11 results on '"sounding reference signal"'
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2. User Equipment Grouping in 5G TDD System using Machine Learning
- Author
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Arslantürk, Korkut and Arslantürk, Korkut
- Abstract
User Equipment (UE) grouping entails categorizing multiple UEs, including mobile phones or smart devices, according to defined criteria. It provides valuable insights for applications to optimize network resources, enhance handover procedures, and improve user experience. This study investigates UE grouping in a Fifth Generation (5G) Time Division Duplex (TDD) system based on Uplink (UL) Sounding Reference Signal (SRS) channel fingerprints using Machine Learning (ML) techniques. Specifically, the study comprises two main blocks: UE position and direction estimation, and UE grouping. In the first block, the estimation model for UE position and Course Over Ground (COG), the actual direction of motion, is developed. This model utilized UL SRS channel estimation results collected from 5G TDD Base Station (BS) for diverse routes, including both Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios. Channel Transfer Function (CTF) snapshots are created according to system specifications using SRS data. To ensure the accuracy of the CTF when encountering missing SRS, we applied forward-filling to maintain data integrity. CTF snapshots are synchronized in time with Global Navigation Satellite System (GNSS) data. Supervised ML techniques, culminating in an ensemble model refined with post-processing methods, achieved highly precise estimation results. The positioning Root Mean Square Error (RMSE) is less than 0.93 meters and the direction RMSE is less than 9 degree across all routes. In the second block, clustering algorithms are used to group UEs based on their estimated positions and directions. Firstly, the timestamps of the UEs' data are synchronized to assume they move simultaneously despite being measured at different times. Moreover, to ensure a fair assessment of clustering results, more UEs are needed than measured ones. Each route is then split into two halves, treating the first and second halves as distinct virtual UEs derived from real data measurements. Va, Have you ever wondered how your smartphone knows precisely where you are? Imagine using your phone to stream a movie or video call a friend on a busy street. Why does the signal sometimes weaken, or does the video start buffering? Since many people use the same network simultaneously, it can get crowded up in the digital world! What if the network could adapt to the dynamic radio environment and provide optimal performance in various situations? This would ensure that your favorite shows do not pause at the most exciting moments or that you do not encounter connection issues during important online job interviews or meetings. We have an idea! We are using advanced computer techniques to figure out exactly where each user is and in which direction they are facing. This way, we can ensure that everyone's signal stays strong and their videos keep streaming without pauses. How does it work? Think of it as having a bunch of invisible helpers in the sky who can see where everyone is and where they are headed. These helpers, powered by machine learning, analyze all the data from base stations to create a digital map of the world around us. Here is the exciting part: Once we know where everyone is, we can start organizing things better. We can group users based on their locations and directions, similar to organizing cars on a busy highway to keep traffic flowing smoothly. This approach allows for strategic capacity planning and load balancing based on user population, enhancing overall user experience. Service providers can strategically plan the placement of new base stations based on user distribution to maintain service continuity effectively. With machine learning and sophisticated data analysis, 5G networks are getting smarter every day! This technology opens up a world of possibilities, and we invite you to be a part of it by delving into our thesis report, "User Equipment Grouping in 5G TDD System using Machine Learning", to understand our methodology for utilizing more...
- Published
- 2024
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3. Uplink Reference Signals for Power-Efficient Handover in Cellular Networks With Mobile Relays
- Author
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Muhammad Tayyab, George P. Koudouridis, Xavier Gelabert, and Riku Jantti
- Subjects
Uplink reference signal ,sounding reference signal ,handover ,3GPP cellular networks (LTE/NR) ,mobile relay node ,simulation ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
When a vehicle moves from one base station (BS) to another, a large number of on-board user equipments (UE) may simultaneously and individually perform a handover (HO) procedure, resulting in increased HO overheads. A mobile relay node (MRN), connected via a wireless backhaul to a donor base station (DBS), is deployed on the rooftop of a bus to improve the link quality and reduce the associated HO overhead via group mobility. However, at moderate to high speeds, the on-board UEs can still suffer from frequent HOs due to the MRN failing to HO to a new DBS using the legacy downlink measurement-based HO (DL-HO) method. As a consequence, the connection towards all associated mobile users will be lost which poses tight reliability requirements on the backhaul link to avoid becoming a single point of failure (SPoF). In order to improve the reliability during group handover, in this work, we propose an uplink reference signal (UL RS) based HO procedure (coined as UL-HO) for the MRN which relies on the existing sounding reference signal in long term evolution (LTE) /new radio (NR). In the proposed scheme, and unlike the legacy DL-HO procedure in LTE/NR, the measurement report (MeasReport) transmission is not required between MRN and the DBS, therefore the HO delay can be reduced, decreasing the SPoF chances and thus, uninterrupted services can be provided to on-board UEs. We investigate the gain in terms of HO rate, HO failure rate, ping-pong rate and power consumption (both at the UE and the BS). Performance evaluations demonstrate that the proposed UL-HO scheme outperforms the legacy DL-HO scheme in current cellular networks. more...
- Published
- 2021
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4. A Hybrid TDOA-Fingerprinting-Based Localization System for LTE Network.
- Author
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He, Jiajun and So, Hing Cheung
- Abstract
To the best of our knowledge, effective indoor positioning for the long term evolution (LTE) has not been addressed in the literature. In this paper, the uplink sounding reference signal (SRS), which contains timing and received signal strength (RSS) information, is exploited to achieve this task. Accordingly, an LTE based localization system using time-difference-of-arrival (TDOA) and fingerprint of RSS that operates in two steps is devised to meet the requirement of high-precision indoor positioning. In the first step, peak value detection is applied to the SRSs from spatially separated sensors to estimate the TDOAs, from which a coarse target location is computed with the use of least squares. Based on deep neural network, fingerprinting in a subarea containing the coarse solution is then performed to obtain the final position estimate. Due to the instability in the RSS values caused by non-line-of-sight and multipath propagation, we propose a novel extraction method to select reliable RSSs as input to the network. Experimental results show that our two-step localization system can provide an accuracy of sub-meter level. [ABSTRACT FROM AUTHOR] more...
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- 2020
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5. Investigation of PUCCH structure with SRS transmission based on BS-CDMA for LTE-Advanced carrier aggregation.
- Author
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Takeda, Kazuaki, Kishiyama, Yoshihisa, Kawamura, Teruo, and Nakamura, Takehiro
- Abstract
In LTE-Advanced, carrier aggregation (CA) employing multiple component carriers (CCs) is supported, and multiple acknowledgement (ACK)/ negative ACK (NACK) bits associated with multiple CCs are required. In order to convey multiple ACK/NACK bits for downlink CA, a physical uplink control channel (PUCCH) based on block spread code division multiple access (BS-CDMA) is used in the LTE-Advanced uplink. There are two PUCCH structures depending on the presence of a sounding reference signal (SRS), which is used to measure the uplink channel quality. In the subframe with SRS transmission, the last symbol in each PUCCH is removed to avoid simultaneous transmissions of the ACK/NACK and SRS so that the single-carrier property is sustained. In this paper, we investigate the optimum PUCCH structure with SRS transmission based on BS-CDMA in the uplink. We propose two schemes: one removes the ACK/NACK symbol and the other removes the demodulation RS symbol. The ACK/NACK performance for these two schemes is evaluated by computer simulation considering discontinuous transmission (DTX) detection at the base station receiver. [ABSTRACT FROM PUBLISHER] more...
- Published
- 2011
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6. High resolution time of arrival estimation algorithm for B5G indoor positioning.
- Author
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Gu, Henghao, Zhao, Kun, Yu, Chao, and Zheng, Zhengqi
- Subjects
TIME-of-arrival estimation ,ADDITIVE white Gaussian noise ,RAYLEIGH fading channels ,ADAPTIVE filters ,ALGORITHMS - Abstract
In beyond 5G (B5G) indoor positioning time of arrival (TOA) positioning method is an important one. Base stations measure reference signals sent by terminals to calculate the TOA. The accuracy of position calculation is highly dependent on the TOA estimation resolution. This paper proposes a high-resolution TOA estimation algorithm based on Sounding Reference Signal (SRS) of 5G communication system. The algorithm achieves high resolution estimation by two steps. The Least Mean Square (LMS) adaptive filtering method is used as the first step to obtain the integer part of TOA, which is a coarse estimation of TOA. In the second step, we use weighted Generalized Cross-Correlation (GCC) algorithm to obtain the fractional part of TOA in frequency domain to get a more precise TOA estimation. Moreover, the stability of the estimated results is improved by the threshold value setting. The proposed algorithm is simulated in both Additive White Gaussian Noise (AWGN) and Rayleigh fading channels. The simulation results show that the TOA error achieves 0.56 m in AWGN and 0.96 m in Rayleigh fading channels for 80 % of test samples respectively. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
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7. A study on channel estimation algorithm with sounding reference signal for TDD downlink scheduling
- Author
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Een-Kee Hong, Jung-Yeon Baek, and Georges Kaddoum
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Computer science ,Duplex (telecommunications) ,020206 networking & telecommunications ,Throughput ,Data_CODINGANDINFORMATIONTHEORY ,02 engineering and technology ,010501 environmental sciences ,Sounding reference signal ,01 natural sciences ,Scheduling (computing) ,Base station ,User equipment ,Telecommunications link ,0202 electrical engineering, electronic engineering, information engineering ,Path loss ,Radio resource management ,Algorithm ,0105 earth and related environmental sciences ,Communication channel ,Power control - Abstract
Coping with the limited amount of available spectrum, time division duplexing (TDD) system is considered as an attractive duplexing method due to exploiting channel reciprocity as well as flexible resource management. The conventional scheduling scheme is based on the channel quality indicator (CQI) reported from the user equipment (UE) to estimate instantaneous data rates for the scheduling metric calculation. However, CQI is insufficient to reflect the state of the channel variation in terms of frequency and time. Based on the channel reciprocity of TDD systems, we utilize uplink sounding reference signal (SRS) to estimate downlink channel status. However the received SRS power is a result of uplink power control where power control effect should be compensated to estimate channel status in downlink scheduling. In order to solve this problem, we propose the SRS path loss estimation method based on the power headroom report. By using this scheme, the base station (BS) can obtain the compensated signal-to-interference-plus-noise-ratio (SINR) and determine the scheduling metric based on its calculated SINR instead of reported CQI from UE. Simulation results show that the proposed scheduling algorithm outperforms the conventional scheme in total throughput, whereas the fairness index experienced by the proposed algorithm is lesser than of the conventional scheme based on CQI. more...
- Published
- 2017
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8. Sounding reference signal measurement in LTE system
- Author
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Jeawook Shin and Eun-Jeong Shin
- Subjects
Depth sounding ,Frequency comb ,business.industry ,Computer science ,Bandwidth (signal processing) ,Telecommunications link ,Real-time computing ,Electronic engineering ,Broadcasting ,Sounding reference signal ,business ,Multiplexing - Abstract
The SRS are physical signals transmitted in uplink to enable the eNB to estimate the CSI over a range of frequencies in LTE system. The estimation of the CSI assists the eNB scheduler to properly allocated radio resource to the UE. The SRS transmission can be also be used to support downlink beamforming. The sub-frame in which SRS is transmitted by any UE within the cell is signaled via cell specific broadcast signaling, there are 15 possible sets of subframe in which SRS may be transmitted within each radio frame. The SRS is based on the extended zadoff-chu sequence and transmitted in the last SC-FDMA symbol of an uplink subframe, the SRS transmitted by the UEs are multiplexed in the time and freq. domain through configuring SRS periodicity SRS, frequency comb pattern, and SRS bandwidth. Different sets of UE-specific sounding signals are independently allocated for SRS transmission, including transmissi on bandwidth, frequency comb pattern, cyclic shift. In this paper, transmission subframe, bandwidth, freq. comb pattern, for it suggests ways to reduce the measurement performance and HW complexity of the UE between the Sounding RS separated by a Cyclic shift value and Timing offset measurement method. more...
- Published
- 2016
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9. An improved noise estimation algorithm of SC-FDMA
- Author
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Chunrong Kan, Haoyang Du, and Yating Luan
- Subjects
Carrier signal ,Noise estimation ,Computer science ,Electronic engineering ,Division (mathematics) ,Sounding reference signal ,Signal leakage ,Hamming code ,Algorithm ,Discrete Fourier transform - Abstract
To improve the performance of Single Carrier Frequency Division Multiple Access (SC-FDMA) system, a simple and effective noise estimation algorithm based on Sounding Reference Signal (SRS) is necessary. An improved noise estimation algorithm based on Discrete Fourier transform (DFT) is proposed for the disadvantage of the traditional DFT. In addition, the influence of signal leakage is effectively reduced by time-domain Hamming windowing operation to the improved noise estimation algorithm based on DFT. Simulation results show that the improved noise estimation algorithm based on DFT has an improvement of 4 dB compared with the traditional algorithm in low Signal-to-Noise Ratio (SNR) regions. Hamming windowing operation can effectively correct the disadvantage of the improved noise estimation algorithm based on DFT which has bad performance to get an improvement of 4 dB at least in high SNR regions. more...
- Published
- 2015
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10. Improved SRS design and channel estimation for LTE-advanced uplink
- Author
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Xingyu Xia, Chengcheng Zhang, and Hui Zhao
- Subjects
Engineering ,business.industry ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Data_CODINGANDINFORMATIONTHEORY ,Spectral efficiency ,Sounding reference signal ,Backward compatibility ,Exponential function ,LTE Advanced ,Telecommunications link ,Electronic engineering ,business ,Power delay profile ,Computer Science::Information Theory ,Coding (social sciences) - Abstract
In 3GPP long term evolution (LTE) specification for uplink, single antenna for transmission is adopted due to its simplicity. However, when it evolves to LTE-A, more transmit antennas are needed for higher spectrum efficiency, which means more reference signals. In the physical uplink share channel (PUSCH) of LTE-A, the estimated channel based on sounding reference signal (SRS) is used for precoder and modulation and coding scheme (MCS) selection. In this paper, an improved SRS design is proposed, which achieves minimum interference between different reference signals. More importantly, it is perfectly backwards compatible with the SRS in LTE uplink. In addition, we propose an improved SRS channel estimation for multiple transmit antennas. Simulation results show that the proposed SRS design leads to less channel estimation error, and the proposed SRS channel estimation can reach similar accuracy to exponential power delay profile (PDP) channel estimation, while with much lower complexity. more...
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- 2013
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11. Investigation on Multi-Cell Sounding Reference Signal Coordination for TD-LTE-Advanced CoMP
- Author
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Na Chongning, Atsushi Harada, and Xiaolin Hou
- Subjects
LTE Advanced ,Depth sounding ,Engineering ,Time-division multiplexing ,business.industry ,Channel state information ,Telecommunications link ,Electronic engineering ,Duplex (telecommunications) ,Cyclic shift ,business ,Sounding reference signal - Abstract
Coordinated Multi-Point (CoMP) transmission is a key technology for LTE-Advanced (LTE-A) to increase the downlink cell-edge throughput. Generally speaking, multi-cell channel state information (CSI) is needed at multiple coordinated eNBs to achieve the performance gain promised by CoMP in downlink. Sounding reference signal (SRS) could be an efficient tool to enable multi-cell CSI acquisition for time division duplex (TDD) LTE-A (TD-LTE-A) systems because of the inherent channel reciprocity in TDD systems. In this study, we investigate multi-cell SRS coordination schemes for TD-LTE-A downlink CoMP. We introduce a CoMP-specific sounding zone that facilitates multi-cell SRS coordination and then propose and compare three coordinated SRS resource allocation schemes within the CoMP-specific sounding zone, i.e., cyclic shift (CS) coordination, comb coordination, and orthogonal cover code (OCC) for the SRS. Computer simulations show the effectiveness of multi-cell SRS coordination and its necessity is revealed by the sum-rate analysis of TD-LTE-A downlink CoMP. more...
- Published
- 2013
- Full Text
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