Abstract

This paper addresses the issue of multiservice support in IEEE 802.16 or WiMAX networks. The capacity for supporting multiple service classes is indeed important for any access technology where bandwidth is limited, which is the case for IEEE 802.16. The standard currently proposes four traffic classes, and specifies that for uplink traffic, the first one (UGS) receives periodic grants whereas the other three are served via polling. Supporting two different scheduling mechanisms may have a significant impact on the complexity of network interface cards, and therefore on the CAPEX for WiMAX networks. Based on this analysis, the present work investigates whether a 802.16 network that only supports the 3 polling based classes is still capable of providing the QoS levels expected for all types of applications. Both the transfer plane QoS, in terms of latency and jitter, and the command plane QoS, in terms of blocking probability are assessed. In particular, a simple, multiservice call admission control (CAC) mechanism is proposed that significantly improves on a previously proposed CAC mechanism by favouring real time traffic over non real time traffic. The outcome of this study shows that it is indeed possible to support stringent QoS with only polling based traffic classes, and fairly simple traffic engineering mechanisms fully described in the paper.

Abstract

This article focuses on testing and investigating further development needs for LiDARs in self-driving cars in adverse weather. The article compares two different LiDARs (Ibeo Lux and Velodyne PUCK), which both use the 905 nm wavelengths, which are used in more than 95% of currently available LiDARs. The performance was tested and estimated in stabilized fog conditions at Cerema fog chamber facilities. This provides a good basis for repeating the same validation procedure multiple times and ensuring the right development decisions. However, performance of the LiDARs suffers when the weather conditions become adverse and visibility range decreases. A 50% reduction in target detection performance was observed over the exhaustive tests. Therefore, changing to higher wavelengths (1550 nm) was considered using redesigned 'pre-prototype LiDAR'. The preliminary results indicate that there is no reason to not use 1550 nm wavelength, which due to eye safety regulations gives an opportunity to use 20 times more power compared to the traditional 905 nm. In order to clarify the expected benefits, additional feasibility studies are still needed.

Abstract

International audience; ECOFRAME ring is a novel network technology for the metropolitan transport that exploits optical packet switching and optical transparency. Each station in this ring is equipped with a tunable transmitter and a number of fixed receivers, able to extract traffic from a predefined set of wavelengths (number of wvl. ≥ 1). Receivers can be shared by different destinations, of- fering to this technology an ability to achieve significant CAPEX savings by using the optimum number of network resources, if properly dimensioned. In this paper we present a wide set of conclusions obtained when applying different network planning and traffic engineering tools in investigating an optimal design and evaluating performances of an ECOFRAME ring. More precisely, regarding network planning issues, we have estimated equipment costs, identified different network configurations and studied their impact on ring performances. Finally, we have found the potential savings when ring is properly designed. On the other hand, based on the previous results, we have identified the optimal ring configuration from price, capacity and scheduling point of view, suggested a cheap and fair scheduling policy for a general case and evaluated the positive impact of statistical multiplexing due to the WDM dimension, on the ring capacity. We have shown that an OPS ring that is properly dimensioned can achieve a solid QoS performance without slot reservation mechanisms.