Models and optimisation methods for interference coordination in self-organising cellular networks

A thesis submitted for the degree of Doctor of PhilosophyWe are at that moment of network evolution when we have realised that our telecommunication systems should mimic features of human kind, e.g., the ability to understand the medium and take advantage of its changes. Looking towards the future, the mobile industry envisions the use of fully automatised cells able to self-organise all their parameters and procedures. A fully self-organised network is the one that is able to avoid human involvement and react to the fluctuations of network, traffic and channel through the automatic/autonomous nature of its functioning. Nowadays, the mobile community is far from this fully self-organised kind of network, but they are taken the first steps to achieve this target in the near future. This thesis hopes to contribute to the automatisation of cellular networks, providing models and tools to understand the behaviour of these networks, and algorithms and optimisation approaches to enhance their performance. This work focuses on the next generation of cellular networks, in more detail, in the DownLink (DL) of Orthogonal Frequency Division Multiple Access (OFDMA) based networks. Within this type of cellular system, attention is paid to interference mitigation in self-organising macrocell scenarios and femtocell deployments. Moreover, this thesis investigates the interference issues that arise when these two cell types are jointly deployed, complementing each other in what is currently known as a two-tier network. This thesis also provides new practical approaches to the inter-cell interference problem in both macro cell and femtocell OFDMA systems as well as in two-tier networks by means of the design of a novel framework and the use of mathematical optimisation. Special attention is paid to the formulation of optimisation problems and the development of well-performing solving methods (accurate and fast)

Effects of practical impairments on cooperative distributed antennas combined with fractional frequency reuse

Cooperative Multiple Point (CoMP) transmission aided Distributed Antenna Systems (DAS) are proposed for increasing the received Signal-to-Interference-plus-Noise-Ratio (SINR) in the cell-edge area of a cellular system employing Fractional Frequency Reuse (FFR) in the presence of realistic imperfect Channel State Information (CSI) as well as synchronisation errors between the transmitters and the receivers. Our simulation results demonstrate that the CoMP aided DAS scenario is capable of increasing the attainable SINR by up to 3dB in the presence of a wide range of realistic imperfections

Analisis Perancangan Fractional Frequency Reuse pada Jaringan Long Term Evolution di Kota Pekanbaru

Long Term Evolution - Advanced (LTE-A) is a 4G wireless broadband technology based on Orthogonal Frequency Division Multiplexing (OFDM). It provides improved system capacity and coverage, high peak data rate and low latency. OFDM technology is used to reduce the Intersymbol Interference (ISI), however it increases the effect of Intercell Interference (ICI) due to single frequency used. The high ICI will give affect to the perfomance of users at the cell edge and cell centre. To avoid the ICI, the ICI management is required.In this paper, the ICI management is described. There are three schemes are analyzed such as Frequency Reuse 1 (FR1), Fractional Frequency Reuse (FFR), Soft Frequency Reuse (SFR). From the simulation results, the best results are provided by SFR. It gives CINR of 21,14 dB, and 40.547,67 kbps of throughpu

Multi-cell Coordination Techniques for DL OFDMA Multi-hop Cellular Networks

The main objective of this project is to design coordinated spectrum sharing and reuse techniques among cells with the goal of mitigating interference at the cell edge and enhance the overall system capacity. The performance of the developed algorithm will be evaluated in an 802.16m (WiMAX) environment. In conventional cellular networks, frequency planning is usually considered to keep an acceptable signal-to-interference-plus noise ratio (SINR) level, especially at cell boundaries. Frequency assignations are done under a cell-by-cell basis, without any coordination between them to manage interference. Particularly this approach, however, hampers the system spectral efficiency at low reuse rates. For a specific reuse factor, the system throughput depends highly on the mobile station (MS) distribution and the channel conditions of the users to be served. If users served from different base stations (BS) experience a low level of interference, radio resources may be reused, applying a high reuse factor and thus, increasing the system spectral efficiency. On the other side, if the served users experience large interference, orthogonal transmissions are better and therefore a lower frequency reuse factor should be used. As a consequence, a dynamic reuse factor is preferable over a fixed one. This work addresses the design of joint multi-cell resource allocation and scheduling with coordination among neighbouring base stations (outer coordination) or sectors belonging to the same one (inner coordination) as a way to achieve flexible reuse factors. We propose a convex optimization framework to address the problem of coordinating bandwidth allocation in BS coordination problems. The proposed framework allows for different scheduling policies, which have an impact on the suitability of the reuse factor, since they determine which users have to be served. Therefore, it makes sense to consider the reuse factor as a result of the scheduling decision. To support the proposed techniques the BSs shall be capable of exchanging information with each other (decentralized approach) or with some control element in the back-haul network as an ASN gateway or some self-organization control entity (centralized approach)

WIMAX LINK PERFORMANCE ANALYSIS FOR WIRELESS AUTOMATION APPLICATIONS

Wireless broadband access technologies are rapidly growing and a corresponding growth in the demand of its applicability transcends faster internet access, high speed file download and different multimedia applications such as voice calls, video streaming, teleconferencing etc, to industrial operations and automation. Industrial and automation systems perform operations that requires the transmission of real time information from one end to another through high-performance wireless broadband communication links. WiMAX, based on IEEE 802.16 standard is one of the wireless broadband access technologies that has overcome location, speed, and access limitations of the traditional Digital Subscriber Line and Wireless Fidelity, and offers high efficient data rates. This thesis presents detailed analysis of operational WiMAX link performance parameters such as throughput, latency, jitter, and packet loss for suitable applicability in wireless automation applications. The theoretical background of components and functionalities of WiMAX physical and MAC layers as well as the network performance features are presented. The equipment deployed for this field experiment are Alvarion BreeZeMAX 3000 fixed WiMAX equipment operating in the 3.5 GHz licensed band with channel bandwidth of 3.5 MHz. The deployed equipment consisting of MBSE and CPE are installed and commissioned prior to field tests. Several measurements are made in three link quality scenarios (sufficient, good and excellent) in the University of Vaasa campus. Observations and results obtained are discussed and analyzed.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

CoMP Aware Radio Resource Management in Integrated PON-OFDM Network

Radio resource management (RRM) is an important component of a mobile wireless network that efficiently utilizes the limited radio resources such as spectrum, transmission power, and network infrastructure. Unfortunately, current RRM schemes do not support cooperative multiple point (CoMP), a promising technology that extends coverage, increases capacity, and improves the spectral efficiency of the next generation broadband network, i.e., 4G network. Specifically, to coordinate with CoMP, a RRM scheme should be aware of three main properties of CoMP - cooperative transmitting information, coordinated scheduling transmission, and single interference noise ratio (SINR) improvement. However, few of the existing RRM schemes consider these properties, since they were designed based on the conventional mobile data networks without CoMP technology. In this dissertation, I present a series of new CoMP aware RRM schemes for ensuring users' throughput and maximizing network capacity in an integrated PON-OFDM network, which is a norm of the 4G network and can best implement the CoMP technology. I call the PON-OFDM network with CoMP a CoMP Network (CoMPNet). I provide two classes of RRM schemes for two practical CoMP technologies, cooperative transmission (CT) and coordinated scheduling (CoS), respectively. In the first class, I propose two groups of RRM schemes using the CT technology. In the first group, three OFDM-TDMA based RRM schemes are designed for three different users' moving speeds. The objective of these schemes is to minimize time slot consumption. The RRM schemes in the third group are contrived for an OFDM-FDMA based CoMPNet. I provide four linear programming (LP) based optimal schemes, one for minimizing bandwidth usage, one for minimizing transmission power consumption, and two for balancing resource costs. An optimized resource allocation solution can be obtained by flexibly choosing one of the schemes according to network load. In the second class, I present a sub-optimal RRM scheme for an OFDM-FDMA based CoMPNet. The CoS technology is applied for ICI mitigation. I formulate the system optimal task into constrained optimization problems for maximizing network capacity. To improve the computation efficiency, fast yet effective heuristic schemes are introduced for divide-and-conquer. The proposed heuristic schemes are featured by CoS based timeslots/subcarriers assignment mechanisms, which are further incorporated with intelligent power control schemes. Through simulations, I study the proposed RRM schemes performances and discuss the effect of the CoMP technology. The performance benefits of CoMP on bandwidth saving and capacity increasing are shown by comparing the new schemes with the conventional schemes without CoMP

D13.2 Techniques and performance analysis on energy- and bandwidth-efficient communications and networking

Deliverable D13.2 del projecte europeu NEWCOM#The report presents the status of the research work of the various Joint Research Activities (JRA) in WP1.3 and the results that were developed up to the second year of the project. For each activity there is a description, an illustration of the adherence to and relevance with the identified fundamental open issues, a short presentation of the main results, and a roadmap for the future joint research. In the Annex, for each JRA, the main technical details on specific scientific activities are described in detail.Peer ReviewedPostprint (published version