The paper deals with the use of bicycle messengers, also called bike couriers, in the modern logistics chain. In an era where almost every actor - from policy makers to senior managers - is thinking ...about the environment and sustainability, new innovative concepts are developed worldwide. On the other hand, an abundance of solutions to improve efficiency and overall sustainability of logistics and other related business activities are already available in the market. Reinventing the wheel all over again might not be necessary. One of the methods to deliver parcels in a more sustainable way, is the transport of freight by bike. People on bike deliver and transport post, parcels or freight with a low volume or weight. Bike couriers are proven to be fast and reliable within congested urban areas. These bikers mainly advertised their ability to go fast from one place to another in a city. Sustainability was a selling argument, but speed was of more importance. Also, in Europe some bike courier markets are reasonably well developed. Specific markets seem to exist for transport of freight by bike. The research question of this paper concerning bicycle messengers is whether these companies can be an economic viable alternative for fossil fuel powered transport, and if so, in what markets these opportunities can be found. The authors draw conclusions about the business model and integrate encountered weaknesses and opportunities. An operational cost calculation is included. A simulation of a round trip delivery scheme in an urban area took place. A van as well as a bike courier solution was compared. To draw some conclusions about the economic feasibility of the round trip by bike courier, the cost per stop is compared and will be discussed. The paper ends with a conclusion on the observations made, and with a number of recommendations.
Mobile network operators are facing the rollout of 5G New Radio small cells in the next few years. High cell density will require intensive support of optical transport, and there are multiple ...options depending on cell configuration and capacity. Comparing these optical technologies in terms of capacity and cost is important to maximize return on the likely limited deployment budget. We developed a model that can be used by operators in the strategy and decision-making phase and present example results on outdoor 5G small cells using the sub-6-GHz spectrum bands.
In the G.fast digital subscriber line frequency range (up to 106 or 212 MHz), where crosstalk channels may even become larger than direct channels, linear zero-forcing (ZF) precoding is no longer ...near-optimal for downstream (DS) vectored transmission. To improve performance, we develop a novel low-complexity algorithm for both linear and nonlinear precoding-based dynamic spectrum management that maximizes the weighted sum-rate under realistic per-line total power and per-tone spectral mask constraints. It applies to DS scenarios with a single copper line at each customer site i.e., broadcast channel (BC) scenarios, as well as to DS scenarios with multiple copper lines at some or all customer sites (i.e., the so-called multiple-input-multiple-output-BC scenarios). The algorithm alternates between precoder and equalizer optimization, where the former relies on a Lagrange multiplier based transformation of the DS dual decomposition approach formulation into its dual upstream (US) formulation, together with a low-complexity iterative fixed-point formula to solve the resulting US problem. Simulations with measured G.fast channel data of a very high crosstalk cable binder are provided revealing a significantly improved performance of this algorithm over ZF techniques for various scenarios, and in addition, a faster convergence rate compared with the state-of-the-art WMMSE algorithm.
Passive optical networks (PONs) facilitate small-cell deployments. Back- and midhaul over PON is being deployed today. As opposed to point-to-point optics, PON extends the aggregation gain into the ...access domain. We explain the steps taken in the mobile and PON industries to enable efficient eCPRI fronthaul over PON. We explain how fronthaul has evolved into a bandwidth-efficient eCPRI and what mechanisms are in place to enable coordinated scheduling decisions of the mobile and PON systems. The recent end-to-end demonstration of coordinated scheduling helps pave the way towards future industry adoption.
In next-generation digital subscriber line networks such as G.fast, employing discrete multi-tone transmission in high frequencies up to 212 MHz, the crosstalk among lines reaches very high levels. ...To precompensate the crosstalk in downstream transmission, QRD-based precoding has been proposed as a near-optimal dynamic spectrum management (DSM) technique. However, the performance of QRD-based precoding is greatly affected by the user encoding ordering (UEO). Since current multi-tone UEO methods are rather heuristic in the way they approach fairness, we develop, in this paper, a set of novel DSM algorithms for joint power allocation and UEO that enforce a generalized <inline-formula> <tex-math notation="LaTeX"> \alpha </tex-math></inline-formula>-fairness policy. Since finding the globally optimal UEO entails a combinatorial optimization problem with excessive computational complexity, an iterative algorithm is proposed which uses per-tone exhaustive searches (PTESs) and provides near-optimal approximate solutions. To further reduce the computational complexity, two suboptimal methods are suggested to replace the expensive PTESs, leading to two additional <inline-formula> <tex-math notation="LaTeX"> \alpha </tex-math></inline-formula>-fair DSM algorithms that are tractable for large scenarios against little performance loss. Simulations of a G.fast cable binder show that the <inline-formula> <tex-math notation="LaTeX"> \alpha </tex-math></inline-formula>-fair DSM algorithms achieve an efficient trade-off between fairness and performance in contrast to current UEO methods.
Digital Subscriber Line technology has democratized broadband access, and over the past several decades, telecommunications providers have evolved from providing plain old telephone service (POTS) ...over a copper loop plant to providing broadband access and high-definition video over hybrid fiber-copper networks. This article focuses on three revolutionary copper technologies in different stages of development that will enable hybrid networks to continue to increase data rates over orders of magnitude for many years to come. The first of the three, vectoring, is a mature technology with massive ongoing rollout that provides end user speeds above 100 Mb/s across typical distances of 500m. The second, G.fast, is the first ultrabroadband technology offering 1 Gb/s speeds, across typical distances of 100m. It has recently gained approval in the standards bodies and is currently undergoing trials both in research labs and in the field by numerous telecom operators. Finally, we discuss Bell Labs' XG-FAST technology, now in proof of concept, which can deliver 10 Gb/s across a 30 meter copper drop cable. XG-FAST paves the way for a homes-passed fiber network, leveraging high speed copper to the premises to increase its homes-connected.
We demonstrate concepts and results of a field trial for a flexible-rate passive optical network (FLCS-PON), which delivers bitrates up to 100 Gbit/s and allows for adaptations in the transmission ...method to match the users' channel conditions and optimize throughput. FLCS-PON builds on top of the hardware ecosystem that will be developed for ITU-T 50 Gbit/s PON and employs three new ingredients: optical network unit (ONU) grouping, flexible modulation format, and flexible forward error correction (FEC) code rate. Together, these techniques take advantage of the optical distribution network (ODN) statistics to realize a system capable of more than twofold throughput increase compared to the upcoming 50 Gbit/s PON, but still able to support a full array of deployed fiber edge cases, which are problematic for legacy PONs. In this paper we explain the concepts behind enabling techniques of FLCS-PON. We then report on a field trial over a deployed fiber infrastructure, using a system consisting of one FLCS-PON OLT and two ONUs. We report both pre- and post-forward-error-correction (post-FEC) performance of our system, demonstrating achievable net bitrate over an operator's fiber infrastructure. We realize a downlink transmission at double the speed of ITU-T 50 Gbit/s PON for ONUs exhibiting lower optical path loss (OPL), while simultaneously continue to support ONUs at high OPLs. We additionally realize a record-high 31.5 dB loss budget for 100 Gbit/s transmission using a direct-detection ONU with an optical preamplifier.
In next-generation digital subscriber line networks such as G.fast, employing discrete multi-tone transmission in high frequencies up to 212 MHz, the crosstalk among lines reaches very high levels. ...To precompensate the crosstalk in downstream transmission, QRD-based precoding has been proposed as a near-optimal dynamic spectrum management (DSM) technique. However, the performance of QRD-based precoding is greatly affected by the user encoding ordering (UEO). Since current multi-tone UEO methods are rather heuristic in the way they approach fairness, we develop, in this paper, a set of novel DSM algorithms for joint power allocation and UEO that enforce a generalized Formula Omitted-fairness policy. Since finding the globally optimal UEO entails a combinatorial optimization problem with excessive computational complexity, an iterative algorithm is proposed which uses per-tone exhaustive searches (PTESs) and provides near-optimal approximate solutions. To further reduce the computational complexity, two suboptimal methods are suggested to replace the expensive PTESs, leading to two additional Formula Omitted-fair DSM algorithms that are tractable for large scenarios against little performance loss. Simulations of a G.fast cable binder show that the Formula Omitted-fair DSM algorithms achieve an efficient trade-off between fairness and performance in contrast to current UEO methods.
We consider nonlinear zero-forcing (ZF) precoding design to improve the downstream G.fast peak-rates when only a few users in the cable binder are active. In order to compute the optimal nonlinear ZF ...precoder under per-line power constraints (PLPCs), we present a novel low-complexity dual decomposition algorithm, in which the key is the use of Lagrange multiplier based virtual precoders to transform the PLPCs into an easier virtual sum-power constraint (SPC), such that the SPC-optimality of the QR decomposition-based precoder may be exploited. We show a reduced computational complexity of this algorithm over the state-of-the-art SVD-block-diagonalization-based dual decomposition algorithm. We present simulations of a 10-line cable binder that demonstrate substantial peak-rate gains over standard QR decomposition-based ZF precoding in DSL, due to the increasingly stronger crosstalk channels in the G.fast frequency range (up to 212 MHz). Furthermore, we show that the proposed algorithm naturally extends to the scenario with multiple lines terminating at the customer premise equipments.
Next-generation passive optical networks (PONs) with upstream rates of 50 Gbit/s and beyond will require a new class of burst-mode transimpedance amplifiers (BMTIAs) that are linear to enable ...(digital) equalization of channel impairments. Such linear BMTIAs also enable higher-order modulation formats like 4-level pulse amplitude modulation (PAM-4). In this paper, we demonstrate operation of a novel linear BMTIA integrated together with a commercial off-the-shelf 25G-class avalanche photodiode (APD), achieving 50 Gbit/s non-return-to-zero (NRZ) operation with a sensitivity of -23.7 dBm optical modulation amplitude (OMA) and dynamic range exceeding 21.7 dB and 100 Gbit/s PAM-4 operation with a sensitivity of -15.8 dBm OMA and dynamic range exceeding 15.4 dB, both at a bit error ratio (BER) of <inline-formula><tex-math notation="LaTeX">10^{-2}</tex-math></inline-formula>. In addition, fast burst-mode gain-control and balancing circuits limit loud-soft sensitivity penalties in the case of AC-coupled circuits to less than 1.3 dB. The chip was designed in a 0.13 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>m SiGe:C BiCMOS technology, has an area of 1.2×1.7 mm<inline-formula><tex-math notation="LaTeX">^{2}</tex-math></inline-formula> and consumes between 260 mW and 310 mW. This receiver paves the way to a next-generation class of BMTIAs, supporting the ITU-T G.9804.3 Amd 1 standard.
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