• Journal of Communications and Networks
• /
• v.17 no.5
• /
• pp.463-472
• /
• 2015

This paper considers a limited feedback system for two-way wireless relaying channels with physical network coding (PNC). For full feedback systems, the optimal structure with the PNC has already been studied where a modulo operation is employed. In this case, phase and power of two end node channels are adjusted to maximize the minimum distance. Based on this result, we design new quantization methods for the phase and the power in the limited feedback system. By investigating the minimum distance of the received constellation, we present a code-book design to maximize the worst minimum distance. Especially, for quantization of the power for 16-QAM, a new power quantization scheme is proposed to maximize the performance. Also, utilizing the characteristics of the minimum distance observed in our codebook design, we present a power allocation method which does not require any feedback information. Simulation results confirm that our proposed scheme outperforms conventional systems with reduced complexity.

• ETRI Journal
• /
• v.35 no.4
• /
• pp.714-717
• /
• 2013

Peak power reduction techniques in orthogonal frequency division multiplexing (OFDM) has been an important subject for many researchers for over 20 years. In this letter, we propose a side-information-free technique that is based on the concept of random variable (RV) transformation. The suggested method transforms RVs into other RVs, aiming to reshape the constellation that will consequently produce OFDM symbols with a reduced peak-to-average power ratio. The proposed method has no limitation on the mapping type or the mapping order and has no significant effect on the bit error rate performance compared to other methods presented in the literature. Additionally, the computational complexity does not increase.

• ETRI Journal
• /
• v.44 no.6
• /
• pp.955-965
• /
• 2022

A low Earth orbit (LEO) satellite constellation could be used to provide network coverage for the entire globe. This study considers multi-beam frequency reuse in LEO satellite systems. In such a system, the channel is time-varying due to the fast movement of the satellite. This study proposes an efficient power and bandwidth allocation method that employs two linear machine learning algorithms and take channel conditions and traffic demand (TD) as input. With the aid of a simple linear system, the proposed scheme allows for the optimum allocation of resources under dynamic channel and TD conditions. Additionally, efficient projection schemes are added to the proposed method so that the provided capacity is best approximated to TD when TD exceeds the maximum allowable system capacity. The simulation results show that the proposed method outperforms existing methods.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.10C
• /
• pp.1010-1015
• /
• 2009

In this paper, we propose a novel detection ordering technique for MIMO signal detection methods based on QR decomposition and successive interference cancellation (SIC). Recently, new signal detection methods for spatially multiplexed (SM) MIMO systems were proposed, where all the constellation points are tried as the first layer symbol, and the remaining layer symbols are estimated via SIC, producing candidate vectors. Finally, the ML metric values are calculated for the candidate vectors, that are again used to select the best symbol vector. It was also shown that the ordering method in the conventional V-BLAST is not suitable to these signal detection methods. In this paper, we propose a novel ordering method, and we show via computer simulations that the proposed ordering method improves the error performance.

• Journal of East-West Nursing Research
• /
• v.14 no.2
• /
• pp.47-53
• /
• 2008

Purpose: Metabolic syndrome (also known as insulin resistance syndrome) represents a constellation of hypertriglyceridemia, hypertension, impaired glucose tolerance, and obesity. Presently, the influence of various factors on metabolic syndrome was assessed in patients of a university hospital comprehensive medical examination center. Methods: Age, sex, blood pressure, height, weight, triglyceride level, high-density lipoprotein cholesterol, and glucose levels were measured in 67 people (37 males and 30 females). These factors were correlated with tobacco use, alcohol consumption, and exercise habits. Metabolic syndrome and abdominal obesity were assessed according to NCEP-ATP III criteria and the Asia-Pacific guidelines (male obesity defined as a waist circumference exceeding 90 cm), respectively. Data was analyzed using t-test, 2-test, and logistic regression. Results: Respective percentages were: tobacco use (14.9% of the 67 people), no tobacco use (85.1%), alcohol consumption (62.7%), no alcohol consumption (37.3%), regular exercise (25.4%), no regular exercise (74.6%). Logistic regression analysis revealed a gender-related odds ratio of 2.3 for metabolic syndrome and no exercise. Conclusions: Weight reduction and physical exercise may decrease the prevalence of metabolic syndrome. Early identification of metabolic syndrome and risk factor modification is prudent in cases of obesity, diabetes, hyperlipidemia, and hypertension.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.2
• /
• pp.197-206
• /
• 1997

The purpose of this paper is to propose an improvement method of BER for coded 16QAM over Rayleigh fading channel. To overcome the BER degradation due to the fading under mobile communication, we apply trellis coded modulation technique which is efficient to get a coding gain without the expansion of bandwidth. Especially, to minimize the burst error which are the main factor of the BER degradation for mobile communication systems, we apply interleaving/deinterleaving method to the studying system. Also we apply asymmetric signal mapping methods to this TCM scheme. From the computer simulation, BER performance of asymmetric case has achieved about 1 dB improvement of about $10^{-4}$, compared to the traditional symmetric case.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.13 no.2
• /
• pp.35-42
• /
• 2017

The TDD LTE MU-MIMO HARQ system is designed and implemented using GPU based on 3GPP Rel.10 standard. The system consists of the DU part of the base station and the terminal using the general computer based on the GeForce GTX TITAN graphics card provided by NIVIDIA, and constructed the part of the RU using USRP N210 provided by Ettus. In the implementation part, SDR standard is applied, so that various communication standards can be compatible with software. The retransmission is implemented by combining the previous data with the retransmission data using Chase Combining among HARQ methods. In order to confirm that the retransmission was successful, the performance evaluation used LLR constellation. First, if there is an error in the data, the LLR value is not distributed at the corresponding position. in this case, a retransmission is performed to chase combine the previously stored error data and retransmitted data. As a result, the LLR value was distributed at the position of the corresponding LLR value per bit. Through this, it can be confirmed that error - free data is formed by using Chase Combining after retransmission.

• Archives of Plastic Surgery
• /
• v.37 no.4
• /
• pp.409-414
• /
• 2010

Purpose: Poland's syndrome encompasses a constellation of congenital chest wall, breast, and upper extremity deformities. We would like to present several techniques, which may be combined if necessary, used to treat the forms involving both the breast and chest wall according to the degree of deformity. Methods: In a retrospective series of 9 patients (3 men and 6 women), we report our experience with reconstructing breast and chest contour deformities associated with Poland syndrome. We recorded their age, gender, the surgical techniques, and the grade in Poland's syndrome according to the classification of Foucras. Results: The breast and chest wall deformities associated with Poland syndrome can be treated in individualized fashion according to the classification of Foucras. In case of 3 male patients with gradeI, II, the latissimus dorsi muscle pedicled flap improved the chest contour deformity. 3 female patients with grade II underwent the latissimus dorsi muscle pedicled flap with breast implant. 2 female patients with gradeIunderwent breast reconstruction with breast implant and fat injection each other. One female patient with severe chest wall deformity (grade III) underwent breast reconstruction using the free TRAM flap. All patients were satisfied with the results without specific complications. Conclusion: The Individualized correction for this syndrome according to the degree of patient's deformity and preference made the overall satisfaction of the patients high.

• Asian Spine Journal
• /
• v.12 no.6
• /
• pp.1043-1052
• /
• 2018

Study Design: Level III retrospective cross-sectional study. Purpose: To define and characterize the presentation, symptom duration, and patient/surgical risk factors associated with 'post-decompressive neuropathy (PDN).' Overview of Literature: PDN is characterized by lower extremity radicular pain that is 'different' from pre-surgical radiculopathy or claudication pain. Although it is a common constellation of postoperative symptoms, PDN is incompletely characterized and poorly understood. We hypothesize that PDN is caused by an intraoperative neuropraxic event and may develop early (within 30 days following the procedure) or late (after 30 days following the procedure) within the postoperative period. Methods: Patients who consented to undergo lumbar laminectomy with or without an instrumented fusion for degenerative lumbar spine disease were followed up prospectively from July 2013 to December 2014. Relevant data were extracted from the charts of the eligible patients. Patient demographics and surgical factors were identified. Patients completed postoperative questionnaires 3 weeks, 3 months, 6 months, and 1 year postoperatively. Questions were designed to characterize the postoperative pain that differed from preoperative pain. A diagnosis of PDN was established if the patient exhibited the following characteristics: pain different from preoperative pain, leg pain worse than back pain, a non-dermatomal pain pattern, and nocturnal pain that often disrupted sleep. A Visual Analog Scale was used to monitor the pain, and patients documented the effectiveness of the prescribed pain management modalities. Patients for whom more than one follow-up survey was missed were excluded from analysis. Results: Of the 164 eligible patients, 118 (72.0%) completed at least one follow-up survey at each time interval. Of these eligible patients, 91 (77.1%) described symptoms consistent with PDN. Additionally, 75 patients (82.4%) described early-onset symptoms, whereas 16 reported symptoms consistent with late-onset PDN. Significantly more female patients reported PDN symptoms (87% vs. 69%, p=0.03). Patients with both early and late development of PDN described their leg pain as an intermittent, constant, burning, sharp/stabbing, or dull ache. Early PDN was categorized more commonly as a dull ache than late-onset PDN (60% vs. 31%, p=0.052); however, the difference did not reach statistical significance. Opioids were significantly more effective for patients with early-onset PDN than for those with late-onset PDN (85% vs. 44%, p=0.001). Gabapentin was most commonly prescribed to patients who cited no resolution of symptoms (70% vs. 31%, p=0.003). Time to symptom resolution ranged from within 1 month to 1 year. Patients' symptoms were considered unresolved if symptoms persisted for more than 1 year postoperatively. In total, 81% of the patients with early-onset PDN reported complete symptom resolution 1 year postoperatively compared with 63% of patients with late-onset PDN (p=0.11). Conclusions: PDN is a discrete postoperative pain phenomenon that occurred in 77% of the patients who underwent lumbar laminectomy with or without instrumented fusion. Attention must be paid to the constellation and natural history of symptoms unique to PDN to effectively manage a self-limiting postoperative issue.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.7 s.98
• /
• pp.690-696
• /
• 2005

It is very important to reduce the PAPR(Peak to Average Power Ratio) in the OFDM(Orthogonal Frequency Division Multiplexing) communication system. The proposed method in this paper is an effective PAPR reduction method using the Golay complementary codes without my side information. There are some PAPR reduction methods with the complementary code pairs or sequences. They are usually a type of the forward ewer correction codes so that they produce more redundancies and lower down the code rate. Because of this, the information rate may be cut down or more bandwidth must be required. In this paper, we propose a PAPR reduction method that uses the multi-phase complementary code f3r converting the 4-QAM into 16-QAM constellation. It does not change the code rate and does not require the side information.