SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "L773:2334 0983 OR L773:2576 6813 "

Sökning: L773:2334 0983 OR L773:2576 6813

  • Resultat 1-33 av 33
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Abu-Shaban, Z., et al. (författare)
  • Random-phase beamforming for initial access in millimeter-wave cellular networks
  • 2016
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813.
  • Konferensbidrag (refereegranskat)abstract
    • The utilization of the millimeter-wave frequency band (mm-wave) in the fifth generation ({5G}) of mobile communication is a highly-debated current topic. Mm-wave MIMO systems will use arrays with large number of antennas at the transmitter and the receiver, implemented on a relatively small area. With the inherent high directivity of these arrays, algorithms to help the user equipment find the base station and establish a communication link should be carefully designed. Towards that, we examine two beamforming schemes, namely, random-phase beamforming (RPBF) and directional beamforming (DBF), and test their impact on the Cram\'er-Rao lower bounds (CRB) of jointly estimating the direction-of-arrival, direction-of-departure, time-of-arrival, and the complex channel gain, under the line-of-sight channel model. The results show that the application of RPBF is more appropriate in the considered scenario as it attains a lower CRB with fewer beams compared to DBF.
  •  
2.
  • Beygi, Sajjad, et al. (författare)
  • Structured Sparse Approximation via Generalized Regularizers: With Application to V2V Channel Estimation
  • 2014
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479935116 ; , s. 3013-3018
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we consider the estimation of a signal that has both group- and element-wise sparsity (joint sparsity); motivated by channel estimation in vehicle-to-vehicle channels. A general approach for the design of separable regularizing functions is proposed to adaptively induce sparsity in the estimation. A joint sparse signal estimation problem is formulated via these regularizers and its optimal solution is computed based on proximity operations. Our optimization results are quite general and they can be applied in the context of hierarchical sparsity models as well. The proposed recovery algorithm is a nested iterative method based on the alternating direction method of multipliers (ADMM). Due to regularizer separability, key operations can be performed in parallel. V2V channels are estimated by exploiting the joint sparsity (group/element-wise) exhibited in the delay-Doppler domain. Simulation results reveal that the proposed method can achieve as much as a 10 dB gain over previously examined methods.
  •  
3.
  • Bing, L., et al. (författare)
  • Continuous phase modulated orthogonal multiple access scheme
  • 2014
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479935116 ; , s. 3886-3891
  • Konferensbidrag (refereegranskat)abstract
    • This paper focuses on the design and performance analysis of continuous phase modulated orthogonal multiple access systems. The multiuser interference is firstly derived in the context of single user detection, which reveals that the interference is determined by the modulation format. Therefore, the interference can be successfully suppressed by carefully chosen modulation parameters. Based on this observation, a class of orthogonal multiple access schemes is proposed. It is shown that the proposed strategy not only facilitates simple detection at the receiver side but also offers improved sum rate.
  •  
4.
  • Bing, L., et al. (författare)
  • Single user detection of continuous phase modulated multiuser systems
  • 2014
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479935116 ; , s. 4008-4013
  • Konferensbidrag (refereegranskat)abstract
    • The performance analysis of single user detection of continuous phase modulated multiuser systems is presented in this paper. The discussion is formulated in the context of a mismatched receiver and the performance of single user detection is analyzed in terms of Euclidean distance. Taking the modulation parameters into consideration, a closed-form expression for the performance evaluation is obtained. Principles of designing the transceiver for spectrally-efficient systems are proposed. Numerical and analytical results show that properly designed spectrally efficient multiuser systems can be successfully detected by the presented detector with low complexity.
  •  
5.
  • Dhamal, Swapnil Vilas, 1988 (författare)
  • Effectiveness of Diffusing Information through a Social Network in Multiple Phases
  • 2018
  • Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings. - 2576-6813 .- 2334-0983. ; , s. 1-7
  • Konferensbidrag (refereegranskat)abstract
    • We study the effectiveness of using multiple phases for maximizing the extent of information diffusion through a social network, and present insights while considering various aspects. In particular, we focus on the independent cascade model with the possibility of adaptively selecting seed nodes in multiple phases based on the observed diffusion in preceding phases, and conduct a detailed simulation study on real-world network datasets and various values of seeding budgets. We first present a negative result that more phases do not guarantee a better spread, however the adaptability advantage of more phases generally leads to a better spread in practice, as observed on real-world datasets. We study how diffusing in multiple phases affects the mean and standard deviation of the distribution representing the extent of diffusion. We then study how the number of phases impacts the effectiveness of multiphase diffusion, how the diffusion progresses phase-by-phase, and what is an optimal way to split the total seeding budget across phases. Our experiments suggest a significant gain when we move from single phase to two phases, and an appreciable gain when we further move to three phases, but the marginal gain thereafter is usually not very significant. Our main conclusion is that, given the number of phases, an optimal way to split the budget across phases is such that the number of nodes influenced in each phase is almost the same.
  •  
6.
  • Duong, Trung Quang, et al. (författare)
  • Cognitive Cooperative Networks in Dual-Hop Asymmetric Fading Channels
  • 2013
  • Ingår i: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM). - 2334-0983 .- 2576-6813. - 9781479913534 ; , s. 955-961
  • Konferensbidrag (refereegranskat)abstract
    • Previous works on cognitive relay networks (CRNs) considered only symmetric fading channels. However, in practical wireless propagation scenarios, it is likely that the channels of the secondary user (SU) and primary user (PU) may undergo different fading characteristics. In this paper, we assume that the channels of the secondary network (SU-source -> SU-relay -> SU-destination) are subject to Rician fading, whereas the channels of the link from the SU to the PU experience Rayleigh fading. Based on this framework, the end-to-end outage probability (OP) of CRNs is investigated for two different relaying schemes: i) in the absence of the direct link with decode-and-forward (DF) protocol and ii) in the presence of the direct link with incremental DF protocol. In particular, we derive both exact and asymptotic OP expressions for the considered CRNs. Our analysis reveals important insights into the impact of fading parameters on the CRN performance under distinct fading distributions.
  •  
7.
  • Ge, Yu, 1995, et al. (författare)
  • Integrated Monostatic and Bistatic mmWave Sensing
  • 2023
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; , s. 3897-3903
  • Konferensbidrag (refereegranskat)abstract
    • Millimeter-wave (mmWave) signals provide attractive opportunities for sensing due to their inherent geometrical connections to physical propagation channels. Two common modalities used in mmWave sensing are monostatic and bistatic sensing, which are usually considered separately. By integrating these two modalities, information can be shared between them, leading to improved sensing performance. In this paper, we investigate the integration of monostatic and bistatic sensing in a 5G mmWave scenario, implement the extended Kalman-Poisson multi-Bernoulli sequential filters to solve the sensing problems, and propose a method to periodically fuse user states and maps from two sensing modalities.
  •  
8.
  • Gustafson, Carl, et al. (författare)
  • Modeling the Polarimetric mm-wave Propagation Channel using Censored Measurements
  • 2016
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781509013289 ; , s. Article number 7842003-
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents results based on polarimetric radio channel measurements at 60 GHz in a small room and in an empty, unfurnished, medium-sized room. The measurements in the small meeting room were performed using dual-polarized virtual antenna array elements at both the transmitter and receiver sides and includes LOS and NLOS scenarios. In the unfurnished room, a directional horn antenna was scanned in the azimuth plane and the Rx antenna was an omnidirectional antenna. Based on these measurements, the paper presents experimental parameter estimates for a novel model of the polarimetric propagation paths, that includes the power-decay as well as a correlated fading for the different polarization components. This work also includes an estimation method that takes measurement limitations caused by the noise floor and the limited cross-polarization discrimination of the antennas into account using censored samples.
  •  
9.
  • Häger, Christian, 1986, et al. (författare)
  • Constellation Optimization for Coherent Optical Channels Distorted by Nonlinear Phase Noise
  • 2012
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; , s. 2870-2875
  • Konferensbidrag (refereegranskat)abstract
    • We consider the design of amplitude phase-shift keying (APSK) constellations, targeting their application to coherent fiber-optical communications. Phase compensation is used at the receiver to combat nonlinear phase noise caused by the Kerr-effect. We derive the probability density function of the post- compensated observation for multilevel constellations. Optimal APSK constellations in terms of symbol error probability (SEP) are found assuming a two-stage detector. Performance gains of 3.2 dB can be achieved compared to 16-QAM at a SEP of 10^−2. We optimize the number of rings, the number of points per ring, as well as the radius distribution of the constellation. For low to moderate nonlinearities, radius optimization only yields minor improvements over an equidistant spacing of rings. In the highly nonlinear regime, however, a smaller SEP can be achieved by “sacrificing” the outer ring of the constellation, in favor of achieving good SEP in the remaining rings.
  •  
10.
  • Ivanov, Mikhail, 1986, et al. (författare)
  • General BER Expression for One-Dimensional Constellations
  • 2012
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; , s. 2162-2167
  • Konferensbidrag (refereegranskat)abstract
    • A novel general ready-to-use bit-error rate (BER) expression for one-dimensional constellations is developed. The BER analysis is performed for bit patterns that form a labeling. The number of patterns for equally spaced M-PAM constellations with different BER is analyzed.
  •  
11.
  • Jacobsson, Sven, 1990, et al. (författare)
  • Massive MU-MIMO-OFDM Downlink with One-Bit DACs and Linear Precoding
  • 2018
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; 2018-January, s. 1-6
  • Konferensbidrag (refereegranskat)abstract
    • Massive multiuser (MU) multiple-input multiple- output (MIMO) is foreseen to be a key technology in future wireless communication systems. In this paper, we analyze the downlink performance of an orthogonal frequency division multiplexing (OFDM)-based massive MU-MIMO system in which the base station (BS) is equipped with 1-bit digital-to-analog converters (DACs). Using Bussgang’s theorem, we characterize the performance achievable with linear precoders (such as maximal-ratio transmission and zero forcing) in terms of bit error rate (BER). Our analysis accounts for the possibility of oversampling the time-domain transmit signal before the DACs. We further develop a lower bound on the information-theoretic sum-rate throughput achievable with Gaussian inputs.Our results suggest that the performance achievable with 1-bit DACs in a massive MU-MIMO-OFDM downlink are satisfactory provided that the number of BS antennas is sufficiently large.
  •  
12.
  • Keshavarz, Mohammad Hossein, et al. (författare)
  • Optimal QoS-Aware Allocation of Virtual Network Resources to Mixed Mobile-Optical Network Slices
  • 2021
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813.
  • Konferensbidrag (refereegranskat)abstract
    • Slicing allows 5G networks to accommodate services with different needs over a unified physical network infrastructure. Particularly, in radio access networks (RANs), the baseband processing functions of different slices are treated as virtual applications running on shared compute nodes. Managing this cloud-native network in a cost-effective way requires tightly cou-pled control of connectivity and processing resources. This paper proposes an optimization problem to minimize the overall cost while guaranteeing distinct latency and reliability requirements of different network slices deployed over the infrastructure. This is achieved by choosing for each service, the functional split and transmission parameters that best adapt to the connectivity and processing resources available in the infrastructure. Results demonstrate that the proposed flexible resource allocation scheme provides considerable cost saving (up to 2.4 times) and reduced request blocking (up to 2 times) compared to conventional fixed deployment techniques. The reliability requirements can be guaranteed by packet duplication and/or virtualized forward error correction at the expense of consuming connectivity and/or processing resources, respectively. The flexible assurance of the reliability requirements in the proposed scheme contributes considerably to the achieved improvements on cost saving and request blocking.
  •  
13.
  • Khanzadi, M Reza, 1983, et al. (författare)
  • Receiver Algorithm based on Differential Signaling for SIMO Phase Noise Channels with Common and Separate Oscillator Configurations
  • 2015
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479959525
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, a receiver algorithm consisting of differential transmission and a two-stage detection for a single-input multiple-output (SIMO) phase-noise channels is studied. Specifically, the phases of the QAM modulated data symbols are manipulated before transmission in order to make them more immune to the random rotational effects of phase noise. At the receiver, a two-stage detector is implemented, which first detects the amplitude of the transmitted symbols from a nonlinear combination of the received signal amplitudes. Then in the second stage, the detector performs phase detection. The studied signaling method does not require transmission of any known symbols that act as pilots. Furthermore, no phase noise estimator (or a tracker) is needed at the receiver to compensate the effect of phase noise. This considerably reduces the complexity of the receiver structure. Moreover, it is observed that the studied algorithm can be used for the setups where a common local oscillator or separate independent oscillators drive the radio-frequency circuitries connected to each antenna. Due to the differential encoding/decoding of the phase, weighted averaging can be employed at a multi-antenna receiver, allowing for phase noise suppression to leverage the large number of antennas. Hence, we observe that the performance improves by increasing the number of antennas, especially in the separate oscillator case. Further increasing the number of receive antennas results in a performance error floor, which is a function of the quality of the oscillator at the transmitter.
  •  
14.
  • Kumar, Siddhartha, 1991, et al. (författare)
  • A Family of Erasure Correcting Codes with Low Repair Bandwidth and Low Repair Complexity
  • 2015
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479959525
  • Konferensbidrag (refereegranskat)abstract
    • We present the construction of a new family of erasure correcting codes for distributed storage that yield low repair bandwidth and low repair complexity. The construction is based on two classes of parity symbols. The primary goal of the first class of symbols is to provide good erasure correcting capability, while the second class facilitates node repair, reducing the repair bandwidth and the repair complexity. We compare the proposed codes with other codes proposed in the literature.
  •  
15.
  • Lancho Serrano, Alejandro, 1991, et al. (författare)
  • On Joint Detection and Decoding in Short-Packet Communications
  • 2021
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813.
  • Konferensbidrag (refereegranskat)abstract
    • We consider a communication problem in which the receiver must first detect the presence of an information packet and, if detected, decode the message carried within it. We present general nonasymptotic upper and lower bounds on the maximum coding rate that depend on the blocklength, the probability of false alarm, the probability of misdetection, and the packet error probability. The bounds, which are expressed in terms of binary-hypothesis-testing performance metrics, generalize finiteblocklength bounds derived previously for the scenario when a genie informs the receiver whether a packet is present. The bounds apply to detection performed either jointly with decoding on the entire data packet, or separately on a dedicated preamble. The results presented in this paper can be used to determine the blocklength values at which the performance of a communication system is limited by its ability to perform packet detection satisfactorily, and to assess the difference inperformance between preamblebased detection, and joint detection and decoding. Numerical results pertaining to the binary-input AWGN channel are provided.
  •  
16.
  • Li, Jingya, 1986, et al. (författare)
  • I/Q Imbalance in Two-Way AF Relaying: Performance Analysis and Detection Mode Switch
  • 2014
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479935116 ; , s. 4001-4007
  • Konferensbidrag (refereegranskat)abstract
    • This paper studies the impact of in-phase and quadrature-phase imbalance (IQI) in two-way amplify-and-forward (AF) relaying systems. In particular, the effective signal-to-interference-plus-noise ratio (SINR) is derived for each source node, considering four different linear detection schemes, namely, uncompensated (Uncomp) scheme, maximal-ratio-combining (MRC), zero-forcing (ZF) and minimum mean-square error (MMSE) based schemes. For each proposed scheme, the outage probability (OP) is investigated over independent, non-identically distributed Nakagami-m fading channels, and exact closed-form expressions are derived for the first three schemes. Based on the closed-form OP expressions, an adaptive detection mode switching scheme is designed for minimizing the OP of both sources. An important observation is that, regardless of the channel conditions and transmit powers, the ZF-based scheme should always be selected if the target SINR is larger than 3 (4.77 dB), while the MRC-based scheme should be avoided if the target SINR is larger than 0.38 (-4.20 dB).
  •  
17.
  • LINDBERG, CHRISTOPHER, 1988, et al. (författare)
  • Distributed Compressed Sensing for Sensor Networks with Packet Erasures
  • 2014
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479935116 ; , s. 13-19
  • Konferensbidrag (refereegranskat)abstract
    • We study two approaches to distributed compressed sensing for in-network data compression and signal reconstruc- tion at a sink. Communication to the sink is considered to be bandwidth-constrained due to the large number of devices. By using distributed compressed sensing for compression of the data in the network, the communication cost (bandwidth usage) to the sink can be decreased at the expense of delay induced by the local communication. We investigate the relation between cost and delay given a certain reconstruction performance requirement when using basis pursuit denoising for reconstruction. Moreover, we analyze and compare the performance degradation due to erased packets sent to the sink.
  •  
18.
  • Makki, Behrooz, 1980, et al. (författare)
  • Green communication via Type-I ARQ: Finite block-length analysis
  • 2014
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479935116 ; , s. 2673-2677
  • Konferensbidrag (refereegranskat)abstract
    • This paper studies the effect of optimal power allocation on the performance of communication systems utilizing automatic repeat request (ARQ). Considering Type-I ARQ, the problem is cast as the minimization of the outage probability subject to an average power constraint. The analysis is based on some recent results on the achievable rates of finite-length codes and we investigate the effect of codewords length on the performance of ARQ-based systems. We show that the performance of ARQ protocols is (almost) insensitive to the length of the codewords, for codewords of length $\ge 50$ channel uses. Also, optimal power allocation improves the power efficiency of the ARQ-based systems substantially. For instance, consider a Rayleigh fading channel, codewords of rate $1$ nats-per-channel-use and outage probability $10^{-3}.$ Then, with a maximum of 2 and 3 transmissions, the implementation of power-adaptive ARQ reduces the average power, compared to the open-loop communication setup, by 17 and 23 dB, respectively, a result which is (almost) independent of the codewords length. Also, optimal power allocation increases the diversity gain of the ARQ protocols considerably.
  •  
19.
  • Makki, Behrooz, 1980, et al. (författare)
  • On the Performance of HARQ-Based RF-FSO Links
  • 2015
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479959525
  • Konferensbidrag (refereegranskat)abstract
    • This paper studies the performance of the hybridradio-frequency (RF) and free-space optical (FSO) links assuming perfect channel state information (CSI) at the receiver. Considering the cases with and without hybrid automatic repeat request (HARQ), we derive closed-form expressions for the message decoding probabilities as well as the throughput and the outage probability of the RF-FSO setups. We also evaluate the effect of different channel conditions on the throughput and the outageprobability. The results show the efficiency of the RF-FSO links in different conditions.
  •  
20.
  • Maschietti, Flavio, et al. (författare)
  • Robust Location-Aided Beam Alignment in Millimeter Wave Massive MIMO
  • 2017
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; 2018-January, s. 1-6
  • Konferensbidrag (refereegranskat)abstract
    • Location-aided beam alignment has been proposed recently as a potential approach for fast link establishment in millimeter wave (mmWave) massive MIMO (mMIMO) communications. However, due to mobility and other imperfections in the estimation process, the spatial information obtained at the base station (BS) and the user (UE) is likely to be noisy, degrading beam alignment performance. In this paper, we introduce a robust beam alignment framework in order to exhibit resilience with respect to this problem. We first recast beam alignment as a decentralized coordination problem where BS and UE seek coordination on the basis of correlated yet individual position information. We formulate the optimum beam alignment solution as the solution of a Bayesian team decision problem. We then propose a suite of algorithms to approach optimality with reduced complexity. The effectiveness of the robust beam alignment procedure, compared with classical designs, is then verified on simulation settings with varying location information accuracies.
  •  
21.
  • Muppirisetty, Srikar, 1984, et al. (författare)
  • Location-Aided Pilot Contamination Elimination for Massive MIMO Systems
  • 2015
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479959525
  • Konferensbidrag (refereegranskat)abstract
    • Massive MIMO systems, while being a promisingtechnology for 5G systems, face a number of practical challenges. Among those, pilot contamination stands out as a key bottleneck to design high-capacity beamforming methods. We propose and analyze a location-aided approach to reduce the pilot contamination effect in uplink channel estimation for massive MIMO systems. The proposed method exploits the location of user terminals, scatterers, and base stations. The approach removes the need for direct estimation of large covariance matrices and provides good channel estimation performance in the large antenna regime.
  •  
22.
  • Ngo, Khac-Hoang, 1992, et al. (författare)
  • Age of Information in Slotted ALOHA With Energy Harvesting
  • 2023
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; , s. 3579-3584
  • Konferensbidrag (refereegranskat)abstract
    • We examine the age of information (AoI) of a status update system that incorporates energy harvesting and uses the slotted ALOHA protocol. We derive analytically the average AoI and the probability that the AoI exceeds a given threshold. Via numerical results, we investigate two strategies to minimize the age of information (AoI): transmitting a new update whenever possible to exploit every chance to reduce the AoI, and transmitting only when sufficient energy is available to increase the chance of successful delivery. The two strategies are beneficial for low and high update generation rates, respectively. However, an optimized approach that balances the two strategies outperforms them significantly in terms of both AoI and throughput.
  •  
23.
  • Rundstedt, Karl, 1990, et al. (författare)
  • On Field Measurements and Modelling of 2x2 Microwave LOS-MIMO Systems
  • 2015
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479959525
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we present channel measurementsand preliminary analyses from three 2x2 microwave Lineof-Sight Multi-Input Multi-Output (LOS-MIMO) outdoor test links, operating on 8 GHz and 32 GHz. The main focus of the measurement campaign is to study channel conditions and the effects of rain and clear-air fading. First, we address the diverse performance measures used in the trials. In particular we introduce the MIMO phase difference as an additional channel metric to the received power. The MIMO phase difference is mainly determined by antenna positions, ground effects and atmospheric variations. The relation between antenna positions and channel conditions was addressed in a number of earlier works, while the atmospheric impact and the resulting link availability are rarely studied. Second, we present the preliminary results from the long-term measurement campaign. The longterm statistics of channel condition from the three links show stable performance. Analysis reveals that fluctuation of the phase difference and the channel condition number is likely due to abnormal atmospheric propagation which can be modelled using a two-ray reflection model. Meanwhile, rain attenuation is strongly correlated between MIMO sub-channels and its contribution to the long-term statistics of power loss is very close to the Single-Input Single-Output (SISO) case.
  •  
24.
  • Soleimani-Nasab, Ehsan, 1984, et al. (författare)
  • Two-way interference-limited AF relaying over Nakagami-m fading channels
  • 2013
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479913534 ; , s. 4275-4281
  • Konferensbidrag (refereegranskat)abstract
    • We investigate the performance of two-way interference-limited amplify-and-forward relaying systems over independent but non-identically distributed (i.n.i.d.) Nakagami-m fading channels. A tight closed-form lower bound on the outage probability of the system is derived, along with a simplified expression in the asymptotically low outage regime. Some special cases of practical interest (e.g., no interference power and interference-limited case) are also examined. The theoretical and numerical results provide important physical insights into the implications of the model parameters on the system performance. © 2013 IEEE.
  •  
25.
  • Wen, Fuxi, 1982, et al. (författare)
  • Tensor Decomposition Based Beamspace ESPRIT for Millimeter Wave MIMO Channel Estimation
  • 2018
  • Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings. - 2576-6813 .- 2334-0983.
  • Konferensbidrag (refereegranskat)abstract
    • We propose a search-free beamspace tensor-ESPRIT algorithm for millimeter wave MIMO channel estimation. It is a multidimensional generalization of beamspace-ESPRIT method by exploiting the multiple invariance structure of the measurements. Geometry-based channel model is considered to contain the channel sparsity feature. In our framework, an alternating least squares problem is solved for low rank tensor decomposition and the multidimensional parameters are automatically associated. The performance of the proposed algorithm is evaluated by considering different transformation schemes.
  •  
26.
  • Wu, Peng, et al. (författare)
  • V2V-Assisted V2I MmWave Communication for Cooperative Perception with Information Value-Based Relay
  • 2021
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; 2021
  • Konferensbidrag (refereegranskat)abstract
    • Millimeter-wave (mmWave) vehicular communication is a key technology that enables autonomous vehicles to collaborate in environment perception, thereby improving traffic efficiency and safety to a new level. Many recent works have focused on relay-based solutions to overcome the inherent defects of mmWave, such as the severe path loss and its sensitivity to blockages. However, the selfishness of the vehicles is often ignored. Considering the application-oriented nature of vehicular communication, we propose an information value-based relay strategy for mmWave vehicle-to-infrastructure (V2I) transmission in this paper. Specifically, the vehicles are allowed to make relay decisions based on the evaluation of the value of messages from their own perspectives. To this end, a simple relay probability model based on the required awareness range is introduced. Through the use of stochastic geometry to model the vehicular network, the outage performance is analyzed and the results are validated by simulations. Impacts of both network and application related parameters on the outage performance are investigated. These preliminary results laid the foundation for the further expansion of the information value-based relay strategies to a wider range of network settings.
  •  
27.
  • Wu, Yibo, 1996, et al. (författare)
  • Impact of Phase Noise on Uplink Cell-Free Massive MIMO OFDM
  • 2023
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; , s. 5829-5834
  • Konferensbidrag (refereegranskat)abstract
    • Cell-Free massive MIMO networks provide huge power gains and resolve inter-cell interference by coherent processing over a massive number of distributed instead of co-located antennas in access points (APs). Cost-efficient hardware is preferred but imperfect local oscillators in both APs and users introduce multiplicative phase noise (PN), which affects the phase coherence between APs and users even with centralized processing. In this paper, we first formulate the system model of a PN-impaired uplink Cell-Free massive MIMO orthogonal frequency division multiplexing network, and then propose a PN-aware linear minimum mean square error channel estimator and derive a PN-impaired uplink spectral efficiency expression. Numerical results are used to quantify the spectral efficiency gain of the proposed channel estimator over alternative schemes for different receiving combiners.
  •  
28.
  • Wymeersch, Henk, 1976, et al. (författare)
  • 5G mm Wave Downlink Vehicular Positioning
  • 2018
  • Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings. - 2576-6813 .- 2334-0983. - 9781538647271
  • Konferensbidrag (refereegranskat)abstract
    • 5G new radio (NR) provides new opportunities for accurate positioning from a single reference station: large bandwidth combined with multiple antennas, at both the base station and user sides, allows for unparalleled angle and delay resolution. Nevertheless, positioning quality is affected by multipath and clock biases. We study, in terms of performance bounds and algorithms, the ability to localize a vehicle in the presence of multipath and unknown user clock bias. We find that when a sufficient number of paths is present, a vehicle can still be localized thanks to redundancy in the geometric constraints. Moreover, the 5G NR signals enable a vehicle to build up a map of the environment.
  •  
29.
  • Wymeersch, Henk, 1976, et al. (författare)
  • Fundamental Performance Bounds for Carrier Phase Positioning in Cellular Networks
  • 2023
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; , s. 7478-7483
  • Konferensbidrag (refereegranskat)abstract
    • The carrier phase of cellular signals can be utilized for highly accurate positioning, with the potential for orders-of-magnitude performance improvements compared to standard time-difference-of-arrival positioning. Due to the integer ambiguities, standard performance evaluation tools such as the Cramér-Rao bound (CRB) are overly optimistic. In this paper, a new performance bound, called the mixed-integer CRB (MICRB) is introduced that explicitly accounts for this integer ambiguity. While computationally more complex than the standard CRB, the MICRB can accurately predict positioning performance, as verified by numerical simulations, and hence it serves as a useful guide to choose the system parameters that facilitate carrier phase positioning.
  •  
30.
  • Zhang, Q., et al. (författare)
  • Power scaling of massive MIMO systems with arbitrary-rank channel means and imperfect CSI
  • 2013
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479913534 ; , s. 4157-4162
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we study the achievable uplink rates of massive multiple-input multiple-output (MIMO) systems using maximal-ratio combining (MRC) and zero-forcing (ZF) receivers, assuming imperfect channel state information (CSI). Unlike all previous studies, the fast fading MIMO channel matrix here is modeled to have an arbitrary-rank deterministic component as well as a Rayleigh-distributed random component. In particular, it is found that with a non-zero Ricean K-factor, the approximations and the exact uplink rates converge to the same constant value if the number of base station antennas, M, grows large, while the transmit power of each user is scaled down proportionally to 1/M. However, if the channel is Rayleigh fading, we can only cut the transmit power of each user proportionally to 1/√M. In addition, we show that with increasing Ricean K-factor, the uplink rates will converge to fixed values for both MRC and ZF receivers. © 2013 IEEE.
  •  
31.
  • Zhao, Juzi, 1986, et al. (författare)
  • QoT- and SLA-aware Survivable Resource Allocation in Translucent Optical Networks
  • 2015
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479959525
  • Konferensbidrag (refereegranskat)abstract
    • Survivability is a critical issue in high-capacity wavelength division multiplexing based optical networks, since even a disruption for a very short time could result in the loss of a large amount of data. Each accepted connection request brings revenue to the network. On the other hand, a service level agreement (SLA) requirement (e.g., 99.9% uptime in terms of availability) is associated with a connection, and a penalty is paid if the requirement is violated. In addition, physical impairments degrade the quality of signals as they traverse along lightpaths. In this paper, the survivable routing and wavelength assignment problem is studied for dynamic traffic in translucent optical networks considering randomly occurring failures of optical fibers and nodes, so that the quality of transmission (QoT) requirement of each connection is satisfied, and the network-level performance metric of total profit is maximized. Two heuristics are developed - the first one aims to allocate resources to each connection to minimize the expected penalty; while the other heuristic prefers to allocate the minimum possible resources to each connection. Simulation results are presented to demonstrate their effectiveness.
  •  
32.
  •  
33.
  • Zou, Y., et al. (författare)
  • Sequential Hybrid Beamforming Design for Multi-Link mmWave Communication
  • 2017
  • Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; 2018-January
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we propose a sequential hybrid beamforming design for multi-link transmission over mmwave frequency bands. As a starting point, a baseline data communication link is established via traditional analog beamforming at both the BS and UE. If an extra RF chain is available at the UE, it can continue to probe the propagation environment at the same frequencies. In case the environment is favorable and system resources allow, a secondary data communication link is established to enable multi-stream transmission. In principle, the secondary link could be served by the same BS and/or one or several other BS(s). To initialize the secondary data communication link, a parallel beam search scheme is proposed, which helps the UE/BS to find a suit-able beam pair with given optimization criteria without interrupting the baseline data communication. By applying the proposed two-step approach, hybrid beamforming becomes an add-on feature that can be easily switched on over an analog beamforming enabled system without interrupting its operation whenever system requires. Meanwhile, the information obtained by deploying the proposed parallel beam search scheme can also be used for deciding a back-up beam pair if signal blockage occurs to the baseline data communication link.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-33 av 33

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy