| 1. |
- You, Xiaohu, et al.
(author)
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Towards 6G wireless communication networks: vision, enabling technologies, and new paradigm shifts
- 2021
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In: Science China Information Sciences. - : Science Press. - 1674-733X .- 1869-1919. ; 64:1
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Research review (peer-reviewed)abstract
- The fifth generation (5G) wireless communication networks are being deployed worldwide from 2020 and more capabilities are in the process of being standardized, such as mass connectivity, ultra-reliability, and guaranteed low latency. However, 5G will not meet all requirements of the future in 2030 and beyond, and sixth generation (6G) wireless communication networks are expected to provide global coverage, enhanced spectral/energy/cost efficiency, better intelligence level and security, etc. To meet these requirements, 6G networks will rely on new enabling technologies, i.e., air interface and transmission technologies and novel network architecture, such as waveform design, multiple access, channel coding schemes, multi-antenna technologies, network slicing, cell-free architecture, and cloud/fog/edge computing. Our vision on 6G is that it will have four new paradigm shifts. First, to satisfy the requirement of global coverage, 6G will not be limited to terrestrial communication networks, which will need to be complemented with non-terrestrial networks such as satellite and unmanned aerial vehicle (UAV) communication networks, thus achieving a space-air-ground-sea integrated communication network. Second, all spectra will be fully explored to further increase data rates and connection density, including the sub-6 GHz, millimeter wave (mmWave), terahertz (THz), and optical frequency bands. Third, facing the big datasets generated by the use of extremely heterogeneous networks, diverse communication scenarios, large numbers of antennas, wide bandwidths, and new service requirements, 6G networks will enable a new range of smart applications with the aid of artificial intelligence (AI) and big data technologies. Fourth, network security will have to be strengthened when developing 6G networks. This article provides a comprehensive survey of recent advances and future trends in these four aspects. Clearly, 6G with additional technical requirements beyond those of 5G will enable faster and further communications to the extent that the boundary between physical and cyber worlds disappears.
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| 2. |
- Ding, Lianghui, et al.
(author)
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Energy minimization in wireless multihop networks using two-way network coding
- 2011
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In: IEEE 73rd Vehicular Technology Conference (VTC-2011-Spring), Budapest, Ungern. - 9781424483310
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Conference paper (peer-reviewed)abstract
- The total energy minimization in wireless multihop networks using two-way network coding is investigated in this paper. The problem is first formulated as a linear programming problem, then decomposed into two sub-problems using the Lagrangian decomposition, and finally solved with the subgradient method. After that, the backpressure based algorithm is proposed to solve the problem in a distributed manner. The performance of the algorithm is evaluated first in a simple topology for analysis and then in a random topology with different number of flows for practical consideration. Simulation results show that the convergence time increases as the number of nodes in the network, and the energy cost per packet can be saved up to 30% by using two-way network coding.
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| 4. |
- Ding, Liang-Hui, et al.
(author)
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Lifetime maximization routing with network coding in wireless multihop networks
- 2013
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In: SCIENCE CHINA-INFORMATION SCIENCES. - : Springer Science and Business Media LLC. - 1674-733X .- 1869-1919. ; 56:2, s. 1-15
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Journal article (peer-reviewed)abstract
- In this paper, we consider the lifetime maximization routing with network coding in wireless multihop networks. We first show that lifetime maximization with network coding is different from pure routing, throughput maximization with network coding and energy minimization with network coding. Then we formulate lifetime maximization problems in three different cases of (i) no network coding, (ii) two-way network coding, and (iii) overhearing network coding. To solve these problems, we use flow augmenting routing (FA) for the first case, and then extend the FA with network coding (FANC) by using energy minimized one-hop network coding. After that, we investigate the influence of parameters of FANC, evaluate the performance of FANC with two-way and overhearing network coding schemes and compare it with that without network coding under two different power control models, namely, protocol and physical ones. The results show that the lifetime can be improved significantly by using network coding, and the performance gain of network coding decreases with the increase of flow asymmetry and the power control ability.
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| 7. |
- Fan, Zhiwen, et al.
(author)
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Porous Ionic Network/CNT Composite Separator as a Polysulfide Snaring Shield for High Performance Lithium–Sulfur Battery
- 2023
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In: Macromolecular rapid communications. - 1022-1336 .- 1521-3927. ; 44:24
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Journal article (peer-reviewed)abstract
- Lithium–sulfur (Li–S) battery features a high theoretical energy density, but the shuttle of soluble polysulfides between the two electrodes often results in a rapid capacity decay. Herein, a straightforward electrostatic adsorption strategy based on a cross-linked polyimidazolium separator as a snaring shield of polysulfides is reported, which suppresses the undesirable migration of polysulfides to the anode. The porous ionic network (PIN)-modified carbon nanotubes (CNTs) are successfully prepared and coated onto a commercial porous polypropylene membrane in a vacuum-filtration step. The favorable affinity of the imidazolium ring toward polysulfide via the polar interaction and the electrostatic effect of ions mitigates the undesirable shuttle of polysulfides in the electrolyte, improving the Li─S battery in terms of rate performance and cycling life. Compared to the reference PIN-free CNT-coated separator, the PIN/CNT-coated one has an increased initial capacity of 1.3 folds (up to 1394.8 mAh g−1 for PIN/CNT/PP-3) at 0.1 C.
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| 8. |
- Wang, Hao, et al.
(author)
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A unified algorithm for mobility load balancing in 3GPP LTE multi-cell networks
- 2013
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In: Science in China. Series F, Information Sciences. - : Science China Press. - 1009-2757. ; 56
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Journal article (peer-reviewed)abstract
- 3GPP long term evolution (LTE) is a promising candidate for the next-generation wireless network, which is expected to achieve high spectrum efficiency by using advanced physical layer techniques and flat network structures. However, the LTE network still faces the problem of load imbalance as in GSM/WCDMA networks, and this may cause significant deterioration of system performance. To deal with this problem, mobility load balancing (MLB) has been proposed as an important use case in 3GPP self-organizing network (SON), in which the serving cell of a user can be selected to achieve load balancing rather than act as the cell with the maximum received power. Furthermore, the LTE network aims to serve users with different quality-of-service (QoS) requirements, and the network-wide objective function for load balancing is distinct for different kinds of users. Thus, in this paper, a unified algorithm is proposed for MLB in the LTE network. The load balancing problem is first formulated as an optimization problem with the optimizing variables being cell-user connections. Then the complexity and overhead of the optimal solution is analyzed and a practical and distributed algorithm is given. After that, the proposed algorithm is evaluated for users with different kinds of QoS requirements, i.e., guaranteed bit rate (GBR) users with the objective function of load balance index and non-GBR (nGBR) users with the objective function of total utility, respectively. Simulation results show that the proposed algorithm leads to significantly balanced load distribution for GBR users to decrease the new call blocking rate, and for nGBR users to improve the cell-edge throughput at the cost of only slight deterioration of total throughput.
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| 11. |
- Wang, Hao, et al.
(author)
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Minimum rate guaranteed call admission control for cumulative rate distribution based scheduling
- 2011
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In: IEEE Communications Letters. - 1089-7798 .- 1558-2558. ; 15:11, s. 1181-1183
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Journal article (peer-reviewed)abstract
- In this letter, we investigate call admission control (CAC) for cumulative rate distribution based scheduling (CS) in wireless communication networks. We first analyze the multi-user diversity gain (MDG) of CS, which is applicable to general channel conditions. Then we propose the minimum rate guaranteed CS/ORR based CAC algorithm, COCAC, which jointly uses CS and opportunistic round robin (ORR) for resource prediction and CAC decision. Furthermore, we evaluate the performance of our COCAC algorithm through simulation. Results show that COCAC can significantly reduce the new call blocking rate, while strictly guarantee the minimum rate requirements of all serving users.
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| 13. |
- Wang, Hao, et al.
(author)
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Three novel opportunistic scheduling algorithms in CoMP-CSB scenario
- 2013
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In: Science China-Information Sciences. - : Springer Science and Business Media LLC. - 1674-733X .- 1869-1919. ; 56:8, s. 082301-
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Journal article (peer-reviewed)abstract
- Coordinated scheduling/beamforming (CSB), which belongs to the coordinated multi-point (CoMP) transmission, has received lots of attention recently due to its great potential to mitigate inter-cell interference (ICI) and to increase the cell-edge throughput, and meanwhile it only requires limited base station cooperation and is easy to implement. However, to the best of our knowledge, there are no effective scheduling algorithms with low complexity and overhead in CoMP-CSB scenario as yet. Thus, in this paper, we propose three novel opportunistic scheduling algorithms in CoMP-CSB scenario. All of them jointly consider the intended channel condition of the scheduled user from its serving cell and the orthogonality between the intended channel and the corresponding interference channels to concurrently scheduled users in nearby cells, thus exploiting multi-user diversity (MUD) and mitigating ICI at the same time. Algorithm 1 cooperatively chooses the most orthogonal user pair within a candidate user set in which all users have a large local channel feedback, while Algorithm 2 concurrently schedules the user pair with the largest ratio between the local channel feedbacks and the aforementioned orthogonality within the same candidate user set. Algorithm 3 performs in the way similar to the proportional fairness scheduling, while making a proper modification for its usage in CoMP-CSB scenario. The performance of the proposed scheduling algorithms are evaluated through simulation. Results show that, they all can significantly enhance the received signal to interference plus noise ratio (SINR) with relatively good fairness guarantee, thus achieving larger throughputs and utilities than several well-known scheduling algorithms. Algorithm 2 even outperforms Algorithm 1 when the aforementioned candidate user set is big enough in size and has a bit more overhead/complexity. Furthermore, Algorithms 3 is the best one among all the three proposed algorithms, but it requires more overhead/complexity than Algorithm 1 and 2. Finally, we give the optimal parameter for all of the three proposed algorithms, which can make a good tradeoff between performance and overhead/complexity.
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| 16. |
- You, Lei, et al.
(author)
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Cross-layer optimization of wireless multihop networks with one-hop two-way network coding
- 2011
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In: Computer Networks. - : Elsevier BV. - 1389-1286 .- 1872-7069. ; 55:8, s. 1747-1769
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Journal article (peer-reviewed)abstract
- In this paper, we investigate optimal cross-layer design of congestion control, routing, one-hop two-way inter-commodity (OTIC) network coding and scheduling in wireless multihop networks utilizing the broadcast advantage of wireless medium. We first present an achievable rate region with OTIC network coding by introducing virtual flow rates in a node. Then we formulate the network utility maximization problem subject to constraints on this achievable rate region, and analyze the complexities of both node- and path-based formulation with no network coding, OTIC network coding, and overhearing network coding. After that, we solve it using dual decomposition and subgradient method. Based on the solution, we present a new queue model, which is able to facilitate the coding operation between two-way commodities, and then propose a backpressure-based cross-layer optimization algorithm with low coding complexity and overhead. Afterwards, we analyze the stability and asymptotical optimality of the proposed cross-layer algorithm by Lyapunov drift technique, and evaluate its performance through extensive simulation. By comparing with the pure routing scheme under both primary and two-hop interference models in an illustrative topology, it is shown that with the proposed joint optimization algorithms, the OTIC network coding can interact adaptively and optimally with other components in different layers and achieve high throughput gain. Simulation of the proposed algorithm in a mesh network with base station and a random ad hoc network justifies that OTIC network coding can obtain considerable throughput gain with low complexity in various kinds of networks.
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