10 research outputs found
Self-optimized Coverage Coordination in Femtocell Networks
This paper proposes a self-optimized coverage coordination scheme for
two-tier femtocell networks, in which a femtocell base station adjusts the
transmit power based on the statistics of the signal and the interference power
that is measured at a femtocell downlink. Furthermore, an analytic expression
is derived for the coverage leakage probability that a femtocell coverage area
leaks into an outdoor macrocell. The coverage analysis is verified by
simulation, which shows that the proposed scheme provides sufficient indoor
femtocell coverage and that the femtocell coverage does not leak into an
outdoor macrocell.Comment: 16 pages, 5 figure
Handover in Mobile Wireless Communication Network - A Review
Mobility is the characteristics of mobile communication that makes it irresistible by all and sundry. The whole world is now engaging in wireless communication as it provides users\u27 ability to communicate on-the-go. This is achieved by transferring users from a radio network to another. This process is called handover. Handover occurs either by cell crossing or by deterioration in signal quality of the current channel. The continuation of an active call is a critical characteristic in cellular systems. Brief overview of handover, handover type, commonly used handover parameters, some methods employed in the literature and we present the convergent point for furtherance in the area of mobile wireless communication Handover
Performance study of FMIPv6-based cross-layer WiMAX handover scheme for supporting VoIP service
This report presents performance study of the FMIPv6-based cross-layer handover scheme for VoIP supports over mobile WiMAX network. For this performance validation and evaluation, the handover delays for four different handover mechanisms are formulated and ns2 based simulation module has been developed. The handover delay, the total delay, and the R factor representing VoIP quality are measured to evaluate the VoIP support characteristics of the FMIPv6-based cross-layer scheme. Simulation results verified that the proposed FMIPv6-based cross-layer handover scheme, compared to the non-cross-layer scheme, successfully reduces total handover delay by almost 50% for the case of layer-3 handover. Further, simulation was also evaluated in terms of R factor indicating voice quality level, of which 70 is a minimum value of a traditional PSTN call to be considered as the lower limit of a VoIP call quality [6]. Through the simulation in this study, the result revealed that the proposed scheme effectively improves VoIP call quality from unacceptable quality to acceptable quality (R factor of 75). Based on these simulation results, it was found that the proposed FMIPv6-based cross-layer handover scheme is an adequate protocol for supporting VoIP services in mobile WiMAX environment
Cloud-CFFR: Coordinated Fractional Frequency Reuse in Cloud Radio Access Network (C-RAN)
MultiPoint (CoMP) processing are two of the conventional meth-ods to mitigate the Inter-Cell Interference (ICI) and to improve the average Signal-to-Interference-plus-Noise Ratio (SINR). How-ever, FFR is associated with low system spectral efficiency and CoMP does not take any action to mitigate the inter-cluster interference. In the context of Cloud Radio Access Network (C-RAN) – a new centralized paradigm for broadband wireless access that addresses efficiently the fluctuation in capacity de-mand through real-time Virtual Base Station (VBS) cooperation in the Cloud – in this paper an innovative uplink solution, called Cloud-CFFR, is proposed to address the aforementioned problems. With respect to both FFR and CoMP, Cloud-CFFR decreases the complexity, delay, and ICI while increasing the system spectral efficiency. Since the system performance in cell-edge regions relies on the cooperation of different VBSs, there is no service interruption in handling handovers; moreover, in order to address the unanticipated change in capacity demand, Cloud-CFFR dynamically changes the sub-band boundaries based on the number of active users in the clusters. Simulation results confirm the validity of our analysis and show the benefits of this novel uplink solution
Low-latency Networking: Where Latency Lurks and How to Tame It
While the current generation of mobile and fixed communication networks has
been standardized for mobile broadband services, the next generation is driven
by the vision of the Internet of Things and mission critical communication
services requiring latency in the order of milliseconds or sub-milliseconds.
However, these new stringent requirements have a large technical impact on the
design of all layers of the communication protocol stack. The cross layer
interactions are complex due to the multiple design principles and technologies
that contribute to the layers' design and fundamental performance limitations.
We will be able to develop low-latency networks only if we address the problem
of these complex interactions from the new point of view of sub-milliseconds
latency. In this article, we propose a holistic analysis and classification of
the main design principles and enabling technologies that will make it possible
to deploy low-latency wireless communication networks. We argue that these
design principles and enabling technologies must be carefully orchestrated to
meet the stringent requirements and to manage the inherent trade-offs between
low latency and traditional performance metrics. We also review currently
ongoing standardization activities in prominent standards associations, and
discuss open problems for future research
LTE 네트워크에서 비디오 전달 서비스의 성능 향상
학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 2. 권태경.LTE includes an enhanced multimedia broadcast/multicast service(eMBMS)but delay-sensitive real-time video streaming requires the combination of efficient handling of wireless link bandwidth and reduced handover delays, which remains a challenge. The 3GPP standard introduces a Multimedia Broadcast and multicast service over a Single Frequency Network (MBSFN) area which is a group of base stations broadcasting the same multicast packets. It can reduce the handover delay within MBSFN areas, but raises the traffic load on LTE networks.
In this dissertation, we first presents an MBSFN architecture based on location management areas (LMAs) which can increase the sizes of MBSFN areas to reduce the average handover delay without too much bandwidth waste. An analytical model is developed to quantify service disruption time, bandwidth usage, and blocking probability for different sizes of MBSFN areas and LMAs while considering user mobility, user distribution, and eMBMS session popularity. Using this model, we also propose how to determine the best sizes of MBSFN areas and LMAs along with performance guarantees. Analytical and simulation results demonstrate that our LMA-based MBSFN scheme can achieve bandwidth-efficient multicast delivery while retaining an acceptable service disruption time.
We next propose to transmit the real-time video streaming packets of eMBMSs proactively and probabilistically, so that the average handover delay perceived by a user is stochastically guaranteed. To quantify the tradeoff between the perceived handover delay and the bandwidth overhead of proactive transmissions, we develop an analytical model considering user mobility, user distribution, and session popularity. Comprehensive simulation is carried out to verify the analysis.
On the other hand, hypertext transfer protocol (HTTP) based adaptive streaming (HAS) is expected to be a dominant technique for non-real-time video delivery in LTE networks. In this dissertation, we first analyze
the root causes of the problems of the existing HAS techniques. Based on the insights gained from our analysis, we propose a network-side HAS solution to provide a fair, efficient, and stable video streaming service. The key characteristics of our solution are: (i) unification of video- and data-users into a single utility framework, (ii) direct rate control conveying the assigned rates to the video client through overwritten HTTP Response messages, and (iii) rate allocation for stability by a stateful approach. By the experiments conducted in a real LTE femtocell network, we compare the proposed solution with state-of-the-art HAS solutions. We reveal that our solution (i) enhances the average video bitrates, (ii) achieves the stability of video quality, and (iii) supports the control of the balance between video- and data-users.Abstract i
I. Introduction 1
II. Performance Improvements on Real-time Multicast Video Delivery 4
2.1 Introduction 4
2.2 Related Work 7
2.3 Location Management Area Based MBSFN 9
2.3.1 Location Management Area (LMA) 10
2.3.2 Handover Delays 12
2.3.3 LMA-based MBSFN Area Planning 12
2.4 Performance Analysis 14
2.4.1 Disruption Time 17
2.4.2 Bandwidth Usage 20
2.4.3 Blocking Probability 21
2.5 Numerical Results 23
2.5.1 Effect of NZ and NL 24
2.5.2 Deciding NZ and NL 27
2.5.3 Effects of v and rho* 31
2.5.4 Effect of alpha 32
2.6 Simulation Results 35
2.7 Conclusion 37
III. Proactive Approach for LMA-based MBSFN 39
3.1 Introduction 39
3.2 Network and MBSFN Modeling 41
3.3 Proactive LMA-based MBSFN 44
3.3.1 Problem Formulation 45
3.3.2 Overall procedure 47
3.4 Performance Evaluation 48
3.4.1 Simulation Setup 48
3.4.2 Computation of pi 50
3.4.3 Simulation Results 51
3.5 Conclusions 53
IV. Performance Improvements on HTTP Adaptive Video Streaming 55
4.1 Introduction 55
4.2 Related Work 57
4.3 Problem Definition 59
4.4 Utility-aware Network-side Streaming Approach 62
4.4.1 Streaming Proxy (SP) 63
4.4.2 Message Flows 65
4.4.3 Characteristics 67
4.5 Bitrate Assignment 68
4.5.1 Bitrate Calculation 69
4.5.2 Enhancing Stability 70
4.5.3 Algorithm for Continuous Bitrates 71
4.5.4 Handling the Bottleneck of Wired Networks 71
4.6 Simulation 73
4.6.1 Static Scenario 73
4.6.2 Mobile Scenarios 75
4.6.3 Algorithm for Continuous Bitrates 77
4.7 Experiments 78
4.7.1 Implementation of DASH Player 79
4.7.2 Implementation of eNB 80
4.7.3 Implementation of Streaming Proxy 83
4.7.4 Experimental Results 83
4.8 Conclusion 87
V. Summary & FutureWork 89
Bibliography 92Docto
Acesso banda larga sem fios em ambientes heterogéneos de próxima geração
Doutoramento em Engenharia InformáticaO acesso ubíquo à Internet é um dos principais desafios para os operadores
de telecomunicações na próxima década. O número de utilizadores da Internet
está a crescer exponencialmente e o paradigma de acesso "always connected,
anytime, anywhere" é um requisito fundamental para as redes móveis de
próxima geração. A tecnologia WiMAX, juntamente com o LTE, foi
recentemente reconhecida pelo ITU como uma das tecnologias de acesso
compatíveis com os requisitos do 4G. Ainda assim, esta tecnologia de acesso
não está completamente preparada para ambientes de próxima geração,
principalmente devido à falta de mecanismos de cross-layer para integração de
QoS e mobilidade. Adicionalmente, para além das tecnologias WiMAX e LTE,
as tecnologias de acesso rádio UMTS/HSPA e Wi-Fi continuarão a ter um
impacto significativo nas comunicações móveis durante os próximos anos.
Deste modo, é fundamental garantir a coexistência das várias tecnologias de
acesso rádio em termos de QoS e mobilidade, permitindo assim a entrega de
serviços multimédia de tempo real em redes móveis.
Para garantir a entrega de serviços multimédia a utilizadores WiMAX, esta
Tese propõe um gestor cross-layer WiMAX integrado com uma arquitectura de
QoS fim-a-fim. A arquitectura apresentada permite o controlo de QoS e a
comunicação bidireccional entre o sistema WiMAX e as entidades das
camadas superiores. Para além disso, o gestor de cross-layer proposto é
estendido com eventos e comandos genéricos e independentes da tecnologia
para optimizar os procedimentos de mobilidade em ambientes WiMAX. Foram
realizados testes para avaliar o desempenho dos procedimentos de QoS e
mobilidade da arquitectura WiMAX definida, demonstrando que esta é
perfeitamente capaz de entregar serviços de tempo real sem introduzir custos
excessivos na rede.
No seguimento das extensões de QoS e mobilidade apresentadas para a
tecnologia WiMAX, o âmbito desta Tese foi alargado para ambientes de
acesso sem-fios heterogéneos. Neste sentido, é proposta uma arquitectura de
mobilidade transparente com suporte de QoS para redes de acesso multitecnologia.
A arquitectura apresentada integra uma versão estendida do IEEE
802.21 com suporte de QoS, bem como um gestor de mobilidade avançado
integrado com os protocolos de gestão de mobilidade do nível IP. Finalmente,
para completar o trabalho desenvolvido no âmbito desta Tese, é proposta uma
extensão aos procedimentos de decisão de mobilidade em ambientes
heterogéneos para incorporar a informação de contexto da rede e do terminal.
Para validar e avaliar as optimizações propostas, foram desenvolvidos testes
de desempenho num demonstrador inter-tecnologia, composta pelas redes de
acesso WiMAX, Wi-Fi e UMTS/HSPA.Ubiquitous Internet access is one of the main challenges for the
telecommunications industry in the next decade. The number of users
accessing the Internet is growing exponentially and the network access
paradigm of “always connected, anytime, anywhere” is a central requirement
for the so-called Next Generation Mobile Networks (NGMN). WiMAX, together
with LTE, was recently recognized by ITU as one of the compliant access
technologies for 4G. Nevertheless, WiMAX is not yet fully prepared for next
generation environments, mainly due to the lack of QoS and mobility crosslayer
procedures to support real-time multimedia services delivery.
Furthermore, besides the 4G compliant WiMAX and LTE radio access
technologies, UMTS/HSPA and Wi-Fi will also have a significant impact in the
mobile communications during the next years. Therefore, it is fundamental to
ensure the coexistence of multiple radio access technologies in what QoS and
mobility procedures are concerned, thereby allowing the delivery of real-time
services in mobile networks.
In order to provide the WiMAX mobile users with the demanded multimedia
services, it is proposed in this Thesis a WiMAX cross-layer manager integrated
in an end-to-end all-IP QoS enabled architecture. The presented framework
enables the QoS control and bidirectional communication between WiMAX and
the upper layer network entities. Furthermore, the proposed cross-layer
framework is extended with media independent events and commands to
optimize the mobility procedures in WiMAX environments. Tests were made to
evaluate the QoS and mobility performance of the defined architecture,
demonstrating that it is perfectly capable of handling and supporting real time
services without introducing an excessive cost in the network.
Following the QoS and mobility extensions provided for WiMAX, the scope of
this Thesis is broaden and a seamless mobility architecture with QoS support in
heterogeneous wireless access environments is proposed. The presented
architecture integrates an extended version of the IEEE 802.21 framework with
QoS support, as well as an advanced mobility manager integrated with the IP
level mobility management protocols. Finally, to complete the work within the
framework of this Thesis, it is proposed an extension to the handover decisionmaking
processes in heterogeneous access environments through the
integration of context information from both the network entities and the enduser.
Performance tests were developed in a real testbed to validate the
proposed optimizations in an inter-technology handover scenario involving
WiMAX, Wi-Fi and UMTS/HSPA