1. 教育部補助「行動寬頻尖端技術跨校教學聯盟第二期計畫 -- 行動寬頻網路與應用 -- 小細胞基站聯盟中心」 模組名稱： 「LTE-Small Cell 核心網路架構及服務」 單元-A3：核心網路 (EPC) 架構 (S-Gateway, P-Gateway, MME, SON)
計畫主持人：許蒼嶺 (國立中山大學 電機工程學系)
授課教師：萬欽德 (國立高雄第一科技大學 電腦與通訊工程系)

2. 課程單元目標 了解 LTE 與 SAE 了解 EPC 核心網路架構 了解 LTE 通訊與協定
了解 Self-Organizing Network

3. System Architecture Evolution

4. LTE and SAE
Long Term Evolution (LTE) refers to the Evolved UMTS Radio Access Network (E-UTRAN)
System Architecture Evolution (SAE) refers to the Evolved Packet Core (EPC)

5. 2G, 3G and 4G Network Architecture

6. All-IP Core, New Network Elements

7. LTE + EPC Elements & Interface

8. LTE Architecture &Terminologies
EPC: Evolved Packet Core
MME: Mobility Management Entity
S-GW: Serving Gateway
P-GW: Packet Data Network Gateway
eUTRAN: Evolved UTRAN
S1: Interface between EPC and eNB
X2: Inter-eNB interface (logical Interface)
SAE: System Architecture Evolution
LTE: Long Term Evolution
EPS: Evolved Packet System
Ref. 3GPP TS

9. Architecture for 3GPP Accesses
HSS: Home Subscriber Server
PCRF: Policy & Charging Rule Function
Ref. 3GPP TS

10. 網路架構 LTE修改3G網路協定架構，使用封包為主網路，達到高傳輸速率及減少延遲
LTE架構分為E-UTRAN與核心網路EPC(Evolved Packet Core)
訊息傳輸分為Control-plane與User-plane區分網路控制封包及用戶傳輸資料封包

11. EPC 核心網路架構

12. Evolved Packet Core (EPC)
All-IP mobile core network
From 3GPP Release:
(Radio access): LTE  E-UTRAN
(eNodeB)
(Core network): SAE  EPC
Evolved Packet System = E-UTRAN + EPC
E-UTRAN
EPC

13. Evolved Packet Core (EPC)
New, all-IP mobile core network introduced with LTE
End-to-end IP (All-IP)
Clear delineation of control plane and data plane
Simplified architecture: flat-IP architecture with a single core
A multi-access core network based on the Internet Protocol (IP)
EPC enables operators to deploy and operate one common packet core network for
3GPP radio access (LTE, 3G, and 2G)
non-3GPP radio access (HRPD, WLAN, and WiMAX)
fixed access (Ethernet, DSL, cable, and fiber).

14. Basic EPC Elements Mobility Management Entity (MME) Serving Gateway
Control-plane element, responsible for high volume mobility management and connection management (up to thousands of eNodeBs)
Serving Gateway
Serving a large number of eNodeBs, focus on scalability and security
Packet Data Network (PDN) Gateway
IP management (“IP anchor”), connection to external data networks
focus on highly scalable data connectivity and QoS enforcement
Policy and Charging Rules Function (PCRF)
Network-wide control of flows: detection, gating, QoS and flow- based charging, authorizes network-wide use of QoS resources (manages millions of service data flows)

15. 核心網路 (EPC) 架構
行動管理實體(MME)、服務閘道(S-GW)及封包資料閘道 (PGW)、HSS(Home subscriber server)、Policy and Charging Rules Function(PCRF)、PSTN(Public Switched Telephone Network)

16. Function Split between E-UTRAN and EPC
Ref. 3GPP TS

18. UE 使用者裝置User Equipment (UE) 一般使用者的手機稱之為使用者裝置 安裝SIM卡，取得電信服務

19. E-UTRAN
演進通用無線存取網路(Evolved Universal Terrestrial Radio Access Network，E-UTRAN)
E-UTRAN包含基站(eNB)、UE及eNB之間透過無線介面LTE-Uu通訊。實際上LTE-Uu通訊協定堆疊(Protocol Stack)，按功能區分為三層
實體層PHY：傳遞無線電波訊號
媒體控制層MAC：實體層傳輸電波轉換成數位訊號
無線資源控制RRC(Radio Resource Control)和EPS(Evolved Packet System)：行動管理用戶資料IP封包

20. All radio access functions
Functions at eNodeB
All radio access functions
Radio admission control
Scheduling of UL and DL data
Scheduling and transmission of paging and system broadcast
IP header compression (PDCP)
Outer-ARQ (RLC)

21. LTE網路元件介紹-PSTN
EPC核心網路，LTE為降低複雜度在設計上採全IP架構，捨棄電話線路交換服務(PSTN)僅保留數據封包交換網路

22. MME
行動管理實體MME：核心網路實際管理UE的元件，處理控制訊號(Control)訊息
例如：移動性、身分認證及安全性等的管理

23. Functions of Mobility Management Entity (MME)
Authentication
Tracking area list management
Idle mode UE reachability
S-GW/PDN-GW selection
Inter core network node signaling for mobility between 2G/3G and LTE
Bearer management functions

24. MME Functionality NAS signaling; NAS signaling security;
Inter CN node signaling for mobility between 3GPP access networks;
Idle mode UE Reachability(including control and execution of paging retransmission);
Tracking Area list management (for UE in idle and active mode);
PDN GW and Serving GW selection;
MME selection for handovers with MME change;
SGSN selection for handovers to 2G or 3G 3GPP access networks;
Roaming;
Authentication;
Bearer management functions including dedicated bearer establishment;
Support for ETWS message transmission.
Ref. 3GPP TS
One user can only be served by ONE MME.

25. S-GW 服務閘道S-GW：主要功能是傳遞用戶資料，也是LTE與其他系統間(2G、3G)相容切換
例如：尋找路由或是轉送資料封包、處理eNB間的換手(Handover)等

26. Functions of Serving Gateway (S-GW)
Local mobility anchor for inter- eNB handovers
Mobility anchoring for inter- 3GPP handovers
Idle mode DL packet buffering
Lawful interception
Packet routing and forwarding

27. S-GW Functionality
The local Mobility Anchor point for inter-eNB handover;
Mobility anchoring for inter-3GPP mobility;
E-UTRAN idle mode downlink packet buffering and initiation of network triggered service request procedure;
Lawful Interception;
Packet routing and forwarding;
Transport level packet marking in the uplink and the downlink;
Accounting on user and QCI granularity for inter-operator charging;
UL and DL charging per UE, PDN, and QCI.
One user can only be served by ONES-GW but more than one P-GW.
Ref. 3GPP TS

28. P-GW
封包資料網路閘道P-GW：負責將用戶資料網PDN傳送，一般的網際網路或是其他專屬的封包網路。也做LTE與非3GPP系統(WLAN、WiMAX)相容切換
負責監控每一個流量，方便核網對網路流量做品質控管(QoS)及付費機制
服務品質(Quality of Service，QoS)：控制機制，針對不同用戶或者不同資料流採用相應不同的優先級，或是根據應用程式要求，保證資料流的效能達到一定水準

29. Functions of Packet Data Network (PDN) Gateway (P-GW)
IP anchor point for bearers
UE IP address allocation
Per-user based packet filtering
Connectivity to packet data network

30. P-GW Functionality Per-user based packet filtering Lawful Interception
UE IP address allocation
Transport level packet marking in the downlink
UL and DL service level charging, gating and rate enforcement
DL rate enforcement based on APN-AMBR (APN- Aggregate Maximum Bit Rate)
One user can only be served by ONES-GW but more than one P-GW.
Ref. 3GPP TS

31. HSS
HSS (Home Subscribe Server)：負責身分認證的資訊、紀錄UE位置、紀錄UE網路能力等儲存許多關於安全性功能資料

32. Functions of Home Subscriber Server (HSS)
Basically, the HSS (for Home Subscriber Server) is a database.
HSS contains user-related and subscriber-related information.
HSS also provides support functions in mobility management, call and session setup, user authentication and access authorization.
It is based on the pre-3GPP Release 4 - Home Location Register (HLR) and Authentication Centre (AuC).

33. PCRF
PCRF(Policy Charging Rule Function)：用於策略控制決策和實現基於流量計費的功能。

34. Functions of Policy, Charging & Rules Function (PCRF)
Network control of Service Data Flow (SDF)
detection, gating, QoS & flow based charging
Dynamic policy decision on service data flow treatment in the PCEF (xGW)
Authorizes QoS resources

35. LTE網路 - S1介面 eNB透過S1介面與核心網路通訊，S1介面分成 Control-plane：S1-MME介面(與MME連結)
User-plane：S1-U介面(與S-GW連結)

36. LTE通訊與協定

37. LTE LTE However, LTE wireless interface
A standard for mobile data communications technology
An evolution of the GSM/UMTS standards
However, LTE wireless interface
Incompatible with 2G and 3G networks
Must be operated on a separate wireless spectrum

38. History of LTE
LTE was first proposed by NTT DoCoMo of Japan in 2004, and studies on the new standard officially commenced in 2005.
The LTE standard was finalized in December 2008.
The first publicly available LTE service was launched by TeliaSonera in Oslo and Stockholm on December 14, 2009 as a data connection with a USB modem.
Samsung Galaxy Indulge: the world’s first LTE smartphone starting (February 10, 2011).
On June 25th, 2013, Korea's SK Telecom announced the launching of LTE-Advanced services in Korea. [15]
On June 26th, 2013, Samsung Electronics released an LTE-Advanced version of the Galaxy S4. [16]
On July 18th, 2013, Korea's LG U Plus unveiled an LTE-Advanced network.[17]
On August 18th, 2013, Philippines’ SMART Communications tests the LTE-Advanced network.[18]
On November 5th 2013, two major carriers in the United Kingdom (Vodafone and EE) announced they would be holding LTE - A trials in the London area.
On November 15th 2013, Telefonica and Vodafone have announced that they are testing LTE-Advanced in the German cities of Munich and Dresden

39. History of LTE (Cont’d)
Initially, CDMA operators planned to upgrade to rival standards called UMB and WiMAX.
But all the major CDMA operators have announced that they intend to migrate to LTE after all.
Verizon, Sprint and MetroPCS in the United States
Bell and Telus in Canada
KDDI in Japan
SK Telecom in South Korea
China Telecom/China Unicom in China

40. LTE-Advanced (LTE-A) The evolution of LTE is LTE Advanced
was standardized in March 2011.
Services of LTE Advanced commenced in 2013.

41. Features of LTE
Increase of capacity and speed of wireless data networks using new DSP and modulation techniques.
Redesign and simplification of the network architecture to an IP-based system
Reduced transfer latency compared to the 3G architecture

42. Major Requirements for LTE
Higher peak data rates: 100 Mbps (downlink) and 50 Mbps (uplink)
Improved spectrum efficiency: 2-4 times better compared to 3GPP release 6
Improved latency:
Radio access network latency (user plane UE – RNC – UE) below 10 ms
Significantly reduced control plane latency
Support of scalable bandwidth: 1.4, 3, 5, 10, 15, 20 MHz
Support of paired and unpaired spectrum (FDD and TDD mode)
Support for interworking with legacy networks

43. Evolution of UMTS FDD and TDD

45. Data Transmission in LTE
Downlink:
Orthogonal Frequency Division Multiple Access (OFDMA)
Uplink:
Single Carrier FDMA (SC-FDMA):
SC-FDMA:
a new single carrier multiple access technique
has similar structure and performance to OFDMA
Advantage of SC-FDMA over OFDM:
Low Peak to Average Power ratio (PAPR) : Increasing battery life

47. Evolution of Radio Access Technologies
802.16m
802.16d/e
LTE (3.9G) : 3GPP release 8~9
LTE-Advanced : 3GPP release 10+

48. Procedure

49. LTE Initial Access

50. Cell Search in LTE (1/4)

51. Cell Search in LTE: Reference Signals (2/4)

52. Downlink Reference Signals (3/4)

53. Cell Search: Essential System Information (4/4)

54. LTE Initial Access

55. How to derive Information

56. LTE Initial Access

57. Indicating PDCCH Format

58. Uplink Physical Channels and Signals

59. Scheduling of Uplink Data

60. Acknowledging UL data packets on PHICH

61. Generic Frame Structure
Allocation of physical resource blocks (PRBs)
Scheduling at the 3GPP base station: Evolved Node B (eNodeB)

62. Frame Structure (DwPTS field)
The downlink part of the special subframe
Its length can be varied from three up to twelve OFDM symbols.

63. Frame Structure (UpPTS field)
The uplink part of the special subframe
It has a short duration with one or two OFDM symbols.

64. Frame Structure (GP field)
The remaining symbols (not allocated to DwPTS or UpPTS) in the special subframe.
Providing the guard period.

65. Resource Blocks for OFDMA
One frame: 10 ms (with 10 subframes)
One subframe: 1ms (with 2 slots)
One slot: N Resource Blocks (6 < N < 110)
The number of downlink resource blocks depends on the transmission bandwidth.
One Resource Block: M subcarriers for each OFDM symbol
M depends on the subcarrier spacing Δf
The number of OFDM symbols in each block depends on both the CP length and the subcarrier spacing.

67. LTE Spectrum (Bandwidth and Duplex) Flexibility

68. LTE Downlink Channels The LTE radio interface:
Various "channels" are used.
Channels are used to segregate the different types of data and allow them to be transported across the radio access network in an orderly fashion.
Physical channels: transmission channels that carry user data and control messages.
Transport channels: the physical layer transport channels offer information transfer to Medium Access Control (MAC) and higher layers.
Logical channels: provide services for the MAC layer within the LTE protocol structure.
Physical Channel，乘載上層資訊並送出訊號給UE或EnodeB，簡單的說就是將Resourse Block(RB)分配的機制，規定每一個RB要做為什麼用途，會介紹這個是為了延續上篇介紹的主題。

69. LTE Downlink Channels Paging Control Channel Paging Channel
Physical Downlink Shared Channel

70. LTE Downlink Logical Channels
UE: User Equipment
RRC: Radio Resource Control

71. LTE Downlink Logical Channels
MBMS: Multimedia Broadcast Multicast Services

72. LTE Downlink Transport Channel

73. LTE Downlink Transport Channel

74. LTE Downlink Physical Channels

75. LTE Downlink Physical Channels

76. LTE Uplink Channels Random Access Channel CQI report
Physical Uplink Shared Channel
Physical Radio Access Channel

77. LTE Uplink Logical Channels

78. LTE Uplink Transport Channel

79. LTE Uplink Physical Channels

80. LTE Release 8 Key Features (1/2)
High spectral efficiency
OFDM in Downlink
Single‐Carrier FDMA in Uplink
Very low latency
Short setup time & Short transfer delay
Short hand over latency and interruption time
Support of variable bandwidth
1.4, 3, 5, 10, 15 and 20 MHz

81. LTE Release 8 Key Features (2/2)
Compatibility and interworking with earlier 3GPP
FDD and TDD within a single radio access technology
Efficient Multicast/Broadcast

82. Evolution of LTE-Advanced
Asymmetric transmission bandwidth
Layered OFDMA
Advanced Multi-cell Transmission/Reception Techniques
Enhanced Multi-antenna Transmission Techniques
Support of Larger Bandwidth in LTE-Advanced

83. Symmetric and Asymmetric Transmission Bandwidth
Voice transmission: UE to UE
Asymmetric transmission
Streaming video : the server to the UE (the downlink)

84. Layered OFDMA The bandwidth of basic frequency block is, 15 - 20 MHz
Layered OFDMA comprises layered transmission bandwidth assignment (bandwidth is assigned to match the required data rate), a layered control signaling structure, and support for layered environments for both the downlink and uplink.

85. Coordinated Multi-Point Transmission/Reception (CoMP)
The CoMP is one of the candidate techniques for LTE-Advanced systems to increase the average cell throughput and cell edge user throughput in the both uplink and downlink.

86. Enhanced Multi-Antenna Transmission Techniques
In LTE-A, the MIMO scheme has to be further improved in the area of spectrum efficiency, average cell throughput and cell edge performances
In LTE-A the antenna configurations of 8x8 in DL and 4x4 in UL are planned

87. Enhanced Techniques to Extend Coverage Area
Remote Radio Requirements (RREs) using optical fiber should be used in LTE-A as effective technique to extend cell coverage

88. Support of Larger Bandwidth in LTE-Advanced
Peak data rates up to 1Gbps are expected from bandwidths of 100MHz. OFDM adds additional sub-carrier to increase bandwidth

89. LTE vs. LTE-Advanced

90. Summary
LTE-A helps in integrating the existing networks, new networks, services and terminals to suit the escalating user demands
LTE-Advanced was standardized in the 3GPP specification Release 10 (LTE-A) and designed to meet the 4G requirements as defined by ITU

91. Self-Organizing Network

92. Introduction to Self-Organizing Network
The Self-Organizing Network (SON) is a concept originated from the Next-Generation Mobile Networks (NGMN) alliance.
The SON network can automatically  extend,  change,  configure, and  optimize its  topology,  coverage,  capacity,  cell size, and  channel allocation, based on changes in  location,  traffic pattern,  interference, and  the environment.
The SON aims at reducing the cost of installation and management by simplifying operational tasks through automated mechanisms such as self-configuration and self-optimization.

93. Main Drivers for SON
From an operator’s perspective, the main drivers for SON in LTE are to reduce OPEX (Operating Expense).

94. Main Objectives of SON (1/2)
The main objective of the SON is to reduce CAPEX (Capital Expense) as well as OPEX.

95. Main Objectives of SON (2/2)
The SON is designed to automatically configure and optimize the LTE network by
Self-configuration, which involves plug-and-play behavior when installing network elements to reduce costs and simplify procedures.
Self-optimization, which means automatic optimization based on network monitoring and measurement data.
Self-healing, which means that the system detects problems itself and mitigates or solves these problems to avoid unnecessary user intervention and to reduce maintenance costs.

96. Operational Benefits by SON
Self-Configuration
Flexibility in logists (eNB not site specific)
Reduced site / parameter planning
Self-Optimization
Self-Healing

97. SON Functions
Initial SON functions can be described as following figure.
OMC = Operations and Maintenance Centre, which is the central location to operate and maintain the network.

98. 3GPP Specified SON Functions (1/2)
A number of SON functions are supported in 3GPP Release-8 and will expand in scope with subsequent releases.
Details will be shown later
PCI = Physical Cell ID
ANR = Automatic Neighbor Relations
RAT = Radio Access Technology

99. 3GPP Specified SON Functions (2/2)
Details will be shown later
P31
RACH = Random Access
Channel

100. SON Structure Category (1/2)
Based on the location of the functions:
Centralized SON, executed in operation and maintenance (OA&M) system
Distributed SON, executed in eNBs
Hybrid SON, executed in both OA&M system and eNBs
P361

101. SON Structure Category (2/2)

102. SON Capabilities
The main SON functionalities consisting of self-configuration, self-optimization and self-healing are referred to as SON capabilities.

103. Interface Uu, X2 and S1