Case study on using the user-centric-backhaul scheme to unlock the realistic backhaul

The fifth generation of mobile networks (5G) is maturing fast and the target year 2020 is around the corner. However, the realistic backhaul network may not be ready for 5G arrival as it is likely to converge to 5G requirements at a slower pace than the radio counterpart. In this work, we develop a method that identifies pertinent backhaul upgrade stages that are ranked based on their associated cost. First, the User-centric- backhaul (UCB) scheme is employed to reveal the bottlenecks of the incumbent backhaul network, as perceived by users and holistic network. A multi- hop hybrid backhaul modelling framework is then employed to quantify possible rectifications that would deliver the highest improvement at the lowest cost. These are implemented and the results are verified following another usage of UCB. A case study is presented that demonstrates the strength of this method in enabling an effective and cost efficient evolution road map towards the 5G backhaul

A Stochastic Hybrid Framework for Driver Behavior Modeling Based on Hierarchical Dirichlet Process

Scalability is one of the major issues for real-world Vehicle-to-Vehicle network realization. To tackle this challenge, a stochastic hybrid modeling framework based on a non-parametric Bayesian inference method, i.e., hierarchical Dirichlet process (HDP), is investigated in this paper. This framework is able to jointly model driver/vehicle behavior through forecasting the vehicle dynamical time-series. This modeling framework could be merged with the notion of model-based information networking, which is recently proposed in the vehicular literature, to overcome the scalability challenges in dense vehicular networks via broadcasting the behavioral models instead of raw information dissemination. This modeling approach has been applied on several scenarios from the realistic Safety Pilot Model Deployment (SPMD) driving data set and the results show a higher performance of this model in comparison with the zero-hold method as the baseline.Comment: This is the accepted version of the paper in 2018 IEEE 88th Vehicular Technology Conference (VTC2018-Fall) (references added, title and abstract modified

Novel search algorithm for closed-loop transmit diversity system with limited number of feedback bits

We propose two simple closed-loop transmit diversity schemes with a fixed number of feedback bits being allocated for each transmit antenna. Under a low mobility condition and with perfect channel knowledge at the receiver, we show that our proposed schemes can achieve signal-to-noise ratio (SNR) values close to the optimal solution but with greatly reduced complexity. We also show that our methods outperform other suboptimal schemes such as the co-phasing method. © 2004 IEEE.published_or_final_versionIEEE 60th Vehicular Technology Conference 2004-Fall (VTC2004-Fall), "Wireless Technologies for Global Security", Los Angeles, CA, USA, 26-29 September 2004. In IEEE - VTS Vehicular Technology Conference Proceedings, 2004, v. 60 n. 3, p. 1849-185

Effect of information on routing performance in multi-hop wireless networks

Proceedings of the IEEE Conference on Vehicular Technology, 2010, p. 1-5A key issue impacting wireless network performance is network information. In wireless networks, a significant amount of bandwidth and power resource is consumed to disseminate and maintain routing information. Previous work has presented different methods to broadcast and store such routing information so as to reduce the overhead. However, the amount of information required for a routing algorithm to be effective is not studied theoretically. In this paper, we consider two kinds of routing information, i.e., location information and link state information, and study the quantitative relationship between the available routing information and network performance. It is assumed that each node in the network can only obtain information of its k-hop neighbors, and for each packet, a distance vector based algorithm is employed to minimize the number of hops for the packet to reach its destination with the limited information. We then present a methodology to derive the analytical result on the quantitative relationship between routing performance and the information available for each node. The analysis in this paper can be a valuable tool on designing routing algorithms in wireless networks. © 2010 IEEE.published_or_final_versionThe 71st IEEE Conference on Vehicular Technology (VTC 2010-Spring), Taipei, Taiwan, 16-19 May 2010. In Proceedings of the 71st IEEE IEEE Conference on Vehicular Technology, 2010, p. 1-

Robust Non-Coherent Beamforming for FDD Downlink Massive MIMO

Designing beamforming techniques for the downlink (DL) of frequency division duplex (FDD) massive MIMO is known to be a challenging problem due to the difficulty of obtaining channel state information (CSI). Indeed, since the uplink-downlink bands are disjoint, the system cannot rely on channel reciprocity to estimate the channel from uplink (UL) pilots as in time division duplexing (TDD) system. Still, in this paper, we propose original designs for robust beamformers that do not require any feedback from the users and only rely on the transmission of UL pilots. The price to pay is that the beamformer is non-coherent in the sense that it does not leverage full knowledge of the phase of each multipath component. A large variety of novel designs are proposed under different criterion and partial phase knowledge

Optimal rate assignment strategy to minimize average waiting time in wireless networks

In a wireless network that supports multiple flows, allocation of bandwidth resource among the flows is one of the critical problems. Different allocation strategies have been developed based on different optimization objectives. Unfortunately, these objectives may not reflect directly the time needed for a flow to transmit what it wants. In this paper, we define a new objective, average waiting time, that reflects the average time needed for the flows to finish their transmissions. For small networks, we develop an optimal scheme that minimizes the average waiting time. We extend the mechanism for general networks, and simulation results show that it can significantly reduce the average waiting time when compared with other existing mechanisms. © 2011 IEEE.published_or_final_versionThe 2011 IEEE Vehicular Technology Conference (VTC Fall), San Francisco, CA., 5-8 September 2011. In IEEEVTS Vehicular Technology Conference Proceedings, 2011, p. 1-

Enhanced Position Verification for VANETs using Subjective Logic

The integrity of messages in vehicular ad-hoc networks has been extensively studied by the research community, resulting in the IEEE~1609.2 standard, which provides typical integrity guarantees. However, the correctness of message contents is still one of the main challenges of applying dependable and secure vehicular ad-hoc networks. One important use case is the validity of position information contained in messages: position verification mechanisms have been proposed in the literature to provide this functionality. A more general approach to validate such information is by applying misbehavior detection mechanisms. In this paper, we consider misbehavior detection by enhancing two position verification mechanisms and fusing their results in a generalized framework using subjective logic. We conduct extensive simulations using VEINS to study the impact of traffic density, as well as several types of attackers and fractions of attackers on our mechanisms. The obtained results show the proposed framework can validate position information as effectively as existing approaches in the literature, without tailoring the framework specifically for this use case.Comment: 7 pages, 18 figures, corrected version of a paper submitted to 2016 IEEE 84th Vehicular Technology Conference (VTC2016-Fall): revised the way an opinion is created with eART, and re-did the experiments (uploaded here as correction in agreement with TPC Chairs