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Quelle est la principale fonction des bearers GBR dans le système LTE?

  • Assurer un coût minimum pour les utilisateurs
  • Garantir un débit binaire minimum (correct)
  • Traiter uniquement le trafic de fond
  • Prioriser les utilisateurs en fonction de la localisation

    • Quelle fonction n'est pas incluse dans le cadre des fonctions de l'EPC?

  • Authentification des utilisateurs
  • Gestion de la mobilité
  • Protection physique du lien réseau
  • Routage de circuit (correct)

    • Quel est l'objectif principal de l'EPS Mobility Management (EMM)?

  • Surveiller l'utilisation des données par les utilisateurs
  • Gérer la mobilité de l'équipement utilisateur (UE) (correct)
  • Créer de nouveaux utilisateurs sur le réseau
  • Assurer la sécurité des données dans le réseau

    • Quelle est une caractéristique des bearers non-GBR?

    <p>Ils dépendent de la charge du système</p> Signup and view all the answers

    Quel aspect joue un rôle crucial dans la gestion de la qualité de service (QoS) dans le LTE?

    <p>L'utilisation de QoS Classes Identifiers (QCI)</p> Signup and view all the answers

    Quel rôle a le Packet Data Network Gateway (PGW) dans l'EPC?

    <p>Il connecte l'EPC à des réseaux externes</p> Signup and view all the answers

    Qu'est-ce que le Scheduling dans le contexte de la gestion des ressources radio LTE?

    <p>Répartition des ressources radio sur plusieurs cellules</p> Signup and view all the answers

    Quelle alternative ne fait pas partie des classes de bearers dans le LTE?

    <p>Prioritaire</p> Signup and view all the answers

    Comment l'EPC intègre-t-il la gestion des ressources radio?

    <p>À l'aide de politiques de gestion de charge et de répartition</p> Signup and view all the answers

    Quel est le résultat de l'intégration de l'EPS avec les réseaux antérieurs 2G et 3G?

    <p>Une meilleure performance QoS pour tous les utilisateurs</p> Signup and view all the answers

    Quel codec est principalement utilisé dans les systèmes LTE pour la gestion des ressources radio ?

    <p>OFDMA</p> Signup and view all the answers

    Quelle est l'une des fonctions clés de la gestion du porteur dans le système LTE ?

    <p>Assurance de débit binaire garanti (GBR)</p> Signup and view all the answers

    Quel mécanisme est utilisé dans le LTE pour gérer l'interférence entre plusieurs cellules ?

    <p>Inter-cell Interference Coordination (ICIC)</p> Signup and view all the answers

    Quel est l'avantage principal d'une architecture de système évolqué comme l'Evolved Packet System (EPS) dans LTE ?

    <p>Division indépendante des réseaux RAN et CN</p> Signup and view all the answers

    Comment la qualité de service est-elle déterminée dans un réseau LTE ?

    <p>Par le QoS Class Identifier (QCI)</p> Signup and view all the answers

    Quelle vitesse de débit de liaison descendante peut atteindre LTE-Advanced avec une largeur de bande de 100 MHz ?

    <p>1 Gbps</p> Signup and view all the answers

    Quelle technique est utilisée dans LTE pour améliorer l'efficacité spectrale en liaison montante ?

    <p>OFDMA</p> Signup and view all the answers

    Quelle caractéristique distingue l'eNodeB dans l'architecture LTE des anciennes NodeB ?

    <p>Gestion indépendante des ressources radio</p> Signup and view all the answers

    Qu'est-ce qu'un débit binaire garanti (GBR) dans le contexte des réseaux LTE ?

    <p>Un débit minimisé pour les applications critiques</p> Signup and view all the answers

    Quelle est l'importance de la spectral efficiency dans la conception de LTE ?

    <p>Elle mesure l'efficacité de l'utilisation de la bande passante</p> Signup and view all the answers

    Qui est responsable de la normalisation de LTE au niveau mondial ?

    <p>3GPP</p> Signup and view all the answers

    Quel est le rôle principal du QoS Class Identifier (QCI) dans la gestion des ressources ?

    <p>Déterminer la priorité et la gestion des erreurs des paquets</p> Signup and view all the answers

    Quelle fonctionnalité est directement associée à la gestion de la mobilité dans l'EPC ?

    <p>Utilisation de l'interface X2 pour le transfert entre RAN</p> Signup and view all the answers

    Quel est l'objectif principal de la coordination de l'inter-cellulaire (ICIC) dans LTE ?

    <p>Réduire les interférences lors de l'utilisation de la même fréquence</p> Signup and view all the answers

    Quelle est la principale différence entre les classes de bearers Guaranteed Bit Rate (GBR) et Non-GBR ?

    <p>GBR garantit une allocation de bande passante minimale</p> Signup and view all the answers

    Quels paramètres sont associés à chaque bearer dans la gestion des bearers ?

    <p>QCI et Taux d'Allocation et de Rétention (ARP)</p> Signup and view all the answers

    Quelle couche du modèle de protocoles LTE est responsable de la transmission réelle des données ?

    <p>Couche physique</p> Signup and view all the answers

    Dans la gestion des bearers, quelle option représente la plus haute priorité dans les paramètres QCI ?

    <p>QCI 1</p> Signup and view all the answers

    Quelle fonction le protocole MAC (Medium Access Control) remplit-il dans LTE ?

    <p>Décision de transmission et gestion des ressources radio</p> Signup and view all the answers

    Quel est le taux de perte de paquets (Packet Error Loss Rate) associé au QCI 4 pour les vidéos non-conversationnelles ?

    <p>$10^{-6}$</p> Signup and view all the answers

    Quel protocole est responsable de la livraison des paquets entre l'UE et le eNodeB ?

    <p>Packet Data Convergence Protocol (PDCP)</p> Signup and view all the answers

    Quelle couche est responsable de la segmentation ou de la concaténation des données dans le modèle de protocole LTE ?

    <p>Contrôle de Lien Radio (RLC)</p> Signup and view all the answers

    Quel type de canaux fournit des services de la couche MAC à la couche RLC ?

    <p>Canaux logiques</p> Signup and view all the answers

    Quel QCI est utilisé typiquement pour le bearer par défaut dans un réseau LTE ?

    <p>QCI 9</p> Signup and view all the answers

    Quels sont les types de ressources que l'ICIC doit gérer pour éviter les interférences ?

    <p>Fréquences et puissance d'émission</p> Signup and view all the answers

    Quel est le type d'handover utilisé lors du changement d'un eNodeB à un autre dans l'EPC ?

    <p>Hard Handover</p> Signup and view all the answers

    Study Notes

    4G Technology and Long Term Evolution (LTE)

    • 4G technology provides high-speed, universally accessible wireless service.
    • It creates a revolution in networking for tablets, smartphones, computers, and other devices, similar to the revolution caused by Wi-Fi.
    • LTE and LTE-Advanced will be studied, covering system architecture, goals, requirements for the core network (Evolved Packet System), LTE channel, and physical layer.
    • The study will begin with LTE Release 8, followed by enhancements from Releases 9-12.

    Purpose, Motivation, and Approach to 4G

    • The goal is ultra-mobile broadband access for various mobile devices.
    • International Telecommunication Union (ITU) 4G directives for IMT-Advanced specify an all-IP packet-switched network.
    • Peak data rates of up to 100 Mbps for high-mobility and up to 1 Gbps for low-mobility are required.
    • Integration with varied network resources, including 2G, 3G networks, small cells (picocells, femtocells, relays), and WLANs, is crucial for seamless experience.
    • High-quality service is needed for multimedia applications.
    • There is no support for circuit-switched voice; instead, Voice over LTE (VoLTE) is used.
    • Spread spectrum is replaced with OFDM.

    Wireless Network Generations (Table 14.1)

    • Historical overview of wireless network generations (1G, 2G, 2.5G, 3G, 4G).
    • Key data about technology, implementation, services, data rate, and core network.

    LTE Architecture

    • Two candidates for 4G technology include IEEE 802.16 WiMax and Long Term Evolution (LTE).
    • IEEE 802.16 WiMax enhances previous fixed wireless standards for mobility.
    • LTE's development was part of the Third Generation Partnership Project (3GPP), a consortium of Asian, European, and North American telecommunications standards organizations.
    • LTE uses OFDM and OFDMA.
    • Some features originated in the 3G era for 3GPP, including initial LTE data rates being similar to 3G.
    • 3GPP Release 8 introduced a clean-slate approach with a completely new air interface incorporating OFDM, OFDMA, and MIMO.
    • 3GPP Release 10, commonly known as LTE-Advanced, further enhanced LTE with additional improvements.

    LTE and LTE-Advanced Performance Comparison (Table 14.2)

    • Comparison table for LTE and LTE-Advanced, showing performance requirements regarding peak rates (downlink and uplink), control plane delay (idle to connected, dormant to active), user plane delay, spectral efficiency (downlink and uplink), and mobility.

    Evolved Packet Core (EPC)

    • The overall architecture is called the Evolved Packet System (EPS).
    • 3GPP standards divide the network into Radio Access Network (RAN) and Core Network (CN).
    • Long Term Evolution (LTE) is the RAN, called Evolved UMTS Terrestrial Radio Access (E-UTRA) or Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).
    • eNodeB is the only logical node in E-UTRAN (no RNC used).
    • EPC is the operator or carrier core network.
    • Key design principles of the EPS include packet-switched transport for various QoS classes (conversational, streaming, real-time, non-real-time, and background), radio resource management (end-to-end QoS, transport, load sharing/balancing, policy management/enforcement, integration with existing 3GPP 2G and 3G networks), scalable bandwidth (1.4 MHz to 20 MHz), and carrier aggregation (100 MHz).

    Functions of the EPS

    • Functions of the Evolved Packet System (EPS) include network access control (selection, authentication, authorization, admission control, policy and charging enforcement, lawful interception), packet routing and transfer, security (ciphering, integrity protection, network interface physical link protection), mobility management, radio resource management (single and multi-cell aspects), network management, IP networking functions, connections of eNodeBs and E-UTRAN sharing, emergency session support.

    EPC Components

    • Key EPC components, such as Mobility Management Entity (MME), Serving Gateway (SGW), Packet Data Network Gateway (PGW), and Home Subscriber Server (HSS).
    • Detailed functions and roles of each component.
    • Interfaces (S1 and X2) enabling communication between eNodeBs and other network entities.

    Non-Access Stratum Protocols

    • Protocols for interaction between the EPC and UE, not part of the Access Stratum (e.g., EPS Mobility Management (EMM) for UE mobility management, and EPS Session Management (ESM) for activating, authenticating, modifying, and deactivating user plane channels).

    LTE Resource Management

    • LTE uses bearers instead of circuits for quality of service (QoS) control (discussed in Chapter 3).
    • EPS bearers connect PGW and UE, mapping to QoS parameters such as data rate, delay, and packet error rate.
    • Service Data Flows (SDFs) differentiate traffic between applications and map to EPS bearers for QoS treatment.
    • End-to-end service is not wholly managed by LTE.

    Classes of Bearers

    • Guaranteed Bit Rate (GBR) bearers supply a minimum bit rate with possible higher rates if resources allow; useful in voice, interactive video, or real-time gaming.
    • Non-GBR bearers do not guarantee a minimum bit rate; performance depends on the number of UEs served and system load; useful for e-mail, file transfer, web browsing, and P2P file sharing.

    Bearer Management

    • Each bearer is assigned a QoS class identifier (QCI).
    • Detailed QoS parameters (packet delay budget, packet error loss rate) are standardized for different QCI values, with corresponding example services.
    • Scheduling policy, admission thresholds, rate-shaping policy, queue management thresholds, and link layer protocol configuration are linked to each QCI.
    • Guaranteed Bit Rate (GBR) and Maximum Bit Rate (MBR).

    EPC Functions

    • EPC functions, including mobility management (using X2 interface for movement within the same MME and S1 interface for movement to another MME, involving hard handovers), inter-cell interference coordination (ICIC) to reduce interference when using the same frequency in neighboring cells (with goal of universal frequency reuse and avoiding interference at cell edges). eNodeBs' role in sending specific interference indicators (relative narrowband transmit power, high interference, and overload indicators).

    LTE Channel Structure and Protocols

    • Detailed structure of the LTE radio interface, dividing into control plane and user plane, and describing user plane protocols (transporting packets between UE and PGW using PDCP, GTP).
    • Protocol layers (RRC, PDCP, RLC, MAC, and PHY).

    Protocol Layers

    • Radio Resource Control (RRC) controls radio resources via RRC_IDLE and RRC_CONNECTED states.
    • Packet Data Convergence Protocol (PDCP), involved in header compression, ciphering, integrity protection and packet forwarding during handovers.
    • Radio Link Control (RLC), segments / concatenates data, and performs ARQ when the MAC layer H-ARQ fails.
    • Medium Access Control (MAC) layer uses H-ARQ, prioritizes and decides which UEs and radio bearers use shared physical resources, defines transmission format (modulation, code rate, MIMO rank), and power level.
    • Physical layer actually transmits data using various types of physical channels (e.g., PCCH, BCCH, CCCH, DCCH, DTCH, MCCH, MTCH, PCH, BCH, UL-SCH, DL-SCH, MCH, V, RACH, PDSCH, PBCH, PUSCH, PDSCH, PMCH, PRACH—various roles for various purposes).

    LTE Radio Access Network

    • LTE uses MIMO and OFDM (OFDMA on the downlink and SC-OFDM on the uplink).
    • Subcarriers are 15 kHz apart, and maximum FFT size is 2048.
    • Basic time unit (Ts) and radio frame duration.
    • LTE uses both TDD and FDD (time division dupleking, frequency division dupleking).
    • Cyclic prefixes (CPs—Normal and Extended—for different environments) are employed.
    • Spectrum allocation details.

    FDD Frame Structure

    • Detailed framework of the FDD frame structure, including slots, subframes, and radio frames, related to time unit measurements, providing channel-dependent scheduling and link adaptation, scheduling distribution/system/reference info, time slots as well as different OFDM (Orthogonal Frequency-Division Multiplexing) symbols in relation to cyclic prefixes.

    TDD Frame Structure

    • Overview of the TDD frame structure (also within a radio frame of 10 ms), including DwPTS, UpPTS, and GP subframes, and their roles in downlink-uplink switching.

    Resource Blocks

    • Time-frequency grid-based allocation of physical resources.
    • Each column represents OFDM symbols (6 or 7 per slot) and rows correspond to a subcarrier of 15 kHz.
    • Guard bands (10% of channel bandwidth) are used.
    • Physical RBs and virtual RBs (contiguous and non-contiguous) on uplink and downlink.
    • MIMO (multi-input, multi-output) configuration (4x4 for LTE, 8x8 for LTE-Advanced), including separate resource grids per antenna port and how eNodeBs assign RBs with channel-dependent scheduling.
    • Multiuser diversity (increase bandwidth usage efficiency, assign blocks to UEs given favorable qualities, taking into account factors such as UE locations, typical channel conditions, and QoS priorities).

    Physical Transmission

    • Release 8 supports up to 4x4 MIMO.
    • eNodeB Communicates using PDCCH (Physical Downlink Control Channel).
    • Resource block allocations and synchronization timing.
    • Different types of rate convolutional codes (e.g., QPSK, 16QAM, 64QAM) based on channel conditions.
    • CQI (Channel Quality Indicator) to determine the best modulation/code rate tradeoff (e.g., Table 14.7) to maximize throughput and maintain a 10% or less block error rate.

    Power-On Procedures

    • Steps involved in powering on a UE, including network selection, cell selection, random access, RRC connection establishment, attaching to the network through to the MME, configuring EPS bearers, sending packets and request for QoS improvement (dedicated bearer).

    LTE-Advanced

    • Summary of 3GPP releases (8, 9-12) and their relevance to LTE-Advanced guidelines, specifications, and enhancements (Carrier Aggregation, MIMO enhancements, Relay Nodes, Heterogeneous Networks, CoMP (Coordinated Multipoint Transmission) and important improvements.)

    Carrier Aggregation

    • Combining multiple component carriers to achieve higher bandwidths (100 MHz).
    • Description of different methods (intra-band/contiguous, intra-band/noncontiguous, inter-band connections). Diagrams illustrating logical views and types of carrier aggregation.

    Enhanced MIMO

    • Expansion of MIMO to 8x8 for 8 parallel layers and multi-user-MIMO considerations.
    • Role of downlink reference signals.
    • Description of how UEs recommend MIMO, precoding, and coding schemes as well as how reference signals are sent on dynamically assigned subframes.

    Relaying

    • Description of relay nodes (RNs) used to extend the coverage area of an eNodeB.
    • Process related to receiving, decoding, and re-transmitting signals.
    • RNs' usage of out-of-band or inband frequencies. Diagrams illustrating relay node structures.

    Heterogeneous Networks

    • Challenges of meeting data demands in densely populated regions, and solutions (small cells and macro cells).
    • Small cells for local access (low power, short range, operating within licensed/unlicensed spectrum), best for stationary users/low speeds.
    • Macro cells for highly mobile users (wide coverage areas).
    • Focus on network densification, introducing small cells to address coverage and capacity issues across areas.
    • Definition of heterogeneous networks (HetNet). Detailed overview of Femtocells; functions, deployment, and application contexts (residential & enterprise/metro locations).

    Coordinated Multipoint Transmission and Reception

    • Techniques involving coordinated beamforming and joint processing in LTE-Advanced Release 11 for intercell interference management, control scheduling across cells, and use of coordinated scheduling/coordinated beamforming (CS/CB), joint processing (JT), dynamic point selection (DPS).

    Other Enhancements in LTE-Advanced

    • Description of traffic off-loading, adjustable capacity and interference coordination, machine-type communications & dynamic TDD adaptation related to traffic fluctuations.

    Voice over LTE

    • GSM Association's role and documented specifications for VoLTE.
    • Employing the IP Multimedia Subsystem (IMS) for voice delivery over IP streams.
    • IMS architecture: not part of LTE, a separate network focusing on signaling (beyond voice), such as video calls, instant messaging, chat, file transfer, all known as Rich Communication Services (RCS).

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