Secure Transmission Scheme for Blocks in Blockchain-Based Unmanned Aerial Vehicle Communication Systems

In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is also affected by the block length.Therefore,it is crucial to balance the transmission performance and blockchain performance of blockchain communication systems,especially in wireless environments involving UAVs.This paper investigates a secure transmission scheme for blocks in blockchain-based UAV communication systems to prevent the information contained in blocks from being completely eavesdropped during transmission.In our scheme,using a friendly jamming UAV to emit jamming signals diminishes the quality of the eavesdropping channel,thus enhancing the communication security performance of the source UAV.Under the constraints of maneuverability and transmission power of the UAV,the joint design of UAV trajectories,transmission power,and block length are proposed to maximize the average minimum secrecy rate(AMSR).Since the optimization problem is non-convex and difficult to solve directly,we first decompose the optimization problem into subproblems of trajectory optimization,transmission power optimization,and block length optimization.Then,based on firstorder approximation techniques,these subproblems are reformulated as convex optimization problems.Finally,we utilize an alternating iteration algorithm based on the successive convex approximation(SCA)technique to solve these subproblems iteratively.The simulation results demonstrate that our proposed scheme can achieve secure transmission for blocks while maintaining the performance of the blockchain.

Spatial-Modulated Physical-Layer Network Coding Based on Block Markov Superposition Transmission for Maritime Relay Communications

As an alternative to satellite communications,multi-hop relay networks can be deployed for maritime long-distance communications.Distinct from terrestrial environment,marine radio signals are affected by many factors,e.g.,weather conditions,evaporation ducting,and ship rocking caused by waves.To ensure the data transmission reliability,the block Markov superposition transmission(BMST)codes,which are easily configurable and have predictable performance,are applied in this study.Meanwhile,the physical-layer network coding(PNC)scheme with spatial modulation(SM)is adopted to improve the spectrum utilization.For the BMST-SMPNC system,we propose an iterative algorithm,which utilizes the channel observations and the a priori information from BMST decoder,to compute the soft information corresponding to the XORed bits constructed by the relay node.The results indicate that the proposed scheme outperforms the convolutional coded SM-PNC over fast-fading Rician channels.Especially,the performance can be easily improved in high spatial correlation maritime channel by increasing the memory m.

Generalized Block Markov Superposition Transmission over Free-Space Optical Links

In free-space optical(FSO) communications, the performance of the communication systems is severely degraded by atmospheric turbulence. Channel coding and diversity techniques are commonly used to combat channel fading induced by atmospheric turbulence. In this paper, we present the generalized block Markov superposition transmission(GBMST) of repetition codes to improve time diversity. In the GBMST scheme, information sub-blocks are transmitted in the block Markov superposition manner, with possibly different transmission memories. Based on analyzing an equivalent system, a lower bound on the bit-error-rate(BER) of the proposed scheme is presented. Simulation results demonstrate that, under a wide range of turbulence conditions, the proposed scheme improves diversity gain with only a slight reduction of transmission rate. In particular, with encoding memory sequence(0, 0, 8) and transmission rate 1/3, a diversity order of eleven is achieved under moderate turbulence conditions. Numerical results also show that, the GBMST systems with appropriate settings can approach the derived lower bound, implying that full diversity is achievable.

Spatially Coupled Codes via Bidirectional Block Markov Superposition Transmission

In this paper,we present a new class of spatially coupled codes obtained by using both non-recursive and recursive block-oriented superposition.The resulting codes are termed as bidirectional block Markov superposition transmission(BiBMST)codes.Firstly,we perform an iterative decoding threshold analysis according to protograph-based extrinsic information transfer(PEXIT)charts for the BiBMST codes over the binary erasure channels(BECs).Secondly,we derive the generator and parity-check matrices of the BiBMST codes.Thirdly,extensive numerical results are presented to show the advantages of the proposed BiBMST codes.Particularly,our numerical results show that,under the constraint of an equal decoding latency,the BiBMST codes perform better than the recursive BMST(rBMST)codes.However,the simulation results show that,in finite-length regime,negligible performance gain is obtained by increasing the encoding memory.We solve this limitation by introducing partial superposition,and the resulting codes are termed as partially-connected BiBMST(PC-BiBMST)code.Analytical results have confirmed the advantages of the PC-BiBMST codes over the original BiBMST codes.We also present extensive simulation results to show the performance advantages of the PC-BiBMST codes over the spatially coupled low-density parity-check(SC-LDPC)codes,spatially coupled generalized LDPC(SC-GLDPC)codes,and the original BiBMST codes in the finite-length regime.

Deterministic Secure Quantum Communication with Cluster State and Bell-Basis Measurements

We present a novel protocol for deterministic secure quantum communication by using the lour-qubit cluster state as quantum channel. It is shown that two legitimate users can directly transmit the secret messages based on Bellbasis measurements and classical communication. The present protocol makes use of the ideas of block transmission and decoy particle checking technique. It has a high capacity as each cluster state can carry two 5its of information, and has a high intrinsic efficieney 5ecause almost all the instances except the decoy checking particles （its numSer is negligible） are useful. Furthermore, this protocol is feasible with present-day technique.

Analytical model for describing ion guiding through capillaries in insulating polymers

An analytical description for guiding of ions through nanocapillaries is given on the basis of previous work. The current entering into the capillary is assumed to be divided into a current fraction transmitted through the capillary, a current fraction flowing away via the capillary conductivity and a current fraction remaining within the capillary, which is responsible for its charge-up. The discharging current is assumed to be governed by the Frenkel–Poole process. At higher conductivities the analytical model shows a blocking of the ion transmission, which is in agreement with recent simulations.Also, it is shown that ion blocking observed in experiments is well reproduced by the analytical formula. Furthermore, the asymptotic fraction of transmitted ions is determined. Apart from the key controlling parameter(charge-to-energy ratio), the ratio of the capillary conductivity to the incident current is included in the model. Differences resulting from the nonlinear and linear limits of the Frenkel–Poole discharge are pointed out.

LLR calculation for LDPC coded SCBT in 60 GHz WPAN

The single-carrier block transmission（SCBT）,a.k.a.,single-carrier frequency-domain equalization（SC-FDE）,is being considered as an option technique for the wireless personal area network（WPAN） operating at 60 GHz.It is found that for residential environment,in non-line-of-sight（NLOS） multi-path channels,the SCBT is much more effective to combat the inter-symbol interference（ISI） compared with orthogonal frequency division multiplexing（OFDM）.Low-density parity-check（LDPC） codes are a class of linear block codes which provide near capacity performance on a large collection of data transmission and storage channels while simultaneously admitting implementable decoders.To facilitate using LDPC codes for SCBT system,a new log-likelihood ratio（LLR） calculation method is proposed based on pilot symbols（PS）.Golay Sequences whose sum autocorrelation has a unique peak and zero sidelobe are used for creating the PS.The position and length of the PS are not fixed in the data blocks.The simulation results show that the proposed method can significantly improve the LDPC decoding performance in SCBT system.This is very promising to support ultra high-data-rate wireless transmission.

Mitigation of spectral leakage for single carrier, block-processing cognitive radio receivers

Cognitive Radio （CR） is a multiuser, wireless communication concept that allows for a dynamic and adaptive assignment of spectral resources. The coexistence of multiple users, often transmitting at significantly different power levels, makes CR receivers vulnerable to spectral leakage caused by components＇ nonlinearities and timetruncation of the processed signal records. In this work we propose a method for mitigating the latter with an adaptive choice of the length of the processing block size. With simulations we show that a significant leakage reduction that leads to receiver dynamic range improvement of around 10 dB can be achieved with the proposed method.

Block Markov superposition transmission of LDPC codes

In this paper,based on the block Markov superposition transmission(BMST)technique,we present a new class of coupled low-density parity-check(LDPC)codes for the transport block(TB)-based transmission to improve the error-correcting performance.For encoding,the previous LDPC codewords corresponding to a TB(at prior time slot)are interleaved and superimposed onto the current LDPC codewords,resulting in the transmitted codewords.For decoding,the sliding window decoding algorithm with sum-product or min-sum implementations can be employed,inheriting a relatively low-latency decoding.A distinguished advantage of the proposed coded transmission over spatially coupled LDPC(SC-LDPC)codes is that the encoder/decoder of the proposed codes can be designed by reusing the encoder/decoder architecture of component block LDPC codes.To analyze the waterfall performance of BMST-LDPC code ensembles,we present the protograph-based EXIT chart analysis,which can efficiently predict the error-correcting performance in waterfall region.To analyze the error-floor performance of BMST-LDPC codes,we employ the genie-aided(GA)lower bound,which can efficiently predict the error-correcting performance in error-floor region.For ease of implementation,the BMST-LDPC codes are constructed by taking the(2,4)-raptor-like LDPC codes or the 5G LDPC codes as the basic components.The numerical results reveal that the proposed codes can have capacity-approaching performance,exhibiting a gap of 0.007 dB away from the corresponding Shannon limit.They also reveal that,by using the proposed BMST construction,the error-correcting performance of the original 5G block LDPC codes can be significantly improved,achieving coding gains up to one dB over the AWGN channels and two dB over the fast fading channels.

Improving Performance of LDPC-Coded Links via Partial Superposition Retransmission

In this paper,we propose a transmission scheme for uplink and downlink transmissions,where the fifth generation(5G)low-density parity-check(LDPC)codes are implemented for error correction.In the proposed scheme,the acknowledgment(ACK)or negative acknowledgment(NACK)feedback information is transmitted along with the payload data by cyclically shifting coded sequence,while the re-transmitted codewords are superimposed(XORed)partially on the current codewords.The distinguished feature of the proposed transmission scheme is that it requires neither extra transmission bandwidth nor extra transmission power.We also propose to truncate the error patterns for the purpose of reducing the implementation complexity and reducing the error propagation.Numerical results show that the proposed scheme significantly outperforms conventional LDPC-coded transmission.For the 5G LDPC code with length 1920 at the signal-to-noise ratio(SNR)of 1.3 dB,the word error rate(WER)of the data transmitted by the proposed scheme is about 10^(−4),while that of the conventional LDPC-coded transmission is about 10^(−2).

Experimental quantum secure direct communication with single photons

Quantum secure direct communication is an important mode of quantum communication in which secret messages are securely communicated directly over a quantum channel.Quantum secure direct communication is also a basic cryptographic primitive for constructing other quantum communication tasks,such as quantum authentication and quantum dialog.Here,we report the first experimental demonstration of quantum secure direct communication based on the DL04 protocol and equipped with single-photon frequency coding that explicitly demonstrated block transmission.In our experiment,we provided 16 different frequency channels,equivalent to a nibble of four-bit binary numbers for direct information transmission.The experiment firmly demonstrated the feasibility of quantum secure direct communication in the presence of noise and loss.

Role of ecological approaches to eliminating schistosomiasis in Eryuan County evaluated by system modelling

Background:Schistosomiasis was severely prevalent in Yunnan Province,and it is difficult to achieve its elimination by convention approaches due to complexity of the nature.We explored the comprehensive model to eliminate schistosomiasis in Eryuan County,Yunnan Province,the People’s Republic of China,through integration with the ecological protection programme in Erhai Lake,in order to promote an efficient elimination strategy.We expected that this model is able to be tailored to other local settings,which help achieve the goal of precisely eliminating the disease in Yunnan Province.Methods:Eryuan County of Yunnan Province was chosen as the study area,where the data on environmental protection activities in Erhai Lake and on the schistosomiasis control programme were collected through different departments of Erhai County government since 2015.System modelling was performed using system dynamics software to establish a simulation model in order to evaluate the effectiveness of intervention activities.Results:Ecological approaches to control schistosomiasis in Eryuan County consist of three major components:(i)implementing precise interventions to stop schistosomiasis transmission by means of controlling the source of infection,blocking the biological transmission chains and cutting off the route of disease transmission;(ii)employing ecological approaches to improve the co-effectiveness of environmental protection and schistosomiasis prevention in the study area;and(iii)strengthening the professional skills of personnel involving in the schistosomiasis control programme.Simulation results showed that this strategy could speed up the progress of schistosomiasis control programme moving from the control stage to the elimination stage.Conclusions:Ecological approaches implemented in schistosomiasis endemic areas of the Eryuan region are able to improve the co-effectiveness of environmental protection and schistosomiasis control,providing a new avenue for eliminating schistosomiasis thanks to the application of precise interventions.