Noncooperative Cellular Wireless with Unlimited Numbers of Base Station Antennas
TL;DR: A cellular base station serves a multiplicity of single-antenna terminals over the same time-frequency interval and a complete multi-cellular analysis yields a number of mathematically exact conclusions and points to a desirable direction towards which cellular wireless could evolve.
Abstract: A cellular base station serves a multiplicity of single-antenna terminals over the same time-frequency interval. Time-division duplex operation combined with reverse-link pilots enables the base station to estimate the reciprocal forward- and reverse-link channels. The conjugate-transpose of the channel estimates are used as a linear precoder and combiner respectively on the forward and reverse links. Propagation, unknown to both terminals and base station, comprises fast fading, log-normal shadow fading, and geometric attenuation. In the limit of an infinite number of antennas a complete multi-cellular analysis, which accounts for inter-cellular interference and the overhead and errors associated with channel-state information, yields a number of mathematically exact conclusions and points to a desirable direction towards which cellular wireless could evolve. In particular the effects of uncorrelated noise and fast fading vanish, throughput and the number of terminals are independent of the size of the cells, spectral efficiency is independent of bandwidth, and the required transmitted energy per bit vanishes. The only remaining impairment is inter-cellular interference caused by re-use of the pilot sequences in other cells (pilot contamination) which does not vanish with unlimited number of antennas.
Citations
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01 Nov 2018
TL;DR: A closed-form expression for the downlink spectral efficiency is derived taking into account the imperfect channel state information (CSI), non-orthogonal pilots, and power control and can be achieved without the knowledge of instantaneous CSI at the users.
Abstract: In this paper, we investigate the impact of multiple-antenna deployment at access points (APs) and users on the performance of cell-free massive multiple-input multiple-output (MIMO). The transmission is done via time-division duplex (TDD) protocol. With this protocol, the channels are first estimated at each AP based on the received pilot signals in the training phase. Then these channel information will be used to decode the symbols before sending to all users. The simple and distributed conjugate beamforming technique is deployed. We derive a closed-form expression for the downlink spectral efficiency taking into account the imperfect channel state information (CSI), non-orthogonal pilots, and power control. This spectral efficiency can be achieved without the knowledge of instantaneous CSI at the users. In addition, the effects of the number antennas per APs and per users are analyzed in the case of using mutual orthogonal pilot sequences and data power control.
42 citations
Cites background from "Noncooperative Cellular Wireless wi..."
...In cellular massive MIMO, the BS with massive antenna arrays simultaneously serves all users in its cell on the same time-frequency resource [4]–[7]....
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TL;DR: In this paper, a phase compensation method by using a staple-shaped probe for alleviating the largest phase offset is proposed conceptually and verified experimentally, which can be effectively applied to a compact staggered dipole array with a wideband simultaneous decoupling.
Abstract: Staggered array antenna is a common array configuration for large-scale array antennas due to its favorable radiation characteristics and relatively large element spacing. In developing a compact staggered dipole array, the most challenging issue is how to simultaneously reduce the four mutual couplings taking place between adjacent co-polarized antenna elements with diversified phase laggings. A large difference in the phase of different mutual couplings makes simultaneous reduction of all the mutual couplings by applying the recently developed array-antenna decoupling surface (ADS) technique difficult. In this article, a phase compensation method by using a staple-shaped probe for alleviating the largest phase offset is proposed conceptually and verified experimentally. With the proposed phase compensation method, the ADS technique can be effectively applied to a compact staggered dipole array with a wideband simultaneous decoupling. The design guideline for the phase compensation probe is presented by EM simulation and a parametric study. Two practical design examples of dual polarized staggered dipole arrays are given to demonstrate the effectiveness of the proposed phase compensation method in conjunction with ADS, showing a promising potential for wideband simultaneous decoupling of a large-scale dual polarized staggered dipole array-antenna.
42 citations
Cites background from "Noncooperative Cellular Wireless wi..."
...elements in a 2-D dual polarized array antenna [4], [5]....
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Proceedings Article•
13 May 2013TL;DR: Stochastic geometric modeling of the BS and MS locations is used and closed-form expressions are derived for the distribution of signal-to-interference-ratio (SIR) for both uplink and downlink, showing that the downlink SIR is greatly influenced by the correlations between the pilot sequences in the non-orthogonal pilots case.
Abstract: We study a multiple input multiple output (MIMO) cellular system where each base-station (BS) is equipped with a large antenna array and serves some single antenna mobile stations (MSs). With the same setup as in [1], the influence of orthogonal and non-orthogonal pilot sequences on the system performance is analytically characterized when each BS has infinitely many antennas. Using stochastic geometric modeling of the BS and MS locations, closed-form expressions are derived for the distribution of signal-to-interference-ratio (SIR) for both uplink and downlink. Moreover, they are shown to be equivalent for the orthogonal pilots case. Further, it is shown that the downlink SIR is greatly influenced by the correlations between the pilot sequences in the non-orthogonal pilots case. Finally, the mathematical tools can be used to study system performances with other general channel estimation methods and transmission-reception schemes.
42 citations
Cites background or methods or result from "Noncooperative Cellular Wireless wi..."
...Note that the transmission-reception schemes studied in [1]...
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...This section generalizes the results in [1] to the case when the pilot sequences are non-orthogonal and when the number of MSs in each cell is an independent and identically distributed (i....
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...The study of such systems has gained immense attention due to their potential for achieving high data rates and throughput gains while ensuring a low transmission powers in both the forward link and reverse link [1]-[3] ....
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...With the same setup as in [1], the influence of...
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...In [1] , a low complexity transmission-reception scheme is studied for the uplink and downlink performance of such a system....
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01 Oct 2018
TL;DR: In this paper, the authors used deep learning to perform user-cell association for sum-rate maximization in massive MIMO networks, where a deep neural network was trained to approach the optimal association rule with a much more limited computational complexity, thus enabling to update the association rule in real-time, on the basis of the mobility patterns of users.
Abstract: This work investigates the use of deep learning to perform user-cell association for sum-rate maximization in Massive MIMO networks. It is shown how a deep neural network can be trained to approach the optimal association rule with a much more limited computational complexity, thus enabling to update the association rule in real-time, on the basis of the mobility patterns of users. In particular, the proposed neural network design requires as input only the users’ geographical positions. Numerical results show that it guarantees the same performance of traditional optimization-oriented methods.
42 citations
01 Mar 2017
TL;DR: This paper proposes a novel, computationally-efficient 1-bit beamforming algorithm referred to as POKEMON (short for PrOjected downlinK bEaMfOrmiNg), which—after its convolution with the MIMO channel matrix—minimizes multi-user interference.
Abstract: One-bit quantization at the base-station (BS) of a massive multiple-input multiple-output (MIMO) wireless system enables significant power and cost savings. While the 1-bit uplink (users communicate to BS) has gained significant attention, the downlink (BS transmits to users) is far less studied. In this paper, we propose a novel, computationally-efficient 1-bit beamforming algorithm referred to as POKEMON (short for PrOjected downlinK bEaMfOrmiNg), which—after its convolution with the MIMO channel matrix—minimizes multi-user interference (a.k.a. spatial leakage). Our algorithm builds upon the biconvex relaxation (BCR) framework, which efficiently approximates the optimal 1-bit beamforming problem that is of combinatorial nature. Our simulation results show that POKEMON significantly outperforms linear beamformers followed by 1-bit quantization in terms of error-rate performance and recent non-linear beamformers in terms of complexity.
42 citations
Cites background from "Noncooperative Cellular Wireless wi..."
...The goal of beamforming in the downlink is to transmit constellation points su ∈ O for u = 1, . . . , U to each user u, where O is the transmit constellation (e.g., QPSK or 16-QAM), while minimizing multi-user interference (MUI) [1, 2]....
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...Scaling such a conventional downlink architecture to massive MIMO systems [1, 2] with hundreds to thousands of active antenna elements would result in prohibitively high power consumption and system costs [3, 4, 5]....
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...We call the quantities β ∈ R+ the beamforming factor and e ∈ CU the residual error vector, which models MUI and other residual distortion caused by the (quantized) beamformer....
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..., QPSK or 16-QAM), while minimizing multi-user interference (MUI) [1, 2]....
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References
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TL;DR: This paper addresses digital communication in a Rayleigh fading environment when the channel characteristic is unknown at the transmitter but is known (tracked) at the receiver with the aim of leveraging the already highly developed 1-D codec technology.
Abstract: This paper addresses digital communication in a Rayleigh fading environment when the channel characteristic is unknown at the transmitter but is known (tracked) at the receiver. Inventing a codec architecture that can realize a significant portion of the great capacity promised by information theory is essential to a standout long-term position in highly competitive arenas like fixed and indoor wireless. Use (n T , n R ) to express the number of antenna elements at the transmitter and receiver. An (n, n) analysis shows that despite the n received waves interfering randomly, capacity grows linearly with n and is enormous. With n = 8 at 1% outage and 21-dB average SNR at each receiving element, 42 b/s/Hz is achieved. The capacity is more than 40 times that of a (1, 1) system at the same total radiated transmitter power and bandwidth. Moreover, in some applications, n could be much larger than 8. In striving for significant fractions of such huge capacities, the question arises: Can one construct an (n, n) system whose capacity scales linearly with n, using as building blocks n separately coded one-dimensional (1-D) subsystems of equal capacity? With the aim of leveraging the already highly developed 1-D codec technology, this paper reports just such an invention. In this new architecture, signals are layered in space and time as suggested by a tight capacity bound.
6,812 citations
"Noncooperative Cellular Wireless wi..." refers background in this paper
...A point-to-point MIMO system [2] requires expensive multiple-antenna terminals....
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TL;DR: Under certain mild conditions, this scheme is found to be throughput-wise asymptotically optimal for both high and low signal-to-noise ratio (SNR), and some numerical results are provided for the ergodic throughput of the simplified zero-forcing scheme in independent Rayleigh fading.
Abstract: A Gaussian broadcast channel (GBC) with r single-antenna receivers and t antennas at the transmitter is considered. Both transmitter and receivers have perfect knowledge of the channel. Despite its apparent simplicity, this model is, in general, a nondegraded broadcast channel (BC), for which the capacity region is not fully known. For the two-user case, we find a special case of Marton's (1979) region that achieves optimal sum-rate (throughput). In brief, the transmitter decomposes the channel into two interference channels, where interference is caused by the other user signal. Users are successively encoded, such that encoding of the second user is based on the noncausal knowledge of the interference caused by the first user. The crosstalk parameters are optimized such that the overall throughput is maximum and, surprisingly, this is shown to be optimal over all possible strategies (not only with respect to Marton's achievable region). For the case of r>2 users, we find a somewhat simpler choice of Marton's region based on ordering and successively encoding the users. For each user i in the given ordering, the interference caused by users j>i is eliminated by zero forcing at the transmitter, while interference caused by users j
2,616 citations
"Noncooperative Cellular Wireless wi..." refers background in this paper
...An alternative to a point-to-point MIMO system is a multiuser MIMO system [3], [4], [5], [6] in which an antenna array simultaneously serves a multiplicity of autonomous terminals....
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Book•
28 Jun 2004TL;DR: A tutorial on random matrices is provided which provides an overview of the theory and brings together in one source the most significant results recently obtained.
Abstract: Random matrix theory has found many applications in physics, statistics and engineering since its inception. Although early developments were motivated by practical experimental problems, random matrices are now used in fields as diverse as Riemann hypothesis, stochastic differential equations, condensed matter physics, statistical physics, chaotic systems, numerical linear algebra, neural networks, multivariate statistics, information theory, signal processing and small-world networks. This article provides a tutorial on random matrices which provides an overview of the theory and brings together in one source the most significant results recently obtained. Furthermore, the application of random matrix theory to the fundamental limits of wireless communication channels is described in depth.
2,308 citations
"Noncooperative Cellular Wireless wi..." refers background in this paper
...It can be shown that the vector φkjΦ ∗ l has exactly the same probability distribution as does any row vector of Φl [15], [16]....
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01 Jan 2004
2,180 citations
TL;DR: It is shown that the dirty paper achievable region achieves the sum-rate capacity of the MIMO BC by establishing that the maximum sum rate of this region equals an upper bound on the sum rate.
Abstract: We consider a multiuser multiple-input multiple- output (MIMO) Gaussian broadcast channel (BC), where the transmitter and receivers have multiple antennas. Since the MIMO BC is in general a nondegraded BC, its capacity region remains an unsolved problem. We establish a duality between what is termed the "dirty paper" achievable region (the Caire-Shamai (see Proc. IEEE Int. Symp. Information Theory, Washington, DC, June 2001, p.322) achievable region) for the MIMO BC and the capacity region of the MIMO multiple-access channel (MAC), which is easy to compute. Using this duality, we greatly reduce the computational complexity required for obtaining the dirty paper achievable region for the MIMO BC. We also show that the dirty paper achievable region achieves the sum-rate capacity of the MIMO BC by establishing that the maximum sum rate of this region equals an upper bound on the sum rate of the MIMO BC.
1,802 citations
"Noncooperative Cellular Wireless wi..." refers background in this paper
...An alternative to a point-to-point MIMO system is a multiuser MIMO system [3], [4], [5], [6] in which an antenna array simultaneously serves a multiplicity of autonomous terminals....
[...]