arXiv subjects

T. Peng

Publications and source records attributed to T. Peng.

11 recordsLinked to original sources

arXiv2026

Laser-intensity-spike-dominated hot electron generation from two-plasmon decay instability driven by moderate-bandwidth pulses

Our direct-drive-relevant experiments on the low-coherence Kunwu laser facility identify two-plasmon decay (TPD) as the primary source of hot electrons, and demonstrate for the first time that broadband laser pulses enhance TPD. Using particle-in-cell simulations, we attribute this TPD enhancement and the consequent hot electron production to stochastic intensity spikes inherent in broadband laser fields, robust in both weakly- and strongly-driven regimes. These findings suggest that mitigating hot electron generation requires suppressing these intensity spikes.

physics.plasm-ph↗

arXiv2022

A multi-cubic-kilometre neutrino telescope in the western Pacific Ocean

Next-generation neutrino telescopes with significantly improved sensitivity are required to pinpoint the sources of the diffuse astrophysical neutrino flux detected by IceCube and uncover the century-old puzzle of cosmic ray origins. A detector near the equator will provide a unique viewpoint of the neutrino sky, complementing IceCube and other neutrino telescopes in the Northern Hemisphere. Here we present results from an expedition to the north-eastern region of the South China Sea, in the western Pacific Ocean. A favorable neutrino telescope site was found on an abyssal plain at a depth of $\sim$ 3.5km. At depths below 3km, the sea current speed, water absorption and scattering lengths for Cherenkov light, were measured to be $v_{\mathrm{c}}<$10cm/s, $\lambda_{\mathrm{abs} }\simeq$ 27m and $\lambda_{\mathrm{sca} }\simeq$ 63m, respectively. Accounting for these measurements, we present the design and expected performance of a next-generation neutrino telescope, TRopIcal DEep-sea Neutrino Telescope (TRIDENT). With its advanced photon-detection technology and large dimensions, TRIDENT expects to observe the IceCube steady source candidate NGC 1068 with 5$\sigma$ significance within 1 year of operation. This level of sensitivity will open a new arena for diagnosing the origin of cosmic rays and probing fundamental physics over astronomical baselines.

astro-ph.HE↗

arXiv2016

Study of Buffer-Aided Distributed Space-Time Coding for Cooperative Wireless Networks

This work proposes adaptive buffer-aided distributed space-time coding schemes and algorithms with feedback for wireless networks equipped with buffer-aided relays. The proposed schemes employ a maximum likelihood receiver at the destination and adjustable codes subject to a power constraint with an amplify-and-forward cooperative strategy at the relays. Each relay is equipped with a buffer and is capable of storing blocks of received symbols and forwarding the data to the destination if selected. Different antenna configurations and wireless channels, such as static block fading channels, are considered. The effects of using buffer-aided relays to improve the bit error rate (BER) performance are also studied. Adjustable relay selection and optimization algorithms that exploit the extra degrees of freedom of relays equipped with buffers are developed to improve the BER performance. We also analyze the pairwise error probability and diversity of the system when using the proposed schemes and algorithms in a cooperative network. Simulation results show that the proposed schemes and algorithms obtain performance gains over previously reported techniques.

cs.IT↗

arXiv2015

Study of Buffer-Aided Space-Time Coding for Multiple-Antenna Cooperative Wireless Networks

In this work we propose an adaptive buffer-aided space-time coding scheme for cooperative wireless networks. A maximum likelihood receiver and adjustable code vectors are considered subject to a power constraint with an amplify-and-forward cooperation strategy. Each multiple-antenna relay is equipped with a buffer and is capable of storing the received symbols before forwarding them to the destination. We also present an adaptive relay selection and optimization algorithm, in which the instantaneous signal to noise ratio in each link is calculated and compared at the destination. An adjustable code vector obtained by a feedback channel at each relay is employed to form a space-time coded vector which achieves a higher coding gain than standard schemes. A stochastic gradient algorithm is developed to compute the parameters of the adjustable code vector with reduced computational complexity. Simulation results show that the proposed buffer-aided scheme and algorithm obtain performance gains over existing schemes.

cs.IT↗

arXiv2014

Adaptive Delay-Tolerant DSTBC in Opportunistic Relaying Cooperative MIMO Systems

An adaptive delay-tolerant distributed space-time coding (DSTC) scheme with feedback is proposed for two-hop cooperative multiple-input multiple-output (MIMO) networks using an amplify-and-forward strategy and opportunistic relaying algorithms. Maximum likelihood receivers and adjustable code matrices are considered subject to a power constraint. In the proposed delay-tolerant DSTC scheme, an adjustable code matrix is employed to transform the space-time coded matrices at the relay nodes. Stochastic gradient algorithms are developed with reduced computational complexity to estimate the parameters of the code matrix. Simulation results show that the proposed algorithms obtain significant performance gains and address the delay issue in cooperative MIMO systems as compared to existing DSTC schemes.

cs.IT↗

arXiv2014

Measurements of the masses and widths of the $Σ_{c}(2455)^{0/++}$ and $Σ_{c}(2520)^{0/++}$ baryons

We present measurements of the masses and decay widths of the baryonic states $Σ_{c}(2455)^{0/++}$ and $Σ_{c}(2520)^{0/++}$ using a data sample corresponding to an integrated luminosity of 711 fb$^{-1}$ collected with the Belle detector at the KEKB $e^{+}e^{-}$ asymmetric-energy collider operating at the $Υ(4S)$ resonance. We report the mass differences with respect to the $Λ_{c}^{+}$ baryon $M(Σ_{c}(2455)^{0})-M(Λ_{c}^{+}) = 167.29\pm0.01\pm0.02$ MeV/$c^{2}$, $M(Σ_{c}(2455)^{++})-M(Λ_{c}^{+}) = 167.51\pm0.01\pm0.02$ MeV/$c^{2}$, $M(Σ_{c}(2520)^{0})-M(Λ_{c}^{+}) = 231.98\pm0.11\pm0.04$ MeV/$c^{2}$, $M(Σ_{c}(2520)^{++})-M(Λ_{c}^{+}) = 231.99\pm0.10\pm0.02$ MeV/$c^{2}$, and the decay widths $Γ(Σ_{c}(2455)^{0}) = 1.76\pm0.04^{+0.09}_{-0.21}$ MeV/$c^{2}$, $Γ(Σ_{c}(2455)^{++}) = 1.84\pm0.04^{+0.07}_{-0.20}$ MeV/$c^{2}$, $Γ(Σ_{c}(2520)^{0}) = 15.41\pm0.41^{+0.20}_{-0.32}$ MeV/$c^{2}$, $Γ(Σ_{c}(2520)^{++}) = 14.77\pm0.25^{+0.18}_{-0.30}$ MeV/$c^{2}$, where the first uncertainties are statistical and the second are systematic. The isospin mass splittings are measured to be $M(Σ_{c}(2455)^{++})-M(Σ_{c}(2455)^{0})=0.22\pm0.01\pm0.01$ MeV/$c^{2}$ and $M(Σ_{c}(2520)^{++})-M(Σ_{c}(2520)^{0})=0.01\pm0.15\pm0.03$ MeV/$c^{2}$. These results are the most precise to date.

hep-ex↗

arXiv2014

Adaptive Power Allocation Strategies using DSTC in Cooperative MIMO Networks

Adaptive Power Allocation (PA) algorithms with different criteria for a cooperative Multiple-Input Multiple-Output (MIMO) network equipped with Distributed Space-Time Coding (DSTC) are proposed and evaluated. Joint constrained optimization algorithms to determine the power allocation parameters, the channel parameters and the receive filter are proposed for each transmitted stream in each link. Linear receive filter and maximum-likelihood (ML) detection are considered with Amplify-and-Forward (AF) and Decode-and-Forward (DF) cooperation strategies. In the proposed algorithms, the elements in the PA matrices are optimized at the destination node and then transmitted back to the relay nodes via a feedback channel. The effects of the feedback errors are considered. Linear MMSE expressions and the PA matrices depend on each other and are updated iteratively. Stochastic gradient (SG) algorithms are developed with reduced computational complexity. Simulation results show that the proposed algorithms obtain significant performance gains as compared to existing power allocation schemes.

cs.IT↗

arXiv2013

Distributed Space-Time Coding Based on Adjustable Code Matrices for Cooperative MIMO Relaying Systems

An adaptive distributed space-time coding (DSTC) scheme is proposed for two-hop cooperative MIMO networks. Linear minimum mean square error (MMSE) receive filters and adjustable code matrices are considered subject to a power constraint with an amplify-and-forward (AF) cooperation strategy. In the proposed adaptive DSTC scheme, an adjustable code matrix obtained by a feedback channel is employed to transform the space-time coded matrix at the relay node. The effects of the limited feedback and the feedback errors are assessed. Linear MMSE expressions are devised to compute the parameters of the adjustable code matrix and the linear receive filters. Stochastic gradient (SG) and least-squares (LS) algorithms are also developed with reduced computational complexity. An upper bound on the pairwise error probability analysis is derived and indicates the advantage of employing the adjustable code matrices at the relay nodes. An alternative optimization algorithm for the adaptive DSTC scheme is also derived in order to eliminate the need for the feedback. The algorithm provides a fully distributed scheme for the adaptive DSTC at the relay node based on the minimization of the error probability. Simulation results show that the proposed algorithms obtain significant performance gains as compared to existing DSTC schemes.

cs.IT↗

arXiv2013

Adaptive Randomized Distributed Space-Time Coding in Cooperative MIMO Relay Systems

An adaptive randomized distributed space-time coding (DSTC) scheme and algorithms are proposed for two-hop cooperative MIMO networks. Linear minimum mean square error (MMSE) receivers and an amplify-and-forward (AF) cooperation strategy are considered. In the proposed DSTC scheme, a randomized matrix obtained by a feedback channel is employed to transform the space-time coded matrix at the relay node. Linear MMSE expressions are devised to compute the parameters of the adaptive randomized matrix and the linear receive filter. A stochastic gradient algorithm is also developed to compute the parameters of the adaptive randomized matrix with reduced computational complexity. We also derive the upper bound of the error probability of a cooperative MIMO system employing the randomized space-time coding scheme first. The simulation results show that the proposed algorithms obtain significant performance gains as compared to existing DSTC schemes.

cs.IT↗

arXiv2013

Adaptive Distributed Space-Time Coding in Cooperative MIMO Relaying Systems using Limited Feedback

An adaptive randomized distributed space-time coding (DSTC) scheme is proposed for two-hop cooperative MIMO networks. Linear minimum mean square error (MMSE) receiver filters and randomized matrices subject to a power constraint are considered with an amplify-and-forward (AF) cooperation strategy. In the proposed DSTC scheme, a randomized matrix obtained by a feedback channel is employed to transform the space-time coded matrix at the relay node. The effect of the limited feedback and feedback errors are considered. Linear MMSE expressions are devised to compute the parameters of the adaptive randomized matrix and the linear receive filters. A stochastic gradient algorithm is also developed with reduced computational complexity. The simulation results show that the proposed algorithms obtain significant performance gains as compared to existing DSTC schemes.

cs.IT↗

arXiv2013

Joint Power Adjustment and Receiver Design for Distributed Space-Time Coded in Cooperative MIMO Systems

In this paper, a joint power allocation algorithm with minimum mean-squared error (MMSE) receiver for a cooperative Multiple-Input and Multiple-Output (MIMO) network which employs multiple relays and a Decode-and-Forward (DF) strategy is proposed. A Distributed Space-Time Coding (DSTC) scheme is applied in each relay node. We present a joint constrained optimization algorithm to determine the power allocation parameters and the MMSE receive filter parameter vectors for each transmitted symbol in each link, as well as the channel coefficients matrix. A Stochastic Gradient (SG) algorithm is derived for the calculation of the joint optimization in order to release the receiver from the massive calculation complexity for the MMSE receive filter and power allocation parameters. The simulation results indicate that the proposed algorithm obtains gains compared to the equal power allocation system.

cs.IT↗