Two-tier OFDMA Femtocell Networks Research Articles

Multiobjective Subchannel and Power Allocation in Interference-Limited Two-Tier OFDMA Femtocell Networks

The cochannel deployment of femtocells in a macrocell network is a cost-effective and efficient way to increase network coverage and capacity. However, such deployment is exigent due to the presence of inter- and intratier interference and the ad hoc operation of femtocells. Motivated by the flexible subchannel allocation capability of orthogonal frequency-division multiple access, in this paper, we consider the problem of joint subchannel and power allocation in both the uplink and downlink of a two-tier orthogonal-frequency-division-multiplexing-based femtocell network. It is a multiobjective optimization problem that aims to maximize the throughput of all users, simultaneously increasing the power efficiency of femtocell base stations. Interference to macrocell users is kept below a certain tolerable threshold. The minimum-rate requirements of delay-sensitive users are also taken into consideration. The problem is solved using nondominated sorting genetic algorithm version II, and the results are compared with the existing solution.

Editorial for “SON and Automatic Configuration/Optimization in LTE-A Networks: Challenges and Practical Solutions”

Editorial: This special issue features six selected papers with high quality on the topic of SON and Automatic Configuration/ Optimization in LTE-A Networks: Challenges and Practical Solutions. The first article, BA Pricing Power Control Scheme with Statistical Delay QoS Provisioning in Uplink of Two-tier OFDMAFemtocell Networks”, co-authored by Shenghua He, Zhaoming Lu, Xiangming Wen, Zhicai Zhang, Jun Zhao and Wenpeng Jing, investigates the interference mitigation problem in LTE-A self-organizing networks (SON). In particular, this work has adopted a price-based power control strategy, where the macrocell base station (MBS) protects itself by pricing the interference from femtocell users (FUs). Based on a mathematical analysis, the authors formulate the problem using game theory and propose an effective power allocation algorithm named PSOPA. The simulation results demonstrate that PSOPA can magnificently improve the average effective capacity of each FU while guaranteeing their statistical delay QoS. The second article titled BA Stackelberg Game Based Intertier Spectrum Sharing Scheme for LTE-A SON^ from Songlin Sun, Liang Gong, Bo Rong, Abdel Mouaki and Amir Basri, develops a spectrum sharing scheme between Micro-eNodeB (MeNB) and Pico-eNodeB (PeNB) in LTE-A HetNets. Their proposed model takes into account a number of LTE-A SON techniques, such as eICIC and CRE, and employs Stackelberg game as the mathematical tool. The authors present a variety of simulation results and conclude that their spectrum sharing scheme can allocate frequency resource efficiently between MeNB and PeNB with respect to the change of user density. The next article investigates spectrum sensing for selforganizing Network. The authors (Mengwei Sun, Shenghong Li, Chenglin Zhao and Bin Li) propose a new spectrum sensing scheme to address the grand challenges engendered by time-varying multipath fading channels and unknown noise variance in realistic cognitive radio (CR) applications. CR is of great significance to the future deployment of self-organizing networks due to the spectrum scarcity problem. To make better use of CR, the authors create a dynamic state-space model, based on which spectrum sensing is realized by estimating the primary user’s state, multipath channel impulse response and noise variance jointly and iteratively. Numerical results show that the proposed scheme provides a promising solution of spectrum sensing in practical adverse communication environments. The fourth article, BData and Control Plane Traffic Modelling for LTE Networks,^ from Dima Dababneh, Marc St-Hilaire and Christian Makaya, develops a traffic model that involves bandwidth, signalling, voice BHSA (BHVSA), data BHSA (BHDSA), and EPSB. The proposed model provides network operators with realistic traffic parameters at the deployment phase of LTE networks. In particular, those parameters cover different aspects of the traffic and consider a variety of practical factors such as signalling, bandwidth, busy hour session attempts and number of simultaneous EPS (Evolved Packet Systems) bearers. The results of this work serve as an important guidance in the future network planning * Min Zhang mzhang@bupt.edu.cn

Improving Energy Efficiency of Two-tier OFDMA Femtocell Networks with Distributed Power Control

Improving Energy Efficiency of Two-tier OFDMA Femtocell Networks with Distributed Power Control