Techniques for Interference Mitigation Using Cooperative Resource Partitioning in Multitier LTE HetNets
TL;DR: Two methods for joint ABS density calculation for macrocells and picocells are proposed—bitrate utility-based optimization and physical resource block (PRB) allocation ratio-based formulation and the concept of universal blanking pattern is introduced to coordinate among various base stations.
Abstract: Almost blank subframes (ABSs) have been proposed in the literature as a means to provide interference-free resources to mobile users. The use of ABS becomes inevitable in LTE heterogeneous cellular networks because of severe interference to small cells. Picocell edge users are typically the victims because of high interference exposure from macrocell tier. In case of hotspots with high-user density, picocells cannot provide coverage to the entire hotspot, thus forming a dense ring of macrocell users around picocells. These macrocell users are highly affected by picocell tier and hence should also be considered as victim users (VUEs). We propose that to protect these macrocell VUEs, macrocells and picocells should operate in a cooperative manner, such that not only macrocells should use ABS, but picocells should also use ABS to provide interference-free resources. We also introduce the concept of universal blanking pattern to coordinate among various base stations. We propose two methods for joint ABS density calculation for macrocells and picocells—bitrate utility-based optimization and physical resource block (PRB) allocation ratio-based formulation. Users with different bitrate demands are considered generating more realistic simulation scenarios. Exhaustive simulations illustrate that the proposed schemes offer significant improvement in VUE throughput as well as overall system throughput.
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TL;DR: This paper presents a novel interference mitigation technique known as reverse frequency allocation (RFA), which provides an efficient resource allocation compared with the other state-of-the-art techniques.
Abstract: The deployment of heterogeneous networks (HetNets) inevitably demands the design of interference management techniques to elevate the overall network performance. This paper presents a novel interference mitigation technique known as reverse frequency allocation (RFA), which provides an efficient resource allocation compared with the other state-of-the-art techniques. RFA reverses the transmission direction of interferers, thereby minimizing the cross-tier interference. Eventually, better coverage as well as increased data rates are achieved by providing complementary spectrum to the macro and pico users. In this paper, we present a tractable approach for modeling HetNets under the proposed RFA scheme. Specifically, we employ well known tools from stochastic geometry to derive closed-form expressions for the coverage probability and rate coverage in two-tier cellular network employing RFA and its variants. The modeling is performed using two approaches; first, where the base stations and users are modeled as independent Poisson point processes (PPPs) and second, the interference is approximated using the fluid model. It is shown that the results obtained from the PPP model are accurate for higher values of path loss exponents, while the results from fluid model are useful for smaller values of path loss exponents. The plausibility of model is validated through the Monte-Carlo simulations and the network performance is evaluated in terms of coverage probability, coverage rate, and outage capacity. The results demonstrate that 2-RFA yields outage capacity gains of 13% as compared with the soft fractional frequency reuse scheme, whereas, the performance gains can be further improved by 14% by employing the proposed variants of RFA.
24 citations
Additional excerpts
...Universal blanking pattern is introduced in [20] to provide coordination among base stations of various tiers and reducing interference by using physical resource block allocation....
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TL;DR: The main idea of time-domain interference coordination and two basic schemes in the eICIC standardization are presented, and a systematic introduction to the interactions of these techniques with other network functions are presented.
Abstract: Time-domain enhanced inter-cell interference coordination (eICIC) is an effective technique to reduce the cross-tier inter-cell interference (ICI) in long term evolution (LTE)-based heterogeneous small cell networks (HetSCNs). This paper first clarifies two main communication scenarios in HetSCNs, i.e., macrocells deployed with femtocells (macro-femto) and with picocells (macro-pico). Then, the main challenges in HetSCNs, particularly the severe cross-tier ICI in macro-femto caused by femtocells with closed subscribe group (CSG) access or in macro-pico caused by picocells with range expansion are analyzed. Based on the prominent feature of dominant interference in HetSCNs, the main idea of time-domain interference coordination and two basic schemes in the eICIC standardization, i.e., almost blank subframe (ABS) and orthogonal frequency division multiplexing symbol shift are presented, with a systematic introduction to the interactions of these techniques with other network functions. Then, given macro-femto and macro-pico HetSCNs, an overview is provided on the advanced designs of ABS-based eICIC, including self-optimized designs with regard to key parameters such as ABS muting ratio, and joint optimized designs of ABS-based eICIC and other radio resource management techniques, such as user association and power control. Finally, the open issues and future research directions are discussed.
18 citations
TL;DR: As macro-cell power increases, the results show that the proposed scheme achieves a full diversity order of two and outperforms all existing non-SMC schemes, suggesting the utility of the proposed schemes for potential deployment in 5G cellular networks.
Abstract: We investigate the impact of small-macro cell cooperation (SMC) in improving the spectral efficiency and reliability of uplink transmission in a heterogeneous network. We consider a network of two user equipments (UEs), a macro-cell base station (BS) and a small-cell BS. Joint SMC involves macro-to-small quantized feedback and decode-forward relaying from small to macro cell. This cooperation utilizes full-duplex transmission and intra-network spectrum sharing. We first propose a transmission scheme based on superposition block Markov encoding at each UE, coherent decode-forward relaying and sliding window decoding at the small-cell BS, and quantize-forward relaying and backward decoding at the macro-cell BS. Second, we derive the optimal macro-cell quantization to maximize the whole spectral efficiency. Third, for a certain non-fading scenario, we prove that the proposed scheme asymptotically achieves the capacity (maximum spectral efficiency) by reaching the cut-set bound as macro-cell power approaches infinity. Fourth, we formulate the outage probability over block fading channels, considering the outage events at the small and macro-cell BSs and the channel variations over different blocks. Last, we generalize the proposed scheme to an $N\; (>2)$ -UE case. As macro-cell power increases, the results show that the proposed scheme achieves a full diversity order of two and outperforms all existing non-SMC schemes. These strong results suggest the utility of the proposed scheme for potential deployment in 5G cellular networks.
11 citations
TL;DR: Simulation results show that the optimized strategy outperforms other solutions in terms of EE and user fairness in average and can further improve the user satisfaction and the performance in the system.
Abstract: To solve the problem of load imbalance and system interference in heterogeneous networks (HetNets), an energy efficiency (EE) optimized strategy based on enhanced intercell interference coordination (eICIC) technology is proposed. The optimization of the EE of the system is established by taking into account four components which are the connection between the users and base stations (BSs), almost blank subframe (ABS) ratio, resource allocation in the frequency domain, and the power transmission of the macro BSs (MBSs). In our optimized strategy, the user’s optimal BS connection status are determined according to the overall EE change of the system, and the allocation of subframes and resource blocks of the MBSs both in the time domain and frequency domain are optimized, respectively. We use the Gauss–Seidel method to iteratively solve the optimization problem. Simulation results show that the optimized strategy outperforms other solutions in terms of EE and user fairness in average. The proposed optimization strategy increases the system EE by 24.2% and 19.1%, respectively, when compared with the maximal reference signal received power (MAX-RSRP) and the low power-ABS (LP-ABS) strategies. The Jain fairness index of our proposed optimization strategy is averagely increased by 33.8% and 23.4%, respectively. In addition, the proposed strategy can further improve the user satisfaction and the performance in the system.
7 citations
Cites background from "Techniques for Interference Mitigat..."
...Introducing ABS into SBS was proposed [40] and Tang et al....
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TL;DR: This paper concludes that clustering and resource allocation are more suitable for UDN than interference alignment, clustering, and resource allocate in terms of principles.
Abstract: The explosive growth of the mobile traffic demand has triggered the investigation of 5th generation mobile networks (5G) for the future development of wireless communications. The ultra-dense network (UDN) has the ability to effectively improve system throughput and spectrum utilization by deploying a large number of low-power, low-cost, low-power home base stations or micro base stations. The dense distribution of micro base stations poses new challenges in terms of energy loss and interference management. Firstly, the overview of 5G is briefly introduced in this paper. Then, interference management method for UDN is summarized. So far, interference management methods for UDN mainly include interference alignment, clustering, and resource allocation. The principles of the three methods are described in detail. Finally, we conclude that clustering and resource allocation are more suitable for UDN.
5 citations
Cites background from "Techniques for Interference Mitigat..."
...When the small cell transmits signal, the macro cell uses ABS (Almost Blank Sub-frame) to reduce the transmission power or doesn’t transmit signals, which can reduce or eliminate inter-layer interference [53] [54] [55] [56]....
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References
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TL;DR: The need for an alternative strategy, where low power nodes are overlaid within a macro network, creating what is referred to as a heterogeneous network is discussed, and a high-level overview of the 3GPP LTE air interface, network nodes, and spectrum allocation options is provided, along with the enabling mechanisms.
Abstract: As the spectral efficiency of a point-to-point link in cellular networks approaches its theoretical limits, with the forecasted explosion of data traffic, there is a need for an increase in the node density to further improve network capacity. However, in already dense deployments in today's networks, cell splitting gains can be severely limited by high inter-cell interference. Moreover, high capital expenditure cost associated with high power macro nodes further limits viability of such an approach. This article discusses the need for an alternative strategy, where low power nodes are overlaid within a macro network, creating what is referred to as a heterogeneous network. We survey current state of the art in heterogeneous deployments and focus on 3GPP LTE air interface to describe future trends. A high-level overview of the 3GPP LTE air interface, network nodes, and spectrum allocation options is provided, along with the enabling mechanisms for heterogeneous deployments. Interference management techniques that are critical for LTE heterogeneous deployments are discussed in greater detail. Cell range expansion, enabled through cell biasing and adaptive resource partitioning, is seen as an effective method to balance the load among the nodes in the network and improve overall trunking efficiency. An interference cancellation receiver plays a crucial role in ensuring acquisition of weak cells and reliability of control and data reception in the presence of legacy signals.
1,734 citations
"Techniques for Interference Mitigat..." refers background in this paper
...Such a network consisting of small cells like picocells and femtocells overlaid in the macrocellular region is known as a heterogeneous cellular network (HetNet) [2]....
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Book•
16 Sep 2010
TL;DR: This book presents an enormous amount of information in a concise and accessible format and begins with the assumption that the reader has never seen a matrix.
1,236 citations
"Techniques for Interference Mitigat..." refers background in this paper
...This is a negative semidefinite matrix [27], since its eigenvalues are nonpositive....
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TL;DR: In this article, the authors address Rayleigh fading, primarily in the UHF band, that affects mobile systems such as cellular and personal communication systems (PCS) and itemizes the fundamental fading mani.
Abstract: The paper addresses Rayleigh fading, primarily in the UHF band, that affects mobile systems such as cellular and personal communication systems (PCS) The paper itemizes the fundamental fading mani
953 citations
01 Jan 2011
TL;DR: The concept of heterogeneous networks is presented and the major technical challenges associated with such network architecture are described and focused on the standardization activities within the 3GPP related to enhanced intercell interference coordination.
Abstract: GPP LTE-Advanced has recently been investigating heterogeneous network (HetNet) deployments as a cost effective way to deal with the unrelenting traffic demand. HetNets consist of a mix of macrocells, remote radio heads, and low-power nodes such as picocells, femtocells, and relays. Leveraging network topology, increasing the proximity between the access net- work and the end users, has the potential to pro- vide the next significant performance leap in wireless networks, improving spatial spectrum reuse and enhancing indoor coverage. Neverthe- less, deployment of a large number of small cells overlaying the macrocells is not without new technical challenges. In this article, we present the concept of heterogeneous networks and also describe the major technical challenges associat- ed with such network architecture. We focus in particular on the standardization activities within the 3GPP related to enhanced intercell interfer- ence coordination.
947 citations
"Techniques for Interference Mitigat..." refers background in this paper
...To mitigate this problem, enhanced intercell interference coordination (eICIC) [6], [7] has been proposed, which exploited the concept of protected subframes (PSFs) or ABSs [8]....
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TL;DR: In this article, the authors present the concept of heterogeneous networks and also describe the major technical challenges associated with such network architecture, focusing in particular on the standardization activities within the 3GPP related to enhanced intercell interference coordination.
Abstract: 3GPP LTE-Advanced has recently been investigating heterogeneous network (HetNet) deployments as a cost effective way to deal with the unrelenting traffic demand. HetNets consist of a mix of macrocells, remote radio heads, and low-power nodes such as picocells, femtocells, and relays. Leveraging network topology, increasing the proximity between the access network and the end users, has the potential to provide the next significant performance leap in wireless networks, improving spatial spectrum reuse and enhancing indoor coverage. Nevertheless, deployment of a large number of small cells overlaying the macrocells is not without new technical challenges. In this article, we present the concept of heterogeneous networks and also describe the major technical challenges associated with such network architecture. We focus in particular on the standardization activities within the 3GPP related to enhanced intercell interference coordination.
945 citations