Multi-source Cooperation Research Articles

Design of Minimizing Expected Energy of Multisource Wireless Cooperative Network Based on Multiobjective Optimization

In order to solve the problems of high average power consumption, low average throughput, high average energy consumption per unit of data, and short network life cycle in traditional multisource wireless cooperation methods, this paper proposes a multisource wireless cooperative network design method based on multiple goals. We analyze the characteristics of heterogeneous deployment of multisource wireless cooperative networks and the energy consumption of nodes and control the energy consumption of network data transmission through distributed opportunistic transmission scheduling methods according to the analysis results. We use the optimal strategy of minimizing expected energy consumption, transform the problem of data transmission energy consumption, establish a mathematical model, and obtain the optimal solution for minimizing expected energy consumption. According to the optimal stop rule, the minimum expected energy consumption threshold is obtained, and then the optimal solution is obtained on the constraint set of the multiobjective optimization problem through the multiobjective optimization method, so as to achieve the goal of minimizing the expected energy of the network. Experimental results show that this method prolongs the network life cycle, reduces the average power consumption of network data transmission, and improves the average network throughput.

Research on Multi-source Cooperative optimal dispatching of Active Distribution Network

Combined with the operation characteristics of active distribution network, the overall architecture of multi-source cooperative optimal dispatching is proposed, The key technologies, such as multi-aspect data association, fast simulation of active distribution network, multi-source cooperative optimal scheduling strategy and evaluation of multi-source cooperative optimal scheduling policy, are studied. The dynamic optimal scheduling target of each unit running state is proposed, and a time dimension optimization scheduling strategy for pre-day and intra-day is proposed, The evaluation method of optimal scheduling strategy is studied. Finally, the proposed multi-source cooperative scheduling scheme of active distribution network is verified by MATLAB simulation in a typical node network.

Multi-Source Cooperative Data Collection with a Mobile Sink for the Wireless Sensor Network.

The multi-source cooperation integrating distributed low-density parity-check codes is investigated to jointly collect data from multiple sensor nodes to the mobile sink in the wireless sensor network. The one-round and two-round cooperative data collection schemes are proposed according to the moving trajectories of the sink node. Specifically, two sparse cooperation models are firstly formed based on geographical locations of sensor source nodes, the impairment of inter-node wireless channels and moving trajectories of the mobile sink. Then, distributed low-density parity-check codes are devised to match the directed graphs and cooperation matrices related with the cooperation models. In the proposed schemes, each source node has quite low complexity attributed to the sparse cooperation and the distributed processing. Simulation results reveal that the proposed cooperative data collection schemes obtain significant bit error rate performance and the two-round cooperation exhibits better performance compared with the one-round scheme. The performance can be further improved when more source nodes participate in the sparse cooperation. For the two-round data collection schemes, the performance is evaluated for the wireless sensor networks with different moving trajectories and the variant data sizes.

A Non-Orthogonal Selection Cooperation Protocol with Interference in Multi-Source Cooperative Networks

This work proposes a non-orthogonal selection cooperation scheme with interference for multi-source and single destination cooperative networks. In our model, the source nodes can cooperate for one another, i.e., each source node plays the dual role of a source and a relay, thus there is no need for relays. In addition, the source nodes can be continuously transmitted and without dedicated timeslots for cooperative transmissions, which can save system resources and improve spectral efficiency. However, by this way, it will introduce interference with the non-orthogonal transmission mechanism. To overcome this problem, we use general reception scheme in source nodes and successive interference cancellation technology in the destination node, which can reduce the effect of interference effectively. For interference-limited networks, we also derive the theoretical upper bound and lower bound of outage probability of our method. Through the outage probability analysis and comparison, the results show that the spectral efficiency is improved while the system still keeps acceptable transmission reliability.

Multi-Source Cooperative Communication With Opportunistic Interference Cancelling Relays

In this paper we present a multi-user cooperative protocol for wireless networks. Two sources transmit simultaneously their information blocks and relays employ opportunistically successive interference cancellation (SIC) in an effort to decode them. An adaptive decode/amplify-and-forward scheme is applied at the relays to the decoded blocks or their sufficient statistic if decoding fails. The main feature of the protocol is that SIC is exploited in a network since more opportunities arise for each block to be decoded as the number of used relays NRU is increased. This feature leads to benefits in terms of diversity and multiplexing gains that are proven with the help of an analytical outage model and a diversity-multiplexing tradeoff (DMT) analysis. The performance improvements are achieved without any network synchronization and coordination. In the final part of this work the closed-form outage probability model is used by a novel approach for offline pre-selection of the NRU relays, that have the best SIC performance, from a larger number of NR nodes. The analytical results are corroborated with extensive simulations, while the protocol is compared with orthogonal and multi-user protocols reported in the literature.

Round-Robin Relaying With Diversity in Amplify-and-Forward Multisource Cooperative Communications

In this paper, a round-robin-based relay protocol dubbed round-robin relaying with source selection protocol (R3SSP) is proposed to achieve full cooperative diversity in multisource cooperative communication networks. In R3SSP, all the sources transmit their individual information in turn. The relays then forward the messages of some specific sources in a fixed order according to the limited feedback information. Compared with traditional relay selection-based protocols, R3SSP is based on round-robin relaying, thus avoiding relay selection and requiring no specific channel state information feedback. R3SSP can therefore be implemented with lower complexity. Furthermore, the exact and asymptotic expressions of the outage probability are derived. The diversity-multiplexing tradeoff (DMT) performance is also analyzed. Theoretical analysis shows that R3SSP achieves full cooperative diversity and provides better DMT performance than relay selection-based protocols in a system where the number of sources is higher than that of the relays. Based on the DMT analysis, we further propose an adaptive relay activation scheme that is capable of achieving higher DMT by dynamically selecting the number of relays to be activated in the entire network. Simulation results also verify the validity and superiority of R3SSP.

Distributed Matching Schemes for Multi-source and Multi-relay Cooperative Wireless Networks

In this paper, we investigate how to assign source-relay pairs to achieve cooperative diversity for multi-source and multi-relay wireless networks. The problem of interest is formulated as a matching problem which can be modeled by a two-sided one-to-one matching game, i.e., a branch of coalitional games. The deferred acceptance procedure is introduced to solve the matching problem, and it turns out that a solution can always be found and is proved in the core of the coalitional game. Consequently, each node is satisfied with its final state and has no incentive to deviate, which leads to a stable matching state. Simulation results demonstrate that the proposed matching scheme has linear time complexity, which means the scheme is easy to implement. However, it can achieve comparable performance to that employing centralized optimal scheme in terms of total profit of the system.

Differential Space-Time Network Coding for Multi-Source Cooperative Communications

Due to the asynchronous nature of cooperative communications, simultaneous transmissions from two or more nodes are challenging in practice. The existing cooperative communications employing successive transmission from one user node to the other can avoid the synchronization problem but results in large transmission delay. In addition, channel estimation in multi-source cooperative communications is a challenging and costly task due to the amount of training, especially when the number of cooperative users is large. Considering these practical challenges in multi-source cooperative communications, this paper proposes a differential space-time network coding (DSTNC) scheme for narrowband multi-source cooperative communications to overcome the problems of imperfect synchronization and complex channel estimation without introducing large transmission delay. Each user in the network linearly combines the correctly decoded symbols via network coding and transmits its packet in time division multiple access (TDMA) mode. The pairwise error probability is analyzed and the design criteria of the DSTNC are derived to achieve full diversity. For broadband cooperative communications, distributed differential space-time-frequency network coding (DSTFNC), which is differentially encoded within each orthogonal frequency-division multiplexing (OFDM) block, is designed through mapping from the proposed DSTNC. When the statistical channel power-delay profile is known at the corresponding user node, each node can permutate its channel independently to improve the performance of the DSTFNC scheme. Simulation results are presented to verify the performance of the proposed schemes.

Distributed Serially Concatenated Codes for Multi-Source Cooperative Relay Networks

In this paper, we propose a distributed turbo-like coding scheme for a multi-source relay scenario where multiple sources communicate with a destination with the help of a common relay, which uses the decode-and-forward strategy and operates in half-duplex mode. The proposed distributed code can be viewed as a serially concatenated code (SCC). Thus, at the destination decoding is performed in an iterative fashion which resembles the decoding of a classic SCC. We consider the two scenarios where the sources transmit over orthogonal channels and where they do not. For the latter, interleave-division multiple-access is used for multiuser detection. For both scenarios we optimize the transmission time allocated to the sources and to the relay and compute the achievable rates. The proposed scheme achieves very low error rates and offers significant performance gains with respect to non-cooperation, even for a very large number of sources. Furthermore, it provides a high flexibility in terms of code rate, number of sources, overall system rate and error protection.

Power Allocation and Relay Selection in Multi-source Cooperative Networks

该文针对多源-多中继放大转发协作通信网络，以最小化系统总功率为目标，在保证系统满足一定中断概率的前提下，提出了一种分布式功率分配与中继选择算法。算法由源节点自主选择为其转发信息的中继节点，并引入定时器，通过竞争方式避免了分布式所导致的中继选择冲突。中继收到来自源节点的信号后，只需根据转发门限自主判断是否进行转发，从而完成传输。仿真结果表明该分布式算法能够有效降低传输所需要的总发射功率。并且与集中式控制所获得的最优中继选择与功率分配算法相比性能相近，但所提分布式算法显著降低了系统的控制开销。

Cooperative communications based on rateless network coding in distributed MIMO systems [Coordinated and Distributed MIMO

In cellular distributed antenna systems, cooperation among base stations or remote antenna units to exploit multiple-input multiple-output gains could mitigate interference as well as provide more spatial diversity, which could significantly improve overall spectrum efficiency. However, most existing cooperation schemes require perfect synchronization, which is difficult and even impossible in practical distributed multi-user systems. When synchronization is not perfect, cooperative communication performance severely degrades. Orthogonal channel assignment among collaborating stations with rateless network coding allows synchronization to be performed independently, and provides a coding scheme with close-to-capacity performance. In this article we discuss how to construct cooperative communication schemes based on rateless network coding in distributed MIMO systems. Specifically, we propose two cooperation strategies: single-source cooperation based on rateless coding and multisource cooperation based on rateless network coding. The proposed cooperative strategies are applicable to both uplink cooperation among users and downlink cooperation among BSs or RAUs in cellular DASs, providing a parameter-flexible, encoding-simple, and bandwidth-efficient cooperative solution.

Interleaved Random Space–Time Coding for Multisource Cooperation

In this paper, we propose a novel distributed interleaved random space-time code (IR-STC) designed for multisource cooperation (MSC) employing various relaying techniques, namely, amplify-forward, decode-forward, soft decode-forward, and differential decode-forward. We introduce a two-phase communication regime for our IR-STC-aided MSC and propose a novel structured embedded (SE) random interleaver-generation method. We also characterize the achievable performance of our proposed IR-STC design in conjunction with various relaying techniques communicating over different intersource Nakagami-m fading channels.

Coding Schemes for Energy Efficient Multi-Source Cooperation Aided Uplink Transmission

In this paper, we consider coding schemes designed for multi-source cooperation, where a cluster of sources cooperatively communicates with the destination. More explicitly, we propose both a powerful superposition coding scheme and a physical-layer algebraic network coding scheme. Our simulation results demonstrate that both of the proposed schemes are capable of performing close to the outage probability bound. Compared to the superposition coding scheme considered, the proposed algebraic network coding arrangement imposes a much lower complexity at the cost of a slight performance degradation, while maintaining the same throughput and delay.

Space-time coding for high-throughput interleave division multiplexing aided multi-source co-operation

Designed is an error-resilient, yet high-throughput interleave division multiplexing based space-time code suitable for multi-source co-operation. Its achievable rate, power efficiency and flexibility have been characterised.

Link-Adaptive Distributed Coding for Multisource Cooperation

Combining multisource cooperation and link-adaptive regenerative techniques, a novel protocol is developed capable of achieving diversity order up to the number of cooperating users and large coding gains. The approach relies on a two-phase protocol. In Phase 1, cooperating sources exchange information-bearing blocks, while in Phase 2, they transmit reencoded versions of the original blocks. Different from existing approaches, participation in the second phase does not require correct decoding of Phase 1 packets. This allows relaying of soft information to the destination, thus increasing coding gains while retaining diversity properties. For any reencoding function the diversity order is expressed as a function of the rank properties of the distributed coding strategy employed. This result is analogous to the diversity properties of colocated multi-antenna systems. Particular cases include repetition coding, distributed complex field coding (DCFC), distributed space-time coding, and distributed error-control coding. Rate, diversity, complexity, and synchronization issues are elaborated. DCFC emerges as an attractive choice because it offers high-rate, full spatial diversity, and relaxed synchronization requirements. Simulations confirm analytically established assessments.

Multi-source cooperation with full-diversity spectral-efficiency and controllable-complexity

A general framework is developed for multi-source cooperation (MSC) protocols to improve diversity and spectral efficiency relative to repetition based alternatives that rely on single-source cooperation. The novel protocols are flexible to balance tradeoffs among diversity, spectral efficiency and decoding-complexity. Users are grouped in clusters and follow a two-phase MSC protocol which involves time division multiple access (TDMA) to separate users within a cluster, and code division multiple access (CDMA) used to separate clusters. An attractive protocol under the general MSC framework relies on distributed complex field coding (DCFC) to enable diversity order equal to the number of users per cluster. Cluster separation based on orthonormal spreading sequences leads to spectral efficiency 1/2. When the number of clusters exceeds the amount of spreading, spectral efficiency can be enhanced without sacrificing diversity, at the expense of controllable increase in complexity. Simulations corroborate our analytical claims