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Journal ArticleDOI: 10.1109/LCOMM.2016.2541662

On the Ergodic Sum-Capacity of Decentralized Multiple Access Channels

14 Mar 2016-IEEE Communications Letters (IEEE)-Vol. 20, Iss: 5, pp 854-857
Abstract: We consider a fast fading AWGN multiple-access channel (MAC) with full receiver CSI and distributed CSI at the transmitters. The objective is to evaluate the ergodic sum-capacity of this decentralized model, under identical average powers and channel statistics across users. While an optimal water-filling solution can be found for centralized MACs with full CSI at all terminals, such an explicit solution is not considered feasible in distributed CSI models. Our main contribution is an upper-bound on the ergodic sum-capacity when each transmitter is aware only of its own fading coefficients. Interestingly, our techniques also suggest an appropriate lower bound. These bounds are shown to be very close to each other, suggesting the tight nature of the results. more

Topics: Fading (56%)

Open accessJournal ArticleDOI: 10.1109/TCOMM.2019.2933515
Maha Zohdy1, Ali Tajer1, Shlomo Shamai Shitz2Institutions (2)
Abstract: A two-user multiple access channel is considered, in which the channels undergo slow block fading and the state of each channel is known only to its corresponding transmitter. This paper proposes a novel broadcast strategy for multiple access communication in this channel. In the broadcast approach, in principle, a transmitter with CSI uncertainty sends multiple independent superimposed information layers where the rate of each layer is adapted to a specific channel realization. In the existing broadcast approaches to multiuser communication, the transmitters often directly adopt a single-user strategy and each transmitter adapts its transmission to one unknown channel. The novel aspect of the proposed strategy is that it adapts the designed codebooks to the state of the entire network. This is motivated by the fact that the contribution of each user to the network-wide measures (e.g., capacity region) depends not only on the user’s direct channel to the receiver, but also on the qualities of other channels. Average achievable rate region and outer bounds on the capacity region are characterized. Furthermore, the expected capacity region is investigated, where most part of the capacity region boundary is characterized. Finally, an asymptotic capacity region is also characterized. more

Topics: Communication channel (57%), Fading (54%), Decoding methods (53%) more

8 Citations

Proceedings ArticleDOI: 10.1109/DEVIC.2017.8074028
01 Mar 2017-
Abstract: Continuous demand of higher bandwidth is an emerging topic in high speed wireless multiple input multiple output (MIMO) systems. Channel capacity is an important paradigm for achieving higher bandwidth as well as higher data rates. This paper mainly focuses on ergodic channel capacity as well as outage capacity of wireless MIMO combined with phase shift keying (PSK) systems over Rayleigh fading channels. First, ergodic channel capacity and distribution capacity in terms of outage channel capacity is analyzed for variable MIMO-PSK systems without knowing the transmitter channel state information (CSI). Finally, joint MIMO-PSK channel capacity in the presence of antenna correlation effect is estimated and consequently the antenna distribution that optimizes the channel capacity is determined. more

Topics: MIMO (69%), Channel capacity (68%), Precoding (66%) more

1 Citations

Journal ArticleDOI: 10.1007/S00542-018-4041-9
Abstract: Due to the continual advancement of future generation communication systems, channel capacity is considered to be an important parameter for achieving greater signal strength by means of faster data transmission speed. Usually in multiple input multiple output (MIMO) systems, the diversity technique lessens the propagation speed significantly than the channel capacity. Using MIMO in combination with phase shift keying (PSK) modulation jointly known as MIMO–PSK systems, the present paper focuses on a novel distribution method in order to optimize the channel capacity over a Rayleigh fading channel. First, ergodic channel capacity and distribution capacity in terms of outage capacity is simulated for different MIMO–PSK configurations as well as channel conditions. Later, the channel performance of MIMO–PSK for the novel distribution conditions with antenna correlation effect is evaluated and finally the optimal channel capacity is determined. more

Topics: MIMO (71%), Channel capacity (68%), Communication channel (60%) more

1 Citations

Proceedings ArticleDOI: 10.1109/ISIT.2019.8849270
07 Jul 2019-
Abstract: In a coherent time-varying MIMO multiple access channel (MAC), the ergodic sum-capacity can be achieved by suitable power control, which adapts the transmit covariance matrices based on the available channel state information (CSI). We consider a MIMO-MAC model where each transmitter is only aware of its own fading realization. For this distributed MAC, we propose decentralized power control schemes. First, some key structural properties on the optimal power control laws are derived, followed by an upper bound on the sum-capacity. Numerical results show that the proposed power control schemes closely characterize the sum-capacity in several regimes of interest. more

Topics: MIMO (60%), Channel state information (58%), Power control (57%) more

1 Citations

Open accessJournal ArticleDOI: 10.1109/LCOMM.2018.2856240
Kamal Singh1Institutions (1)
Abstract: We consider the decentralized power optimization problem for Gaussian fast-fading multiple access channel (MAC) so that the average sum throughput is maximized. In our MAC setup, each transmitter has access to only its own fading coefficient or channel state information (CSI), while the receiver has full CSI available at all instants. Unlike centralized MAC (full CSIT MAC) where the optimal powers are known explicitly, the analytical solution for optimal decentralized powers does not seem feasible. In this letter, we specialize the alternating-maximization (AM) method for numerically computing the optimal powers and ergodic capacity of the decentralized MAC for general fading statistics and average power constraints. For illustration, we apply our AM method to compute the capacity of MAC channels with fading distributions such as Rayleigh and Rician. more

Topics: Channel state information (59%), Rician fading (58%), Fading (57%) more


Open accessBook
David Tse1, Pramod Viswanath2Institutions (2)
01 Jan 2005-
Abstract: 1. Introduction 2. The wireless channel 3. Point-to-point communication: detection, diversity and channel uncertainty 4. Cellular systems: multiple access and interference management 5. Capacity of wireless channels 6. Multiuser capacity and opportunistic communication 7. MIMO I: spatial multiplexing and channel modeling 8. MIMO II: capacity and multiplexing architectures 9. MIMO III: diversity-multiplexing tradeoff and universal space-time codes 10. MIMO IV: multiuser communication A. Detection and estimation in additive Gaussian noise B. Information theory background. more

Topics: Multi-user MIMO (72%), Spatial multiplexing (72%), MIMO (71%) more

7,400 Citations

Open accessBook
01 Jan 1997-
Abstract: p. 27, l. −11, replace “Schwartz” by “Schwarz” p. 69, l. −13: “ai∗x = bi” should be “ai∗x = bi∗” p. 126, l. 16, replace “inequality constraints” by “linear inequality constraints” p. 153, l. −8, replace aix 6= bi by aix 6= bi p. 163, Example 4.9, first line: replace “from” with “form” p. 165, l. 11, replace p′Ax ≥ 0 by p′Ax ≥ 0 p. 175, l. 1, replace “To this see” by “To see this” p. 203, l. 12: replace x ≥ 0 by x ≥ 0, xn+1 ≥ 0 p. 216, l. −6: replace “≤ c}” by “≤ c′}” p. 216, l. −3: replace c′ by (c1)′ p. 216, l. −2: replace c′ by (c2)′ p. 216, l. −1: right-hand side should be λ(c1)′ + (1− λ)(c2)′ p. 220, l. −12: replace “added to the pivot row” by “added to the zeroth row” more

Topics: Linear programming (57%)

2,645 Citations

Open accessBook
Abbas El Gamal1, Young-Han Kim2Institutions (2)
16 Jan 2012-
Abstract: This comprehensive treatment of network information theory and its applications provides the first unified coverage of both classical and recent results. With an approach that balances the introduction of new models and new coding techniques, readers are guided through Shannon's point-to-point information theory, single-hop networks, multihop networks, and extensions to distributed computing, secrecy, wireless communication, and networking. Elementary mathematical tools and techniques are used throughout, requiring only basic knowledge of probability, whilst unified proofs of coding theorems are based on a few simple lemmas, making the text accessible to newcomers. Key topics covered include successive cancellation and superposition coding, MIMO wireless communication, network coding, and cooperative relaying. Also covered are feedback and interactive communication, capacity approximations and scaling laws, and asynchronous and random access channels. This book is ideal for use in the classroom, for self-study, and as a reference for researchers and engineers in industry and academia. more

Topics: Information theory (60%), Linear network coding (60%), Asynchronous communication (53%) more

2,440 Citations

Proceedings ArticleDOI: 10.1109/ICC.1995.525188
Raymond Knopp1, Pierre A. Humblet1Institutions (1)
18 Jun 1995-
Abstract: We consider a power control scheme for maximizing the information capacity of the uplink in single-cell multiuser communications with frequency-flat fading, under the assumption that the users attenuations are measured perfectly. Its main characteristics are that only one user transmits over the entire bandwidth at any particular time instant and that the users are allocated more power when their channels are good, and less when they are bad. Moreover, these features are independent of the statistics of the fading. Numerical results are presented for the case of single-path Rayleigh fading. We show that an increase in capacity over a perfectly-power controlled (Gaussian) channel can be achieved, especially if the number of users is large. By examining the bit error-rate with antipodal signalling, we show the inherent diversity in multiuser communications over fading channels. more

Topics: Fading (65%), Fading distribution (65%), Channel state information (64%) more

2,247 Citations

Journal ArticleDOI: 10.1109/18.737513
David Tse1, Stephen V. Hanly2Institutions (2)
Abstract: In multiaccess wireless systems, dynamic allocation of resources such as transmit power, bandwidths, and rates is an important means to deal with the time-varying nature of the environment. We consider the problem of optimal resource allocation from an information-theoretic point of view. We focus on the multiaccess fading channel with Gaussian noise, and define two notions of capacity depending on whether the traffic is delay-sensitive or not. We characterize the throughput capacity region which contains the long-term achievable rates through the time-varying channel. We show that each point on the boundary of the region can be achieved by successive decoding. Moreover, the optimal rate and power allocations in each fading state can be explicitly obtained in a greedy manner. The solution can be viewed as the generalization of the water-filling construction for single-user channels to multiaccess channels with arbitrary number of users, and exploits the underlying polymatroid structure of the capacity region. more

Topics: Fading (57%), Polymatroid (56%), Resource allocation (55%) more

1,205 Citations

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