| 1. |
- Ahmed, Zakir, et al.
(författare)
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A time domain based efficient block decision algorithm for audio coders
- 2007
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Ingår i: International Symposium on Communications and Information Technologies, 2007. ISCIT '07. - : IEEE Press. - 9781424409761 ; , s. 1077-1081
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Konferensbidrag (refereegranskat)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.
(författare)
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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 (populärvet., debatt m.m.)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.
(författare)
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Estimation of Sample Clock Frequency Offset Using Error Vector Magnitude
- 2011
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Patent (populärvet., debatt m.m.)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.
(författare)
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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 (populärvet., debatt m.m.)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.
(författare)
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Positioning and Sensing in 6G: Gaps, Challenges, and Opportunities
- 2023
-
Ingår i: IEEE Vehicular Technology Magazine. - 1556-6080 .- 1556-6072. ; 18:1, s. 40-48
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Towards joint communication and sensing (Chapter 4)
- 2023
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Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 121-158
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Bokkapitel (övrigt vetenskapligt/konstnärligt)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.
(författare)
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A Novel Initial Ranging Algorithm for mobile WiMAX (802.16e)
- 2010
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Ingår i: International Journal of Computer Applications. - : Foundation of Computer Science. - 0975-8887. ; 1:3, s. 95-100
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Tidskriftsartikel (refereegranskat)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.
(författare)
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End-to-End Learning for Integrated Sensing and Communication
- 2022
-
Ingår i: IEEE International Conference on Communications. - 1550-3607. ; 2022-May, s. 1942-1947
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Konferensbidrag (refereegranskat)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.
(författare)
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Spatial Signal Design for Positioning via End-to-End Learning
- 2023
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Ingår i: IEEE Wireless Communications Letters. - 2162-2345 .- 2162-2337. ; 12:3, s. 525-529
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Unit Testing and Analysis Using a Stored Reference Signal
- 2014
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Patent (populärvet., debatt m.m.)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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| 11. |
- Sartaj, Chaudhary, et al.
(författare)
-
Blind Mechanism for Demodulating Offset QPSK Signals in the Presence of Carrier Phase Error
- 2012
-
Patent (populärvet., debatt m.m.)abstract
- A computer-implemented system and method for blind demodulation of an offset QPSK input signal, involving repeatedly performing a set of operations, including: (a) applying a phase correction to the input signal based on an estimate of a carrier phase offset of the input signal to obtain a first modified signal; (b) shifting a quadrature component of the first modified signal by half a symbol period relative to an inphase component to obtain a second modified signal; (c) extracting a first sequence of symbols from the second modified signal, where the extraction includes estimating a symbol timing offset from the second modified signal; (d) performing hard-decision demodulation on the first sequence of symbols to obtain a second sequence of reference symbols; (e) computing a phase difference between the first sequence of symbols and second sequence of reference symbols; and (f) updating the carrier phase offset estimate using the phase difference.
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| 12. |
- Wymeersch, Henk, 1976, et al.
(författare)
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Integration of Communication and Sensing in 6G: A Joint Industrial and Academic Perspective
- 2021
-
Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. ; 2021-September
-
Konferensbidrag (refereegranskat)abstract
- 6G will likely be the first generation of mobile communication that will feature tight integration of localization and sensing with communication functionalities. Among several worldwide initiatives, the Hexa-X flagship project stands out as it brings together 25 key players from adjacent industries and academia, and has among its explicit goals to research fundamentally new radio access technologies and high-resolution localization and sensing. Such features will not only enable novel use cases requiring extreme localization performance, but also provide a means to support and improve communication functionalities. This paper provides an overview of the Hexa-X vision alongside the envisioned use cases. To close the required performance gap of these use cases with respect to 5G, several technical enablers will be discussed, together with the associated research challenges for the coming years.
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| 13. |
- Yajnanarayana, Vijaya, et al.
(författare)
-
A Simple Controller for displaying Restricted Patterns On RMS Responding LCDs
- 1999
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Ingår i: Society for Information Display Journal. - : Wiley. ; , s. 234-237
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Tidskriftsartikel (refereegranskat)abstract
- A controller for displaying restricted patterns inpassive matrix LCDs will be presented. Hardwarecomplexity and the computational time forgenerating column signals are reduced considerablyby using serial arithmetic directly from digitisedsamples and hence eliminating the frame buffer inmulti-line addressing techniques.
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| 14. |
- Yajnanarayana, Vijaya, et al.
(författare)
-
A Technique to Improve Performance of MPEG/H264 Video Decoder for Low Motion Video Applications using Vector Processor
- 2005
-
Patent (populärvet., debatt m.m.)abstract
- Motion Compensation for video decoding in standards like MPEG and H.264 typically take more than 50% of the computational time, a new technique is proposed to speed up this process for low motion video sequence. This technique can be primarily employed for systems which have vector processors as video decode accelerators. The typical gain using this technique on an ideal vector processor can be more than 50% for a low motion video sequence. An ideal vector processor satisfies the below equation.
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| 15. |
- Yajnanarayana, Vijaya, et al.
(författare)
-
Design of impulse radio UWB transmitter for short range communications using PPM signals
- 2013
-
Ingår i: IEEE International Conference on Electronics, Computing and Communication Technologies (CONECCT), 2013. - : IEEE conference proceedings. - 9781467346092 ; , s. 1-4
-
Konferensbidrag (refereegranskat)abstract
- There are several practical challenges in designing an ultra wideband (UWB) device for communication. From the physical layer perspective, signaling technique should be optimally designed to work in synergy with the underneath hardware to achieve maximum performance. In this paper we propose a new cost effective hardware architecture for UWB communication and propose a variant of pulse position modulation (PPM) method which achieves maximum bit rate under the practical constraints imposed by UWB hardware.
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| 16. |
- Yajnanarayana, Vijaya, et al.
(författare)
-
Design of impulse radio UWB transmitter with improved range performance using PPM signals
- 2014
-
Ingår i: 2014 IEEE International Conference on Electronics, Computing and Communication Technologies (IEEE CONECCT). - : IEEE Computer Society. - 9781479923182 ; , s. 1-5
-
Konferensbidrag (refereegranskat)abstract
- There are several practical challenges in designing an ultra wideband (UWB) device for communication. From the physical layer signaling perspective it is important to avoid the strong peaks in the transmitted signal to fully exploit the regulatory bodies power constraint requirements. This will result in increased range performance for the sensors. Design of the transmit impulse radio (IR) UWB signals under the practical constraints of hardware and regulatory body is a critical optimization issue in the UWB system design. In this paper, we propose a IR-UWB signaling, which is a variant of pulse position modulation (PPM) method and achieves an increased range performance under the practical constraints of hardware and Federal Communications Commission (FCC) regulations.
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| 17. |
- Yajnanarayana, Vijaya, et al.
(författare)
-
IR-UWB detection and fusion strategies using multiple detector types
- 2016
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Ingår i: IEEE Wireless Communications and Networking Conference, WCNC. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467398145
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Konferensbidrag (refereegranskat)abstract
- Optimal detection of ultra wideband (UWB) pulses in a UWB transceiver employing multiple detector types is proposed and analyzed in this paper. To enable the transceiver to be used for multiple applications, the designers have different types of detectors such as energy detector, amplitude detector, etc., built in to a single transceiver architecture. We propose several fusion techniques for fusing decisions made by individual IR-UWB detectors. In order to get early insight into theoretical achievable performance of these fusion techniques, we assess the performance of these fusion techniques for commonly used detector types like matched filter, energy detector and amplitude detector under Gaussian assumption. These are valid for ultra short distance communication and in UWB systems operating in millimeter wave (mmwave) band with high directivity gain. In this paper, we utilize the performance equations of different detectors, to device distinct fusion algorithms. We show that the performance can be improved approximately by 4 dB in terms of signal to noise ratio (SNR) for high probability of detection of a UWB signal (> 95%), by fusing decisions from multiple detector types compared to a standalone energy detector, in a practical scenario.
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| 18. |
- Yajnanarayana, Vijaya, et al.
(författare)
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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
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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).
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| 19. |
- Yajnanarayana, Vijaya, et al.
(författare)
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Multistatic Sensing of Passive Targets Using 6G Cellular Infrastructure
- 2023
-
Ingår i: 2023 Joint European Conference on Networks and Communications and 6G Summit, EuCNC/6G Summit 2023. ; , s. 132-137
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Konferensbidrag (refereegranskat)abstract
- Sensing using cellular infrastructure may be one of the defining feature of sixth generation (6G) wireless systems. 6G communication channels operating at higher frequency bands (upper mmWave bands) are better modeled using clustered geometric channel models. In this paper, we propose methods for detection of passive targets and estimating their position using communication deployment without any assistance from the target. A novel AI architecture called CsiSenseNet is developed for this purpose. We analyze resolution, coverage and position uncertainty for practical indoor deployments. Using the proposed method, we show that human sized target can be sensed with high accuracy and sub-meter positioning errors in a practical indoor deployment scenario.
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| 20. |
- Yajnanarayana, Vijaya, et al.
(författare)
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Novel method for blind constellation detection using template based classifier for quadrature digital modulation schemes.
- 2011
-
Ingår i: IEEE 2011 10th International Conference on Electronic Measurement and Instruments, ICEMI 2011. - 9781424481583 ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- Template based classifiers are very popular classifiers in biomedical and computer vision area. In computer vision they are typically used to understand or classify the scenes captured by camera. In biomedical field they are typically used to provide non-intrusive disease identification. For example to classify a tissue samples as cancerous or not. In this paper we apply the learnings of this area to device an algorithm for automatic modulation detection problem. Automatic modulation detection problem in communication receivers involves auto detecting the modulation scheme from the received samples at the communication receiver without the prior knowledge of the encoded modulation scheme. The method can efficiently recognize almost all quadrature digital modulation schemes and the accuracy rate is over 95% at the SNRs of 4.5 dB with as low as 512 bits. The performance of this algorithm is evaluated using simulations on LabVIEW.
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| 21. |
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| 22. |
- Yajnanarayana, Vijaya, et al.
(författare)
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Optimal Scheduling for Interference Mitigation by Range Information
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes several algorithms for generating an optimal schedule for multiple access on a shared channel by utilizing range information in a fully connected network. We also provide detailed analysis for the proposed algorithms in terms of their complexity, convergence, and effect of non-idealities in the network. The performance of the proposed schemes are compared with non-aided methods to quantify the benefits of using the range information in the communication. We argue that the proposed techniques yield significant benefits as the number of nodes in the network increases. We provide simulation results in support of the claim. The proposed methods indicate that the throughput can be increased on average by 3-10 times for typical network configurations.
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| 23. |
- Yajnanarayana, Vijaya Parampalli
(författare)
-
Ultra Wideband: Communication and Localization
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The first part of this thesis develops methods for UWB communication. To meet the stringent regulatory body constraints, the physical layer signaling technique of the UWB transceiver should be optimally designed. We propose two signaling schemes which are variants of pulse position modulation (PPM) signaling for impulse radio (IR) UWB communication. We also discuss the detectors for the signaling schemes and evaluate the performance of these detectors. IR-UWB can be used for precise range measurements as it provides a very high time resolution. This enables accurate time of arrival (TOA) estimations from which precise range values can be derived. We propose methods which use range information to arrive at optimal schedules for an all-to-all broadcast problem. Results indicate that throughput can be increased on average by three to ten times for typical network configurations compared to the traditional methods. Next, we discuss hypothesis testing in the context of UWB transceivers. We show that, when multiple detector outputs from a hardware platform are available, fusing the results from them can yield better performance in hypothesis testing than relying on a single detector output. In the second part of this thesis, the emphasis is placed on localization and joint estimation of location and communication parameters. Here, we focus on estimating the TOA of the signal. The wide bandwidth of the UWB signal requires high speed analog to digital converts (ADC) which makes the cost of the digital transceivers prohibitively high. To address this problem, we take two different strategies. In the first approach, we propose a multichannel receiver with each channel having a low-cost energy detector operating at a sub-Nyquist rate. In the second approach, we consider a compressive sampling based technique. Here, we propose a new acquisition front end, using which the sampling rate of the ADC can be significantly reduced. We extended the idea of compressive sampling based TOA estimation towards joint estimation of TOA and PPM symbols. Here, two signaling methods along with the algorithms are proposed based on the dynamicity of the target. They provide similar performance to the ML based estimation, however with a significant savings in the ADC resources.
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| 24. |
- Yajnanarayana, Vijaya, et al.
(författare)
-
Performance evaluation of IR-UWB detectors and fusion techniques for UWB transceiver platforms
- 2018
-
Ingår i: International Journal of Ultra Wideband Communications and Systems. - : Inderscience Enterprises Ltd.. - 1758-728X. ; 3:4, s. 177-191
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we analyse the performance of a multi-pulse impulse radio based ultra-wideband (IR-UWB) detector in an AWGN setting and provide different fusion strategies for fusing these detector outputs. To enable the transceiver to be used for multiple applications, the designers have different types of detectors such as energy detectors, amplitude detectors, etc., built in to a single transceiver architecture. In this paper, we derive the detection performance equation for commonly used detectors in terms of false alarm rate, shape of the pulse, and number of UWB pulses used in the detection and apply these in the fusion algorithms. We show that the performance can be improved by approximately 4 dB in terms of signal to noise ratio (SNR) for high probability of detection of a UWB signal (95%), by fusing decisions from multiple detector types compared to a standalone energy detector, in a practical scenario.
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| 25. |
- Yajnanarayana, Vijaya, et al.
(författare)
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Spectral efficient IR-UWB communication design for low complexity transceivers
- 2014
-
Ingår i: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 2014:158
-
Tidskriftsartikel (refereegranskat)abstract
- Ultra wideband (UWB) radio for communication has several challenges. From the physical layer perspective, asignaling technique should be optimally designed to work in synergy with the underneath hardware to achievemaximum performance. In this paper, we propose a variant of pulse position modulation (PPM) for physical layersignaling, which can achieve raw bitrate in excess of 150 Mbps on a low complexity in-house developed impulseradio UWB platform. The signaling system is optimized to maximize bitrate under practical constraints of lowcomplexity hardware and regulatory bodies. We propose a detector and derive its theoretical performance boundsand compare the performance in simulation in terms of symbol error rates (SER). Modifications to the signaling, whichcan increase the range by 4 times with a slight increase in hardware complexity, is proposed. Detectors for thismodification and a comparative study of the performance of the proposed UWB physical layer signaling schemes interms of symbol error rates are discussed.
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| 26. |
- Yajnanarayana, Vijaya, et al.
(författare)
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Techniques to improve motion compensation performance of H264 video decoder using a vector processor
- 2007
-
Ingår i: IEEE International Symposium on Communications and Information Technologies. - : IEEE Press. - 9781424409761 ; , s. 1082-1087
-
Konferensbidrag (refereegranskat)abstract
- Motion Compensation for video decoding in standards like H.264 requires significant amount of computation. This is primarily because of H.264 six-tap FIR filtering for sub-sample computation. These algorithms typically take more than 50% of the computational time on a RISC processor like ARM. Novel algorithms proposed through this paper can be employed for systems which use vector processors as video decode accelerators to accelerate this process. The proposed algorithms are implemented on H264 video decode system with ARM9 host-processor and RSVP vector processor as an accelerator for key decode algorithms. By employing the proposed algorithms we were able to accelerate the motion compensation module by more than 4 times as compared to plain RISC implementation. This is achieved by efficiently vectorizing data on which FIR-filtering and reconstruction algorithm is operated on, together with optimal representation of FIR-filtering and reconstruction algorithm itself on vector processor.
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