Nokia (Italy)

Purpose The purpose of this paper is to describe how demand planning can increase agility in supply chains. The paper builds on a case study from mobile infrastructure industry with explicit focus on project business environment. Design/methodology/approach The paper contains a short theoretical review on supply chain agility, different planning and forecasting concepts and explores the linkages between them. Empiric evidence is collected from Nokia Networks as a case study. Main lessons are primarily taken from integrated project management program that is to implement a truly customer‐focused delivery process in the case company. Findings Suppliers should pay more attention on effectively utilizing customer's project plans for aligning their supply chain. Supply chain agility does not just happen but requires continuous planning. Practical implications Common project planning is the most natural way for customers to share future demand information between the supply chain players. Instead separate and often laborious demand forecasting process, suppliers should utilize customer's project plans in building agility in their supply chains. Originality/value Focuses on the importance of the ability to adapt to rapid and unexpected changes and asserts that a continuous, customer driven planning process is a pre‐requirement for being agile in supply chains.

Abstract One of the main challenges of next generation optical communication is to increase the available bandwidth while reducing the size, cost and power consumption of photonic integrated circuits. Graphene has been recently proposed to be integrated with silicon photonics to meet these goals because of its high mobility, fast carrier dynamics and ultra-broadband optical properties. We focus on graphene photodetectors for high speed datacom and telecom applications based on the photo-thermo-electric effect, allowing for direct optical power to voltage conversion, zero dark current, and ultra-fast operation. We report on a chemical vapour deposition graphene photodetector based on the photo-thermoelectric effect, integrated on a silicon waveguide, providing frequency response >65 GHz and optimized to be interfaced to a 50 Ω voltage amplifier for direct voltage amplification. We demonstrate a system test leading to direct detection of 105 Gbit s −1 non-return to zero and 120 Gbit s −1 4-level pulse amplitude modulation optical signals.

Abstract One of the main challenges of next generation optical communication is to increase the available bandwidth while reducing the size, cost and power consumption of photonic integrated circuits. Graphene has been recently proposed to be integrated with silicon photonics to meet these goals because of its high mobility, fast carrier dynamics and ultra-broadband optical properties. We focus on graphene photodetectors for high speed datacom and telecom applications based on the photo-thermo-electric effect, allowing for direct optical power to voltage conversion, zero dark current, and ultra-fast operation. We report on a chemical vapour deposition graphene photodetector based on the photo-thermoelectric effect, integrated on a silicon waveguide, providing frequency response >65 GHz and optimized to be interfaced to a 50 Ω voltage amplifier for direct voltage amplification. We demonstrate a system test leading to direct detection of 105 Gbit s−1 non-return to zero and 120 Gbit s−1 4-level pulse amplitude modulation optical signals.

This correspondence describes an efficient Bayesian framework for localization of moving terminals (MTs) in wideband wireless networks. In a previous paper, the authors have presented a grid-based technique, based on a hidden Markov model, that used the power delay profiles of the received signals to track the MT position. This grid-based Bayesian method has proved its efficacy in reducing localization errors in realistic indoor environments with multipath effects and mixed line-of-sight/non-line-of-sight (LOS/NLOS) conditions. However, the computational power and the memory storage requirements limit its use in practical wireless networks. To improve the computational efficiency, here we propose a jump-Markov particle-filter approach as an extension of the previous work; the LOS/NLOS sight process is the jumping feature that drives the MT motion dynamics, while the particle filter is used to track the MT position. Performance analyses, carried out for realistic multipath indoor environments, show that, with respect to the previous grid-based algorithm, this novel approach greatly reduces the tracking filter complexity still preserving the same localization accuracy. Simulation results prove also the robustness of the proposed method with respect to the uncertainty of sight statistics information.

A 16-element 140–160-GHz phased array transceiver is reported. The chipset is fabricated using STMicroelectronics’ 55-nm SiGe BiCMOS process. Five different chips are implemented: a 4-channel transmitter with a maximum gain per channel of 15 dB and 0-dBm saturated output power; a 4-channel receiver with a maximum gain of 8 dB, a −10.4-dBm input 1-dB compression point (IP1 dB), and a minimum noise figure (NF) of 15.6 dB per channel; a 0–1-GHz to 140–160-GHz I/Q up-converter with integrated frequency doubler, exhibiting a −13.5-dB conversion gain (CG) and −6-dBm output 1-dB compression point using a 70–80-GHz local oscillator (LO); a 140–160-GHz to 0–1-GHz I/Q down-converter with integrated frequency doubler, exhibiting a CG of 0 dB and IP1 dB of 0 dBm using a 70–80-GHz LO and an 11.67–13.33-GHz to 70–80-GHz x6 frequency multiplier for the LO, delivering 5.6-dBm maximum output power. The chips are assembled together with 16 cavity-backed aperture-coupled patch antennas using a high-performance and low-cost commercial PCB, supported over a heat sink. The main challenges encountered during the integration of the proposed system are also discussed. The complete system is used to build a wireless radio link in the laboratory, demonstrating 2-D beam steering in a range of ±30°.

Detector-grade undoped chemical vapor deposited (CVD) diamond samples have been studied with thermally stimulated currents (TSC) and photoinduced current transient spectroscopy (PICTS) analyses in the temperature range 300–650 K. Two previously unknown defects have been identified, characterized by activation energies E1=1.14 eV and E2=1.23 eV, cross sections of about σ≈10−13 cm2 and concentrations of Nt≈1016 cm−3. They have been clearly observed by PICTS and isolated in TSC measurements by use of a fractional annealing cycle in the temperature range 300–400 K. Due to their trap parameters, in particular the high cross section, the levels corresponding to E1 and E2 are characterized by capture times of the order of 10–100 ps. A dominant TSC peak observed at ≈500 K has been also investigated and has been resolved into four components with activation energies of the order of 1 eV and cross sections in the range 10−19–10−17 cm2. Three of these levels exhibit a fast capture rate (0.1–10 ns) in spite of their small cross sections, due to their high concentration in the investigated sample. Correlating our results with room temperature charge collection studies, we propose that the observed traps with their fast capture rates can be effective in limiting the carrier lifetimes and, consequently, the charge collection efficiency of CVD diamond particle detectors

A fully operational 4G long-term evolution (LTE) base station is tested in a reverberation chamber to analyze its performance in the presence of a multipath environment, typical of wireless and vehicular communications. Transmission quality parameters are measured ranging from the empty chamber situation (very rich multipath channel) to a very high loading condition to mitigate multipath. In that way, both outdoor and indoor propagation are accounted for a large attenuation is inserted between the transmitter and the antenna to reduce the signal received by the user to real-life values encountered in both outdoor and indoor environments. In these scenarios, operators may choose to transmit a constant power spectral density throughout all LTE spectrum, or to increase the energy of control channels at the expense of data channels in order to enforce transmission and provide better quality to the user, especially in poor radio conditions. This is called “power boosting,” and its effect is analyzed in this paper.

The uplink performance of a real fourth-generation long-term-evolution (LTE) frequency-division multiplexing base station was observed by adopting a reverberation chamber as propagating environment. In the downlink direction, the reception of the LTE signal is limited to mobile station receivers. On the other hand, different reception schemes could be implemented by the base station in the uplink direction. Interference rejection and coordinated multipoint reception criteria are based on spatial diversity and are analyzed in a rich multipath environment. These options could be susceptible to impairments due to the presence of Gaussian noise, also including the more realistic case of a discontinuous noise source. The testing session was carried out under a collaboration program between TIM S.p.A., Nokia, and Università Politecnica delle Marche, and it ended up by introducing envisioned reception solutions of the base station in a live customer's cellular network.

After reviewing models and mitigation strategies for interchannel nonlinear interference (NLI), we study its characteristics and coherence properties. Based on this study, we devise an NLI mitigation strategy, which exploits the synergic effect of phase and polarization noise (PPN) compensation and subcarrier multiplexing with symbol-rate optimization. This synergy persists even for high-order modulation alphabets and Gaussian symbols. A particle method for the computation of the resulting achievable information rate and spectral efficiency (SE) is presented and employed to lower-bound the channel capacity. The dependence of the SE on the link length, amplifier spacing, and presence or absence of in-line dispersion compensation is studied. Single-polarization and dual-polarization scenarios with either independent or joint processing of the two polarizations are considered. Numerical results show that, in links with ideal distributed amplification, an SE gain of about 1 bit/s/Hz/polarization can be obtained (or, in alternative, the system reach can be doubled at a given SE) with respect to single-carrier systems without PPN mitigation. The gain is lower with lumped amplification, increases with the number of spans, decreases with the span length, and is further reduced by in-line dispersion compensation. For instance, considering a dispersion-unmanaged link with lumped amplification and an amplifier spacing of 60 km, the SE after 80 spans can be be increased from 4.5 to 4.8 bit/s/Hz/polarization, or the reach raised up to 100 spans (+25%) for a fixed SE.

For the first time, the carrier aggregation feature of a live fourth-generation Long-Term Evolution (4G-LTE) base station (BS) is checked, adopting a reverberation chamber as a propagating environment. For this purpose, two nonadjacent bands were chosen, i.e., 800 and 1800 MHz, and alternatively set as primary and secondary cells. The multipath conditions were tuned by adding the absorbing material inside the chamber and ranging from an empty condition with a rich multipath to a real environment such as an indoor scenario. The latter is a very interesting and popular situation as it represents one in which people use mobile phones. The multipath variation effect on the BS performance was accurately verified by introducing power compensation to account for the variation of the chamber quality factor Q due to the insertion of absorbers. A complete over-the-air test was carried out by checking typical transmission quality parameters, which are of interest to manufacturers and mobile network operators. Results highlight the differences between the performance of the two bands as a function of multipath degree and signal strength.

The mobile data traffic increase and the future connection of billions of Internet of Things (IoT) devices require operators to reshape the existing transport network architecture. Today, more than 50 % of Base-stations (BTS) are backhauled via radio. Radio technology can continue to play this vital role in future transport networks if it is able to evolve to cope with the new capacity level and latency requirements supporting the new 5G services. In this paper, a possible answer to this demand is provided, proposing a radio solution working in D-Band (130-170 GHz) and enabling a reconfigurable meshed network that can support the backhaul needs of future 5G and beyond networks.

This paper presents a study of the D-band radio solutions, with beam-steering functionality, intended for use in the reconfigurable meshed network. The regulation and radio network constraints defining the specifications of a D-Band transceiver are reviewed. The architecture of the radio link is proposed and key enabling technologies needed to build the D-band transceiver are presented. The proposed solutions can be used for plenty of different radio connections, since they can provide a capacity level up to 100 Gbps over 160 meter and, at reduced capacity, hop lengths exceeding 1 km.

.

High-speed trains are nowadays a reality in most of the countries. Internet services and connectivity are required by the passengers on board using smartphones and laptops. Nevertheless, the higher the speed, the bigger the issues that operators have to face to implement mobility and to reduce the effect of fast fading signal and Doppler shift, which may cause throughput reduction and problems to access the network. In the past, operators tried to optimize the cellular access to universal mobile telecommunications system cells covering railways. Now that 4G networks have become mature and deployed, a similar approach needs to be optimized and implemented to long-term evolution cells covering the same targets. We present the results of a testing campaign replicating real “high-speed train” propagation scenarios, like a train running in open space or in tunnels with the help of a reverberation chamber. The chamber was partially filled by absorbing panels and equipped with rotating stirrers in order to approach the multipath propagation and to replicate the fading conditions that is typical of smartphones in a train coach. The effects of Doppler and its fast variations are presented, together with an analysis of the efficiency of different transmission solutions for tunnels (single-input single-output cells propagating inside them). The testing sessions were performed under a collaboration program between Telecom Italia (in the paper referred as “operator”), Nokia Networks, and Università Politecnica delle Marche. After the experiments in our laboratory, some features were introduced in the operator's live network, covering the high-speed railway between the two Italian cities of Piacenza and Bologna.

We demonstrate, to the best of our knowledge, the highest reported single- and multi-channel capacities over a field-deployed data center interconnection (DCI) system operating over 93 km of standard single-mode fiber using only Erbium-doped fiber amplification. Using off-the-shelf hardware components, and in particular using only a single digital-to-analog converter per complex signal dimension, we achieve a net bit rate of 1.3 Tb/s per wavelength (single-channel operation) and more than 1.25 Tb/s per channel in a 40-channel wavelength-division multiplexed (WDM) system with a spectral efficiency of 11.29 bits/s/Hz. We achieve a total WDM capacity of 50.8 Tb/s across the C-band.

Mobile terminals have evolved from basic portable telephones to complex and diverse devices that encompass dozens of other features, ranging from tri-dimensional games to office suites with data transmission capabilities. Variability is value: mobile terminal manufacturers must succeed in fulfilling the requirements of hundreds of mobile telecom operators worldwide, and at the same time increase the value of their brand by adopting a common user interface style while offering the features that the target end-user category desires. This makes for practically infinite variability and creates a business problem. The complexity of the variability problem increases due to issues such as the ability to ‘plug and play’ and ‘feature descension’ (the down-scaling of high-end features and their introduction into lower-end models). The main lesson we have learned from our experience in this field is that the application of relatively simple architectural patterns usually eases up management of the complexity at the architectural level. However, tackling the variability problem at the technical level is ineffective unless the organization is able to ensure the application of the solutions. We analyze the main challenges that lie behind the variability problem in mobile terminals, at both technical and organizational level, and illustrate some of the solutions we have implemented together with our product developers and system architects. Our experience calls for more applied research in the area of variability management, as well as for a number of enhancements to academic curricula. Copyright © 2005 John Wiley & Sons, Ltd.

This paper describes an innovative approach to radio channel characterization in UMTS and LTE mobile networks. In place of traditional drive tests (DT), which employ a single test mobile, a massive collection of georeferenced radio measurements is made from a wide population of user equipment (UE). This is possible with new 3GPP features, called “minimization of DTs” (MDT), which are implemented in the last generation UEs and enable the reporting of additional periodical measurements, including GPS position and estimated UE distance (i.e. delay) over the radio path. This opens to new fields of investigation in the mobile radio channel, unreachable with the legacy DT approach, such as multipath and Doppler analysis. The UE MDT data of UMTS and LTE RAN of Telecom Italia Mobile, in the Italian midsized city of Bologna, have been statistically analyzed. The big data elaboration has been performed with the Nokia proprietary system “GeoSynthesis.” The results give a high-resolution geographical view of the above-mentioned channel phenomena affecting the quality and user experience. They are in good accordance with network performance indicators: the higher the multipath time, the worse the decoding performance of radio blocks (block error rate). The estimated Doppler shift also fits the known mobility patterns in the urban environment.

Testing of wireless devices and systems is becoming increasingly important in the technological development of Long Term Evolution (LTE) and 5G mobile networks. Both mobile and base station manufacturers are interested in assessing system performance and user perceived quality in realistic propagation environments, including indoor and outdoor conditions. Real-life electromagnetic environments exhibit rich multipath propagation and a strong attenuation of the wireless signal over the propagation channel. Emulating those conditions in anechoic chambers requires the careful arrangement of many interference sources in multiple configurations, which leads to complex and time-consuming measurements. The reverberation chamber (RC) is a metallic cavity where the signal created by a single source is reflected and diffused to create multipath fading. This paper gives an overview of how an RC can be tuned to emulate channel parameters, e.g., power delay profile, time delay spread, coherence bandwidth and Rician K-factor, of real-life environments The addition of absorbing material inside the RC allows for varying those parameters, thus recreating line of sight and imperfect propagation conditions experienced by the user equipment (UE). Compliant electromagnetic compatibility downlink and uplink tests are shown for selected MIMO configurations as well as for Internet of Things devices. The tests are carried out using a commercial base station connected to the live national mobile network of a mobile operator. Evaluated network parameters are throughput, signal to noise ratio, modulation schemes and other settings of both the base station and of the UE to assess the quality of the digital communication.

With the advent of novel elastic optical transponders allowing for fine rate granularity, network designers can maximize the throughput of current installed and future wavelength-division multiplexing (WDM) infrastructures. In this sense, data flow can be properly optimized for each optical connection, while avoiding unnecessary margins. Such a connection mode of operation should rely on a simple mechanism. This paper illustrates how a SNR-driven self-optimization of optical connections is relevant for elastic WDM networks, especially when associated with probabilistic constellation shaping, allowing rate tunability while maximizing spectral efficiency. In addition, we study a WDM North American backbone network to quantify the savings brought by this self-optimization in terms of transponder equipment for 10 years, as compared to conventional planning usually relying upon “end of life” assumptions.

3G long-term evolution (LTE) is a recent effort taken by cellular industries to step into wireless broadband market. The key enhancements target an introduction of new all- IP architecture, enhanced link layer and radio access with OFDM modulation and multiple antenna techniques. In this study, we focus on the overhead deriving from the multilayer ARQ employed at the link and transport layers. To the aim of reducing unnecessary burden on the wireless link, we propose a cross-layer ARQ approach, called ARQ Proxy, which substitutes the transmission of TCP ACK packet with a short MAC layer request on the radio link. Packet identification is achieved through association of a hash function to the raw packet data. Performance of the ARQ Proxy is evaluated using EURAE extensions for ns2 simulator. Results demonstrate significant improvements in terms of system capacity, TCP throughput performance, and higher tolerance to transmission errors.