1. 第四代行動通訊系統 (4G)－－ Long Term Evolution Advanced (LTE Advanced)
陳昱仁
長庚大學資訊管理學系

2. 第四代行動通訊系統 (Fourth Generation, 4G)
2008年3月，在國際電信聯盟-無線電通訊部門（ITU-R）指定一組用於4G標準的要求，命名為 IMT-Advanced 規範，設定4G服務的峰值速度要求在高速移動的通訊（如在火車和汽車上使用）達到100 Mbit/s，固定或低速移動的通訊（如行人和定點上網的用戶）達到1 Gbit/s
第一發布版本的LTE（3GPP Release 8）和WiMAX（IEEE e）支援遠小於1 Gbit/s的峰值位元率，它們不是完全IMT-Advanced的標準，但往往許多電信服務提供商宣傳其為4G網路
2009年9月，各項技術提案被提交給國際電信聯盟（ITU）為4G候選者，基本上所有的建議都是基於下列兩種技術：
LTE-Advanced（3GPP Release 10）：由3GPP標準化
WirelessMAN-Advanced（IEEE m）：由IEEE標準化

3. IMT-Advanced
International Mobile Telecommunications-Advanced (IMT-Advanced) systems are mobile systems that include the new capabilities of IMT that go beyond those of IMT-2000
Such systems provide access to a wide range of telecommunication services including advanced mobile services, supported by mobile and fixed networks, which are increasingly packet-based
IMT-Advanced systems support low to high mobility applications and a wide range of data rates in accordance with user and service demands in multiple user environments
IMT-Advanced also has capabilities for high quality multimedia applications within a wide range of services and platforms, providing a significant improvement in performance and quality of service

4. The “VAN diagram”

5. Requirements of IMT-Advanced
Based on an all-Internet Protocol (IP) packet switched network
Interoperability with existing wireless standards
A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions
Dynamically share and use the network resources to support more simultaneous users per cell
Scalable channel bandwidth 5–20 MHz, optionally up to 40 MHz
Peak link spectral efficiency of 15 bit/s/Hz in the downlink, and 6.75 bit/s/Hz in the uplink (meaning that 1 Gbit/s in the downlink should be possible over less than 67 MHz bandwidth)
System spectral efficiency of up to 3 bit/s/Hz/cell in the downlink and 2.25 bit/s/Hz/cell for indoor usage
Seamless connectivity and global roaming across multiple networks with smooth handovers
Ability to offer high quality of service for multimedia support

6. Key features of IMT-Advanced
a high degree of commonality of functionality worldwide while retaining the flexibility to support a wide range of services and applications in a cost efficient manner
compatibility of services within IMT and with fixed networks
capability of interworking with other radio access systems
high quality mobile services
user equipment suitable for worldwide use
user-friendly applications, services and equipment
worldwide roaming capability
enhanced peak data rates to support advanced services and applications
100 Mbit/s for high and 1 Gbit/s for low mobility were established as targets for research

7. Principal technologies
MIMO: To attain ultra high spectral efficiency by means of spatial processing including multi-antenna and multi-user MIMO
Frequency-domain-equalization, for example Multi-carrier modulation (OFDM) in the downlink or single-carrier frequency-domain-equalization (SC-FDE) in the uplink: To exploit the frequency selective channel property without complex equalization
Frequency-domain statistical multiplexing, for example (OFDMA) or (Single-carrier FDMA) (SC-FDMA, Linearly precoded OFDMA, LP-OFDMA) in the uplink: Variable bit rate by assigning different sub-channels to different users based on the channel conditions
Turbo principle error-correcting codes: To minimize the required SNR at the reception side
Channel-dependent scheduling: To utilize the time-varying channel
Link adaptation: Adaptive modulation and error-correcting codes
Relaying, including fixed relay networks (FRNs), and the cooperative relaying concept, known as multi-mode protocol

8. Candidate systems
The first set of 3GPP requirements on LTE Advanced was approved in June 2008
On October 21, 2010, ITU-R Working Party 5D has completed the assessment of six candidate submissions for the global 4G mobile wireless broadband technology (IMT-Advanced)
Harmonization among these proposals has resulted in two technologies, “LTE-Advanced” and “WirelessMAN-Advanced” (WiMAX Release 2, IEEE m-2011) being accorded the official designation of IMT-Advanced, qualifying them as true 4G technologies
On December 6, 2010, ITU noted that while current versions of LTE, WiMax and other evolved 3G technologies (e.g., HSPA+) do not fulfill IMT-Advanced requirements for 4G, some may use the term "4G" in an "undefined" fashion to represent forerunners to IMT-Advanced that show "a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed"

9. IMT-Advanced技術趨勢演進

10. 4G 技術標準 LTE Advanced（長期演進技術升級版） WiMAX-Advanced（全球互通微波存取升級版）
LTE FDD（分頻雙工長期演進技術）
LTE TDD（分時雙工長期演進技術）又稱TD-LTE
由上海貝爾、諾基亞西門子通訊、大唐電信、華為技術、中興通訊、中國移動、高通、ST-Ericsson等業者共同開發
WiMAX-Advanced（全球互通微波存取升級版）
IEEE m是WiMAX的增強，由WiMAX Forum所主導

11. 台灣 4G LTE 業者 電信業者 頻率 (MHz) 中華電信 895-905MHz / 940-950MHz
台灣大哥大
MHz / MHz
MHz / MHz
台灣之星
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亞太電信
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國碁電子（與亞太電信合併）
MHz / MHz
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遠傳電信
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MHz / MHz MHz / MHz

14. LTE Standardization effort started in late 2004 LTE focus:
With HSPA (downlink and uplink), UTRA will remain highly competitive for several years
IEEE is standardizing mobile WiMAX => Threat for loosing competitive edge
LTE focus:
Enhancement of the UTRA
Optimisation of the UTRAN architecture
To ensure the continued competitiveness of the 3GPP technologies for the future
LTE was the first technology recognized by the Next Generation Mobile Network alliance to meet its broad requirements

15. Key Features of LTE Many different bands: 700/1500/1700/2100/2600 MHz
Flexible Bandwidth: 1.4/3/5/10/15/20 MHz
Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD) => Both paired and unpaired spectrum
4x4 MIMO, Multi-user collaborative MIMO
Beamforming in the downlink
Data Rate: 326 Mbps/down 86 Mbps up (4x4 MIMO 20 MHz)
Modulation: OFDM with QPSK, 16 QAM, 64 QAM
OFDMA downlink, Single Carrier Frequency Division Multiple Access (SC- FDMA) uplink
Hybrid ARQ Transmission
Short Frame Sizes of 10ms and 1ms => faster feedback and better efficiency at high speed
Persistent scheduling to reduce control channel overhead for low bit rate voice transmission
IP based flat network architecture

16. Elements of the LTE System
LTE encompasses the evolution of
Radio access through E-UTRAN (eNodeB)
Non-radio aspects under the term System Architecture Evolution (SAE)
Entire system composed of LTE & SAE is called Evolved Packet System (EPS)
At a high level a LTE network is composed of
Access network comprised of E-UTRAN
Core Network called Evolved Packet Core (EPC)

17. LTE Network Elements
UE – User Equipment used to connect to the EPS (Evolved Packet System)
Access Network
ENB (eNodeB) – The evolved RAN consists of single node, the eNodeB that interfaces with UE; The eNodeB hosts the PHY, MAC, RLC & RRC layers; It handles radio resource management & scheduling
Core Network (Evolved Packet Core-EPC)
MME (Mobility Management Entity) – Performs paging, chooses the SGW during UE attach
S-GW (Serving Gateway) – routes & and forwards user data packets
P-GW (Packet Gateway) – provides connectivity between the UE and the external packet networks

19. LTE Network Architecture

21. New Functionalities of LTE-Advanced (LTE Release10)
Carrier Aggregation
Multiple Input Multiple Output (MIMO) (Spatial Multiplexing)
Relay Nodes
Coordinated Multi Point operation (CoMP) – R11

22. Carrier Aggregation

24. Multiple Input Multiple Output (MIMO)

25. Relay Nodes

26. Coordinated Multi Point operation (CoMP)