Layered Coded Cache Placement and Cooperative Delivery with Sharing Links in Satellite-Terrestrial Integrated Networks

Cooperative utilization of multidimensional resources including cache, power and spectrum in satellite-terrestrial integrated networks(STINs) can provide a feasible approach for massive streaming media content delivery over the seamless global coverage area. However, the on-board supportable resources of a single satellite are extremely limited and lack of interaction with others. In this paper, we design a network model with two-layered cache deployment, i.e., satellite layer and ground base station layer, and two types of sharing links, i.e., terrestrial-satellite sharing(TSS) links and inter-satellite sharing(ISS) links, to enhance the capability of cooperative delivery over STINs. Thus, we use rateless codes for the content divided-packet transmission, and derive the total energy efficiency(EE) in the whole transmission procedure, which is defined as the ratio of traffic offloading and energy consumption. We formulate two optimization problems about maximizing EE in different sharing scenarios(only TSS and TSS-ISS),and propose two optimized algorithms to obtain the optimal content placement matrixes, respectively.Simulation results demonstrate that, enabling sharing links with optimized cache placement have more than 2 times improvement of EE performance than other traditional placement schemes. Particularly, TSS-ISS schemes have the higher EE performance than only TSS schemes under the conditions of enough number of satellites and smaller inter-satellite distances.

An Energy-Efficient Network Coded Cooperation Scheme in Wireless Sensor Networks

Energy-efficient communications is crucial for wireless sensor networks(WSN) where energy consumption is constrained. The transmission and reception energy can be saved by applying network coding to many wireless communications systems. In this paper,we present a coded cooperation scheme which employs network coding to WSN. In the scheme,the partner node forwards the combination of the source data and its own data instead of sending the source data alone. Afterward,both of the system block error rates(BLERs) and energy performance are evaluated. Experiment results show that the proposed scheme has higher energy efficiency. When Noise power spectral density is-171dBm/Hz,the energy consumption of the coded cooperation scheme is 81.1% lower than that of the single-path scheme,43.9% lower than that of the cooperation scheme to reach the target average BLER of 10-2. When the channel condition is getting worse,the energy saving effect is more obvious.

Complex field network-coded cooperation based on multi-user detection in wireless networks

Cooperative communication can achieve spatial diversity gains,and consequently combats signal fading due to multipath propagation in wireless networks powerfully.A novel complex field network-coded cooperation（CFNCC） scheme based on multi-user detection for the multiple unicast transmission is proposed.Theoretic analysis and simulation results demonstrate that,compared with the conventional cooperation（CC） scheme and network-coded cooperation（NCC） scheme,CFNCC would obtain higher network throughput and consumes less time slots.Moreover,a further investigation is made for the symbol error probability（SEP） performance of CFNCC scheme,and SEPs of CFNCC scheme are compared with those of NCC scheme in various scenarios for different signal to noise ratio（SNR） values.

JOINT ITERATIVE DECODING FOR SIMPLE-ENCODING SYSTEMATIC IRREGULAR-LDPC-BASED CODED COOPERATION IN NON-IDEAL RELAY CHANNEL

In this paper, a new kind of simple-encoding irregular systematic LDPC codes suitable for one-relay coded cooperation is designed, where the proposed joint iterative decoding is effectively performed in the destination which is in accordance with the corresponding joint Tanner graph characterizing two different component LDPC codes used by the source and relay in ideal and non-ideal relay cooperations. The theoretical analysis and simulations show that the coded cooperation scheme obviously outperforms the coded non-cooperation one under the same code rate and decoding complex. The significant performance improvement can be virtually credited to the additional mutual exchange of the extrinsic information resulted by the LDPC code employed by the source and its counterpart used by the relay in both ideal and non-ideal cooperations.

V-BLAST BASED LDPC-CODED RELAY COOPERATION

An efficient LDPC-coded multi-relay cooperation architecture is proposed based on virtual vertical Bell Labs layered space-time （V-BLAST） processing for uplink communication, where minimum-mean-square-error （MMSE） and BP-based joint iterative decoding based on the introduced muhi-layer Tanner graph are effectively de- signed to detect and decode the corrupted received sequence at the destination. By introducing V-BLAST transmis- sion to the coded multi-relay cooperation, relays send their streams of symbols simultaneously, which increases the data rate and significantly reduces the transmission delay. The theoretical analysis and numerical results show that the new LDPC coded cooperation scheme outperforms the coded non-cooperation under the same code rate, and it also achieves a good trade-off among the performance, signal delay, and the encoding complexity associated with the number of relays. The performance gain can be credited to the proposed V-BLAST processing architecture and BP-based joint iterative decoding by the introduced multi-layer Tanner graph at a receiver-side.

Power auction and allocation for network-coded cooperation

Optimal resource allocation is critical to the efficiency of cooperative communiCations. In this paper, we develop an auction-based power allocation mechanism for network-coded cooperation in wireless networks, in which the sources compete for the relay power for maximum utility, while the relay node assigns the resource in accordance with the bids from the sources. Moreover, to improve the resource utilization, the relay node is allowed to perform network coding across the received information for the same destination. Finally, numerical results validate the performance of the proposed algorithm, and show that there exists a tradeoff between the system outage probability and the power consumed at the relay node.

SR-DCSK Cooperative Communication System with Code Index Modulation:A New Design for 6G New Radios

This paper proposes a high-throughput short reference differential chaos shift keying cooperative communication system with the aid of code index modulation,referred to as CIM-SR-DCSK-CC system.In the proposed CIM-SR-DCSK-CC system,the source transmits information bits to both the relay and destination in the first time slot,while the relay not only forwards the source information bits but also sends new information bits to the destination in the second time slot.To be specific,the relay employs an N-order Walsh code to carry additional log_(2)N information bits,which are superimposed onto the SRDCSK signal carrying the decoded source information bits.Subsequently,the superimposed signal carrying both the source and relay information bits is transmitted to the destination.Moreover,the theoretical bit error rate(BER)expressions of the proposed CIMSR-DCSK-CC system are derived over additive white Gaussian noise(AWGN)and multipath Rayleigh fading channels.Compared with the conventional DCSKCC system and SR-DCSK-CC system,the proposed CIM-SR-DCSK-CC system can significantly improve the throughput without deteriorating any BER performance.As a consequence,the proposed system is very promising for the applications of the 6G-enabled lowpower and high-rate communication.

Joint Iterative Decoding for Network-Coding-Based Multisource LDPC-Coded Cooperative MIMO

A network-coding-based multisource LDPC-coded cooperative MIMO scheme is proposed,where multiple sources transmit their messages to the destination with the assistance from a single relay.The relay cooperates with multiple sources simultaneously via network-coding.It avoids the issues of imperfect frequency/timing synchronization and large transmission delay which may be introduced by frequency-division multiple access(FDMA)/code-division multiple access(CDMA)and time-division multiple access(TDMA)manners.The proposed joint″Min-Sum″iterative decoding is effectively carried out in the destination.Such a decoding algorithm agrees with the introduced equivalent joint Tanner graph which can be used to fully characterize LDPC codes employed by the sources and relay.Theoretical analysis and numerical simulation show that the proposed scheme with joint iterative decoding can achieve significant cooperation diversity gain.Furthermore,for the relay,compared with the cascade scheme,the proposed scheme has much lower complexity of LDPC-encoding and is easier to be implemented in the hardware with similar bit error rate(BER)performance.

Iterative Noncoherent Block Detection of Coded MPSK for Cooperative Relay Systems

Maximum likelihood(ML) noncoherent block detection techniques are investigated for block-coded MPSK modulation in cooperative decode-and-forward relay systems over slow fading channels.A decision-directed iterative Viterbi algorithm(IVA) is derived for a suboptimal ML noncoherent detection.Simulation results show that the IVA can approach the error performances of the exhaustive detection method but at a lower complexity.

China Maritime Industry Seeking Cooperation——An Interview with Li Kejun President of CCS (extract)

Reporter: Presently, China’s shipbuilding is the world No. 3 and its fleet size the world No.5.China has become a large shipping country and is striding toward a strong shipping power. Whatdo you think are the decisive factors that lead to such great achievements in China’s maritimeindustry?

子宫动脉超声血流参数、血清LncRNA FAM99A、CCL21水平与妊娠期高血压疾病患者病情程度及预后的相关性分析

目的:探讨妊娠期高血压疾病(hypertensive disorders of pregnancy,HDP)患者子宫动脉超声血流参数、血清长链非编码RNA家族成员A序列相似性99(LncRNA FAM99A)、CC趋化因子配体21(CCL21)水平变化,并分析其与病情程度相关性及其对预后的评估价值。方法:回顾性选取2021年1月至2023年12月于开封市第三人民医院诊治的126例HDP患者作为研究组,另选取健康孕产妇42例作为对照组。比较两组不同病情程度者子宫动脉超声血流参数[子宫动脉收缩期/舒张期血流最大速度(systolic/diastolic,S/D)、子宫动脉阻力指数(resistance index,RI)、子宫动脉搏动指数(pulsation index,PI)]、血清LncRNA FAM99A、CCL21水平。分析子宫动脉超声血流参数、血清LncRNA FAM99A、CCL21与病情程度相关性。依据预后情况分为预后不良亚组27例、预后良好亚组99例,比较其子宫动脉超声血流参数、血清LncRNA FAM99A、CCL21水平。分析预后不良的影响因素。评价子宫动脉超声血流参数、血清LncRNA FAM99A、CCL21对预后不良的评估价值。结果:研究组S/D、RI、PI及血清CCL21水平高于对照组,血清LncRNA FAM99A水平低于对照组(P<0.05);S/D、RI、PI、CCL21与病情程度呈正相关(r=0.526、0.418、0.509、0.624,P<0.05),LncRNA FAM99A与病情程度呈负相关(r=-0.637,P<0.05);预后不良亚组S/D、RI、PI及血清CCL21水平高于预后良好亚组,血清LncRNA FAM99A水平低于预后良好亚组(P<0.05);S/D、RI、PI、CCL21为预后不良的危险因素,LncRNA FAM99A为预后不良的保护因素(P<0.05);S/D、RI、PI、LncRNA FAM99A、CCL21联合评估预后的AUC大于单项指标评估(P<0.05)。结论:HDP患者S/D、RI、PI及血清CCL21水平升高,血清LncRNA FAM99A水平降低,且与病情程度及预后密切相关,联合检测其水平对预后具有一定评估价值。

Network Coding Cooperation Performance Analysis in Wireless Network over a Lossy Channel, M Users and a Destination Scenario

Network coding (NC), introduced at the turn of the century, enables nodes in a network to combine data algebraically before either sending or forwarding them. Random network coding has gained popularity over the years by combining the received packet randomly before forwarding them, resulting in a complex Jordan Gaussian Elimination (JGE) decoding process. The effectiveness of random NC is through cooperation among nodes. In this paper, we propose a simple, low-complexity cooperative protocol that exploits NC in a deterministic manner resulting in improved diversity, data rate, and less complex JGE decoding process. The proposed system is applied over a lossy wireless network. The scenario under investigation is as follows: M users must send their information to a common destination D and to exchange the information between each others, over erasure channels;typically the channels between the users and the destination are worse than the channels between users. It is possible to significantly reduce the traffic among users and destination, achieving significant bandwidth savings, by combining packets from different users in simple, deterministic ways without resorting to extensive header information before being forwarded to the destination and the M users. The key problem we try to address is how to efficiently combine the packets at each user while exploiting user cooperation and the probability of successfully recovering information from all users at D with k < 2M unique linear equations, accounting for the fact that the remaining packets will be lost in the network and there are two transmission stages. Simulation results show the behaviour for two and three transmission stages. Our results show that applying NC protocols in two or three stages decreases the traffic significantly, beside the fact that the proposed protocols enable the system to retrieve the lost packets rather than asking for ARQ, resulting in improved data flow, and less power consumption. In fact, in some protocols the ARQ dropped from the rate 10ˉ1 to 10ˉ4, because of the proposed combining algorithm that enables the nodes to generate additional unique linear equations to broadcast rather than repeating the same ones via ARQ. Moreover, the number of the transmitted packets in each cooperative stage dropped from M (M - 1) to just M packets, resulting to 2 M packets instead 2 (M2 - 1) when three stages of transmission system are used instead of one stage (two cooperative stages).

Cooperative diversity based on rotation code

In order to obtain coding gain along with diversity gain,rotation code was applied to cooperative diversity employing decoded-and-forward cooperative protocol.Different from the same two symbols transmitted in conventional repetition-coded scheme,two different symbols were transmitted separately in two successive timeslots in the proposed rotation-coded cooperative diversity.In this way,constellation spread in the available two-dimensional signal space rather than on a single-dimensional line in repetition-coded scheme,which was supposed to be responsible for the additional coding gain.Under the proposed cooperative transmission model,upper bounds for the symbol-error-rate(SER)of cooperative diversity based on repetition code and rotation code were derived respectively.Both analytical and simulated results show that cooperative diversity based on rotation code can obtain an improved coding gain(by about 2 dB)than repetition-coded scheme without the expense of power or bandwidth.

RELAY ASSISTED TRANSMISSSION WITH BIT-INTERLEAVED CODED MODULATION

We investigate an adaptive cooperative protocol in a Two-Hop-Relay (THR) wireless system that combines the following: (1) adaptive relaying based on repetition coding; (2) single or two transmit antennas and one receive antenna configurations for all nodes, each using high order constellation; (3) Bit-Interleaved Coded Modulation (BICM). We focus on a simple decoded relaying (i.e. no error correcting at a relay node) and simple signal quality thresholds for relaying. Then the impact of the two simple thresholds on the system performance is studied. Our results suggest that compared with the traditional scheme for direct transmission, the proposed scheme can increase average throughput in high spectral efficiency region with low implementa-tion-cost at the relay.

PERFORMANCE ANALYSIS OF USER FAIR-BASED RELAY ADAPTIVE POWER ALLOCATION IN PHYSICAL-LAYER NETWORK CODING COOPERATION

Network Coding (NC) is an effective technology to enhance the cooperative system spectral efficiency. However, since it is network-oriented, the existing performance metric of single-user outage can not comprehensively evaluate its gain and the impact to the entire network, which affect the user fairness. This paper proposes two novel user fair-based adaptive relay power allocation algorithms in single-relay NC cooperative multiple access channels. Firstly, common outage probability is employed as the performance metric, and to minimize it, a specific condition is deduced. On this basis, the instantaneous channel information-based adaptive relay power allocation scheme and the channel statistic information-based one with lower complexity are designed respectively, which make users' signals superimposed at accurately calculated proportion to maintain fairness. Simulation results show that compared with other existing schemes, the proposed schemes can best maintain user fairness, and effectively improve the common outage performance of the whole system, at the expense of small spectral efficiency.

A Novel Cooperative Multicast Scheme Based on Fountain Code

Multicast is an efficient way to support emerging multimedia services over wireless network. Fountain codes are used in multicast systems to enable a robust transmission without CSI feedback and ARQ. We propose a cooperative multicast scheme based on fountain code to improve the performance of multicast. The users are coordinated with each other to decode the message at different time slots within the data transmission of a multicast session. Speci?cally, we take the local channel state information (CSI) and the local residual energy information (REI) into consideration, and apply a relay-selection and power-allocation strategy in our cooperative multicast scheme to prolong the network lifetime, while keeping the transmission delay as low as possible. The simulation results show that the proposed scheme can achieve a good tradeoff between transmission delay and network lifetime.

A cooperative spectrum sensing results transmission scheme with LT code based on energy efficiency priority

To deal with a sharp increase in transmission energy consumption due to the presence of a large number of secondary users( SUs),an energy-efficient cooperative spectrum sensing results transmission scheme is proposed for cognitive radio systems. First,a cluster-based structure is introduced into the sensing results transmission scheme to reduce the transmission power. Then,the centralized sensing results transmission model is employed,and the non-fixed code rate Luby transform( LT)code is selected as the channel coding since its code rate can dynamically adapt to channel conditions and therefore avoid unnecessary redundancy in the transmission power.Furthermore,an improved optimal degree distribution( ODD)is designed for the LT code. The simulation results show that the choice of the appropriate parameters in degree distribution is very helpful for the LT code to achieve a promising performance. The ODD with optimized parameters can achieve more than 2 d B performance gain than other typical degree distributions when the bit error rate( BER) is 10-3. The energy consumption of the proposed scheme is not only at least71. 4% lower than that of the non-coding system,but also lower than that of the convolutional coding system with different code rates. Meanwhile, the energy consumption can be further reduced in the case that a suitable clustering method is selected.

Achieving fairness by aggregate power allocation in opportunistic cooperation networks

Within a wireless opportunistic network,one of the lucky users gets an opportunity to utilize thewhole radio resource.However some of the unlucky users keep silent during an unexpected period result-ing from severe wireless environment and imperfect scheduling algorithms .An opportunistic cooperationprotocol is proposed that can achieve equivalent performance measured in terms of outage probability,inwhich scheme the opportunistic user helps to relay what need retransmitting indicated by the destinationand selects the appropriate power allocation to pursue fairness.The proposed scheme deploys superposi-tion coding and successive interference cancellation at relay and destination,respectively .To improve thespectral efficiency,the modified cooperation architecture involves two opportunistic users which work inturn.The simulation results demonstrate that the protocol obtains better performance compared with theconventional methods.

Regenerative Strategy for Sum-rate Enhancement in Bi-directional Three-node Cooperation

In bi-directional three-node cooperation, one regenerative strategy with network coding and power optimization is proposed for system sum-rate under a total energy constraint. In this paper, the network coding and power optimization are applied to improve system sum-rate. But max-rain optimization problem in power allocation is a NP-hard problem. In high Signal-to-Noise Ratio regime, this NP-hard problem is transformed into constrained polynomial optimization problem, which can be computed in polynomial time. Although it is a suboptimal solution, numerical simulations show that this strategy enhances the system sum-rate up to 45% as compared to a traditional four-phase strategy, and up to 13% as compared to the three-phase strategy without power optimization.

Chained user cooperation scheme employing joint network-channel coding

This paper proposes a joint network-channel codingbased on turbo codes for user cooperation. The scenario under consideration is one in which two ＂partners＂--UE1 and UE2---cooperate in transmitting information to the base station （BS）. Each partner transmits both locally generated information and the relayed information that originated at the other partner. The local information and relayed information are jointly network-channel coded to form a superimposed codeword, and the adjacent codewords transmitted in turn by the two partners are tightly correlative like a chain. It is shown via simulation that the proposed scheme achieves full diversity gain compared with the other user cooperation schemes, including those based on coded cooperation and distributed space-time coded cooperation.