| 1. |
- Ahmed, Zakir, et al.
(author)
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A time domain based efficient block decision algorithm for audio coders
- 2007
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In: International Symposium on Communications and Information Technologies, 2007. ISCIT '07. - : IEEE Press. - 9781424409761 ; , s. 1077-1081
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Conference paper (peer-reviewed)abstract
- In typical audio encoders the block decision is done either using time-domain techniques like energy computation or frequency domain techniques like temporal noise shaping (TNS) [1], [2]. The time-domain energy computation based decisions are less effective for detecting many of the stringent scenarios presented by test cases like castanets and fatboy. The frequency domain based algorithms have better decision making capabilities, however they are inherently complex as they require the computation of the FFT, additionally in case of TNS the computation of LPC (Linear Prediction coding) in the frequency domain. An improved time-domain technique with better block decision capability compared to TNS and with lesser computational complexity is proposed in this paper.
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| 2. |
- Ahmed, Zakir, et al.
(author)
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Blind mechanism for the joint estimation of frequency offset and phase offset for QAM modulated signals
- 2010
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Patent (pop. science, debate, etc.)abstract
- A mechanism for jointly correcting carrier phase and carrier frequency errors in a demodulated signal. A computer system may receive samples of a baseband input signal (resulting from QAM demodulation). The computer system may compute values of a cost function J over a grid in a 2D angle-frequency space. A cost function value J(theta,omega) is computed for each point (theta,omega) in the grid by (a) applying a phase adjustment of angle theta and a frequency adjustment of frequency omega to the input signal; (b) performing one or more iterations of the K-means algorithm on the samples of the adjusted signal; (c) generated a sum on each K-means cluster; and (d) adding the sums. The point (thetae,omegae) in the 2D angle-frequency space that minimizes the cost function J serves an estimate for the carrier phase error and carrier frequency error.; The estimated errors may be used to correct the input signal.
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| 3. |
- Ahmed, Zakir, et al.
(author)
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Estimation of Sample Clock Frequency Offset Using Error Vector Magnitude
- 2011
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Patent (pop. science, debate, etc.)abstract
- A low complexity system and method for operating a receiver in order to estimate an offset between the actual sample clock rate 1/TS' of a receiver and an intended sample clock rate 1/TS. The receiver captures samples of a received baseband signal at the rate 1/TS', operates on the captured samples to generate an estimate for the clock rate offset, and fractionally resamples the captured samples using the clock rate offset. The resampled data represents an estimate of baseband symbols transmitted by the transmitter. The action of operating on the captured samples involves computing an error vector signal and then estimating the clock rate offset using the error vector signal. The error vector signal may be computed in different ways depending on whether or not carrier frequency offset and carrier phase offset are assumed to be present in the received baseband signal.
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| 4. |
- Ahmed, Zakir, et al.
(author)
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Maximizing the Viterbi Winning Path Metric to Estimate Carrier Frequency and Phase Offsets in Continuous Phase Modulated Signals
- 2012
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Patent (pop. science, debate, etc.)abstract
- A system and method for estimating carrier frequency offset Δf and carrier phase offset φ0 inherent in a received CPM signal. Samples of a continuous phase modulated (CPM) signal are received. A maximum of an objective function J is determined over a two-dimensional region parameterized by frequency offset v and phase offset w. The coordinates vmax and wmax of a maximizing point in the region represent estimates of the carrier frequency offset Δf and the carrier phase offset φ0. To evaluate the objective function J at a point (v, w), apply a frequency shift of amount −v and a phase shift of amount −w to the received samples to obtain modified samples, and perform Viterbi demodulation on the modified samples to obtain a winning path metric value at a final time. The winning path metric value is the objective function value J(v, w).
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| 5. |
- Behravan, Ali, 1971, et al.
(author)
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Positioning and Sensing in 6G: Gaps, Challenges, and Opportunities
- 2023
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In: IEEE Vehicular Technology Magazine. - 1556-6080 .- 1556-6072. ; 18:1, s. 40-48
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Journal article (peer-reviewed)abstract
- Among the key differentiators of 6G compared to 5G will be the increased emphasis on radio-based positioning and sensing. These will be utilized not only for conventional location-aware services and for enhancing communication performance but also to support new use case families with extreme performance requirements. This article presents a unified vision from stakeholders across the value chain in terms of both opportunities and challenges for 6G positioning and sensing as well as use cases, performance requirements, and gap analysis. Combined, this motivates the technical advances in 6G and guides system design.
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| 6. |
- Cosmas, John, et al.
(author)
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Towards joint communication and sensing (Chapter 4)
- 2023
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In: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 121-158
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Book chapter (other academic/artistic)abstract
- Localization of user equipment (UE) in mobile communication networks has been supported from the early stages of 3rd generation partnership project (3GPP). With 5th Generation (5G) and its target use cases, localization is increasingly gaining importance. Integrated sensing and localization in 6th Generation (6G) networks promise the introduction of more efficient networks and compelling applications to be developed.
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| 7. |
- Girish, V V, et al.
(author)
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A Novel Initial Ranging Algorithm for mobile WiMAX (802.16e)
- 2010
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In: International Journal of Computer Applications. - : Foundation of Computer Science. - 0975-8887. ; 1:3, s. 95-100
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Journal article (peer-reviewed)abstract
- Initial ranging process plays an important role in the mobile worldwide interoperability for microwave access (WiMAX) standard (IEEE 802.16e). Timing offset adjustment, power offset calculation and synchronization between the base station and all the users within a cell are achieved during the initial ranging process. A comparative study of existing and a novel ranging algorithm is proposed in this paper. Most of the current ranging algorithms do not take in to account the interference created by the ranging codes sent by other ranging users in an Orthogonal Frequency Division Multiple Access (OFDMA) setup [2][4][5][7]. The novel ranging method cancels the interference created due to the other raging codes in the ranging area. The simulation results indicate a significant improvement in performance under practical scenarios.
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| 8. |
- Mateos Ramos, José Miguel, 1998, et al.
(author)
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End-to-End Learning for Integrated Sensing and Communication
- 2022
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In: IEEE International Conference on Communications. - 1550-3607. ; 2022-May, s. 1942-1947
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Conference paper (peer-reviewed)abstract
- Integrated sensing and communication (ISAC) aims to unify radar and communication systems through a combination of joint hardware, joint waveforms, joint signal design, and joint signal processing. At high carrier frequencies, where ISAC is expected to play a major role, joint designs are challenging due to several hardware limitations. Model-based approaches, while powerful and flexible, are inherently limited by how well the models represent reality. Under model deficit, data-driven methods can provide robust ISAC performance. We present a novel approach for data-driven ISAC using an auto-encoder (AE) structure. The approach includes the proposal of the AE architecture, a novel ISAC loss function, and the training procedure. Numerical results demonstrate the power of the proposed AE, in particular under hardware impairments.
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| 9. |
- Rivetti, Steven, 1998, et al.
(author)
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Spatial Signal Design for Positioning via End-to-End Learning
- 2023
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In: IEEE Wireless Communications Letters. - 2162-2345 .- 2162-2337. ; 12:3, s. 525-529
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Journal article (peer-reviewed)abstract
- This letter considers the problem of end-to-end (E2E) learning for joint optimization of transmitter precoding and receiver processing for mmWave downlink positioning. Considering a multiple-input single-output (MISO) scenario, we propose a novel autoencoder (AE) architecture to estimate user equipment (UE) position with multiple base stations (BSs) and demonstrate that E2E learning can match model-based design, both for angle-of-departure (AoD) and position estimation, under ideal conditions without model deficits and outperform it in the presence of hardware impairments.
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| 10. |
- Rupp, Craig, et al.
(author)
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Unit Testing and Analysis Using a Stored Reference Signal
- 2014
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Patent (pop. science, debate, etc.)abstract
- Method and system for a test process. The method may include performing tests on one or more units under test (UUTs). At least one test on one or more UUTs may be performed. A signal may be acquired from the UUT. A reference signal may be retrieved. The reference signal may be derived from a transmitted signal characteristic of the UUT. The signal may be analyzed with respect to the reference signal. Results, useable to characterize the one or more UUTs, from performing the at least one test on the one or more UUTs may be stored. The reference signal may be derived from an initial test and may be stored for subsequent retrieval. A respective reference signal may be retrieved for all UUTs of the one or more UUTs for a respective test. The signal may be a radio frequency signal. The UUT may be a wireless mobile device.
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