### Citations

528 |
visual networking index: Global mobile data traffic forecast update
- “Cisco
- 2014
(Show Context)
Citation Context ...nication devices, such as smartphones, tablets and laptops, the demand for mobile data traffic is almost getting doubled every year and the trend is expected to continue for at least a few more years =-=[2]-=-. In typical dense urban scenarios, a large proportion of data traffic is generated by highly concentrated groups of users, e.g., at the coffee shops or the airports, which are often termed as hotspot... |

371 | Zero-forcing methods for downlink spatial multiplexing in multiuser MIMO channels
- Spencer, Swindlehurst, et al.
- 2004
(Show Context)
Citation Context ...be independently designed across all groups g. PGP results in an additional inter-group interference term, given by the sum over g′ 6= g in (5), which can be eliminated by block diagonalization [15], =-=[28]-=- or by serving groups of users with disjoint angular support using DFT prebeamforming, in the limit of very large M (see details in [15]). With PGP, the precoding matrix P g depends only on the instan... |

308 | On the optimality of multiantenna broadcast scheduling using zero-forcing beamforming,”
- Yoo, Goldsmith
- 2006
(Show Context)
Citation Context ... peak power P1. The presence of multiple users gives rise to intra-cell interference, which is handled by zero forcing beamforming. In the regime of massive-MIMO, it is well known that user selection =-=[25]-=-, [26], [27] yields negligible gains at the cost of a high channel state information overhead. Therefore, we assume that each small cell simply schedules a random set of S̄f users in its group with un... |

274 |
Noncooperative cellular wireless with unlimited numbers of base station antennas
- Marzetta
- 2010
(Show Context)
Citation Context ...is large (commonly referred to as “massive-MIMO”). The main idea is to use random matrix theory results to reduce channel gains to deterministic constants, which simplifies the analysis significantly =-=[13]-=-, [14]. This forms the foundation of massive-MIMO analysis, which is also a key element of this paper. Having a large number of antennas at the macrocells provides an interesting alternative to interf... |

154 | Modeling and analysis of k-tier downlink heterogeneous cellular networks
- Dhillon, Ganti, et al.
- 2012
(Show Context)
Citation Context ...ll cells are modeled as independent Poisson Point Processes (PPPs) and tools from stochastic geometry are used to derive easy to use expressions for key performance metrics, such as coverage and rate =-=[7]-=-. Since these results are averaged 3over network realizations, these are ideal to understand the “macroscopic” performance trends. The performance of fractional frequency reuse in single antenna HetNe... |

119 | Multi-antenna downlink channels with limited feedback and user selection
- Yoo, Jindal, et al.
- 2007
(Show Context)
Citation Context ...power P1. The presence of multiple users gives rise to intra-cell interference, which is handled by zero forcing beamforming. In the regime of massive-MIMO, it is well known that user selection [25], =-=[26]-=-, [27] yields negligible gains at the cost of a high channel state information overhead. Therefore, we assume that each small cell simply schedules a random set of S̄f users in its group with uniform ... |

109 | On downlink beamforming with greedy user selection: performance analysis and a simple new algorithm.
- Dimic, Sidiropoulos
- 2005
(Show Context)
Citation Context ...P1. The presence of multiple users gives rise to intra-cell interference, which is handled by zero forcing beamforming. In the regime of massive-MIMO, it is well known that user selection [25], [26], =-=[27]-=- yields negligible gains at the cost of a high channel state information overhead. Therefore, we assume that each small cell simply schedules a random set of S̄f users in its group with uniform probab... |

78 |
Interference Coordination and Cancellation for 4G Networks.
- Boudreau, Panicker, et al.
- 2009
(Show Context)
Citation Context ...the interior of all the cells are scheduled on the same frequency resources, whereas the users at the cell edge of the neighboring cells are scheduled on orthogonal resources to mitigate interference =-=[5]-=-. Orthogonalization over time is achieved by introducing almost-blank subframes where the idea is to blank (turn off) some sub-frames of the macrocell so as to reduce the inter-tier interference cause... |

72 |
Achieving ‘massive MIMO’ spectral efficiency with a not-so-large number of antennas
- Huh, Caire, et al.
- 2012
(Show Context)
Citation Context ...after as a transmission resource block). In particular, we denote by M and L the number of antennas at the macrocells and at the small cells, respectively, and assume the regime of massive-MIMO [13], =-=[19]-=-, for which M ≫ L ≫ 1, and the number of users simultaneously served by each base station is significantly less than the corresponding number of transmit antennas. Note that this setup where massive-M... |

67 |
Enhanced intercell interference coordination challenges in heterogeneous networks,”
- Lopez-Perez, Guvenc, et al.
- 2011
(Show Context)
Citation Context ... the main focus of this paper. A. Related Work Interference coordination in HetNets has attracted a lot of attention both in standards bodies, such as 3GPP, as well as in academic research, e.g., see =-=[3]-=-, [4] and the references therein. The typical approach for mitigating this interference involves orthogonalizing the time-frequency resources allocated to the macrocells and small cells. This is also ... |

67 | Offloading in heterogeneous networks: Modeling, analysis, and design insights,”
- Singh, Dhillon, et al.
- 2013
(Show Context)
Citation Context ...tspots increases their rate while reducing the rate of small cells, which may not eventually affect the system performance because of the limited backhaul capacity of the small cells. Please refer to =-=[17]-=-, [18] for more insights on traffic offloading and load balancing in HetNets. 5II. SYSTEM MODEL We consider a HetNet formed by macrocell base stations coexisting in the same coverage area and channel ... |

64 |
Effects on correlation between two mobile radio base-station antennas
- Lee
- 1973
(Show Context)
Citation Context ...e several wavelength separation between the users) but are identically distributed with the same covariance matrix (due to the fact that the scattering landscape is the same for all such users) [15], =-=[21]-=-, [22]. We defer more details to Sections II-B and II-C. 1The extension of this work to a multi-cell setting without any explicit coordination across macrocells is straightforward. 6In order to captur... |

52 | Large system analysis of linear precoding in correlated MISO broadcast channels under limited feedback,”
- Wagner, Couillet, et al.
- 2012
(Show Context)
Citation Context ...ge (commonly referred to as “massive-MIMO”). The main idea is to use random matrix theory results to reduce channel gains to deterministic constants, which simplifies the analysis significantly [13], =-=[14]-=-. This forms the foundation of massive-MIMO analysis, which is also a key element of this paper. Having a large number of antennas at the macrocells provides an interesting alternative to interference... |

39 | Analytical evaluation of fractional frequency reuse for heterogeneous cellular networks,”
- Novlan, Ganti, et al.
- 2012
(Show Context)
Citation Context ...3over network realizations, these are ideal to understand the “macroscopic” performance trends. The performance of fractional frequency reuse in single antenna HetNets is studied using these tools in =-=[8]-=-. The performance of almost-blank subframes is also studied using these tools in [9], [10], where the general idea is to derive a tractable expression for the performance metric, e.g., downlink rate d... |

39 |
Joint spatial division and multiplexing – the large-scale array regime,”
- Adhikary, Nam, et al.
- 2013
(Show Context)
Citation Context ...ith a small number of dominant eigenmodes (eigenvectors of their covariance matrix). The macrocell can exploit this directionality by using Joint Spatial Division and Multiplexing (JSDM), proposed in =-=[15]-=-, in order to simultaneously provide spatial multiplexing to its own users as well as mitigate the cross-tier interference to the small cells. This can be achieved explicitly by nulling certain spatia... |

23 | Joint resource partitioning and offloading in heterogeneous cellular networks,” arXiv preprint arXiv:1303.7039
- Singh, Andrews
- 2013
(Show Context)
Citation Context ...nce trends. The performance of fractional frequency reuse in single antenna HetNets is studied using these tools in [8]. The performance of almost-blank subframes is also studied using these tools in =-=[9]-=-, [10], where the general idea is to derive a tractable expression for the performance metric, e.g., downlink rate distribution, in terms of the fraction of the sub-frame that is blanked along with ot... |

22 |
An overview of load balancing in hetnets: Old myths and open problems,” arXiv preprint arXiv:1307.7779
- Andrews, Singh, et al.
- 2013
(Show Context)
Citation Context ... increases their rate while reducing the rate of small cells, which may not eventually affect the system performance because of the limited backhaul capacity of the small cells. Please refer to [17], =-=[18]-=- for more insights on traffic offloading and load balancing in HetNets. 5II. SYSTEM MODEL We consider a HetNet formed by macrocell base stations coexisting in the same coverage area and channel freque... |

20 |
et al., “Heterogeneous Cellular Networks: From Theory to Practice
- Ghosh
- 2012
(Show Context)
Citation Context ...main focus of this paper. A. Related Work Interference coordination in HetNets has attracted a lot of attention both in standards bodies, such as 3GPP, as well as in academic research, e.g., see [3], =-=[4]-=- and the references therein. The typical approach for mitigating this interference involves orthogonalizing the time-frequency resources allocated to the macrocells and small cells. This is also the m... |

20 | MIMO downlink scheduling with non-perfect channel state knowledge,”
- Shirani-Mehr, Caire, et al.
(Show Context)
Citation Context ...e end of the 6More advanced schemes that guarantee more general notions of fairness can be formulated as a weighted sum rate maximization problem using tools from stochastic network optimization (see =-=[29]-=- and references therein), and by defining a suitable concave network utility function of the user long-term averaged rates. Such schemes give a performance guarantee that depends on a parameter δ, whe... |

18 | Cognitive femtocells: breaking the spatial reuse barrier of cellular systems,”
- Caire, Adhikary, et al.
- 2011
(Show Context)
Citation Context ...nterference caused to the small cells [3]. Note that the interference coordination can also be achieved through distance-based power control, as demonstrated in the case of “cognitive” small cells in =-=[6]-=-. In the literature, there are two main directions taken for the analysis of interference coordination in HetNets. The first one focuses mainly on the spatial aspects (geometry) of the network, where ... |

17 | Joint spatial division and multiplexing: Opportunistic beamforming, user grouping and simplified downlink scheduling,”
- Nam, Adhikary, et al.
- 2014
(Show Context)
Citation Context ...s Ru ≪ Rmc, giving rise to the one-ring channel model between the macrocell and each user group.2 As 2Interested readers should refer to [23] for the discussion on the validity of this statement, and =-=[24]-=- for efficient user grouping algorithms. 7Fig. 1. The hollow “blue” circles denote the user groups that do not contain a small cell, and the filled “red” circles denote the user groups containing a sm... |

14 | Downlink MIMO HetNets: Modeling, ordering results and performance analysis,”
- Dhillon, Kountouris, et al.
- 2013
(Show Context)
Citation Context ...e macrocell and small cell densities. This fraction can then be tuned to optimize the given performance metric. While the performance of multi-antenna HetNets using these tools is under investigation =-=[11]-=-, [12], the analysis of interference coordination for this case does not appear in the literature. Moreover, active interference coordination using antenna beamforming techniques introduces statistica... |

14 |
ITLinQ: A new approach for spectrum sharing in device-to-device communication systems,”
- NaderiAlizadeh, Avestimehr
- 2014
(Show Context)
Citation Context ...tisfies the TIN optimality condition has a worst case complexity that is polynomial in the number of links. However, finding a set that is maximal and optimizes a desired objective is in general hard =-=[31]-=-. We therefore propose the “TIN Selection Algorithm”, which is a greedy heuristic for choosing a set of user groups so that the set of scheduled links in the network is of maximal size and satisfies t... |

11 |
The role of small cells, coordinated multipoint, and massive MIMO in 5G
- Jungnickel, Manolakis, et al.
- 2014
(Show Context)
Citation Context ...s than the corresponding number of transmit antennas. Note that this setup where massive-MIMO macrocells coexist with multiantenna small cells is well motivated in the context of 5G cellular networks =-=[20]-=-. A. Spatial Setup We assume a single-cell scenario, with a macrocell located at the center of a disk of radius Rmc, where Rmc denotes the macrocell coverage radius.1 We focus on a non-uniform user di... |

11 |
Joint spatial division and multiplexing for mm-wave channels,”
- Adhikary
- 2014
(Show Context)
Citation Context ...r group is surrounded by a circular ring of scatterers of radius Ru ≪ Rmc, giving rise to the one-ring channel model between the macrocell and each user group.2 As 2Interested readers should refer to =-=[23]-=- for the discussion on the validity of this statement, and [24] for efficient user grouping algorithms. 7Fig. 1. The hollow “blue” circles denote the user groups that do not contain a small cell, and ... |

7 | Massive MIMO and inter-tier interference coordination - Adhikary, Safadi, et al. - 2014 |

5 |
On number of almost blank subframes in heterogeneous cellular networks
- Cierny, Wang, et al.
- 2013
(Show Context)
Citation Context ...rends. The performance of fractional frequency reuse in single antenna HetNets is studied using these tools in [8]. The performance of almost-blank subframes is also studied using these tools in [9], =-=[10]-=-, where the general idea is to derive a tractable expression for the performance metric, e.g., downlink rate distribution, in terms of the fraction of the sub-frame that is blanked along with other pa... |

5 |
Downlink multi-antenna heterogeneous cellular network with load balancing,” submitted to
- Gupta, Dhillon, et al.
- 2013
(Show Context)
Citation Context ...ocell and small cell densities. This fraction can then be tuned to optimize the given performance metric. While the performance of multi-antenna HetNets using these tools is under investigation [11], =-=[12]-=-, the analysis of interference coordination for this case does not appear in the literature. Moreover, active interference coordination using antenna beamforming techniques introduces statistical depe... |

2 | Spatial blanking and inter-tier coordination in massive-MIMO heterogeneous cellular networks,” submitted to
- Adhikary, Dhillon, et al.
- 2014
(Show Context)
Citation Context ...ia, Los Angeles, CA (email: {adhikary; hdhillon; caire}@usc.edu). This paper is submitted in part to IEEE Globecom, Workshop on Heterogeneous and Small Cell Networks (HetSNets), Austin, TX, Dec. 2014 =-=[1]-=-. Manuscript last updated: July 23, 2014. 2I. INTRODUCTION Since the introduction of advanced communication devices, such as smartphones, tablets and laptops, the demand for mobile data traffic is alm... |

2 |
On the optimality of treating interference as noise,” arXiv preprint arXiv:1305.4610
- Geng, Naderializadeh, et al.
- 2013
(Show Context)
Citation Context ...g scheduling decisions) without any significant protocol overhead. D. Coordination Scheme 3: TIN In this section, we propose an inter-tier interference coordination scheme based on a recent result in =-=[30]-=-, that gives conditions on the (approximated) optimality of treating interference as noise (TIN) in a Gaussian interference channel, i.e., a network consisting of several mutually interfering links. T... |