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Distributed resource allocation for femtocell interference coordination via power minimisation
Abstract and Figures
This paper proposes a decentralized model for the allocation of modulation and coding schemes, subchannels and transmit power to users in OFDMA femtocell deployments. The proposed model does not rely on any exchanged information between cells, which is especially useful for femtocell networks. Coordination between femtocells is achieved through the intrinsic properties of minimising transmit power independently at each cell, which leads the network to self-organize into an efficient frequency reuse pattern. This paper also provides a two-level decomposition approach for solving this intricate resource assignment problem that is able to find optimal solutions at cell level in reduced periods of time. System-level simulations show a significant performance improvement in terms of user outages and network capacity when using the proposed distributed resource allocation in comparison with scheduling techniques based on uniform power distributions among subcarriers.
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... In this regard, game theory 16 is seen as a typical and important mathematical tool that analyzes strategic interactions among CSCs. On one hand, noncooperative game models have been studied to solve the distributed access management between SCs in the literature, [17][18][19][20][21][22][23] where each SC focuses on its own utility while ignoring other SCs. On the other hand, the cooperation games, namely, coalitional games, [24][25][26][27] have also begun to draw attentions in the researches on distributed access management between SCs, [28][29][30][31][32][33] where SCs carry out cooperative access management through proper information exchange. ...
... Non-cooperative game models have been studied to solve the distributed interference management between SCs in the literature. [17][18][19][20][21][22][23] Dynamic channel selection, frequency reuse, and power control have been studied for SC networks in the literature 11,17,18,19 In Ladanyi et al., 20 the overall transmit power is minimized by a distributed algorithm. Chandrasekhar and Andrews 17 investigated the problem of joint throughput optimization, spectrum allocation, and access control. ...
... Non-cooperative game models have been studied to solve the distributed interference management between SCs in the literature. [17][18][19][20][21][22][23] Dynamic channel selection, frequency reuse, and power control have been studied for SC networks in the literature 11,17,18,19 In Ladanyi et al., 20 the overall transmit power is minimized by a distributed algorithm. Chandrasekhar and Andrews 17 investigated the problem of joint throughput optimization, spectrum allocation, and access control. ...
This article investigates the problem of efficient spectrum access for traffic demands of self-organizing cognitive small-cell networks, using the coalitional game approach. In particular, we propose a novel spectrum and time two-dimensional Traffic Cooperation Coalitional Game model which aims to improve the network throughput. The main motivation is to complete the data traffics of users, and the main idea is to make use of spectrum resource efficiently by reducing mutual interference in the spectrum dimension and considering cooperative data transmission in the time dimension at the same time. With the approach of coalition formation, compared with the traditional binary order in most existing coalition formation algorithms, the proposed functional order indicates a more flexibly preferring action which is a functional value determined by the environment information. To solve the distributed self-organizing traffic cooperation coalition formation problem, we propose three coalition formation algorithms: the first one is the Binary Preferring Traffic Cooperation Coalition Formation Algorithm based on the traditional Binary Preferring order; the second one is the Best Selection Traffic Cooperation Coalition Formation Algorithm based on the functional Best Selection order to improve the converging speed; and the third one is the Probabilistic Decision Traffic Cooperation Coalition Formation Algorithm based on the functional Probabilistic Decision order to improve the performance of the formed coalition. The proposed three algorithms are proved to converge to Nash-stable coalition structure. Simulation results verify the theoretic analysis and the proposed approaches.
... Moreover, the inventions present completely theoretical methods. In contrast, authors in [37] introduce the AMC scheme in the OFDMA-LTE network for the resource allocation and interference management context. The research consists to allocate MCS, RB and power. ...
Responding to the huge demand for high data rates and satisfying Quality of Service (QoS) requirements are the main objectives of the wireless mobile operators. LTE-based small cell system is a promising technology offering the required services, enhanced indoor coverage and increased system capacity. However, many challenges face the constructors and the operators for an effective deployment of these systems. In this thesis, in order to evolve such systems and adduce significant enhancement in terms of QoS and throughput, we adopt a complementary strategy based on both data link layer and physical layer.First, we propose, on the link layer level, two scheduling and joint resource allocation algorithm based on the Adaptive Modulation and Coding (AMC) and the power control mechanism for OFDMA-Downlink and SC-FDMA-Uplink connections respectively. Namely, they refer to: “Downlink AMC-QRAP” and “Uplink AMC-QRAP”. The joint adaptation of the transmission power and the Modulation and Coding Scheme reliably interacts with the link quality on each allocated sub-channel. Two distinct user categories are considered to differentiate between different QoS levels required. Accordingly, a linear optimization model is performed for the problem resolution. A clustering approach proposed in the literature has been used as a tradeoff between centralized and distributed schemes. Particularly, we used the spectrum sensing technique as proposed on the physical layer to detect surrounding transmissions.After that, we tackle the physical layer “signal processing” techniques as an LTE enhancement approach. Thus, two contributions based on the “wavelet transform” (WT) are proposed.The “wavelet-based OFDM” technique is firstly proposed as an alternative transmission mode for both downlink and uplink of the LTE and beyond wireless systems. In fact, theOFDM suffers from several limitations in terms of PAPR, spectral efficiency, synchronization cost and the inter-carrier interference. We proved that with substituting the Fourier transform by the wavelet transform in the OFDM technique, the different OFDM limitations can be significantly overcame. Second, we proposed an enhanced spectrum sensing approach based on WT tool that accurately delimits the occupied resource blocks in the whole spectrum. These physical layer enhancements help improving the scheduling algorithm for the uplink proposed in our second contribution.Extensive network simulations with different network densities have been conducted, using several metrics such as spectral efficiency, throughput satisfaction rate, user outage and transmission power. We have compared our methods to several existing works in the literature and proved the outperformance for the different considered metrics.
... However, most of the existing work is focused on different NUM formulations of ICIC problems, such as self-organized fractional frequency reuse through distributed interference coordination [140], power control and scheduling for interference minimization [77], and heuristic fractional frequency reuse methods for interference avoidance and coordination [127]. Furthermore, interference mitigation aimed at distributed network power minimization and network capacity maximization is considered in [87]. The MLB and user-association problems are discussed in [137,153], and the use of transmit beamforming for interference coordination is covered in [49]. ...
... The aim of the maximum throughput approach is to maximize the overall link throughput by selecting the most appropriate modulation and coding in response to SINR values that allows the maximum throughput based on channel conditions. This is suitable for a high bit-rate system such as conversational and streaming traffic with a lower sensitivity to error probability [54]. For a modulation order, we [55] derive the symbol error probability and bit error probability. ...
Small cell networks (SCNs) are envisaged as a key technology enabling the fifth-generation (5G) wireless communication system to address the challenge of rising mobile data demand. Green communications will be another major attribute of 5G systems, as power consumption from the Information and Communication Technology (ICT) sector is forecast to increase significantly by 2030. Accordingly, energy-efficient small cell network design has attracted significant attention from researchers in recent years. In addition, to enable the ubiquitous deployment of dense small cells, service providers require energy-efficient backhauling solutions. In this paper, we present an energyefficient communication model for 5G heterogeneous networks (HetNets). The proposed model considers both the access and backhaul network elements. We formulate and present an analytical model to calculate the optimum number of small cells that need to be kept active at various times of the day in order to minimize power consumption while meeting users’ quality of service (QoS) demands. Based on our critical investigation of backhaul power consumption, we also isolate and present two energy-efficient backhauling solutions for 5G HetNets. Simulated results reveal that the proposed green communication model saves up to 48% more power than other existing models.
... In this section, we evaluate the efficiency of our proposed Two-tier Cluster-based Resource and Power Assignment approach TCRPA via extensive simulation experiments on a highly congested scenario. To prove the forcefulness of our approach, we compare its performance to the distributed resource and power allocation scheme DRAPM [11] with a contention phase and the semi-centralized QP-FCRA [6] approach previously presented. It is worth noting that the modulation and coding scheme adaptation of DRAPM was not taken into consideration to allow a fair comparison between all schemes. ...
In this paper, we propose a joint power control and resource allocation approach for co-channel deployed femto- and macro-cell networks, denoted as Two-tier Cluster-based Resource and Power Allocation Scheme (TCRPA). The rational behind our proposal is to efficiently mitigate the significant interference faced by indoor users in downlink communications in order to satisfy the resource allocation requirements of femto-users (FU). To this end, we first formulate the resulting optimization problem as a Mixed-Integer Linear Program (MILP). Then, we provide a semi-centralized scheme to solve it. Our proposed scheme TCRPA is based on clustering, which is an arrangement aiming to take the advantages of both centralized and distributed approaches. Simulation results demonstrate that TCRPA can efficiently allocate power and fairly distribute spectrum resources to FUs without affecting the quality of the active macro-users (MU) communications. In particular, significant gains in terms of the overall throughput and the SINR level are achieved in comparison with two prominent state of the art solutions.
... While abundant research on femto-to-macro interference has been carried out [106,107], including the application of POPC [143,144], few techniques have been considered to manage the interference between several densely deployed FBSs. Although, recent research into exactly this area has yielded capacity improvements for both centralised [145] and distributed techniques [146,147]. ...
In wireless networks, there is an ever-increasing demand for higher system throughputs, along
with growing expectation for all users to be available to multimedia and Internet services. This
is especially difficult to maintain at the cell-edge. Therefore, a key challenge for future orthogonal
frequency division multiple access (OFDMA)-based networks is inter-cell interference
coordination (ICIC). With full frequency reuse, small inter-site distances (ISDs), and heterogeneous
architectures, coping with co-channel interference (CCI) in such networks has become
paramount. Further, the needs for more energy efficient, or “green,” technologies is growing.
In this light, Uplink Interference Protection (ULIP), a technique to combat CCI via power
reduction, is investigated. By reducing the transmit power on a subset of resource blocks (RBs),
the uplink interference to neighbouring cells can be controlled. Utilisation of existing reference
signals limits additional signalling. Furthermore, cell-edge performance can be significantly
improved through a priority class scheduler, enhancing the throughput fairness of the system.
Finally, analytic derivations reveal ULIP guarantees enhanced energy efficiency for all mobile
stations (MSs), with the added benefit that overall system throughput gains are also achievable.
Following this, a novel scheduler that enhances both network spectral and energy efficiency
is proposed. In order to facilitate the application of Pareto optimal power control (POPC)
in cellular networks, a simple feasibility condition based on path gains and signal-to-noise-plus-
interference ratio (SINR) targets is derived. Power Control Scheduling (PCS) maximises
the number of concurrently transmitting MSs and minimises their transmit powers. In addition,
cell/link removal is extended to OFDMA operation. Subsequently, an SINR variation
technique, Power SINR Scheduling (PSS), is employed in femto-cell networks where full bandwidth
users prohibit orthogonal resource allocation. Extensive simulation results show substantial
gains in system throughput and energy efficiency over conventional power control schemes.
Finally, the evolution of future systems to heterogeneous networks (HetNets), and the consequently
enhanced network management difficulties necessitate the need for a distributed and autonomous
ICIC approach. Using a fuzzy logic system, locally available information is utilised
to allocate time-frequency resources and transmit powers such that requested rates are satisfied.
An empirical investigation indicates close-to-optimal system performance at significantly
reduced complexity (and signalling). Additionally, base station (BS) reference signals are appropriated
to provide autonomous cell association amongst multiple co-located BSs. Detailed
analytical signal modelling of the femto-cell and macro/pico-cell layouts reveal high correlation
to experimentally gathered statistics. Further, superior performance to benchmarks in terms of
system throughput, energy efficiency, availability and fairness indicate enormous potential for
future wireless networks.
... 모든 사용자에 대한 데이터 전송에는 AMC (adaptive modulation and coding) 기법이 사용된다. 사용자의 수신 SINR에 따른 MCS(modulation and coding scheme) 수준은 표 1과 같이 결정된다[13] .Femtocell Forum에서 제시한 시뮬레이션 파라메 터 값에 따라, 채널의 중심주파수는 2 GHz, 전체 채널의 대역폭은 10 MHz, 매크로셀 기지국의 전송 전력은 43 dBm, 펨토셀 기지국의 최소 및 최대 전 송전력은 각각 -10 및 20 dBm로 설정하였다[14].경로 손실 모델은 표 2와 같다[14] . ...
In the cellular networks adopting femtocells, the macrocell users can suffer from severe interference by the femtocells. In this paper, we propose a distributed transmission power control scheme for femtocells to protect macrocell users. With the proposed scheme, when a macrocell user experiences outage due to severe interference, it informs the interfering femtocell base station (BS) of the outage occurrence, via the macrocell BS. Then, the femtocell BS reduces the transmission power to protect the macrocell user. The proposed scheme does not require too much control information among the macrocell BS, the macrocell users, and the femtocell BS. Moreover, the computational complexity in femtocell BS is very low. By using simulation, we show that the performance of the proposed scheme is good enough to use in practice, in spite of its simplicity.
In recent years, green communications and networks have drawn increasing attention from researchers and relevant industries owing to their economic and environmental benefits. In mobile networks, base stations (BSs) account for 56% of network power consumption. Hence, using green technologies in base stations would have a considerable impact on service providers’ energy bills. Consequently, researchers have investigated various green communication techniques. In this paper, we introduce a new traffic steering technique for energy conservation in next generation communication networks. By leveraging spectrum-based cell zooming techniques, the long-term evolution licensed assisted access (LTE-LAA) concept and software defined radio technology, we introduce a green traffic-steering framework that endeavors to minimize overall network on-grid power consumption and maximize aggregated throughput. Considering the time complexity of the optimum solution, we also propose a heuristic solution. We examine the proposed solution against existing solutions, and our obtained results show that the proposed framework saves up to 15% of on-grid power and increases aggregated throughput by 23%.
Heterogeneous cellular networks (HCN) consist of different layers with shared spectrum; hence, resource management algorithms would play a key role in improving the network efficiency. Almost every present resource allocation algorithm in HCN assumes that the spectrum which is dedicated to each layer is fixed. In this paper, we propose a dynamic spectrum and multicell logarithmic resource allocation algorithm to select the number of shared channels between macros and small cells along with subcarrier and power allocation. Besides, backhaul bandwidth limit in multicell scenario is also suggested, which can be considered as another contribution of this paper. In order to achieve maximum downlink network throughput, we formulate the problem with two primary considerations: interference management and small cell backhaul capacity limitation. This involves the mixed continuous, nonlinear integer and a non-convex problem which in turn is broken to smaller parts. Then by using the upper bounds, a near-optimal solution is found which satisfies the Karush–Kuhn–Tucker conditions. Based on numerical analysis, the network throughput is improved up to 61 % compared to fixed spectrum allocation techniques which use half of the spectrum for shared channels.
OFDMA femtocells have been pointed out by the industry as a good solution not only to overcome the indoor coverage problem but also to deal with the growth of traffic within macrocells. However, the deployment of a new femtocell layer may have an undesired impact on the performance of the macrocell layer. The allocation of spectrum resources and the avoidance of electromagnetic interference are some of the more urgent challenges that operators face before femtocells become widely deployed. In this article a coverage and interference analysis based on a realistic OFDMA macro/femtocell scenario is provided, as well as some guidelines on how the spectrum allocation and interference mitigation problems can be approached in these networks. Special attention is paid to the use of self-configuration and self-optimization techniques for the avoidance of interference.
Femtocells offer a promising way of extending macrocellular network coverage to indoor residential environments. If femtocells are spaced one per home, each on it's own lot, interference low. For dense deployments, i.e. multi-unit construction, SIRS can become very low. Thus we propose a greedy frequency planning algorithm which only uses measurements at the femto-access point. Simulation results show an improvement in SIR due to using the new frequency plan.
This book provides an in-depth guide to femtocell technologies In this book, the authors provide a comprehensive and organized explanation of the femtocell concepts, architecture, air interface technologies, and challenging issues arising from the deployment of femtocells, such as interference, mobility management and self-organization. The book details a system level simulation based methodology addressing the key concerns of femtocell deployment such as interference between femto and macrocells, and the performance of both femto and macrocell layers. In addition, key research topics in interference modeling and mitigation, mobility management and Self-Organizing Network (SON) are highlighted. The authors also introduce HNB/HeNB standardization in 3GPP.. Furthermore, access methods (closed, open and hybrid), applications, timing synchronization, health issues, business models and security are discussed. The authors also provide a comparison between femtocells and other indoor coverage techniques such as picocells, repeaters, distributed antenna systems and radio over fiber. Lastly, both CDMA and OFDMA based femtocells are covered. Key Features: Provides a comprehensive reference on femtocells and related topics Offers the latest research results on femtocells based on simulation and measurements Gives an overview of indoor coverage techniques such as picocells, repeaters, distributed antenna systems, radio over fiber and femtocells Includes chapters on femtocell access network architecture, air interface technologies (GSM, UMTS, HSPA, WiMAX and LTE), femtocell simulation, interference analysis and mitigation in femto/macrocell networks, mobility management in femto/macrocell networks, femtocell self-organization and other key challenges such as timing synchronization and security faced by femtocell deployment Points to over 240 references from 3GPP, The Femto Forum, journals and conference proceedings This book will be an invaluable guide for RF engineers from operators, R&D engineers from femtocells hardware manufacturers, employees from regulatory bodies, radio network planners, academics and researchers from universities and research organizations. Students undertaking wireless communications courses will also find this book insightful.
Femtocells are low–power wireless access points used in the home and office. They operate in licensed spectrum to connect standard mobile phones (WCDMA, LTE, WiMAX, CDMA and GSM) and other mobile devices to a mobile operator s network via standard broadband internet connections. This technology is of high interest for mobile operators and for millions of users who will benefit from enhanced access to mobile broadband services. Femtocells outlines how wireless access points can be used by mobile operators to provide high–speed wireless access, enhancing coverage and capacity and delivering entirely new services, while maximising the benefits of licensed spectrum. The book examines the market, exploring commercial and technical factors which are critical in the initial deployment and long–term success of femtocells. Business, standards and regulatory aspects are also considered to provide a complete but concise overview.
One of the first authoritative texts to concentrate on femtocells
Written by expert authors from industry including leading analysts, femtocell and system vendors
Covers both technology and business aspects in detail
Provides overview of the relevant standards across WCDMA, LTE, CDMA, WiMAX and GSM air interfaces
This paper considers the problem of subcarrier scheduling in the downlink of multicell OFDMA networks. It proposes a dynamic fractional frequency reuse cell architecture that partitions subcarriers into two groups. One is reused in the whole cell area whereas the other is partitioned into sectors and used orthogonally. The proposed architecture allows dynamic allocation of users to the group of subcarriers. This dynamic allocation of users is different from the existing architectures where users are partitioned according to fixed thresholds. Next, we propose an efficient hierarchical solution which first allocates subcarriers to the groups and next opportunistically schedules subcarriers to the users. The overall scheme allows frequency reuse factor of 1 with reduced inter-cell interference, increased trunking gain and satisfied minimum data rate requirements. Simulation results illustrate the usefulness of the proposed solution.
Bell System Technical Journal, also pp. 623-656 (October)
This paper proposes a dynamic fractional frequency reused cell architecture that simplifies the problem of subcarrier allocation with frequency reuse in multicell OFDMA networks. The architecture divides the cell surface into two overlapping geographical regions and orthogonally allocates subcarriers, which are called super and regular group of subcarriers, to the regions. The proposed architecture allows a frequency reuse factor of 1 with reduced inter-cell interference and increased trunking gain, while satisfying minimum data rate requirements. We also propose an efficient hierarchical solution to realize the proposed architecture. The solution first allocates subcarriers to the groups so that long term performance is maximized and next opportunistically schedules subcarriers to the users. The opportunistic scheduling is performed at the base stations considering the fairness requirements of the users. Simulation results illustrate the performance improvements of the proposed solution in comparison to the traditional frequency allocation schemes.