The Experts below are selected from a list of 51519 Experts worldwide ranked by ideXlab platform
Lajos Hanzo - One of the best experts on this subject based on the ideXlab platform.
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the Effective Throughput of miso systems over kappa mu fading channels
IEEE Transactions on Vehicular Technology, 2014Co-Authors: Jiayi Zhang, Zhenhui Tan, Haibo Wang, Qing Huang, Lajos HanzoAbstract:The Effective Throughput of multiple-input-single-output (MISO) systems communicating over both independent and identically distributed (i.i.d.) and independent and nonidentically distributed (i.n.i.d.) κ- μ fading channels is investigated under delay constraints. New analytical expressions are derived for the exact Effective Throughput of both channels. Moreover, we present tractable closed-form Effective Throughput expressions in the asymptotically high- and low-signal-to-noise-ratio (SNR) regimes for i.i.d. κ- μ fading channels. These results enable us to investigate the impact of system parameters on the Effective Throughput of MISO κ- μ fading channels. We demonstrate that as the affordable delay tends to infinity, the Effective Throughput is increased to the classic ergodic capacity. By contrast, the Effective Throughput of delay-constrained near-real-time systems fails to approach the ergodic capacity.
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The Effective Throughput of MISO Systems Over $\kappa$ – $\mu$ Fading Channels
IEEE Transactions on Vehicular Technology, 2014Co-Authors: Jiayi Zhang, Zhenhui Tan, Haibo Wang, Qing Huang, Lajos HanzoAbstract:The Effective Throughput of multiple-input-single-output (MISO) systems communicating over both independent and identically distributed (i.i.d.) and independent and nonidentically distributed (i.n.i.d.) κ- μ fading channels is investigated under delay constraints. New analytical expressions are derived for the exact Effective Throughput of both channels. Moreover, we present tractable closed-form Effective Throughput expressions in the asymptotically high- and low-signal-to-noise-ratio (SNR) regimes for i.i.d. κ- μ fading channels. These results enable us to investigate the impact of system parameters on the Effective Throughput of MISO κ- μ fading channels. We demonstrate that as the affordable delay tends to infinity, the Effective Throughput is increased to the classic ergodic capacity. By contrast, the Effective Throughput of delay-constrained near-real-time systems fails to approach the ergodic capacity.
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maximum Throughput irregular distributed space time code for near capacity cooperative communications
IEEE Transactions on Vehicular Technology, 2010Co-Authors: Lingkun Kong, Soon Xin Ng, Robert G Maunder, Lajos HanzoAbstract:This paper presents an irregular distributed space-time (Ir-DST) coding scheme designed for near-capacity cooperative communications where the system's Effective Throughput is also maximized with the aid of a joint source-and-relay mode design procedure. At the source node, a serially concatenated scheme comprising an IRregular Convolutional Code (IRCC), a recursive unity-rate code (URC), and a space-time block code (STBC) was designed for the sake of approaching the corresponding source-to-relay link capacity, where the IRCC was optimized with the aid of EXtrinsic Information Transfer (EXIT) charts. At the relay node, another IRCC is serially concatenated with an identical STBC. Before transmitting the relayed information, the relay's IRCC is reoptimized based on EXIT chart analysis for the sake of approaching the relay channel's capacity and to maximize the relay's coding rate, which results in a maximized Effective Throughput. We will demonstrate that the topology of the Ir-DST system coincides with that of a distributed turbo code (DTC). At the destination node, a novel three-stage iterative decoding scheme is constructed to achieve decoding convergence to an infinitesimally low bit-error ratio (BER). Finally, our numerical results show the proficiency of our joint source-and-relay mode design procedure, demonstrating that the proposed Ir-DST coding scheme is capable of near-capacity cooperative communications and of maximizing the Effective Throughput.
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VTC Spring - Optimum Physical-Layer Frame Size for Maximising the Application-Layer Rateless Code's Effective Throughput
2010 IEEE 71st Vehicular Technology Conference, 2010Co-Authors: T. Stevens, Robert G Maunder, Lajos HanzoAbstract:The tolerable packet-loss ratio of an \ipLng based wireless networks varies according to the specific services considered. File transfer for example must be error free but tolerates higher delays, whereas maintaining a low delay is typically more important in interactive \voipLng or video services. Classic \fecLng may be applied to the data to provide resilience against bit errors. A wireless \ipAcr network provides the opportunity for the inclusion of \fecAcr at the physical, transport and application layers. The demarcation between the analogue and digital domain imposed at the \phyLng predetermines the nature of the \fecAcr scheme implemented at the various layers. At the \phyAcr individual packets may be offered \fecAcr protection, which increases the likelihood of their error-free insertion into the protocol stack. Higher layers receive packets that are error free and the purpose of a \fecAcr scheme implemented here is to regenerate any missing packets obliterated for example by the \becLng of the \ipAcr network's routers. A rateless code may be beneficially employed at a higher \osiLng layer for replenishing the obliterated packets, but unless the characteristics of the channel are considered, the ultimate rate achieved by such a code may be compromised, as shown in this contribution.
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WCNC - Adaptive Differential Space-Time-Spreading-Assisted Turbo-Detected Sphere Packing Modulation
2007 IEEE Wireless Communications and Networking Conference, 2007Co-Authors: Mohammed El-hajjar, Osamah Alamri, Lajos HanzoAbstract:In this contribution a novel adaptive differential space-time spreading assisted turbo detected sphere packing modulation scheme is proposed for improving the achievable Throughput of code division multiple access (CDMA) systems. The scheme is capable of accommodating the channel signal-to-noise ratio (SNR) variation of wireless systems by adapting the system parameters. Explicitly, an adaptive transmission scheme constituted by a novel reconfigurable four transmit antenna aided arrangement using a variable spreading factor based differential space-time spreading scheme, as well as variable code rate recursive systematic convolutional codes is introduced. Our results demonstrate that significant Effective Throughput improvement can be achieved while maintaining a target bit-error-ratio of 10-4. Explicitly, when assuming an ideal Nyquist filter having a zero excess bandwidth, the system's Effective Throughput varies from 0.25 bits/sec/Hz to 16 bits/sec/Hz.
Jerry D. Gibson - One of the best experts on this subject based on the ideXlab platform.
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WCNC - Joint PHY/MAC based link adaptation for wireless LANs with multipath fading
IEEE Wireless Communications and Networking Conference 2006. WCNC 2006., 2006Co-Authors: Sayantan Choudhury, Jerry D. GibsonAbstract:Wireless local area networks offer a range of transmitted data rates that are to be selected according to estimated channel conditions. However, due to packet overheads and contention times introduced by the CSMA/CA multiple access protocol, Effective Throughput is much less than the nominal data rates. Most multimedia applications use small payload sizes in order to ensure reliable, low latency transmission. This results in a further loss in Effective Throughput thereby reducing network capacity drastically. Thus, a cross-layer based design approach along with link adaptation is required to improve the network performance under different channel conditions. We investigate the effect of payload size variations on single-user Throughput for both non-fading and multipath fading environments. We explore the difference in link adaptation thresholds for different payload sizes with varying channel characteristics. A link adaptation scheme to maximize the Throughput with a packet error constraint is presented
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VTC Spring - Payload Length and Rate Adaptation for Throughput Optimization in Wireless LANs
2006 IEEE 63rd Vehicular Technology Conference, 1Co-Authors: Sayantan Choudhury, Jerry D. GibsonAbstract:Wireless local area networks offer a range of transmitted data rates that are to be selected according to estimated channel conditions. However, due to packet overheads and contention times introduced by the CSMA/CA multiple access protocol, Effective Throughput is much less than the transmitted bit rates. Furthermore, if there is even a single bit error in the packet, the entire packet is discarded and the packet is retransmitted. This causes the Effective Throughput to be a function of the packet payload length. We provide a theoretical framework to optimize single-user Throughput by selecting the transmitted bit rate and payload size as a function of channel conditions for both additive white Gaussian noise (AWGN) and Nakagami-m fading channels. Numerical results reveal that careful payload adaptation significantly improves the Throughput performance at low signal to noise ratios (SNRs) while at higher SNRs, rate adaptation with higher payload lengths provides better performance. We compare the range of SNRs over which payload length adaptation is crucial for AWGN and different fading channels based on the m-parameter of Nakagami fading realization. We then specify SNR values for switching between transmitted bit rates and payload lengths such that the Effective Throughput is maximized.
Hui Wu - One of the best experts on this subject based on the ideXlab platform.
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ISCA - Enhancing Effective Throughput for transmission line-based bus
ACM SIGARCH Computer Architecture News, 2012Co-Authors: Aaron Carpenter, Jianyun Hu, Ovunc Kocabas, Michael C. Huang, Hui WuAbstract:Main-stream general-purpose microprocessors require a collection of high-performance interconnects to supply the necessary data movement. The trend of continued increase in core count has prompted designs of packet-switched network as a scalable solution for future-generation chips. However, the cost of scalability can be significant and especially hard to justify for smaller-scale chips. In contrast, a circuit-switched bus using transmission lines and corresponding circuits offers lower latencies and much lower energy costs for smaller-scale chips, making it a better choice than a full-blown network-on-chip (NoC) architecture. However, shared-medium designs are perceived as only a niche solution for small- to medium-scale chips. In this paper, we show that there are many low-cost mechanisms to enhance the Effective Throughput of a bus architecture. When a handful of highly cost-Effective techniques are applied, the performance advantage of even the most idealistically configured NoCs becomes vanishingly small. We find transmission line-based buses to be a more compelling interconnect even for large-scale chip-multiprocessors, and thus bring into doubt the centrality of packet switching in future on-chip interconnect.
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Enhancing Effective Throughput for transmission line-based bus
2012 39th Annual International Symposium on Computer Architecture (ISCA), 2012Co-Authors: Aaron Carpenter, Jianyun Hu, Ovunc Kocabas, Michael Huang, Hui WuAbstract:Main-stream general-purpose microprocessors require a collection of high-performance interconnects to supply the necessary data movement. The trend of continued increase in core count has prompted designs of packet-switched network as a scalable solution for future-generation chips. However, the cost of scalability can be significant and especially hard to justify for smaller-scale chips. In contrast, a circuit-switched bus using transmission lines and corresponding circuits offers lower latencies and much lower energy costs for smaller-scale chips, making it a better choice than a full-blown network-on-chip (NoC) architecture. However, shared-medium designs are perceived as only a niche solution for small- to medium-scale chips. In this paper, we show that there are many low-cost mechanisms to enhance the Effective Throughput of a bus architecture. When a handful of highly cost-Effective techniques are applied, the performance advantage of even the most idealistically configured NoCs becomes vanishingly small. We find transmission line-based buses to be a more compelling interconnect even for large-scale chip-multiprocessors, and thus bring into doubt the centrality of packet switching in future on-chip interconnect.
Wei Chen - One of the best experts on this subject based on the ideXlab platform.
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on the Effective Throughput of coded caching with heterogeneous user preferences a game theoretic perspective
IEEE Transactions on Communications, 2021Co-Authors: Wei Chen, Vincent H PoorAbstract:Proactive caching has emerged as a promising means to accommodate increased demands for wireless capacity. However, studies of proactive caching usually focus on minimizing the overall load of cache-aided networks. How to calculate each user’s caching gain is still an open problem. In this paper, a two-phase cache-aided network is investigated, in which users with heterogeneous preferences are served by a base station through a shared link. Effective Throughput is considered as a performance metric, which describes the reduction in each user’s transmission cost. All possible values of Effective Throughputs achieved by legitimate caching policies form an achievable domain. It is proved that the achievable domain is a convex set and can be characterized by its boundary. A special type of caching policies, termed uncoded placement absolutely-fair (UPAF) caching, is studied. For the two-user case, games are formulated to allocate Effective Throughput gains for the two users. For the general multiuser case, a UPAF policy is proposed to organize user cooperation. It is shown that users with more concentrated preferences can obtain higher Effective Throughputs.
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On the Effective Throughput of Coded Caching: A Game Theoretic Perspective.
arXiv: Information Theory, 2019Co-Authors: Wei Chen, H. Vincent PoorAbstract:Recently coded caching has emerged as a promising means to handle continuously increasing wireless traffic. However, coded caching requires users to cooperate in order to minimize the overall transmission rate. How users with heterogeneous preferences cooperate in coded caching and how to calculate the resulting caching gains are still open problems. In this paper, a two-phase cache-aided network is investigated, in which users with heterogeneous preferences are served by a base station through a shared link. Effective Throughput is considered as a performance metric. It is proved that the achievable domain of Effective Throughputs is a convex set and can be characterized by its boundary. A special type of caching schemes, named uncoded placement absolutely-fair (UPAF) caching, is studied. For the two-user case, games are formulated to allocate Effective Throughput gains for the two users. For the general multiuser case, a UPAF policy is proposed to organize user cooperation. It is shown that users with more concentrated preferences can obtain higher Effective Throughputs.
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coded caching under heterogeneous user preferences an Effective Throughput perspective
International Conference on Communications, 2019Co-Authors: Wei Chen, Vincent H PoorAbstract:Proactive caching is a promising means to handle increasing wireless traffic. However, how heterogeneous user preferences impact the caching gain is still an open problem. In this paper, a two-phase cache-aided multicasting network is investigated, in which users with heterogeneous preferences are served by a base station through a shared link. It is shown that the achievable domain of Effective Throughput of the users is a convex set and can be characterized by its boundary in the positive orthant. A special type of caching schemes, named uncoded placement absolutely fair (UPAF) caching, is studied. For the two user case, the achievable domain of UPAF policies has a piecewise linear boundary. For the multiuser case, a feasible UPAF policy is proposed to obtain caching and multicasting gains. Simulation results demonstrate that users with more concentrated preferences can attain higher Effective Throughput.
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ICC - Coded Caching Under Heterogeneous User Preferences: An Effective Throughput Perspective
ICC 2019 - 2019 IEEE International Conference on Communications (ICC), 2019Co-Authors: Wei Chen, H. Vincent PoorAbstract:Proactive caching is a promising means to handle increasing wireless traffic. However, how heterogeneous user preferences impact the caching gain is still an open problem. In this paper, a two-phase cache-aided multicasting network is investigated, in which users with heterogeneous preferences are served by a base station through a shared link. It is shown that the achievable domain of Effective Throughput of the users is a convex set and can be characterized by its boundary in the positive orthant. A special type of caching schemes, named uncoded placement absolutely fair (UPAF) caching, is studied. For the two user case, the achievable domain of UPAF policies has a piecewise linear boundary. For the multiuser case, a feasible UPAF policy is proposed to obtain caching and multicasting gains. Simulation results demonstrate that users with more concentrated preferences can attain higher Effective Throughput.
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Content Pushing Over Multiuser MISO Downlinks With Multicast Beamforming and Recommendation: A Cross-Layer Approach
IEEE Transactions on Communications, 2019Co-Authors: Zhiyuan Lin, Wei ChenAbstract:Proactive caching is recognized as a promising approach to handle the rapid growth of data traffic, thereby attracting much attention recently. As a key performance metric of caching, the hit ratio is determined by demand probabilities of users for content items and caching decisions. Because the recommendation system is capable of shaping user demands, the joint caching and recommendation holds the potential of improving the hit ratio substantially. In this paper, joint pushing and recommendation (JPR) schemes are presented for multiuser multiple-input single-output (MISO) systems, in which content items are pushed over MISO downlinks with multicast beamforming. Aiming at maximizing the Effective Throughput, we formulate a multi-stage stochastic programming problem under the constraints of transmit power and quality of experience (QoE). Since the formulated problem is intractable, suboptimal online JPR policies are presented based on the convex–concave procedure and branch-and-bound methods. Simulations show that presented JPR policies are capable of attaining significant Effective Throughput gains.
Lie-liang Yang - One of the best experts on this subject based on the ideXlab platform.
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Adaptive rate DS-CDMA systems using variable spreading factors
IEEE Transactions on Vehicular Technology, 2004Co-Authors: Lie-liang Yang, Lajos HanzoAbstract:In this contribution, adaptive rate transmissions are investigated in the context of direct-sequence code-division multiple-access (DS-CDMA) systems using variable spreading factors (VSFs). In the context of the recently established family of adaptive rate-transmission schemes, the transmission rate is typically adapted in response to the channel's fading-induced quality fluctuation. By contrast, in this contribution the transmission rate is adapted in response to the multiuser interference fluctuations encountered. We present the philosophy of the proposed adaptive rate-transmission scheme and analyze the Effective Throughput as well as the achievable bit error rate (BER) performance, when communicating over additive white Gaussian noise channels. Our study shows that by employing the proposed VSF-assisted adaptive rate-transmission scheme, the Effective Throughput may be increased by up to 40%, when compared to that of DS-CDMA systems using constant spreading factors. This increased Throughput is achieved without wasting power, without imposing extra interference upon other users, and without increasing the BER.
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Improving the Throughput of DS-CDMA systems using adaptive rate transmissions based on variable spreading factors
Proceedings IEEE 56th Vehicular Technology Conference, 1Co-Authors: Lie-liang Yang, Lajos HanzoAbstract:In this contribution adaptive rate transmissions are investigated in the context of DS-CDMA systems using variable spreading factors (VSF). In contrast to conventional adaptive rate transmission schemes, where the transmission rate is usually adapted in response to the channel fading, in this contribution the transmission rate is adapted in response to the multiuser interference (MUI) level. We present the philosophy of the proposed adaptive rate transmission scheme and analyze the Effective Throughput as well as the resultant bit error rate (BER) performance, when communicating over additive white Gaussian noise (AWGN) channels. Our study shows that when the number of active users in a DS-CDMA system can be modelled with the aid of a Markov chain and when the conventional matched filter based receiver is employed, the VSF-assisted adaptive rate transmission scheme is capable of substantially increasing the system's Effective Throughput. Specifically, our results show that the Effective Throughput may be increased by up to 40%, when compared to that of DS-CDMA systems using constant spreading factors. This increased Throughput is achieved without wasting power, without imposing extra interference upon other users and without increasing the BER.
