| 1. |
- Amin, Shoaib, et al.
(författare)
-
2D Extended envelope memory polynomial model for concurrent dual-band RF transmitters
- 2017
-
Ingår i: International journal of microwave and wireless technologies. - : Cambridge University Press. - 1759-0795 .- 1759-0787. ; 9:8, s. 1619-1627
-
Tidskriftsartikel (refereegranskat)abstract
- The paper presents a 2D extended envelope memory polynomial (2D-EEMP) model for concurrent dual-band radio frequency (RF) power amplifiers (PAs). The model is derived based on the physical knowledge of a dual-band RF PA. The derived model contains cross-modulation terms not included in previously published models; these terms are found to be of importance for both behavioral modeling and digital pre-distortion (DPD). The performance of the derived model is evaluated both as the behavioral model and DPD, and the performance is compared with state-of-the-art2D-DPD and dual-band generalized memory polynomial (DB-GMP) models. Experimental result shows that the proposed model resulted in normalized mean square error (NMSE) of -51.7/-51.6dB and adjacent channel error power ratio (ACEPR) of -63.1/-63.4 dB, for channel 1/2, whereas the 2D-DPD resulted in the largest model error and DB-GMP resulted in model parameters that are 3 times more than those resulted with the proposed model with the same performance. As pre-distorter, the proposed model resulted in adjacent channel power ratio (ACPR) of -55.8/ -54.6 dB for channel 1/2 and is 7-10 dB lower than those resulted with the 2D-DPD model and2-4 dB lower compared to the DB-GMP model.
|
|
| 2. |
|
|
| 3. |
- Bose, Subhojyoti, et al.
(författare)
-
On The Noise And Power Performance Of A Shoe-Mounted Multi-Imu Inertial Positioning System
- 2017
-
Ingår i: 2017 international conference on indoor positioning and indoor navigation (ipin). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- Shoe-mounted inertial navigation systems, aka pedestrian dead reckoning or PDR sensors, are being preferred for pedestrian navigation because of the accuracy offered by them. Such shoe sensors are, for example, the obvious choice for real time location systems of first responders. The opensource platform OpenShoe has reported application of multiple IMUs in shoe-mounted PDR sensors to enhance noise performance. In this paper, we present an experimental study of the noise performance and the operating clocks based power consumption of multi-IMU platforms. The noise performances of a multi-IMU system with different combinations of IMUs are studied. It is observed that four-IMU system is best optimized for cost, area and power. Experiments with varying operating clocks frequency are performed on an in-house four-IMU shoe-mounted inertial navigation module (the Oblu module). Based on the outcome, power-optimized operating clock frequencies are obtained. Thus the overall study suggests that by selecting a well-designed operating point, a multi-IMU system can be made cost, size and power efficient without practically affecting its superior positioning performance.
|
|
| 4. |
- Khan, Zain Ahmed, 1987-, et al.
(författare)
-
A Comparative Analysis of the Complexity/Accuracy Tradeoff in the Mitigation of RF MIMO Transmitter Impairments
- 2017
-
Ingår i: 2017 89th ARFTG Microwave Measurement Conference (ARFTG). - : IEEE. - 9781538627471 - 9781538627488
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a comparative analysis of the complexity accuracy tradeoff in state-of-the-art RF MIMO transmitter mitigation models. The complexity and accuracy of the candidate models depends on the basis functions considered in these models. Therefore, a brief description of the mitigation models is presented accompanied by derivations of the model complexities in terms of the number of FLOPs. Consequently, the complexity accuracy tradeoff in the candidate models is evaluated for a 2 × 2 RF MIMO transmitter. Furthermore, the model complexities are analyzed for increasing nonlinear orders and number of antennas.
|
|
| 5. |
- Pasku, Valter, et al.
(författare)
-
A Magnetic Ranging-Aided Dead-Reckoning Positioning System for Pedestrian Applications
- 2017
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 66:5, s. 953-963
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the applicability of a developed Magnetic Positioning System (MPS) as a support for a dead-reckoning inertial navigation system (DR-INS) for pedestrian applications. The integrated system combines the complementary properties of the separate systems, operating over long periods of time and in cluttered indoor areas with partial nonline-of-sight conditions. The obtained results show that the proposed approach can effectively improve the coverage area of the MPS and the operation time with bounded errors of the DR-INS. In particular, a solution that provides bounded position errors of 1-2 m over significantly long periods of time up to 45 min, in realistic indoor environments, is demonstrated. Moreover, system applicability is also shown in those scenarios where arbitrary orientations of the MPS mobile node are considered and an MPS position estimate is not available due to less than three distance measurements.
|
|
| 6. |
- Wahlström, Johan, et al.
(författare)
-
A Hidden Markov Model for Seismocardiography
- 2017
-
Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9294 .- 1558-2531. ; 64:10, s. 2361-2372
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a hidden Markov model approach for processing seismocardiograms. The seismocardiogram morphology is learned using the expectation-maximization algorithm, and the state of the heart at a given time instant is estimated by the Viterbi algorithm. From the obtained Viterbi sequence, it is then straightforward to estimate instantaneous heart rate, heart rate variability measures, and cardiac time intervals (the latter requiring a small number of manual annotations). As is shown in the conducted experimental study, the presented algorithm outperforms the state-of-the-art in seismocardiogram-based heart rate and heart rate variability estimation. Moreover, the isovolumic contraction time and the left ventricular ejection time are estimated with mean absolute errors of about 5 [ms] and 9 [ms], respectively. The proposed algorithm can be applied to any set of inertial sensors; does not require access to any additional sensor modalities; does not make any assumptions on the seismocardiogram morphology; and explicitly models sensor noise and beat-to-beat variations (both in amplitude and temporal scaling) in the seismocardiogram morphology. As such, it is well suited for low-cost implementations using off-the-shelf inertial sensors and targeting, e.g., at-home medical services.
|
|
| 7. |
|
|
| 8. |
- Wahlström, Jens, 1979-, et al.
(författare)
-
The beta-Model-Maximum Likelihood, Cramer-Rao Bounds, and Hypothesis Testing
- 2017
-
Ingår i: IEEE Transactions on Signal Processing. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1053-587X .- 1941-0476. ; 65:12, s. 3234-3246
-
Tidskriftsartikel (refereegranskat)abstract
- We study the maximum-likelihood estimator in a setting where the dependent variable is a random graph and covariates are available on a graph level. The model generalizes the well-known beta-model for random graphs by replacing the constant model parameters with regression functions. Cramer-Rao bounds are derived for special cases of the undirected beta-model, the directed beta-model, and the covariate-based beta-model. The corresponding maximum-likelihood estimators are compared with the bounds by means of simulations. Moreover, examples are given on how to use the presented maximum-likelihood estimators to test for directionality and significance. Finally, the applicability of the model is demonstrated using temporal social network data describing communication among healthcare workers.
|
|
| 9. |
- Yajnanarayana, Vijaya, et al.
(författare)
-
Joint Estimation of TOA and PPM Symbols Using Sub-Nyquist Sampled IR-UWB Signal
- 2017
-
Ingår i: IEEE Communications Letters. - : IEEE. - 1089-7798 .- 1558-2558. ; 21:4, s. 949-952
-
Tidskriftsartikel (refereegranskat)abstract
- Impulse radio ultra wideband (UWB) signals are used in various applications which require joint localization and communication. Due to the large bandwidth of the UWB signal, the estimation of time of arrival (TOA) and data symbols requires high sampling rates. This letter describes a sub-Nyquist rate receiver, which can jointly estimate TOA and data symbols. We first represent the received UWB signal in a new domain in which it is sparse. Then, we design physical layer waveforms and estimation algorithms to exploit this sparsity for joint estimation of TOA and pulse position modulation data symbols. The performance of the receiver is compared against the maximum likelihood (ML)-based receiver using an IEEE 802.15.4a CM1 line of sight UWB channel model. The proposed algorithm yields performance similar to the ML-based algorithms with only a fraction of sampling rate at high SNRs (> 25 dB).
|
|
| 10. |
|
|
