A Light Signalling Approach to Node Grouping for Massive MIMO IoT Networks

Massive MIMO is a promising technology to connect very large numbers of energy constrained nodes, as it offers both extensive spatial multiplexing and large array gain. A challenge resides in partitioning the many nodes in groups that can communicate simultaneously such that the mutual interference is minimized. We here propose node partitioning strategies that do not require full channel state information, but rather are based on nodes' respective directional channel properties. In our considered scenarios, these typically have a time constant that is far larger than the coherence time of the channel. We developed both an optimal and an approximation algorithm to partition users based on directional channel properties, and evaluated them numerically. Our results show that both algorithms, despite using only these directional channel properties, achieve similar performance in terms of the minimum signal-to-interference-plus-noise ratio for any user, compared with a reference method using full channel knowledge. In particular, we demonstrate that grouping nodes with related directional properties is to be avoided. We hence realise a simple partitioning method requiring minimal information to be collected from the nodes, and where this information typically remains stable over a long term, thus promoting their autonomy and energy efficiency

Digestibility of silage and hay for horses in training

Horses are made to eat mainly roughage and it is essential for optimal health to offer them an appropriate amount of roughage with good hygienic and nutritional qualities. To produce good hay at the right time and be able to keep the hygienic quality until next summer is a problem. This has the effect that horse owners today choose haylage and silage to a larger extent. Science in this area is scarce, i.e. if the change from hay to silage has any effect on the horse. The aim of this study was to compare hay and silage from the same crop and measure digestibility, eating behaviour and plasma glucose levels in athletic horses and the effect of an abrupt feed change between hay and silage. Five standardbred trotters in training were used and fed two roughage-only diets (hay and silage) supplemented with minerals and salt. The study started with an adaptation period of nine days when two of the horses were fed one of the roughages and the rest of the horses were fed the other. At the morning meal the first day after the adaptation period there was an abrupt feed change that was the start of the first experimental period. All urine and feaces were collected the first 48 hours after the feed change. Also at the end of the experimental period, day 18-20, all urine and feaces were collected. Another abrupt feed change started the second experimental period that was designed exactly as the first. To calculate digestibility and fluid balance (results not shown in this paper) the samples of urine and feaces were weighed and analyzed. The digestibility for DM, OM, CP, ADF and lignin were higher on silage compared to hay already within 48 h after the feed change. There were no differences in the digestibility of NDF. There were no differences between plasma glucose or insulin levels in horses fed hay or silage. One hour after the feed change the plasma lactate were higher in horses fed silage compared to horses fed hay. Half a kg DM of silage was eaten during a longer period of time than half a kg DM of hay. Chewing frequency were however the same which means that in order to eat half a kg DM of silage a horse has to chew more times than to eat half a kg DM of hay. If the horses were allowed to choose freely between the two feeds they chose silage seven times out of ten.Hästar är grovfoderomvandlare och att kunna erbjuda hästarna tillräcklig mängd av ett hygieniskt och näringsmässigt bra grovfoder är nödvändigt för att uppnå optimal hälsa. Problemen med att skörda ett bra hö vid rätt tidpunkt och få det att hålla sig hygieniskt ända tills nästa sommar har gjort att fler väljer att utfodra sina hästar med inplastat grovfoder såsom hösilage och ensilage. Det finns relativt lite forskning genomförd som belyser hur ett byte från hö till ensilage påverkar hästar. Syftet med den här studien var att jämföra hö och ensilage från samma gröda och mäta smältbarhet, ätbeteende och vilken effekt ett tvärt foderbyte mellan hö och ensilage har på hästen. Fem varmblodiga travhästar i träning användes och de utfodrades med enbart grovfoder (hö eller ensilage), mineraler och salt. Försöket inleddes med en tillvänjningsperiod på nio dagar då två av hästarna åt det ena fodret och resten åt det andra fodret. Vid morgonfodringen första dagen efter tillvänjningsperioden gjordes ett tvärt foderbyte vilket inledde den första försöksperioden. Två dygn efter foderbytet samlades all träck och urin upp. I slutet av försöksperioden, dag 18-20, samlades också all träck och urin upp. Sedan gjordes ett nytt tvärt foderbyte som inledning på den andra försöksperioden vilken var upplagd likadant som den första. Träck- och urinproverna vägdes och analyserades för att kunna räkna ut bland annat smältbarhet och vätskebalans (ej redovisat i detta arbete). Smältbarheten av ts, OS, RP, ADF och lignin var högre i ensilage än i hö redan 48 timmar efter foderbytet. Smältbarheten av NDF skilde sig inte. Det var ingen skillnad i koncentration i plasma av glukos eller insulin hos hästar fodrade med hö respektive ensilage. En timme efter foderbytet var det högre nivåer av laktat i plasman hos hästar fodrade med ensilage jämfört med hästar fodrade med hö. Det tog längre tid för hästarna att äta ett halvt kg ts ensilage är ett halvt kg ts hö. Tuggfrekvensen var densamma vilket innebar att det gick åt fler antal tuggningar för att tugga ett halvt kg ts ensilage jämfört med ett halvt kg ts hö. Om hästarna fick välja foder själva så valde de sju gånger av tio ensilaget framför höet

Internet of Buoys: An Internet of Things Implementation at Sea

Internet of Things (IoT) applications are emerging in many different areas, including maritime environments. One of the applications in this area is the monitoring of buoys at sea. To realize wireless tracking of buoys, an accurate prediction of the path loss in an open-sea environment is essential. So far, channel measurements at sea have mainly been conducted with antennas placed a couple of meters above the sea surface, which is higher than the buoys themselves. Therefore, we investigated the validity of the published channel models at sea by means of path loss measurements using a LoRa link with a transmitter antenna height of 0.35 m and a base station antenna height of 2.65 m and 5.2 m. Our results show that the round earth loss model is not accurate at these antenna heights. The ITU-R P.2001-3 model and a model by Bullington show a better agreement with our measurements. However, the difference between our two measurement campaigns shows that more investigation is needed on the dependence of the path loss on the sea state. Additionally, the availability of Sigfox, Narrowband Internet of Things (NB-IoT), and The Things Network at sea has been explored. We found that NB-IoT and Sigfox can be used for IoT applications in the tested area at low antenna heights

Easier said than done! Organic farmers consider free-ranging important for laying hen welfare but outdoor areas need more shelter - important gaps between research and practice

1. The aim of the present study was to investigate the design and management of free-range areas and their use by birds on commercial organic laying hen farms in Sweden and to document farmers' perspectives on outdoor access for poultry.2. Eleven Swedish organic laying hen farms were visited. The farmers were interviewed about general farm management, bird health and behaviour and outdoor access. The free-range areas were assessed in terms of proportion covered by protective (high) vegetation and any artificial shelters provided. The numbers of hens ranging at different distances from the house were recorded twice during the day.3. The outdoor area within 250m from the house contained 0-5% vegetation cover on six of the farms and at least 80% pasture on seven farms. On 10 farms, no more than 13% of the flock was observed outdoors. Of the hens observed in the free-range area, the median proportion ranging within 20m from the house or veranda per observation event was 99% (IQR=55-100%), confirming reports by the farmers.4. Free-range access was considered important by all farmers, primarily for welfare reasons and most agreed that protective vegetation cover and/or artificial shelters were important in encouraging free-ranging. However, there was marked variation among the farmers in their suggestions on how to attract hens outside

Forest-edge effects on sea-salt aerosol deposition : a wind-tunnel study using living oak leaves

Landscape patchiness creates aerodynamic transition zones that affect the exchange of nutrients and pollutants between the atmosphere and vegetation. Using an artificially-generated NaCl aerosol (mass-versus-particle-size distribution with aerodynamic mean particle diameter 1.6 mu m; geometric standard deviation 1.9), we investigated the forest-edge effect on aerosol deposition within a model oak (Quercus robur) canopy in a wind tunnel with an emulated beach-to-forest transition. The deposition rate around the forest edge was 2-3 times higher than to the beach and 50%-60% higher than to the interior of the forest. The deposition velocity at the edge was 0.06 cm s(-1), which is 2-3 times higher than the beach-deposition velocity. Our results can help improve estimates of aerosol-borne inputs of nutrients or pollutants to forested landscapes that experience shifts in meteorological regimes due to changes in climate and forestry practices, in particular with respect to deciduous species in coastal environments

Outsouring av kundservice

Bakgrund: Synen på kunden har förändrats där det skett en förskjutning från produkt- till kundfokus där kunden numera står i centrum. Nära och starka relationer till sina kunder är avgörande för företagets framtida konkurrenskraft. Bra kundrelationer bygger på att företag lyckas leverera tjänster med hög servicekvalitet som uppfyller och överträffar kundens behov. Många företag saknar förmågan eller resurser att säkerställa den servicekvalitet som kunderna efterfrågar. Allt fler företag väljer därför att outsourca sin kundservice till ett annat företag som specialiserar sig på kundservice och kundvård. Outsourcing av kundservice kan komma att bli en av de mest växande trenderna inom outsourcing. Problematiken i uppsatsen utgår från hur ett externt företag skapar värde. Syfte: Syftet med uppsatsen är att förstå hur kontaktcenter bedriver det operativa arbetet för värdeskapande. Utifrån detta vill vi förstå vilken roll kontaktcenter har i tjänstesamhället. Genomförande: Undersökningen baseras på ett induktivt förhållningssätt mellan empiri och teori, där det empiriska materialet baseras på sju djupintervjuer med respondenter från två olika kontaktcenter samt en uppdragsgivare. Intervjuerna har kompletterats med dokumentstudier samt en observation. Utifrån ett hermeneutiskt perspektiv har det empiriska materialet tolkats och sedan analyserats tillsammans med teorier som berör värdeskapande, outsourcing, standardisering samt utbildning. Slutsats: Undersökningen visar att de studerade kontaktcenter organiserar sin verksamhet på ett standardiserat sätt där relationen med uppdragsgivaren utgör grunden för att kontaktcenter ska kunna organisera för värdeskapande. Medarbetarna på kontaktcenter är en viktig resurs vilket innebär att kontaktcenter måste organisera sig utifrån dem där utbildning utgör en avgörande faktor för slutkundens upplevda värde. Dessa organisatoriska aspekter har stor betydelse för att kunna tillgodose kundens förväntningar gällande servicekvalitet där bland annat faktorer som tillgänglighet, bemötande och kompetens påverkar kundens upplevda värde. Kontaktcenter har kommit att bli specialister på kundservice och får en allt mer betydande roll i det framtida tjänstesamhället.Introduction: The view of the customer has changed, since focus has shifted from product oriented to service oriented. It is vital for a company to have close and strong relationships to their customers to be able to maintain future competitiveness. Companies need to deliver services with high service quality to meet customer’s needs, which creates good customer relationships. There are companies who lack the ability to ensure service quality that customers are requesting. Therefore a lot of companies choose to outsource their customer service to another company who is specialized in customer service and customer care. Outsourcing customer service may become one of the most growing trends in outsourcing. The problem in this paper is based on how an outside company can create value. Purpose: The purpose with this paper is to understand how a contact centre organizes their operational work to create value and what impact and role do they have in the community of services. Methodology: The study is based on an inductive approach between empirical materials and theory. The empirical material is based on seven interviews with respondents from two different contact centres and one client. There are also studies of documents and one observation to complement the interviews. The empirical evidence has been interpreted from a hermeneutic perspective and then analysed with theories concerning value creation, outsourcing, standardization and education. Conclusion: The survey shows that the studied contact centres organize their operational work in a standardized way and the relationship and cooperation between the client and contact centre are two of the most important organizational aspects to create value. Education is a crucial organizational aspect for contact centre and is necessary to create value for the consumer. These organizational factors are of great importance in order to meet customer expectations of service quality, which includes aspects such as accessibility, friendliness and expertise that affect the customer’s perceived value. Contact centre has become an expert of customer service, therefore they have a more significant role in the community of service. Keywords: Outsourcing, Contact Centre, Value creation, Service quality, Standardization, Educatio

Channel Hardening in Massive MIMO: Model Parameters and Experimental Assessment

Reliability is becoming increasingly important for many applications envisioned for future wireless systems. A technology that could improve reliability in these systems is massive MIMO (Multiple-Input Multiple-Output). One reason for this is a phenomenon called channel hardening, which means that as the number of antennas in the system increases, the variations of channel gain decrease in both the time- and frequency domain. Our analysis of channel hardening is based on a joint comparison of theory, measurements and simulations. Data from measurement campaigns including both indoor and outdoor scenarios, as well as cylindrical and planar base station arrays, are analyzed. The simulation analysis includes a comparison with the COST 2100 channel model with its massive MIMO extension. The conclusion is that the COST 2100 model is well suited to represent real scenarios, and provides a reasonable match to actual measurements up to the uncertainty of antenna patterns and user interaction. Also, the channel hardening effect in practical massive MIMO channels is less pronounced than in complex independent and identically distributed (i.i.d.) Gaussian channels, which are often considered in theoretical work.Comment: Accepted to IEEE Open Journal of the Communications Societ

Channel Hardening in Massive MIMO - A Measurement Based Analysis

Wireless-controlled robots, cars and other critical applications are in need of technologies that offer high reliability and low latency. Massive MIMO, Multiple-Input Multiple-Output, is a key technology for the upcoming 5G systems and is one part of the solution to increase the reliability of wireless systems. More specifically, when increasing the number of base station antennas in a massive MIMO systems the channel variations decrease and the so-called channel hardening effect appears. This means that the variations of the channel gain in time and frequency decrease. In this paper, channel hardening in massive MIMO systems is assessed based on analysis of measurement data. For an indoor scenario, the channels are measured with a 128-port cylindrical array for nine single-antenna users. The analysis shows that in a real scenario a channel hardening of 3.2-4.6 dB, measured as a reduction of the standard deviation of the channel gain, can be expected depending on the amount of user interaction. Also, some practical implications and insights are presented.Comment: Accepted to SPAWC 201

Heritage science contribution to the understanding of meaningful khipu colours

Funding: Financial support by the Access to Research Infrastructures activity in the Horizon 2020 Programme of the EU (IPERION HS Grant Agreement n.871034) is gratefully acknowledged.This work is the first scientific study of khipu dyes and inorganic mordants and auxiliaries, paving the way for a new approach to understanding khipus’ meaningful materiality, technology, and colours. Khipus have usually been described as “Andean knotted records”, but they are much more than complex knotted cords: a great part of the information encoded resides in khipus’ incredible colours. The objects of this study are two Wari khipus, 1932.08.0001 and 1932.08.0002, now at the Museum of World Culture in Gothenburg, Sweden. After a morphological study of the khipus, the objects were imaged with multiband imaging (MBI) as an aid for the sampling decisional process. The khipus were then analysed non-invasively by X-ray fluorescence (XRF) spectroscopy on selected areas of particular interest. The khipus were consequently sampled for elemental characterisation by micro-XRF, and liquid chromatography coupled with high-resolution mass spectrometry (HPLC–HRMS) for characterising the organic dye composition. This paper presents a part of the results of the project “Meaningful materials in the khipu code”, with the intent to shed light on the difficulties and possibilities of investigating khipu colours and dyestuffs. MBI and XRF revealed unforeseeable structural characteristics, such as remnants from a heavily degraded thread in an area of missing thread wrapping and a dual-coloured thread that was previously deemed single-coloured. The organic dyes identified by HPLC–HRMS comprised indigoids, cochineal, and an unknown flavonoid-based dyestuff. XRF of the inorganic components revealed associations of several elements with specific colours.Publisher PDFPeer reviewe

Positioning for the Internet of Things: A 3GPP Perspective

Many use cases in the Internet of Things (IoT) will require or benefit from location information, making positioning a vital dimension of the IoT. The 3rd Generation Partnership Project (3GPP) has dedicated a significant effort during its Release 14 to enhance positioning support for its IoT technologies to further improve the 3GPP-based IoT eco-system. In this article, we identify the design challenges of positioning support in Long-Term Evolution Machine Type Communication (LTE-M) and Narrowband IoT (NB-IoT), and overview the 3GPP's work in enhancing the positioning support for LTE-M and NB-IoT. We focus on Observed Time Difference of Arrival (OTDOA), which is a downlink based positioning method. We provide an overview of the OTDOA architecture and protocols, summarize the designs of OTDOA positioning reference signals, and present simulation results to illustrate the positioning performance.Comment: 8 pages; 7 figures; 1 table; submitted for publicatio