ANALISIS PENGGUNAAN ALGORITMA GENETIKA UNTUK PENGALOKASIAN DAYA PADA SISTEM FEMTOCELL BERBASIS MIMO-OFDM DENGAN BEAMFORMING

Meningkatnya penggunaan sistem komunikasi nirkabel mengakibatkan alokasi sumber daya radio menjadi hal yang perlu diperhatikan. Buruknya sistem pengalokasian sumber daya akan menurunkan performansi yang didapat user. Hal ini terjadi tidak hanya pada jaringan yang besar, tetapi untuk cakupan wilayah yang kecil seperti femtocell. Karena Macro Base Station (MBS) dan Femto Base Station (FBS) bekerja pada frekuensi yang sama, maka dapat terjadi permasalahan ¬co-channel interference. Co-channel interferece ini terjadi pada sistem multiuser Orthogonal Frequency Division Multiplexing (OFDM) arah downlink khususnya pada Macro User Equipment (MUE) yang berada dekat dengan FBS. Oleh karena itu, dibutuhkan metode untuk mengurangi co-channel interference dan meningkatkan nilai performansi user. Dalam tugas akhir ini digunakan metode Zero Forcing (ZF) Beamforming untuk mengurangi co-channel interference dan metode Algoritma Genetika untuk meningkatkan nilai Signal to Interference plus Noise Ratio (SINR) di sisi MUE dengan mengatur power allocation. Zero-forcing (Null Steering) precoding adalah pemrosesan sinyal pada multiple antena transmitter dimana tidak ada gangguan multiuser dalam komunikasi nirkabelnya. Sedangkan Algoritma genetika merupakan metode yang digunakan untuk memecahkan suatu masalah optimasi yang kompleks yang biasanya sulit diatasi dengan metode yang sederhana. Dari hasil simulasi didapatkan bahwa dengan menggunakan gabungan dua metode tersebut dapat meningkatkan nilai SINR Macro User hingga 39,763 dB lebih baik dibanding tidak menggunakan metode keduanya, 20,899 dB lebih baik dibanding hanya penerapan algoritma genetika, dan 17,097 dB lebih baik dibanding hanya implementasi ZF-beamforming

On the optimisation of practical wireless indoor and outdoor microcells subject to QOS constraints

Wireless indoor and outdoor microcells (WIOMs) have emerged as a promising means to deal with a high demand of mobile users for a variety of services. Over such heterogeneous networks, the deployment of WIOMs costs mobile/telecommunications company high capital expenditures and operating expenses. This paper aims at optimising the WIOMs taking into account various network communication environments. We first develop an optimisation problem to minimise the number of cells as well as determining their optimal locations subject to the constraints of the coverage and quality-of-service (QoS) requirements. In particular, we propose a binary-search based cell positioning (BSCP) algorithm to find the optimal number of cells given a preset candidate antenna positions. The proposed BSCP algorithm is shown to not only reduce the number of cells for saving resources but also requires a low computational complexity compared to the conventional approaches with exhaustive search over all available sites. Moreover, EDX SignalPro is exploited as a simulation platform to verify the effectiveness of the proposed BSCP for the WIOMs with respect to various propagation modes and antenna parameters of different types, including isotropic, multiple-input single-output and multiple-input multiple-output

On the optimisation of practical wireless indoor and outdoor microcells subject to QOS constraints

Wireless indoor and outdoor microcells (WIOMs) have emerged as a promising means to deal with a high demand of mobile users for a variety of services. Over such heterogeneous networks, the deployment of WIOMs costs mobile/telecommunications company high capital expenditures and operating expenses. This paper aims at optimising the WIOMs taking into account various network communication environments. We first develop an optimisation problem to minimise the number of cells as well as determining their optimal locations subject to the constraints of the coverage and quality-of-service (QoS) requirements. In particular, we propose a binary-search based cell positioning (BSCP) algorithm to find the optimal number of cells given a preset candidate antenna positions. The proposed BSCP algorithm is shown to not only reduce the number of cells for saving resources but also requires a low computational complexity compared to the conventional approaches with exhaustive search over all available sites. Moreover, EDX SignalPro is exploited as a simulation platform to verify the effectiveness of the proposed BSCP for the WIOMs with respect to various propagation modes and antenna parameters of different types, including isotropic, multiple-input single-output and multiple-input multiple-output

Resource management for macrocell users in hybrid access femtocells

Abstract-The constant evolution of mobile-phone traffic demands for novel networking solutions especially focused on indoor environment. In this context, the use of femtocells, i.e., cells with very limited coverage area, has been proposed. In this paper, a femtocell network with hybrid access control mode is considered. The activity profile of the Femtocell Users (FUs) is modeled to compute the maximum achievable throughput and the consumed energy per successfully transmitted data bit by the Macrocell Users (MUs), depending on which set of channels are operated in open access mode, i.e., which channels can be used by MUs. Thus, it is identified how many and which channels must be operated in open access mode, depending on the physical capacities of the channels and the amount of time these channels are not occupied by FUs. The results motivate the need for novel resource management schemes which can dynamically adapt the set of open access channels to the network conditions

Improving Macrocell - Small Cell Coexistence through Adaptive Interference Draining

The deployment of underlay small base stations (SBSs) is expected to significantly boost the spectrum efficiency and the coverage of next-generation cellular networks. However, the coexistence of SBSs underlaid to an existing macro-cellular network faces important challenges, notably in terms of spectrum sharing and interference management. In this paper, we propose a novel game-theoretic model that enables the SBSs to optimize their transmission rates by making decisions on the resource occupation jointly in the frequency and spatial domains. This procedure, known as interference draining, is performed among cooperative SBSs and allows to drastically reduce the interference experienced by both macro- and small cell users. At the macrocell side, we consider a modified water-filling policy for the power allocation that allows each macrocell user (MUE) to focus the transmissions on the degrees of freedom over which the MUE experiences the best channel and interference conditions. This approach not only represents an effective way to decrease the received interference at the MUEs but also grants the SBSs tier additional transmission opportunities and allows for a more agile interference management. Simulation results show that the proposed approach yields significant gains at both macrocell and small cell tiers, in terms of average achievable rate per user, reaching up to 37%, relative to the non-cooperative case, for a network with 150 MUEs and 200 SBSs

Control Channel Interference Measurement in LTE-TDD Heterogeneous Network

Deploying low power eNodeBs inside macro-cells is an effective way to enhance indoor coverage. By reusing frequency between macro-cells and indoor femto-cells, the efficiency of expensive licensed spectrum can be further increased. This thesis measured Physical Downlink Control Channel (PDCCH) performance in such a heterogeneous LTE-TDD network. Four USRP software radio terminals and connected Linux workstations were deployed to build a test environment. They acted as eNodeB and UE respectively. During the test, the femto-cell was configured to coordinate its radio frame with the macro-cell. Several criteria including received block error rate, payload bit error rate and symbols signal to interference and noise ratio were used to evaluate the PDCCH performance in macro-cell under heterogeneous environment

プライマリシステムの干渉制限を考慮した周波数共用のためのリソース割り当てに関する研究

In wireless communications, the improvement of spectral efficiency isrequired due to the shortage of frequency resource. As an effectivesolution, spectrum sharing has been attracted attention. A cognitiveradio is promising technology for realization of spectrum sharing. Inthe spectrum sharing, cognitive user (secondary user) has to protectlicensed user (primary user) according to the interference constraint.However, conventional metric of interference constraint cannot avoidlarge performance degradation in primary system with widely rangeof Signal to Noise Ratio (SNR) such as a cellular system. Additionally,conventional interference constraints do not considers schedulingbehavior in cellular system. In order to solve these problems, thispaper proposes novel metric of the interference constraint whichsupports the widely SNR region of the primary system, so calledcapacity conservation ratio (CCR). The CCR is defined as the ratio ofthe capacity of the Primary receiver without interference from thesecondary transmitter, to the decreased primary capacity due tointerference. Proposed interference constraint based on CCR canprotect primary capacities over the widely SNR region. In addition,scheduling behavior of the primary system can be protected by usingproposed interference constraint. In addition, we propose transmitpower control schemes: exact and simplified power control. The exactpower control can satisfy requirement of interference constraintwithout large margin; however, transmit power cannot be derivewithout numerical analysis. In contrast, transmit power isclosed-form solution in the simplified power control with satisfyingthe interference constraint. Finally, this thesis proposes the resourcescheduling under the interference constraint. Proposed schedulingachieves the high throughput and high user fairness in the secondarysystem without increasing feedback information compared withconventional algorithm.現在、無線通信において周波数リソース不足が深刻な問題となっており、抜本的な対策技術としてコグニティブ周波数共用が注目されている。本論文では、周波数共用において既存システムの周波数帯を他システム（2 次システム）が二次利用するために干渉制限指標及びリソース割り当てに関する研究を行った。一つ目の研究では、既存システムに与える与干渉状態の評価指標について提案を行い，幅広い通信品質の既存システムを保護可能な干渉制限について評価を行った．評価ではシステムのリンクが静的モデルおよび動的なリソース配分で変更される動的モデルを用いた．二つ目の研究では，その干渉制限達成可能な送信電力制御の検討を行った。送信電力制御を行う際に，外部からチャネル情報の一部のみが得られると仮定し，確率的に変動するフェージング要素について所望のアウテージ確率を満足できるように数値解析を行い，厳密設計および簡易設計について提案を行った．三つ目の研究では、既存システムが複数端末に対して無線リソースをスケジューリングするモデルへと拡張し，2 次システムが干渉を回避しつつ，効率的リソース割り当てに関する検討を行った。電気通信大学201