TL;DR: This paper provides a tractable method to investigate the performance of the small-cell networks with fractal coverage characteristics and finds the average achievable rate and area spectral efficiency with anisotropic path loss models have been underestimated in the fractal small- cell networks.
Abstract: To meet massive wireless traffic demand in the future fifth generation (5G) cellular networks, small-cell networks are emerging as an attractive solution for 5G network deployments. The cellular coverage characteristic is a key issue for the deployment of the small-cell networks. Considering the anisotropic path loss in wireless channels of real cellular scenarios, in this paper the fractal coverage characteristic is first used to evaluate the performance of the small-cell networks. Moreover, the coverage probability, average achievable rate, and the area spectral efficiency are derived for fractal small-cell networks. Compared with the average achievable rate and area spectral efficiency with isotropic path loss models, the average achievable rate and area spectral efficiency with anisotropic path loss models have been underestimated in the fractal small-cell networks. Considering the impact of the anisotropic path loss on wireless channels, most of performances of wireless cellular networks need to be re-evaluated. This paper provides a tractable method to investigate the performance of the small-cell networks with fractal coverage characteristics.
Cites methods from "Coverage Probability and Achievable..."
TL;DR: The derived expression for outage probability is derived when the signal-of-interest and interferers both experience $\kappa$ - $\mu$ shadowed fading in an interference limited scenario and can be expressed in terms of Pochhammer integral.
Abstract: The $\kappa$ - $\mu$ shadowed fading model is a very general fading model as it includes both $\kappa$ - $\mu$ and $\eta$ - $\mu$ as special cases. In this paper, we derive the expression for outage probability when the signal-of-interest (SoI) and interferers both experience $\kappa$ - $\mu$ shadowed fading in an interference limited scenario. The derived expression is valid for arbitrary SoI parameters, arbitrary $\kappa$ , and $\mu$ parameters for all interferers and any value of the parameter $m$ for the interferers excepting the limiting value of $m\rightarrow \infty$ . The expression can be expressed in terms of Pochhammer integral, where the integrands of integral only contains elementary functions. The outage probability expression is then simplified for various special cases, especially when SoI experiences $\eta$ - $\mu$ or $\kappa$ - $\mu$ fading. Furthermore, the rate expression is derived when the SoI experiences $\kappa$ - $\mu$ shadowed fading with the integer values of $\mu$ , and the interferers experience $\kappa$ - $\mu$ shadowed fading with arbitrary parameters. The rate expression can be expressed in terms of sum of Lauricella’s function of the fourth kind. The utility of our results is demonstrated by using the derived expression to study and compare fractional frequency reuse and soft frequency reuse in the presence of $\kappa$ - $\mu$ shadowed fading. Extensive simulation results are provided and these further validate our theoretical results.
Cites methods from "Coverage Probability and Achievable..."
TL;DR: It is shown that the FFR provides better edge CP and average rate when compared with the SFR in single-input single-output (SISO) networks, thereby suggesting thatThe FFR should be preferred over S FR in cellular SISO OFDMA systems.
Abstract: In soft frequency reuse (SFR) when the user is classified as a cell-center user based on signal-to-interference-plus-noise-ratio in a sub-band, the user retains its sub-band. On the other hand, if the user is classified as a cell-edge user, a new sub-band is allocated. We analyze the impact of correlation between the cell-center sub-band and the cell-edge sub-band for a user when the SFR technique is used in a cellular orthogonal frequency division multiple access (OFDMA) system. The coverage probability (CP) and the average rate are derived for the following two cases: 1) when the sub-bands are independent and 2) when the sub-bands are completely correlated. We show that correlation significantly decreases the edge CP and the average rate of the SFR technique, and as the power control factor increases, the impact of correlation decreases. Fractional frequency reuse (FFR) and SFR techniques are compared and it is shown that the impact of correlation on the FFR is significantly lower. Furthermore, it is also shown that the FFR provides better edge CP and average rate when compared with the SFR in single-input single-output (SISO) networks, thereby suggesting that the FFR should be preferred over SFR in cellular SISO OFDMA systems. However, for single-input multiple-output networks, the SFR provides a better average rate when compared with the FFR, especially when the sub-band correlation is not significant. Finally, the impact of log-normal shadowing has been carefully studied.
Cites background or methods from "Coverage Probability and Achievable..."
TL;DR: This paper presents a novel optimal fifth-percentile user rate constrained design for FFR/SFR-based networks that clearly outperforms previous schemes in terms of throughput fairness control due to a more rational compromise between average cell throughput and cell-edge ICIC.
Abstract: Interference mitigation strategies are deemed to play a key role in the context of the next generation (B4G/5G) of multicellular networks based on orthogonal frequency division multiple access. Fractional and soft frequency reuse (FFR, SFR) constitute two powerful mechanisms for intercell interference coordination that have been already adopted by emerging cellular deployments as an efficient way to improve the throughput performance perceived by cell-edge users. This paper presents a novel optimal fifth-percentile user rate constrained design for FFR/SFR-based networks that, by appropriately dimensioning the center and edge regions of the cell, rightly splitting the available bandwidth among these two areas while assigning the corresponding transmit power, allows a tradeoff between cell throughput performance and fairness to be established. To this end, both the cumulative distribution function of the user throughput and the average spectral efficiency of the system are derived assuming the use of the ubiquitous proportional fair scheduling policy. The mathematical framework is then used to obtain numerical results showing that the novel proposed design clearly outperforms previous schemes in terms of throughput fairness control due to a more rational compromise between average cell throughput and cell-edge ICIC.
TL;DR: It is proved that the optimal Full FR coverage is a non-increasing function of BS power when the powers of all BSs in the network are scaled up or down at the same rate.
Abstract: A fractional frequency reuse (FFR) system is an inter-cell interference coordination scheme used in cellular networks. In FFR systems, the available bandwidth is partitioned into orthogonal subbands such that the users near the cell center adopt subbands of a frequency reuse (FR) factor equal to one (i.e., Full FR), and the users near the cell edge adopt the subbands of an FR factor greater than one (i.e., Partial FR). The proper design of Full FR coverage, which is used to distinguish Full FR regions from Partial FR regions, plays a critical role in FFR system performance. This paper studies the optimal Full FR coverage that maximizes system throughput in the downlink in multiple-input multiple-output (MIMO) cellular networks. For MIMO systems, orthogonal space–time block codes are considered. We analytically compare the outage probabilities of Full FR and Partial FR for a given user’s location, where the outage probability is evaluated through small-scale multipath fading. By doing so, subject to the constraint that a given target outage probability (quality-of-service) is satisfied, the optimal Full FR coverage is analyzed as a function of base station (BS) power. We prove that the optimal Full FR coverage is a non-increasing function of BS power when the powers of all BSs in the network are scaled up or down at the same rate. This result offers insight into the design of Full FR coverage in relation to BS power; we gain insight into the complicated relationship between crucial FFR design parameters.
TL;DR: In this paper, the authors propose a multiuser communication architecture for point-to-point wireless networks with additive Gaussian noise detection and estimation in the context of MIMO networks.
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.
TL;DR: Scrase et al. as discussed by the authors provide a comprehensive system-level understanding of LTE, built on explanations of the theories which underlie it, and provide a broad, balanced and reliable perspective on this important technology Lucid yet thorough, the book devotes particular effort to explaining the theoretical concepts in an accessible way.
Abstract: Where this book is exceptional is that the reader will not just learn how LTE works but why it works Adrian Scrase, ETSI Vice-President, International Partnership Projects LTE - The UMTS Long Term Evolution: From Theory to Practice provides the reader with a comprehensive system-level understanding of LTE, built on explanations of the theories which underlie it The book is the product of a collaborative effort of key experts representing a wide range of companies actively participating in the development of LTE, as well as academia This gives the book a broad, balanced and reliable perspective on this important technology Lucid yet thorough, the book devotes particular effort to explaining the theoretical concepts in an accessible way, while retaining scientific rigour It highlights practical implications and draws comparisons with the well-known WCDMA/HSPA standards The authors not only pay special attention to the physical layer, giving insight into the fundamental concepts of OFDMA, SC-FDMA and MIMO, but also cover the higher protocol layers and system architecture to enable the reader to gain an overall understanding of the system Key Features: Draws on the breadth of experience of a wide range of key experts from both industry and academia, giving the book a balanced and broad perspective on LTE Provides a detailed description and analysis of the complete LTE system, especially the ground-breaking new physical layer Offers a solid treatment of the underlying advances in fundamental communications and information theory on which LTE is based Addresses practical issues and implementation challenges related to the deployment of LTE as a cellular system Includes an accompanying website containing a complete list of acronyms related to LTE, with a brief description of each (http://wwwwileycom/go/sesia_theumts) This book is an invaluable reference for all research and development engineers involved in LTE implementation, as well as graduate and PhD students in wireless communications Network operators, service providers and R&D managers will also find this book insightful
TL;DR: While the proposed algorithms are suboptimal, they lead to simpler transmitter and receiver structures and allow for a reasonable tradeoff between performance and complexity.
Abstract: The use of space-division multiple access (SDMA) in the downlink of a multiuser multiple-input, multiple-output (MIMO) wireless communications network can provide a substantial gain in system throughput. The challenge in such multiuser systems is designing transmit vectors while considering the co-channel interference of other users. Typical optimization problems of interest include the capacity problem - maximizing the sum information rate subject to a power constraint-or the power control problem-minimizing transmitted power such that a certain quality-of-service metric for each user is met. Neither of these problems possess closed-form solutions for the general multiuser MIMO channel, but the imposition of certain constraints can lead to closed-form solutions. This paper presents two such constrained solutions. The first, referred to as "block-diagonalization," is a generalization of channel inversion when there are multiple antennas at each receiver. It is easily adapted to optimize for either maximum transmission rate or minimum power and approaches the optimal solution at high SNR. The second, known as "successive optimization," is an alternative method for solving the power minimization problem one user at a time, and it yields superior results in some (e.g., low SNR) situations. Both of these algorithms are limited to cases where the transmitter has more antennas than all receive antennas combined. In order to accommodate more general scenarios, we also propose a framework for coordinated transmitter-receiver processing that generalizes the two algorithms to cases involving more receive than transmit antennas. While the proposed algorithms are suboptimal, they lead to simpler transmitter and receiver structures and allow for a reasonable tradeoff between performance and complexity.
"Coverage Probability and Achievable..." refers background in this paper
TL;DR: Multi-user MIMO (MU-MIMO) networks reveal the unique opportunities arising from a joint optimization of antenna combining techniques with resource allocation protocols, and brings robustness with respect to multipath richness, yielding the diversity and multiplexing gains without the need for multiple antenna user terminals.
Abstract: Multi-user MIMO (MU-MIMO) networks reveal the unique opportunities arising from a joint optimization of antenna combining techniques with resource allocation protocols. Furthermore, it brings robustness with respect to multipath richness, allowing for compact antenna spacing at the BS and, crucially, yielding the diversity and multiplexing gains without the need for multiple antenna user terminals. To realize these gains, however, the BS should be informed with the user's channel coefficients, which may limit practical application to TDD or low-mobility settings. To circumvent this problem and reduce feedback load, combining MU-MIMO with opportunistic scheduling seems a promising direction. The success for this type of scheduler is strongly traffic and QoS-dependent, however.
TL;DR: An overview of the LTE radio interface, recently approved by the 3GPP, together with a more in-depth description of its features such as spectrum flexibility, multi-antenna transmission, and inter-cell interference control are provided.
Abstract: This article provides an overview of the LTE radio interface, recently approved by the 3GPP, together with a more in-depth description of its features such as spectrum flexibility, multi-antenna transmission, and inter-cell interference control. The performance of LTE and some of its key features is illustrated with simulation results. The article is concluded with an outlook into the future evolution of LTE.
"Coverage Probability and Achievable..." refers background in this paper
Q1. What are the contributions in "Coverage probability and achievable rate analysis of ffr-aided multi-user ofdm-based mimo and simo systems" ?
In 8 particular, given a reuse region of 3 ( FR3 ) and a reuse region of 9 1 ( FR1 ) as well as a signal-to-interference-plus-noise-ratio ( SINR ) 10 threshold Sth, which decides the user assignment to either the FR1 11 or FR3 regions, the authors theoretically show that: 1 ) the optimal choice 12 of Sth which maximizes the coverage probability is Sth = T, where 13 T is the target SINR required for ensuring adequate coverage, and 14 2 ) the optimal choice of Sth which maximizes the average rate is 15 given by Sth = 21 Furthermore, the performance of their FFR-aided MU-MIMO and 22 SIMO systems is compared.