Pilot Arrangement Research Articles

“A life-changing experience and the beginning of a lifelong commitment”: experiences and impact of Global Health Community Service-Learning in undergraduate dental curriculum in Canada

BackgroundGlobal Health Community Service-Learning (GHCSL) can have a profound professional and personal impact on learners. This pedagogy provides understanding of unfamiliar environments and challenges learners to step out of their comfort zones, adapt to new cultures, and navigate unique situations. Yet, there are relatively few studies exploring the experiences of learners participating in community service-learning placements in global regions as part of undergraduate dental curriculum. This study aimed to explore the experiences and impact of the GHCSL program in East Africa among undergraduate dental learners at the Schulich School of Dentistry.MethodsEight undergraduate dental learners were enrolled in GHCSL pilot placements. Placement agreements were established with Makerere University in Kampala, Uganda, and the University of Rwanda in Kigali, Rwanda for the summer of 2022. Stakeholders from both institutions were engaged in the development and implementation of these placements. Learners were required to engage in weekly reflection through a ‘storytelling and incident-based narrative’ while carrying out their placement. A qualitative study design was employed, and an inductive interpretive approach was utilized to thematically analyze the learners’ reflective essays.ResultsFive major themes emerged from the learners’ reflective essays: (1) experiential clinical learning; (2) cultural humility and social awareness; (3) awareness of contrasting healthcare systems; (4) commitment to service; and (5) personal and professional growth. Most learners reflected on their engagement with diverse communities, being exposed to unique patient cases, and witnessing the adaptability exuded in resource-constrained environments. These experiences presented the learners with an opportunity to develop cultural humility and gain a newfound motivation to mitigate global oral health disparities in populations beyond that of their local communities. Learners also reflected on enhanced social awareness experiences and the awareness of contrasting healthcare systems in Canada and their placements, which encouraged the development of empathy, communication, and compassion skills, as well as an understanding of the disproportionate burden of conditions in low-resource settings.ConclusionThe reflective essays concluded that the GHCSL placements had a positive impact on the learners, encouraging many to develop a heightened desire for lifelong learning to address oral health disparities within a global context.

Dual-repetitive pilot aided parameter estimation for underwater orthogonal frequency division multiplexing acoustic communications in the presence of strong composite noise

In this work, a novel design of signaling parameters and pilot placement is proposed for supporting robust underwater orthogonal frequency division multiplexing acoustic communications in the presence of strong composite noise. The proposed design allows for high-resolution estimation of various channel parameters that are essential to successful symbol recovery. Receiver processing algorithms are developed by exploring special properties of the received signal that hold valid despite complicated channel and noise effects. These algorithms are efficient since they reuse the same set of pilot symbols for multiple tasks of estimation that often require separate sets of pilots. They are also extremely effective because they largely avoid the effects of noise even when the noise is composite. The performance of these algorithms is evaluated via both extensive simulations and an at-sea experiment.

Channel Estimation of MC-CDMA aided with Evolutionary Algorithms

Currently wireless communication has gained great demand. In order to satisfy current need of customer’s, new technologies are required. Multi-Carrier Code Division Multiple Access (MC-CDMA) is one of the promising technologies for mobile radio communications. In this article MC-CDMA performance is evaluated by estimating the channel with the help of evolutionary algorithms. Block type pilot arrangement is used for estimating the channel with least square (LS) estimation algorithm. Matlab used for simulation

Adaptive Coded Modulation for OFDM System

This paper studies the adaptive coded modulation for coded OFDM system using punctured convolutional code, channel estimation, equalization and SNR estimation. The channel estimation based on block type pilot arrangement is performed by sending pilots at every sub carrier and using this estimation for a specific number of following symbols. Signal to noise ratio is estimated at receiver and then transmitted to the transmitter through feedback channel ,the transmitter according to the estimated SNR select appropriate modulation scheme and coding rate which maintain constant bit error ratelower than the requested BER. Simulation results show that better performance is confirmed for target bit error rate (BER) of (10-3) as compared to conventional modulation schemes, the convolutional coded modulation offers a SNR gains of 5 dB compared to uncoded state at BER of 10-3. The proposed adaptive OFDM scheme maintains fixed BER under changing channel conditions.

Production of vetiver root as a support for the cliffs of irrigation canals in the Bendung sub-district, Serang City

Irrigation canals in Bendung Village, Kasemen District, Serang, only partially have masonry installed, most of them are still open canals. As time went by, the condition became deplorable, due to rain which eroded the cliffs due to surface erosion. This program aims to provide education about the vetiver system as a method of controlling surface erosion in irrigation canals. The method used in this activity was socialization about prevention of surface erosion in irrigation canals with vetiver roots, training and mentoring in making a pilot arrangement of vetiver in irrigation canals. As a result of the community service activities that have been carried out, it can be concluded that the socialization activities and shallow landslide/erosion control training with the "vetiver system" have provided new knowledge and skills for the people of Bendung Village.

A Multi-Antenna Pilot Predistortion Scheme and Channel Estimation Algorithm for LTE-Based Terrestrial Broadcast System

Multi-Antenna technology is a physical layer technique widely used in mobile communication and terrestrial broadcast systems. For fully utilizing the antenna diversity, conventional Multi-Antenna pilots usually meet the characteristic of orthogonality in terms of the pilot arrangement to avoid inter-pilot interference between different transmitting antennas. However, the scheme with orthogonality leads to the doubling of the pilot overhead, which seriously reduces the transmission efficiency. The latest LTE-based terrestrial broadcast system, Further evolved Multimedia Broadcast Multicast Service (FeMBMS), is probably to adopt the Multi-Antenna technique in the future, but no corresponding pilot scheme has been provided. This paper proposes a novel pilot pre-distortion scheme and Channel Estimation (CHE) algorithm for FeMBMS. The pre-distortion scheme does not require the pilot on different antennas to meet the restriction of orthogonality, so to address the problem of pilot overhead doubling. Meanwhile, it deals with the issue of inter-pilot interference by converting the interference into the white noise spreading over the whole OFDM symbol. Furthermore, the proposed CHE algorithm effectively eliminates the whitened interference by utilizing the processing of DFT-based windowing and Iterative Interference Cancellation (IIC). Simulation shows that the pre-distortion scheme and CHE algorithm could provide a CHE performance with accuracy same or close to that of the orthogonality scheme while significantly improving the transmission efficiency.

Delay-Doppler and Angular Domain 4D-Sparse CSI Estimation in OTFS Aided MIMO Systems

A convenient delay, Doppler and angular-(DDA) domain representation of the multiple-input multiple-output (MIMO) wireless channel is conceived for deriving the end to end relationship in the delay-Doppler (DD)-domain for orthogonal time frequency space (OTFS)-based communications. Subsequently, a time-domain pilot based model is developed for estimating the DDA-domain channel state information (CSI) of our MIMO OTFS system. The key differentiating feature of the CSI estimation model derived is its ability to exploit the 4-dimensional (4D)-sparsity arising in the DDA-domain, given the limited number of dominant scatterers. Furthermore, the training overhead of the proposed framework is low, and the pilot placement is quite flexible, necessitating no guard-interval. Finally, an orthogonal matching pursuit (OMP) framework is employed for 4D-sparse CSI acquisition, followed by deriving the Oracle minimum mean squared error (Oracle-MMSE) and its Bayesian Cramer-Rao lower bound (BCRLB). Our simulation results confirm the improved CSI estimation performance attained over the benchmarks.

Pilot impact on turbulent premixed methane/air and hydrogen-enriched methane/air flames in a laboratory-scale gas turbine model combustor

The impact of pilot flame operation on the combustion of pure methane and hydrogen-enriched methane (H2/CH4: 50/50 in vol%) fuels was investigated in a gas turbine model combustor under atmospheric conditions. The burner assembly was designed to mimic the geometry of an industrial burner, the Siemens DLE Burner, in which a concentric annular ring equipped with pilot flame burners is implemented in the dome of the combustor. Two pilot burner configurations have been investigated: a non-premixed and a partially premixed pilot arrangement. The performance of the pilot burners was evaluated for varying Reynolds number (Re) and H2 enrichment. High-speed OH∗ chemiluminescence imaging, as well as simultaneous planar laser-induced fluorescence measurements of the OH radicals and formaldehyde (CH2O) were used for evaluating the dynamics and structures of the flames for different conditions. Furthermore, emission measurements were carried out to determine the influence of hydrogen dilution on the NOx and CO emission levels. The main findings are (a) the effect of the pilot flame is sensitive to the Reynolds number of the main flame and the type of the pilot flame, (b) the stability range becomes narrower with increasing hydrogen ratio, due to the tendency to flashback, (c) non-premixed pilot flames lower the NOx and increase the CO emissions, albeit rather small differences in the emissions have been detected, and (d) the NOx and CO emissions become significantly lower with increasing hydrogen ratio.

Analysis and Design for Pilot Power Allocation and Placement in OFDM Based Integrated Radar and Communication in Automobile Systems

In this paper, we consider the orthogonal frequency division modulation (OFDM) based integrated radar-communication (Rad-Com) for automobile systems operating in millimeter wave band with imperfect time-frequency synchronization for communications. Since different pilot power allocation and placement strategies can result in different performance, we investigate the power allocation and placement design for the Rad-Com system. We analyze the effect of power allocation and pilot placement on the system performance. Based on the analysis, we provide, along with a channel estimation scheme, the pilot power allocation and placement designs that can optimize the radar and communication performance, respectively. Moreover, the tradeoff between radar and communication performance is discussed and a tradeoff design is presented. We conduct simulations to validate our analysis and evaluate the proposed designs. Results show that our analysis is valid and insightful and the proposed designs are effective.

Advancing Nursing Informatics Through Clinical Placements: Pilot Study.

Work integrated learning in the space of nursing informatics is a new concept in Australian nursing curriculum. This study examined nursing students' experiences in the pilot nursing informatics clinical placement centered on electronic medical records, their use in patient care and clinical decision making. Students completed reflective diaries of their learning during the four-week placement. Data was explored by thematic analysis. Emergent themes included: importance of adequate training in using EMR; impact of EMR on nursing workflow and patient care; shaping future career choices; forming rewarding relationships; and potential for improvements. These themes will be used to enhance teaching and learning opportunities as this pilot placement evolves into permeant part of the nursing curriculum.

A Novel Adaptive Pilot Placement Algorithm for Channel Estimation in OFDM Based Systems

Çok taşıyıcılı haberleşme sistemlerinden biri olan dikgen frekans bölmeli çoğullama (orthogonal frequency division multiplexing, OFDM) sistemi, bant genişliğini etkin kullanarak yüksek hızlı veri haberleşmesine olanak sağlaması ve yankı gecikmelerine karşı dayanıklılığı nedeniyle günümüzde yaygın olarak kullanılmaktadır. OFDM sisteminde gezgin iletim kanalının bozucu etkileri alıcıda kanal kestirimi yapılarak azaltılabilir. Bu çalışmada OFDM sistemi için kanalın yapısına göre uyarlamalı olarak değişebilen yeni bir pilot yerleşimli kanal kestirim algoritması önerilmiştir. Önerilen algoritma kanalın derin sönümlenmelerinin olduğu bölgelere daha sık pilot yerleştirilmesi temeline dayanmaktadır. Benzetim sonuçlarından, önerilen uyarlamalı kanal kestirim algoritmasının klasik kanal kestirim algoritmalarına göre daha iyi sonuç verdiği ve bit hata oranı (BHO) başarımında 11.6 dB’e varan bir iyileşme sağladığı görülmüştür. Ayrıca literatürdeki çalışmalardan farklı olarak bu çalışmada frekans düzleminde pilot sıklığının artırılacağı bölgelerin eşik seviyesini belirlemek için yeni bir matematiksel ifade önerilmiştir.

Joint Channel Estimation and Coding Over Channels With Memory Using Polar Codes

A joint channel estimation and channel coding scheme is presented for channels with memory using polar codes. Unlike the conventional approach of first estimating all channel parameters and then performing channel decoding separately, the proposed scheme incorporates a subset of reliable estimates of channel parameters into the decoding procedure and computes decoding metrics averaged over the statistical behavior of the channel. Specifically, decoding algorithms for finite-state Markov channels of any order, for the Gauss-Markov channel and for flat-fading channels are presented. Further, by adapting list decoding to identify reliably-decoded bits within a codeword, channel estimation and decoding steps are performed iteratively to boost the reliability of channel estimation as well as error correction. In order to improve the performance even further, a new pilot arrangement scheme is developed that utilizes the structure of polar codes and sends pilot symbols embedded within the polar codewords. This construction can be viewed as a new family of shortened polar codes that can be of independent interest. Simulation results demonstrate the benefit of the proposed approach compared to existing solutions.

A Very-Low Pilot Scheme for mmWave Hybrid Massive MIMO-OFDM Systems

To reduce the large training overhead required by a millimeter-wave (mmWave) massive MIMO system, this letter proposes a pilot placement scheme and the corresponding receiver technique for multi-user uplink channel estimation and data detection over frequency-selective fading channels when OFDM is employed. Specifically, a small group of subcarriers transmit a small segment of pilots followed by data payloads; and all other subcarriers transmit data payloads only. To recover all channels and payload data, the basic idea is that for pilot subcarriers, a semi-blind method is employed for channel estimation and data detection based on low-rank matrix completion; while for the non-pilot subcarriers, the sparsity of mmWave channels in the delay-domain is exploited, based on which the channel estimation can be solved using the compressed-sensing (CS) technique. Simulation results show that significant performance gains can be achieved by our proposed scheme with very low pilot overhead.

Adaptive Pilot Pattern for Massive MIMO Systems

This work proposes a new adaptive pilot pattern used for pilot arrangement at the mobile station and a new channel estimation at the base station. It addresses the bit error rate (BER) performance optimization of wireless channel estimation in massive multiple-input multiple-output systems. First, we propose a new adaptive pilot pattern (APP) that offers a lower BER than the conventional pilot patterns. Then, we suggest a new channel estimation algorithm based on the APP. It is called the shifted APP-channel estimation (SACE). As a result, APP guarantees an optimal BER performance for the different system configurations, channel models, and carrier frequencies. It offers better BER performance than conventional pilot patterns, such as the long-term evolution (LTE) pilot pattern. Moreover, the shifted APP-based channel estimation algorithm solves the error floor caused by the usage of multiple subcarriers. It also offers a signal-to-noise ratio (SNR) improvement that reaches 17 dB at BER $= 10^{-2}$ compared to the conventional minimum mean square error (MMSE) channel estimation.

OFDM-IDMA Sistemi İçin Genetik Algoritmaya Dayalı Biyo-İlhamlı Pilot Dizayn Yaklaşımı

It is well known that the efficiency of a channel estimator employing the strategy of comb-type pilot placement can be controlled by adjusting the positions of pilot tones. In this paper, by considering this situation, in order to maximize the estimation precision of the least squares (LS) algorithm utilized as a channel estimator in orthogonal frequency division multiplexing – interleave division multiple access (OFDM-IDMA) scheme, the genetic algorithm (GA) possessing a wide range of uses due to its powerful problem solving capability was utilized in the optimization of pilot positions. Besides, the computational load of mean square error (MSE) which is used as the objective function of GA was avoided by employing its upper bound during the optimization process. The upper bound of MSE was achieved by utilizing the Gershgorin disc theorem. In the simulations, the suggested pilot arrangement strategy based on the GA was compared to the conventional techniques like equispaced and random pilot placements in point of two criteria known as bit error rate (BER) and MSE. Simulation results put forth that GA-based pilot design strategy establishes a very clear superiority over the other considered methods by providing significant MSE and BER performances.

Estimation of UFMC Fading Channels Using H∞ Filter

Universal filtered multi-carrier (UFMC) modulation is a very powerful candidate to be employed for future 5G mobile systems. It overcomes the limitations and restrictions in current modulation techniques employed in 4G mobile systems and supports future applications, such as machineto-machine (M2M), device-to-device (D2D), and vehicle-tovehicle (V2V) communications. In this paper, we address the estimation of UFMC fading channels based on the comb-type pilot arrangement in the frequency domain. The basic solution is to estimate the fading channel based on the mean square error (MSE) or least square (LS) criteria with adaptive implementation using least mean square (LMS) or recursive least square (RLS) algorithms. However, these adaptive filters seem not to be effective, as they cannot fully exploit fading channel statistics, particularly at high Doppler rates. To take advantage of these statistics, time-variations of the fading channel are modeled by an autoregressive process (AR), and are tracked by an H∞ filter. This, however, requires that AR model parameters be known, which are estimated by solving the Yule-Walker equation (YWE), based on the Bessel autocorrelation function (ACF) of the fading channel with a known Doppler rate. Results of Matlab simulations show that the proposed H∞ filter-based channel estimator is more effective when compared with existing estimators

Pilot Design for BEM-Based Channel Estimation in Doubly Selective Channel

This paper investigates pilot design for enhanced channel estimation in single carrier communication systems over doubly-selective channels (DSC). Our contribution is twofold: first, we propose to use Huffman sequences as pilot clusters with low peak-to-average power ratio (PAPR), yet with good channel estimation performance when periodic pilot placement is adopted; second, we propose a low-complexity pilot placement strategy based on the analysis of the complex-exponential basis expansion model (CE-BEM) of the DSC. The latter leads to improved channel estimation performance with useful insights for pilot placement.

Pilot spacing controller in orthogonal frequency division multiplexing systems

As the backbone of the fifth generation, 5G communications, Orthogonal Frequency Division Multiplexing, OFDM is seen to be reliable in addressing Inter-symbol Interference, ISI issues as well as providing high-speed access to broadband. Channel estimation and tracking are generally carried out by transmitting known pilot symbols in given positions of the frequency-time grid. However, the use of a fixed amount of pilot for all channel circumstances is hugely detrimental. Several methods, especially on block-type and comb-type pilot arrangement, have presented. In this paper, the method of determining the pilot space depends on the current channel quality. The proposed technique focused on improving estimation and bandwidth in time-varying and frequency-selective fading channels without increasing the complexity and sacrifice the bandwidth efficiency of the OFDM system.

3D Multiple Input Multiple Output Large-Scale Antenna Systems

The channel could be evaluated by utilizing several estimation algorithms. The various patterns of pilot arrangements for the channel appreciation are a huge problem in channel appreciation techniques since all the processes depends on it; this paper discusses improvements in channel selection. The Least Square and Least Square Mean methods are common, simple ways to begin to estimate a channel; however, they are less efficient than more complex approaches. Due to the boost in demand with high data rates in communications, developers continue to invent new methods and mechanisms to adjust the capacity and the accuracy of the communication network. One of the primary troubles in wireless communication is the communication channel, which is affected by nonlinear and random noise sources, which decrease the quality of the service on the network; in this case, the channel must be equalized to increase performance with minimal error. In this paper, a Massive Multiple Input Multiple Output was designed and simulated in order to estimate the channel and the performance of the network through using Least Square and Least Square Mean.

Compressed channel estimation for massive MIMO-OFDM systems over doubly selective channels

Doubly selective (DS) channel estimation for the downlink massive multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems is a challenging problem, due to the requirements on high pilots overhead and prohibitive complexity. In this paper, by exploiting the highly correlated spatial structure of the obtained array response vectors and sparsity of the multipath signal components of the massive MIMO-OFDM channels, a modified spatial basis expansion model (modified-SBEM) is introduced. Thus, using complex exponential (CE-) modified-SBEM (i.e., modified CE-SBEM) can improve the resolution of the angles of departures (AoDs) information to represent the downlink with far fewer parameter dimensions, since the AoDs are much slower than path gains. Subsequently, we jointly design the effective pilot power and pilot placement for sparse channel estimation by means of an extended model. Our design is based on the block-coherence and sub-coherence simultaneous minimization of the measurement matrix associated with the massive MIMO-OFDM system pilot subcarriers. Furthermore, we leverage the sparse nature of the massive MIMO-OFDM system to formulate the quantized AoDs estimation into a block-sparse signal recovery problem, where the measurement matrix is designed based on the estimated virtual AoD. Thus, a new algorithm namely, generalized quasi-block simultaneous orthogonal matching pursuit (gQBSO), is introduced to solve the problem by providing sparse signal reconstruction solution. Simulation results demonstrate that the proposed scheme can effectively estimate the DS channel for massive MIMO-OFDM systems compared with other existing algorithms. For example, at SNR=20 dB for K=4 users, Doppler shift=0.093 with NT=32 antenna size, the adaptive-QBSO algorithm with G-SBEM and the proposed gQBSO with modified-SBEM can realize approximately 75.44%and 85.14% of the NMSE achieved by the oracle estimator with modified-SBEM.