Energy and spectral-efficient lens antenna subarray design in MmWave MIMO Systems

Lens antenna subarray (LAS) is one of the recently introduced technologies for future wireless networks that significantly improves the energy efficiency of multiple-input multiple-output (MIMO) systems while achieving higher spectral efficiency compared to single-lens MIMO systems. However, a control mechanism for the LAS-MIMO design is considered a challenging task to efficiently manage the network resources and serve multiple users in the system. Therefore, in this paper, a sub-grouped LAS-MIMO architecture along with a hybrid precoding algorithm are proposed to reduce the cost and hardware overhead of traditional hybrid MIMO systems. Specifically, the LAS structure is divided into sub-groups to serve multiple users with different requirements, and an optimization problem based on the achievable sum-rate is formulated to maximize the spectral efficiency of the system. By splitting the sum-rate problem into sub-rate optimization problems, we develop a low-complexity hybrid precoding algorithm to effectively control the proposed architecture and maximize the achievable sum-rate of each subgroup. The proposed precoding algorithm selects the beam of each lens from a predefined set within a subgroup that maximizes the subgroup sum-rate, while the phase shifters and digital precoders in each subgroup are computed independently. The link between subgroups is updated based on successive interference cancelation to minimize interference between users of different subgroups. Our analysis and simulation results show that the proposed precoding algorithm of the sub-grouped LAS-MIMO architecture performs almost as well as traditional fully-connected hybrid MIMO systems in terms of spectral efficiency at low and high signal-to-noise ratio (SNR). It also outperforms traditional fully-connected and sub-connected hybrid MIMO systems in terms of energy efficiency, even when a large number of lenses are employed.National Science Foundation (NSF

A spatially adaptive antenna array for mm-wave wireless channel control with microfluidics based reconfiguration

Spatially adaptive antenna array (SAA) is an electronically scanned antenna array with capability of changing its physical location. This new capability allows SAA to control the wireless channel environment to increase link capacity without employing an increased number of antenna elements. Compact and cost-effective implementation of SAA requires a strategically designed RF feed network that can allow the radiating antenna elements to be repositioned while other RF and digital electronics remain stationary. This manuscript introduces a novel RF feed network and demonstrates the first experimental verification of SAA by using microfluidic based reconfiguration. The presented microfluidically reconfigurable SAA (MRSA) exhibits the best possible compact form - a total footprint that is approximately equal to the spatial adaptation range. MRSA operates at 28 GHz with 45 mm (4.2 lambda(0)) spatial adaptation capability. Evaluating MRSA in communication systems using its measured realized gain patterns show that link level performance of the wireless channel is improved by 24% from 8.5 bps/Hz to 10.5 bps/Hz. Additionally, spectral efficiency is improved by 100% with 5 dB improvement in average signal to interference ratio.National Science Foundation (NSF); Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK

Heuristic inspired precoding for millimeter-wave MIMO systems with lens antenna subarrays

A traditional array (TA) multiple-input multiple-output (MIMO) architecture in mmWave with hybrid beamforming suffers from high power consumption and hardware overhead. Therefore, a lens antenna subarray (LAS)-MIMO architecture has been recently proposed as a promising technology for a power-efficient system and reducing hardware cost and complexity. Additionally, the LAS-MIMO can offer spectral efficiency (SE) performance close to TA-MIMO and higher than single-lens antenna array (SLA)-MIMO. In this paper, we propose a hybrid precoding algorithm for the LAS-MIMO in mmWave to efficiently control the LAS design. The precoding problem is formulated as a sparse reconstruction problem due to the sparse behavior of mmWave channel. The proposed algorithm is an iterative process developed jointly using artificial bee colony (ABC) optimization with orthogonal matching pursuit (OMP) algorithms. In each iteration, the algorithm first selects the switches for each lens randomly using ABC and then uses OMP to approximate optimal unconstrained precoders. This process continues until achieving maximum SE. The simulation results show that LAS has around a 30% increase in SE compared to SLA while providing a significant gain in energy efficiency (EE) for single radio-frequency (RF) chain and multi RF chain scenarios.Huawei ; Nokia ; Pix Moving ; Samsung ; Technology Innovation Institute (TII

Oral health and oral quality of life in inactive patients with familial Mediterranean fever without amyloidosis

OBJECTIVES: The aim of this study was to investigate oral and general health-related quality of life (QoL) in patients with familial Mediterranean fever (FMF) disease. METHODS: In this cross-sectional study, 45 patients with FMF, 50 age- and sex-matched healthy controls (HC), and 50 patients with Behçet's disease (BD) as the disease control group were included. FMF disease activity was evaluated by using the FMF-severity score, as well as with erythrocyte sedimentation rate (ESR), and serum C-reactive protein and fibrinogen levels. Oral health-related QoL and general QoL were evaluated using oral health impact profile-14 (OHIP-14) and Medical Outcomes Short-Form Health Survey Questionnaire 36 (SF-36), respectively. RESULTS: Only the numbers of extracted teeth (4.13±4.72 vs. 1.55±3.6) and filled teeth (2.33±3.19 vs. 0.66±1.46) were significantly higher in FMF group compared to HC group (p=0.005 and p=0.013, respectively). OHIP-14 score was significantly higher in FMF and BD groups compared to HC group. In FMF patients, OHIP-14 score was positively correlated with the number of extracted teeth (r=0.38, p=0.010), while the number of carious teeth was positively correlated with ESR (r=0.43, p=0.003). When FMF patients were sub-classified according to disease severity, no significant difference was observed with respect to oral health status. CONCLUSIONS: In patients with FMF, some of the parameters of oral health status were found to be worse compared to HC group. Tooth loss appears to be to be a critical factor contributing to impaired oral QoL. In general, oral health status in FMF patients is better than in BD patients

Predictive factors for work-day loss in Behçet's syndrome: A multi-center study

Objective: The aim of this multi-center study was to assess predictive factors for work-day loss as an indirect cost element in Behçet's syndrome (BS). Methods: In this cross-sectional, multi-center study, 834 BS patients (F/M: 441/393, age mean: 38.4 ± 10.9 years) were included. Data were collected by a questionnaire regarding treatment protocols, disease duration, smoking pattern, frequency of medical visits during the previous year and self-reported work-day loss during the previous year. Results: Work-day loss was observed in 16.2% of patients (M/F: 103/32). The percentages of being a smoker (81.8%), using immunosuppressive (IS) medications (82%), and having disease duration <5 years (74%) were higher in male patients with work-day loss (P < .05). The majority of males (90.9%) had more than four clinic visits during the previous year. Moreover, the mean work-day loss (30.8 ± 57.7 days) was higher in patients with vascular involvement (56.1 ± 85.9) than those without (26.4 ± 50.6 days) (P = .046). In addition, increased frequency of ocular involvement (25.9%) was also observed in patients with work-day loss compared to others (8.6%) (P = .059). Conclusion: Work-day loss was associated with both vascular and ocular involvement. Close associations were observed among male gender, early period of the disease, frequent medical visits, being a smoker and treatment with IS medications in patients with work-day loss.PubMe