Resource allocation in spectrum-sharing ofdma femtocells with heterogeneous services (original) (raw)
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In this paper, we consider the joint subchannel and power allocation problem in both the uplink and the downlink for two-tier networks comprising spectrum-sharing macrocells and femtocells. A joint subchannel and power allocation scheme for co-channel femtocells is proposed, aiming to maximize the capacity for delay-tolerant users subject to delay-sensitive users' quality of service and interference constraints imposed by macrocells. The joint subchannel and power allocation problem is modeled as an mixed integer programming problem, then transformed into a convex optimization problem by relaxing subchannel sharing, and finally solved by a dual decomposition approach. The effectiveness of the proposed approach is verified by simulations and compared with existing scheme.
Interference-aware resource allocation in co-channel deployment of OFDMA femtocells
2012
Macrocells may suffer serious uplink interference introduced by the deployment of co-channel femtocells. In this paper, an interference-aware pricing-based resource allocation algorithm for co-channel femtocells is proposed to alleviate their interference to macrocells without degrading the femtocell's capacity. The subchannel and power allocation problem is modeled as a non-cooperative game. A suboptimal subchannel allocation algorithm and an optimal power allocation algorithm are proposed to implement the resource allocation game. Simulation results show that the proposed algorithm not only improves the capacity of the macrocell but also the total capacity of the two-tier network, as compared with the unpriced subchannel allocation and Modified Iterative Water Filling (MIWF) power allocation algorithm.
Resource allocation with interference mitigation in OFDMA femtocells for co-channel deploymenta
2012
The introduction of femtocells enabled high data rates and better indoor coverage without the need for expanding or increasing the density of cellular networks deployment or upgrading the cellular network infrastructure. Despite this direct advantage, the introduction of femtocells challenges traditional interference mechanisms because of the ad hoc and dense nature of femtocell deployment. In this paper, we propose an optimal downlink frequency assignment scheme. The proposed algorithm is modeled as a transportation problem to optimally allocate frequency subcarriers with the objective of maximizing the system capacity. The scheme can be used as a benchmark for assessing the suitability of interference mitigation schemes in femtocellular networks.
Throughput Optimization, Spectrum Allocation, and Access Control in Two-Tier Femtocell Networks
IEEE Journal on Selected Areas in Communications, 2000
The deployment of femtocells in a macrocell network is an economical and effective way to increase network capacity and coverage. Nevertheless, such deployment is challenging due to the presence of inter-tier and intra-tier interference, and the ad hoc operation of femtocells. Motivated by the flexible subchannel allocation capability of OFDMA, we investigate the effect of spectrum allocation in two-tier networks,
IET Communications, 2016
This paper investigates the downlink resource allocation problem in Orthogonal Frequency Division Multiple Access (OFDMA) Heterogeneous Networks (HetNets) consisting of macrocells and femtocells sharing the same frequency band. The focus is to devise optimised policies for femtocells' access to the shared spectrum, in terms of femtocell transmissions, in order to maximise femto users sum data rate while ensuring that certain level of quality of service (QoS) for the macro-cell users in the vicinity of femtocells is provided. The optimal solution to this problem is obtained by employing the well-known Dual Lagrangian method and the optimal femtocell transmit power and resource allocation solution is derived in detail. However, the optimal solution introduces high computational complexity and may not be feasible to apply in real-time systems. To this end, we propose a heuristic solution to the problem. The algorithms to implement both optimal and efficient suboptimal schemes in a practical system are also given in detail while their complexity is compared. Simulation results show that our proposed dynamic resource allocation scheme a) ensures the macro users QoS requirements compared to the Reuse-1 scheme, where femtocells are allowed to transmit at full power and bandwidth; b) can maintain femto user data rates at high levels, compared to the Orthogonal Frequency Reuse scheme, where the network bandwidth resources are partially divided amongst macro and femtocells; and c) provides performance close to the optimal solution, while introducing much lower complexity.
EURASIP Journal on Advances in Signal Processing, 2015
Femtocell is a novel technology that is used for escalating indoor coverage as well as the capacity of traditional cellular networks. However, interference is the limiting factor for performance improvement due to co-channel deployment between macrocells and femtocells. The traditional network planning is not feasible because of the random deployment of femtocells. Therefore, self-organization approaches are the key to having successful deployment of femtocells. This study presents the joint resource block (RB) and power allocation task for the two-tier femtocell network in a self-organizing manner, with the concern to minimizing the impact of interference and maximizing the energy efficiency. In this study, we analyze the performance of the system in terms of the energy efficiency, which is composed of both the transmission and circuit power. Most of the previous studies investigate the performance regarding the throughput requirement of the two-tier femtocell network while the ene...
Capacity Enhancement with Joint Subchannel and Power Allocation Scheme for OFDMA Femtocell Networks
Efficient power and subchannel allocation methods are required for orthogonal frequency division multiple access (OFDMA) based femtocell networks to improve the capacity of the system. This paper considers a joint subchannel and power allocation algorithm with capacity maximization for downlink of an OFDMA based femtocell networks. In the proposed algorithm subchannel allocation is first performed based on signal to interference plus noise ratio (SINR) of the channel with equal power distribution. Then for enhancing capacity with optimal power allocation, successive convex approximation (SCA) based power optimization is adopted. The effect of Arithmetic geometric mean (AGM) approximation with SCA on power optimization is also investigated. The optimal power is subsequently distributed by water-filling algorithm.
Joint Subchannel Assignment and Power Allocation for OFDMA Femtocell Networks
IEEE Transactions on Wireless Communications, 2014
In this paper, we propose a joint subchannel and power allocation algorithm for the downlink of an orthogonal frequency-division multiple access (OFDMA) mixed femtocell/macrocell network deployment. Specifically, the total throughput of all femtocell user equipments (FUEs) is maximized while the network capacity of an existing macrocell is always protected. Towards this end, we employ an iterative approach in which OFDM subchannels and transmit powers of base stations (BS) are alternatively assigned and optimized at every step. For a fixed power allocation, we prove that the optimal policy in each cell is to give each subchannel to the user with the highest signal-to-interference-plus-noise ratio (SINR) on that subchannel. For a given subchannel assignment, we adopt the successive convex approximation (SCA) approach and transform the highly nonconvex power allocation problem into a sequence of convex subproblems. In the arithmetic-geometric mean (AGM) approximation, we apply geometric programming to find optimal solutions after condensing a posynomial into a monomial. On the other hand, logarithmic and difference-of-two-concave-functions (D.C.) approximations lead us to solving a series of convex relaxation programs. With the three proposed SCA-based power optimization solutions, we show that the overall joint subchannel and power allocation algorithm converges to some local maximum of the original design problem. While a central processing unit is required to implement the AGM approximation-based solution, each BS locally computes the optimal subchannel and power allocation for its own servicing cell in the logarithmic and D.C. approximation-based solutions. Numerical examples confirm the merits of the proposed algorithm.
Spectrum Sharing and Energy-Efficient Power Optimization for Two-tier Femtocell Networks
Proceedings of the 9th International Conference on Cognitive Radio Oriented Wireless Networks, 2014
Two-tier femtocell network is considered a promising solution for the rapidly rising mobile data rate demand due to its high spectrum efficiency. However, underlaying femtocells with macrocells will result in co-channel interference (CCI) which severely deteriorates network performance. Therefore, optimized power control is required in femtocell network to avoid such interference. Additionally, energy efficiency of cellular network is becoming increasingly important under current trend of green communication. Thus, in this paper, we propose an energy efficient power control algorithm for femtocell network. Our proposed model is based on Stackelberg game, in which macro base station (MBS) acts as leader while femto base stations (FBSs) act as followers. MBS adjusts its power and imposes interference price on femtocells to maintain its user's minimum rate requirement and earns revenue. Subsequently, FBSs optimize their power based on the imposed price which takes into account the cost of both spectrum sharing and energy usage. Two cases, namely uniform and non-uniform pricing are considered. And an iterative algorithm which converges rapidly is also proposed to calculate the interference price and power allocation strategy in the two cases. Finally, our model is validated by simulations and the results show the superior performance of our schemes over existing one.
Fair Resource Allocation for OFDMA Femtocell Networks With Macrocell Protection
IEEE Transactions on Vehicular Technology, 2000
We consider the joint subchannel allocation and power control problem for OFDMA femtocell networks in this paper. Specifically, we are interested in the fair resource sharing solution for users in each femtocell that maximizes the total minimum spectral efficiency of all femtocells subject to protection constraints for the prioritized macro users. Toward this end, we present the mathematical formulation for the uplink resource allocation problem and propose an optimal exhaustive search algorithm. Given the exponential complexity of the optimal algorithm, we develop a distributed and low-complexity algorithm to find an efficient solution for the problem. We prove that the proposed algorithm converges and analyze its complexity. Then, we extend the proposed algorithm in three different directions, namely downlink context; resource allocation with rate adaption for femto users; and consideration of a hybrid access strategy where some macro users are allowed to connect with nearby femto base stations to improve the performance of the femto tier. Finally, numerical results are presented to demonstrate the desirable performance of the proposed algorithms.