This paper considers three aspects of Massive MIMO (multiple- input multiple-output) communication networks that have received little attention in previous works, but are important to understand when ...designing and implementing this promising wireless technology. First, we analyze how bursty data traffic behaviors affect the system. Using a probabilistic model for intermittent user activity, we show that the spectral efficiency (SE) scales gracefully with reduced user activity. Then, we make an analytic comparison between synchronous and asynchronous pilot signaling, and prove that the choice between these has no impact on the SE. Finally, we provide an analytical and numerical study of the SE achieved with random network deployment.
Space-time coding has been receiving much attention due to its potentials offered by fully exploiting the spatial and temporal diversities of multiple transmit and receive antennas. A differential ...space-time modulation (DSTM) scheme was previously proposed for demodulation without channel state information, which is attractive in fast fading channels where accurate channel estimates are difficult to obtain. However, this technique is sensitive to interference and is likely to deteriorate or even break down in a wireless environment, where interference (including intentional and unintentional jamming) signals exist. We propose a new coding and modulation scheme, referred to as the differential space-code modulation (DSCM), which is interference resistant. Our focus is on single-user communications. We show that DSCM outperforms DSTM significantly when interference is present. This advantage is achieved at the cost of a lower data rate or a wider bandwidth or a combination of both. To alleviate this problem, a high-rate DSCM (HR-DSCM) scheme is also presented, which increases the data rate considerably at the cost of a slightly higher bit-error rate (BER), while still maintaining the interference suppression capability.
System-on-chips (SOCs) and 3D stacked ICs are often tested for manufacturing defects in a modular fashion, enabling us to record the module test pass probability. We use this pass probability to ...exploit the abort-on-fail feature of automatic test equipment (ATE) and hence reduce the expected test time in the context of single-site testing. We present a model for calculation of expected test time, for which the abortable test unit can be a module test, a test pattern or a clock cycle. Given an SOC, with test architecture consisting of module test wrappers and test access mechanisms (TAMs), and given module test pass probabilities, we schedule the tests on each TAM to minimize the expected test time. We describe four scheduling heuristics, one without and three with preemption. Experimental results for the ITC'02 SOC Test Benchmarks show 3.5 and 20 percent reduction of expected test time in SOCs with 0.89 and 0.71 SOC test pass probability respectively, without modification of SOC or ATE. Further experiments show how accurate estimates for the module test pass probability or the distribution of pass probability over test patterns need to be to lead to effective test scheduling.
In this paper we study the benefits that Internet-of-Things (IoT) devices will have from connecting to a massive multiple-input-multiple-output (MIMO) base station. In particular, we study how many ...users that could be simultaneously spatially multiplexed and how much the range can be increased by deploying massive base station arrays. We also investigate how the devices can scale down their uplink power as the number of antennas grows with retained rates. We consider the uplink and utilize upper and lower bounds on known achievable rate expressions to study the effects of the massive arrays. We conduct a case study where we use simulations in the settings of existing IoT systems to draw realistic conclusions. We find that the gains which ultra narrowband systems get from utilizing massive MIMO are limited by the bandwidth and therefore those systems will not be able to spatially multiplex any significant number of users. We also conclude that the power scaling is highly dependent on the nominal signal-to-noise ratio (SNR) in the single-antenna case.
We point out an error in a derivation in the recent paper, and provide a correct and much shorter calculation of the result in question. In passing, we also connect the results in to the literature ...on array signal processing and on principal component analysis, and show that the signal detection methods proposed in follow as special cases of standard results in these fields.
Prevalence of and risk factors associated with polymerase chain reaction (PCR)-determined
positivity were assessed on day 3 after initiation of treatment, pre-implementation and up to 8 years ...post-deployment of artemether-lumefantrine as first-line treatment for uncomplicated malaria in Bagamoyo district, Tanzania. Samples originated from previously reported trials conducted between 2006 and 2014. Cytochrome b-nested PCR was used to detect malaria parasites from blood samples collected on a filter paper on day 3. Chi-square and McNemar chi-squared tests, logistic regression models, and analysis of variance were used as appropriate. Primary outcome was based on the proportion of patients with day 3 PCR-determined
positivity. Overall, 256/584 (43.8%) of screened patients had day 3 PCR-determined positivity, whereas only 2/584 (0.3%) had microscopy-determined asexual parasitemia. Day 3 PCR-determined positivity increased from 28.0% (14/50) in 2006 to 74.2% (132/178) in 2007-2008 and declined, thereafter, to 36.0% (50/139) in 2012-2013 and 27.6% (60/217) in 2014. When data were pooled, pretreatment microscopy-determined asexual parasitemia ≥ 100,000/µL, hemoglobin < 10 g/dL, age < 5 years, temperature ≥ 37.5°C, and year of study 2007-2008 and 2012-2013 were significantly associated with PCR-determined positivity on day 3. Significant increases in
multidrug resistance gene 1 N86 and
chloroquine resistant transporter K76 across years were not associated with PCR-determined positivity on day 3. No statistically significant association was observed between day 3 PCR-determined positivity and PCR-adjusted recrudescence. Day 3 PCR-determined
positivity remained common in patients treated before and after implementation of artemether-lumefantrine in Bagamoyo district, Tanzania. However, its presence was associated with pretreatment characteristics. Trials registration numbers: NCT00336375, ISRCTN69189899, NCT01998295, and NCT02090036.
Distributed massive multiple-input multiple-output (MIMO) combines the array gain of coherent MIMO processing with the proximity gains of distributed antenna setups. In this paper, we analyze how ...transceiver hardware impairments affect the downlink with maximum ratio transmission. We derive closed-form spectral efficiencies expressions and study their asymptotic behavior as the number of the antennas increases. We prove a scaling law on the hardware quality, which reveals that massive MIMO is resilient to additive distortions, while multiplicative phase noise is a limiting factor. It is also better to have separate oscillators at each antenna than one per BS.
The prevalence of posterior crossbite among pacifier-sucking girls in Falköping, Sweden, was previously found to be 26%. The aim of this investigation was to follow the development of crossbites in ...pacifier suckers and to determinate the possibility of reducing the prevalence of crossbite by informing and instructing the parents about sucking habits and reducing the time the child has the pacifier in the mouth. Parents of 60 consecutively born girls belonging to St Olof's health district, Falköping, Sweden, were invited to take part in the study. All parents agreed to participate. Five interviews or examinations of each girl took place from birth until 3 years of age. Fifty-four (90%) of the 60 girls were breast-fed. The mean duration of breast-feeding was 8 months, and 67% of the girls were breast-fed for half a year or more. Forty-three children (72%) developed a pacifier-sucking habit, 6 (10%), a digit-sucking habit, and 11 (18%), no sucking habits. The mean duration of breast-feeding was longer for the nonsuckers (11 months) than for the pacifier- and digit-sucking children (5 months). Of the 39 girls who still had the pacifier habit at 3 years of age, 2 had developed a posterior crossbite. Another girl stopped the habit when a crossbite was registered at the 2 1/2-year examination. At the next appointment, the crossbite had corrected itself spontaneously. One of the 2 girls with crossbite at 3 years of age developed a prenormal occlusion with both anterior and posterior crossbites. For 12 more pacifier suckers, an interfering contact was noted with a forced guidance of the mandible and a midline shift. In all 12 cases, the interfering teeth were primary canines. We conclude that parents should be instructed to reduce the "in the mouth time" of the pacifier. The transverse occlusal relationship in pacifier-sucking children should be evaluated between 2 and 3 years of age. If interfering contacts of the primary canines exist, the parents should be instructed to reduce the pacifier-sucking time.
Affibody molecules are small (7 kDa) nonimmunoglobulin scaffold proteins with favorable tumor-targeting properties. Studies concerning the influence of chelators on biodistribution of (99m)Tc-labeled ...Affibody molecules demonstrated that the variant with a C-terminal glycyl-glycyl-glycyl-cysteine peptide-based chelator (designated ZHER2:V2) has the best biodistribution profile in vivo and the lowest renal retention of radioactivity. The aim of this study was to evaluate (188)Re-ZHER2:V2 as a potential candidate for radionuclide therapy of human epidermal growth factor receptor type 2 (HER2)-expressing tumors.
ZHER2:V2 was labeled with (188)Re using a gluconate-containing kit. Targeting of HER2-overexpressing SKOV-3 ovarian carcinoma xenografts in nude mice was studied for a dosimetry assessment.
Binding of (188)Re-ZHER2:V2 to living SKOV-3 cells was demonstrated to be specific, with an affinity of 6.4 ± 0.4 pM. The biodistribution study showed a rapid blood clearance (1.4 ± 0.1 percentage injected activity per gram %ID/g at 1 h after injection). The tumor uptake was 14 ± 2, 12 ± 2, 5 ± 2, and 1.8 ± 0.5 %IA/g at 1, 4, 24, and 48 h after injection, respectively. The in vivo targeting of HER2-expressing xenografts was specific. Already at 4 h after injection, tumor uptake exceeded kidney uptake (2.1 ± 0.2 %IA/g). Scintillation-camera imaging showed that tumor xenografts were the only sites with prominent accumulation of radioactivity at 4 h after injection. Based on the biokinetics, a dosimetry evaluation for humans suggests that (188)Re-ZHER2:V2 would provide an absorbed dose to tumor of 79 Gy without exceeding absorbed doses of 23 Gy to kidneys and 2 Gy to bone marrow. This indicates that future human radiotherapy studies may be feasible.
(188)Re-ZHER2:V2 can deliver high absorbed doses to tumors without exceeding kidney and bone marrow toxicity limits.
PDF
