current trends drive towards increased number of users and bandwidth hungry applications and services. In this paper, two concepts for targeting this capacity challenge are addressed: cooperative and localization based radio resource management. In cooperation we refer to the concept of a sole entity responsible for managing radio resources for heterogeneous networking environments, and herein we explore an HSPA with an overlay LTE/network. For optimized decisions in such an environment, utilizing mobile positioning information seems to show enhanced system performance. This paper investigates the application of suitability based RAT selection using positioning information for enhanced throughput performance in heterogeneous networking environments. The results clearly show that, for optimized decisions in such an environment, utilizing mobile positioning information clearly shows enhanced system performance.

Millimetre-wave channel impulse response experimental evaluation and relation between delay spread and channel coherence bandwidth

The paper describes the experimental set-up and presents some results of a channel impulse response measurement campaign. The measurements were performed in the frequency domain, in the 40 GHz band, and the channel impulse response was obtained applying spectral analysis. A wide indoor sports pavilion was selected for the experiments, considering several static discrete positions for the mobile terminal, therefore allowing the propagation channel to be characterised in different cell coverage regions. From the channel impulse response, power and time dispersion parameters were calculated and analysed. Furthermore, the channel coherence bandwidth was estimated both from direct frequency measurements and from the delay spread estimations; the results were analysed.

Optimal load suitability based RAT selection for HSDPA and IEEE 802.11e

Networks of the future envisage a network-of-wireless-networks that provide the end user the means to connect to the best available network at anytime and at any place. However, equally challenging for the operators is to provide these services at low cost in an era where spectral resources are a premium. This paper investigates cooperation between networks based Radio Access Technology (RAT) selection algorithm that uses suitability to optimize the choice between WiFi and High Speed Downlink Packet Access (HSDPA). It has been shown that this approach has the potential to provide gain by allocating a user terminal to the most preferred network based on traffic type and network load. Optimal load threshold values that maximise the total QoS throughput for the given interworking scenario are 0.6 and 0.53 for HSDPA and WiFi, respectively. This corresponds to a CRRM gain on throughput of 80% with 60 users.

Service Suitability Based RAT Selection for Beyond 3G Systems

In beyond 3G systems, one of the important factors is to address radio access technology (RAT) selection and load balancing between heterogeneous networks to ensure high spectral efficiency in an era where spectral resources are at a premium. This work aims to address the feasibility of utilizing WiFi as complementary service for HSDPA, to prevent quality of service deterioration in the event of network overload in HSDPA during the busy period. The proposed RAT selection algorithm is based on the load of each system, and the results show that the outage probability can be improved by up to 45% relative to a stand-alone HSDPA system.

Experimental System Level Platform for B3G Scenarios

This paper provides a complete specification of the packet based cellular wireless system level simulator that addresses a beyond 3G scenario involving heterogeneous wireless systems interconnected via an IP backbone network. Important aspects as the Link layer design (including the MAC layer) are specified, as well as the C++ object oriented simulation architecture. Since the IP level and the physical layer aspects should be avoided, interfaces representing these layers are proposed for different type of radio access systems. The concept is showcased by a multi-RAT system composed of HSDPA and a Wi-Fi system using load balancing techniques.

4MORE system level performance

While the third generation terrestrial mobile system (UMTS-UTRA) is currently being deployed, there is already a significant research activity towards what is called B3G systems. The vision for this new generation includes provision of a broadband component for which various implementation technologies are being considered, one of them being MC-CDMA. The 4MORE project focuses at the system concept on techniques believed to be crucial to reach the broadband capabilities envisioned, namely Multiple Transmit Multiple Receive (MTMR) antennas and cross-layer design (LI and L2). Specifically, the joint application of dynamic resource allocation with double Alamouti encoding is considered to ensure seamless IP packet transport with broadband capabilities. The simulation results have shown that the 4MORE system can match the anticipated throughputs required for the cellular component of B3G systems.

Self-Organized Energy Efficient Scheduling in LTE-A

Traditional packet scheduling is mainly designed for increasing spectral efficiency (SE) but not for the energy efficiency (EE). Self-organized network (SON) has prospective for self- configuring, self-optimizing self-healing and minimizes the energy consumption in the network. We consider self-optimizing and self-healing property of SON and investigate a novel energy efficient scheduling algorithm for LTEA. We first compare the state the of art scheduling in view of energy efficiency, then explain the tradeoff between EE and SE. System level simulation (SLS) analysis shows that the investigated SON approach achieves notable energy gain over traditional scheduling algorithm.

3D video streaming transmission over OFDMA-based systems

Coordinated Multipoint systems (CoMP) have spurred considerable research activity in recent years as they enable both capacity and coverage improvement over conventional cellular systems with open issues in the design of radio resource management algorithms for this type of systems with the challenge of multiple sub-carriers resources available in the OFDMA (orthogonal frequency division multiple access) based systems. To partially solve these issues this paper proposes a user scheduling and resource allocation algorithm for distributed broadband wireless systems based on OFDMA (orthogonal frequency division multiple access) for the 3D video streaming service. The study considers a Manhattan network which is one of the most promising scenarios for CoMP. The algorithm combines the concepts of maximum carrier-to-interference scheduling and antenna selection to increase throughput and ensure zero intra-cell interference. The results show that the use of CoMP can provide significant advantages over conventional deployments in the 3D video streaming services.