Samsung L7IU B1C User Manual

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L TE 1 .9 GHz Indoor Pi co Cel l

System Description

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This manual is proprietary to SAMSUNG Electronics Co., Ltd. and is protected by copyright. No information contained herein may be copied, translated, transcribed or duplicated for any commercial purposes or disclosed to the third party in any form without the prior written consent of SAMSUNG Electronics Co., Ltd.

TRADEMARKS

Product names mentioned in this manual may be trademarks and/or registered trademarks of their respective companies.

This manual should be read and used as a guideline for properly installing and operating the product.

All reasonable care has been made to ensure that this documen t is accurate. If you have any comments on this manual, please contact our documentation centre at the following address:

Address: Document Center 3rd Floor Jeong-bo-tong-sin-dong. 129, Samsung-ro, Yeongtong-gu, Suwon-si,

Gyeonggi-do, Korea 443-742

Homepage: http://www.samsungdocs.com

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INTRODUCTION

Purpose

This description describes the characteristics, features and structure of the 1.9 GHz Indoor Pico Cell, an LTE eNB.

Document Content and Organization

This manual consists of five Chapters and a list of Abbreviations.

CHAPTER 1. Samsung LTE System Overview



Introduction to Samsung LTE System

 Samsung LTE Network Configuration

CHAPTER 2. System Overview



Introduction to System

 Main Functions  Specifications  Intersystem Interface

CHAPTER 3. Syst em St ru ct ure



Hardware Structure

 Software Structure

CHAPTER 4. Message Flow



Call Processing Message Flow

 Data Traffic Flow  Network Sync Flow  Alarm Signal Flow  Loading Flow  Operation and Maintenance Message Flow

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First Version

CHAPTER 5. Supplementary Functions and Tools

LMT

ABBREVIATION

Describes the acronyms used in this manual.

Conventions

The following types of paragraphs contain special information that must be carefully read and thoroughly understood. Such information may or may not be enclosed in a rectangular box, separating it from the main text, but is always preceded by an icon and/or a bold title.

NOTE Indicates additional information as a reference.

Revision Histor y

VERSION DATE OF ISSUE REMARKS

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INTRODUCTION 3

Purpose ..................................................................................................................................................... 3

Document Content and Organization ...................................................................................................... 3

Conventions ............................................................................................................................................... 4

Revision History ........................................................................................................................................ 4

CHAPTER 1. Samsung LTE System Overview 8

1.1 Introduction to Samsung LTE S ystem .................................................................................... 8

1.2 Samsung LTE Network Configuration .................................................................................... 11

CHAPTER 2. System Overview 14

2.1 ntroduction to System .............................................................................................................14

2.2 Main Functions ........................................................................................................................15

2.2.1 Physical Layer Processing ......................................................................................................... 15

2.2.2 Call Processing Function ........................................................................................................... 19

2.2.3 IP Processing .............................................................................................................................. 21

2.2.4 SON Function ............................................................................................................................. 21

2.2.5 Easy Operation and Maintenance ............................................................................................. 23

2.3 Specifications...........................................................................................................................25

2.4 Intersystem Interface ...............................................................................................................28

2.4.1 Interface Structure ...................................................................................................................... 28

2.4.2 Protocol St ack ............................................................................................................................. 29

CHAPTER 3. System Structure 33

3.1 Hardware Structure ..................................................................................................................33

3.2 Software Structure ...................................................................................................................38

3.2.1 Basic Software Structure ............................................................................................................ 38

3.2.2 CPS Block ................................................................................................................................... 40

3.2.3 OAM Blocks ................................................................................................................................ 43

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CHAPTER 4. Message Flow 46

4.1 Call Processing Message Flow .............................................................................................. 46

4.2 Data Traffic Flow ...................................................................................................................... 60

4.3 Network Sync Flow.................................................................................................................. 61

4.4 Alarm Signal Flow ................................................................................................................... 62

4.5 Loading Flow ........................................................................................................................... 63

4.6 Operation and Maintenance Mess age Flo w .......................................................................... 64

CHAPTER 5. Supplementary Functions and Tools 65

5.1 LMT ........................................................................................................................................... 65

ABBREVIATION 66

LIST OF FIGURES

Figure 1. Functional Distinctions of E-UTRAN and EPC .............................................................. 9

Figure 2. Samsung LTE System Architecture ............................................................................. 11

Figure 3. Inter-System Interface Structure .................................................................................. 28

Figure 4. Protocol Stack between UE and eNB .......................................................................... 29

Figure 5. Protocol Stack between eNB and S-GW User Plane ................................................... 30

Figure 6. Protocol Stack between eNB and MME Control Plane ................................................ 30

Figure 7. Inter-eNB User Plane Protocol Stack ........................................................................... 31

Figure 8. Inter-eNB Control Plane Protocol Stack ....................................................................... 31

Figure 9. Interface Proto col Stack between eNB and LSM ......................................................... 32

Figure 10. Indoor Pico Cell Configuration ................................................................................... 33

Figure 11. External Interface of Indoor Pico Cell ........................................................................ 34

Figure 12. Internal Configuration of Indoor Pico Cell .................................................................. 35

Figure 13. Power Supply Configuration ...................................................................................... 37

Figure 14. Indoor Pico Cell Software Structure ........................................................................... 38

Figure 15. Attach Procedure ....................................................................................................... 47

Figure 16. Service Request Procedure by UE ............................................................................ 50

Figure 17. Service Request Procedure by Network .................................................................... 52

Figure 18. Detach Procedure by UE ........................................................................................... 53

Figure 19. Detach Procedure by MME ....................................................................................... 54

Figure 20. X2 Based Handover Procedure ................................................................................. 55

Figure 21. S1-based Handover Procedure ................................................................................. 57

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Figure 22. Data Traffic Flow ........................................................................................................60

Figure 23. Network Synchronization Flow ...................................................................................61

Figure 24. Alarm flow ..................................................................................................................62

Figure 25. Loading Signal Flow...................................................................................................63

Figure 26. Operation and Maintenance Signal Flow ...................................................................64

Figure 27. LMT Interface .............................................................................................................65

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CHAPTER 1. Samsung LTE System

Overview

1.1 Introduction to Samsung LTE System

The Samsung LTE system supports 3GPP LTE (hereinafter, LTE) based services. LTE is a next generation wireless network system which solves the disadvantages of existing 3GPP mobile systems allows high-speed data serv ice at low cost reg ard le ss of tim e and place. The Samsung LTE system supports downlink Orthogonal Frequency Division Multiple Access (OFDMA), the uplink Single Carrier (SC) Frequency Division Multiple Access (FDMA), and scalable bandwidths for various spectrum allocation and provides high-speed data service. It also provides high-performance hardware for improved system performance and capacity and supports various functions and services.

Compliance Standards

The Samsung LTE system is based on the Rel-8 and Rel-9 standards of the LTE

3rd Generation Partnership Project (3GPP).

The Samsung LTE system consists of the evolved UTRAN Node B (eNB), Evolved Packet Core (EPC) and LTE System Manager (LSM). The eNB exists between the EPC and the User Equipment (UE). It establishes wireless connections with the UE and processes packet calls according to the LTE air interface standard. The eNB manages the UE in connected mode at the Access Stratum (AS) level. The EPC is the system located between the eNB and Packet Data Network to perform various control functions. The EPC consists of the Mobility Management Entity (MME), Serving Gateway (S-GW) and PDN Gateway (P-GW). The MME manages the UE in idle mode at the Non-Access St ratum (NAS ) lev el; and the S-GW and the P-GW manage user data at the NAS level and interworks with other networks. The LSM provides the man-machine interface; manages the software, configuration, performance and failures; and acts as a Self Organizing Network (SON) server.

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MME

Idle State Mobility

Mobility Anchoring

Inter Cell RRM

RB Control

eNB Measurement

Dynamic Resource

RRC

PHY

E-UTRAN

The figure below shows the functional distinctions between the eNB of E-UTRAN, MME, S-GW, and P-GW according to the 3GPP standard. The eNB has a layer structure and the EPC has no layer.

eNB

Connection Mobility Cont.

Radio Admission Control

Configuration & Provision

Allocation (Scheduler)

PDCP

RLC

MAC

Figure 1. Functional Distinctions of E-UTRAN and EPC

NAS Security

Handling

EPS Bearer Control

S-GW

P-GW

UE IP address allocation

Packet Filtering

EPC

eNB

An eNB is a logical network component of the Evolved UTRAN (E-UTRAN) which is on the access side in the LTE system. eNBs can be interconnected with each other by means of the X2 interface. The eNBs are connected by means of the S1 interface to the Evolved Packet Core (EPC). The wireless protocol layer of the eNB is divided into layer 2 and layer 3. Layer 2 is subdivided into the Media Access Control (MAC) layer, the Radio Link Control (RLC) layer, and the PDCP layer, each of which performs independent functions. Layer3 has the RRC layer.

he MAC layer distributes air resources to each bearer according to its priority, and performs the multiplexing function and the HARQ function for the data received from the multiple upper logical channels.

he RLC layer performs the following functions.

 Segments and reassembles the data receiv ed from the PDCP layer in accordanc e with

the size specified by the MAC layer

 Requests retransmission to recov er if data transmission fails in the lower layer (ARQ)  Reorders the data recovered by performing HARQ in the MAC layer (re-ordering)

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The PDCP layer performs the following functions.

 Header compression and decompression  Encrypts/decrypts user plane and control plane data  Protects and verifies the integrity of control plane data  Transmits data including sequence number related function  Removes data and redundant data based on a timer

The RRC layer performs mobility management within the wireless access network, maintaining and control of the Radio Bearer (RB), RRC connection management, and system information transmission, etc.

MME

The MME interworks with the E-UTRAN (eNB) to process the Stream Control Transmission Protocol (SCTP)-based S1 Application Protocol (S1-AP) signaling messages for controlling call connections between the MME and the eNB and to process the SCTPbased NAS signaling messages for controlling mobility connection and call connection between the UE and the EPC. The MME is responsible for collecting/modifying the user information and authenticating the user by interworking with the HSS. It is also responsible for requesting the allocation/ release/change of the bearer path for data routing and retransmission with the GTP-C protocol by interworking with S-GW. The MME interworks with the 2G and 3G systems, the SGSN and the MSC for providing mobility and Handover (HO), Circuit Service (CS) Fallback and Short Message Service (SMS). The MME is responsible for inter-eNB mobility, idle mode UE reachability, Tracking Area (TA) list management, choosing P-GW/S-GW, authentication, and bearer management. The MME supports mobility during inter-eNB handover and the inter-MME handover. It also supports the SGSN selection function upon handover to a 2G or 3G 3GPP network.

S-GW

The S-GW acts as the mobility anchor during inter-eNB handover and inter-3GPP handover, and routes and forwards user data packets. The S-GW allows the operator to apply application-specific charging policies to UE, PDN or QCI and manages the packet transmission layers for uplink/downlink data. The S-GW also supports GPRS Tunneling Protocol (GTP) and Proxy Mobile IP (PMIP) by interworking with the MME, P-GW, and SGSN.

PDN Gateway (P-GW)

The P-GW is responsible for charging and bearer policy according to the policy and manages charging and transmission rate according to the service level by interworking with the PCRF. The P-GW also performs packet filtering for each user, IP address allocation for each UE, and downlink data packet transmission layer management.

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PCRF

HSS

EMS

eNB

EPC

P-GW

1.2 Samsung LTE Network Configuration

A Samsung LTE system consists of the eNB, LSM, and EPC. The Samsung LTE system comprising multiple eNBs and EPCs (MME, S-GW/P-GW) is a subnet of the PDN, which allows the User Equipment (UE) to access external networks. In addition, the Samsung LTE system provides the LSM and self-optimization function for operation and maintenance of eNBs. The following shows the Samsung LTE system architecture.

PDN

OCS

OFCS

TL1

S-GW

CSM

S1-U

SNMP/FTP/UDP

EMS

LSM

S10

S5/S8

S11 S6a

MME

S1-MME

X2-C

X2-U

Figure 2. Samsung L TE Sy stem Ar chitecture

eNB

The eNB is located between the UE and EPC. It processes packet calls by connecting to the UE wirelessly according to the LTE air standard. The eNB is responsible for transmission and receipt of wireless signals, modulation and demodulation of packet traffic signals, packet scheduling for efficient utilization of wireless resources, Hybrid Automatic Repeat request (HARQ)/ARQ processing, Packet Data Convergence Protoco l (PD CP ) fo r p ack e t header compression, and wireless resources control. In addition, the eNB performs handover by interworking with the EPC.

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EPC

The EPC is a system located between the eNB and PDN. The subcomponents of the EPC are the MME, S-GW and P-GW.

 MME: Processes control messages using the NAS signaling protocol with the eNB and

performs control plane functions such as UE mobility management, tracking area list

management, and bearer and session management.

 S-GW: Acts as the anchor for the user plane between the 2G/3G access system and the

LTE system, and manages and changes the packet transmission layer for downlink/

uplink data.

 P-GW : Allocates an IP address to the UE, acts as the anchor for mobility between the LTE

and non-3GPP access systems, and manages/changes charging and the transmission rate

according to the service level.

LTE System Manager (LSM)

The LSM provides the user interface for the operator to operate and maintain the eNB. The LSM is responsible for software management, configuration management, performance management and fault management, and acts as a Self-Organizing Network (SON) server.

Core System Manager (CSM)

The CSM provides the user interface for the operator to operate and maintain the MME, S-GW, and P-GW.

Home Subscribe r Se rv e r (H SS)

The HSS is a database management system that stores and manages the parameters and location information for all registered mobile subscribers. The HSS manages key data such as the mobile subscriber’s access capability, basic services and supplementary services, and provides a routing function to the subscribed receivers.

Policy and Charging Rule Function (PCRF)

The PCRF server creates policy rules to dynamically apply the QoS and charging policies differentiated by service flow, or creates the policy rules that can be applied commonly to multiple service flows. The P-GW includes the Policy and Charging Enforcement Function (PCEF), which allows application of policy rules received from the PCRF to each service flow.

Online Charging System (OCS)

The OCS collects online charging information by interfacing with S-GW and P-GW. When a subscriber for whom online char g ing inform ati on is requir ed mak es a call, the P-GW transmits and re ceiv es th e subs crib er’s charging information by interworking with th e OCS.

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Offline Charging System (OFCS)

The OFCS collects offline charging information by interfacing with S-GW and P-GW. The OFCS uses the GTP’ (Gz) or Diameter (Rf) interface to interface with the S-GW and P-GW.

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CHAPTER 2. System Overview

2.1 Introduction to System

Indoor Pico Cell, an LTE eNB, is located between the UE and the EPC. It provides mobile communications services to subscribers according to the LTE air interface standard. The Indoor Pico Cell transmits/receives radio signals to/from the UE and processes the modulation and demodulation of packet traffic signals. The Indoor Pico Cell is also responsible for packet scheduling and radio bandwidth allocation and performs handover via interface with the EPC.

The Indoor Pico Cell can be installed vertically or horizontally; and it can be installed on the wall, pole or rack by using the installation brackets. The Indoor Pico Cell is an all-inone unit. If a fault occurs, the unit must be replaced with new one.

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2.2 Main Functions

The main functions of the Indoor Pico Cell (hereinafter, eNB) are as follows:

 Physical Layer Processing  Call Processing Function  IP Processing  SON Function  Easy Operation and Maintenance

Availability of System Features and Functions For availability and provision schedule of the features and functions described in

the system manual, please refer to separate documentations.

2.2.1 Physical Layer Processing

CHAPTER 2. System Overview

The eNB transmits/receives data through the radio channel between the EPC and UE. To do so, the eNB provides the following functions.

 OFDMA/SC-FDMA Scheme  Downlink Reference Signal Creation and Transmission  Downlink Synchronization Signal Creation and Transmission  Channel Encoding/Decoding  Modulation/Demodulation  Resource Allocation and Scheduling  Link Adapta tion  HARQ  Power Control  MIMO

OFDMA/SC-FDMA Scheme

The eNB performs the downlink OFDMA/uplink SC-FDMA channel processing that supports the LTE standard physical layer. The downlink OFDMA scheme allows the system to transmit data to multiple users simultaneously using the subcarrier allocated to each user. Depending on the channel status and the transmission rate requested by the user, the downlink OFDM can allocate one or more subcarriers to a specific subscriber to transmit data. In addition, when all sub-carriers are divided for multiple users, the eNB can select and assign to each subscriber a sub-carrier with the most appropriate features using the OFDMA scheme, thus to distribute resources efficiently and increase data throughput. For uplink SC-FDMA, which is similar to OFDMA modulation and demodulation, a

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Discrete Fourier Transform (DFT) is applied to each subscriber in the modulation at the transmitting side. An inverse Discrete Fourier Transform (IDFT) is applied for minimizing the Peak to Average Power Ratio (PAPR) at the transmitting side, which allows continuous allocation of frequency resources available for individual subscribers. As a result, the eNB can reduce the power consumption of the UE.

Downlink Reference Signal Creation and Transmission

The UE must estimate the downlink channel to perform the coherent demodulation on the physical channel in the LTE system. The LTE uses the OFDM/OFDMA-based methods for transmitting and therefore the channel can be estimated by inserting the reference symbols from the receiving terminal to the grid of each time and frequency. These reference symbols are referred to as the downlink reference signal. The following refe ren ce sig nals are defined for the LTE downlink.

 Cell-specific reference signal: The cell specific reference signal is transmitted to every

subframe across the entire bandwidth of the downlink cell. It is mainly used for

channel estimation, MIMO rank calculation, MIMO precoding matrix selection and

signal strength measurement for handover.

Downlink Synchronization Signal Creatio n and Transmission

The synchronization signal is used for the initial synchronization when the UE starts to communicate with the eNB. There are two types of synchronization signals: Primary Synchronization Signal (PSS) and Secondary Synchronization Sig n al (S SS ). The UE can obtain the cell identity through the synchronization signal. It can obtain other information about the cell through the broadcast channel. Since synchronization signals and broadcast channels are transmitted in the 1.08 MHz range, which is right in the middle of the cell’s channel bandwidth, the UE can obtain the basic cell information such as cell ID regardless of the transmission bandwidth of the eNB.

Channel Encoding/Decoding

The eNB is responsible for channel encoding/decoding to correct the channel errors that occurred on a wireless channel. In LTE, the turbo coding and the 1/3 tail-biting convolutional coding are used. Turbo coding is mainly used for transmission of large data packets on downlink and uplink, while convolutional coding is used for control information transmission and broadcast channel for downlink and uplink.

Modulation/Demodulation

For the data received over the downlink from the upper layer, the eNB processes it through the baseband of the physical layer and then transmits it via a wireless channel. At this time, to transmit a baseband signal as far as it can go via the wireless channel, the system modulates and transmits it on a specific high frequency bandwidth. For the data received over the uplink from the UE through a wireless channel, the eNB demodulates and changes it to the baseband signal to perform decoding.

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Resource Allocation and Scheduli n g

To support multiple accesses, the eNB uses OFDMA for downlink and SC-FDMA for uplink. By allocating the 2-dimensional resources of time and frequency to multiple UEs without overlay, both methods enable the eNB to communicate with multiple UEs simultaneously. The eNB can mux multiple UE information for the control channel and allocate signals from multiple UEs to the same time and frequency resources, which is the orthogonal resource allocation method using the cyclic shift function of the Zadoff-Chu sequence. Such allocation of cell resources to multiple UEs is called scheduling and each cell has its own scheduler for this function. The LTE scheduler of the eNB allocates resources to maximize the overall throughput of the cell by considering the channel environment of each UE, the data transmission volume required, and other QoS elements. In addition, to reduce interferences with other cells, the eNB can share information with the schedulers of other cells over the X2 interface.

Link Adaptation

The wireless channel environment can become faster or slower, better or worse depending on various factors. The system is capable of increasing the transmission rate or maximizing the total cell throughput in response to the changes in the channel environment, and this is called link adaptation. In particular, the Modulation and Coding Scheme (MCS) is used for changing the modulation method and channel coding rate according to the channel status. If the channel environment is good, the MCS increases the number of transmission bits per symbol using a high-order modulation, such as 64QAM. If the channel environment is bad, it uses a loworder modulation, such as QPSK and a low coding rate to minimize channel errors. In addition, in the environment where MIMO mode can be used, the eNB operates in MIMO mode to increase the peak data rate of subscribers and can greatly increase the cell throughput. If the channel information obtained is incorrect or modulation method of higher order or higher coding rate than the given channel environment is used, errors may occur. In such cases, the errors can be corrected by the HARD function.

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reliability of the link. The Alamouti codes are used.

when the UE’s channel is unknown or changes fast due

H-ARQ

The H-ARQ is a retransmission method in the physical layer, which uses the stop-and-wait protocol. The eNB provides the H-ARQ function to retransmit or combine frames in the physical layer so that the effects of wireless channel environment changes or interference signal level changes can be minimized, which results in throughput improvement. The LTE uses the Incremental Redundancy (IR)-based H-ARQ method and regards the Chase Combining (CC) method as a special case of the IR method. The eNB uses the asynchronous method for downlink and the synchronous method for uplink.

Power Control

When transmitting a specific data rate, too high a power level may result in unnecessary interferences and too low a power level may result in an increased error rate, causing retransmission or delay. Unlike in other schemes such as CDMA, the power control is relatively less important in LTE. Nevertheless, adequate power contro l can improve performance of the LTE system. Therefore, the UE should use adequate power levels for data transmission in order not to interfere with nearby cells. Likewise, the power level for each UE could be controlled for reducing the inter-cell interference level. In the LTE downlink, the eNB can reduce inter-cell interference by transmitting data at adequate power levels according to the location of the UE and the MCS, which results in improvement of the entire cell throughput.

MIMO

The eNB can support the MIMO by using multiple antennas. For this purpose, the channel card of the eNB has the baseband part to process the MIMO, and individual RF paths can be processed separately. The eNB supports various types of the MIMO to provide the highperformance data servic e.

The eNB uses multiple antennas to support the MIMO. MIMO has the following schemes.

Direction Item Description

Downlink SFBC (Space Frequency

Block Coding)

SM (Spatial Multiplexing) Different data are divided to multiple antenna paths for

This scheme implements the space-time block codi ng (STBC) on frequency instead of on time for increased

transmission so as to increase the peak data rate. (Each path uses the same time/frequen cy resource.)

- Single User (SU)-MIMO: The SM between one eNB and one UE to increase peak data rate for one UE.

- Open-loop SM: The SM that works without the Precoding Matrix Indicator (PMI) feedback of the UE

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movement of the UE.

selection of Tx antenna)

UEs.

Direction Item Description

to fast movement of the UE.

- Closed-loop SM: The SM that works with the Precoding Matrix Indicator (PMI) feedback of the UE when the UE’s channel is known or changes slow due to slow

Uplink UL Transmit A ntenna

Selection

Multi-User (MU) MIMO or Collaborative MIMO

The 1 RF chain/2Tx antenna is used; and the eNB notifies the UE what Tx antenna to use. (Closed-loop

The peak data rate of each UE is not increased but the cell throughput is increased. In the uplink, two different UEs use the same time/frequency resources for transmitting different data at the same time. The eNB uses a single Tx antenna for selecting two orthogonal

2.2.2 Call Processing Function

Cell Information Transmission

In a serving cell, the eNB periodically transmits a Master Information Block (MIB) and System Information Blocks (SIBs), which are system information, to allow the UE that receives them to perform proper call processing.

Call Control and Air Resource Assignment

The eNB allows the UE to be connected to or disconnected from the network. When the UE is connected to or released from the network, the eNB transmits and receives the signaling messages required for call processing to and from the UE via the Uu interface, and to and from the EPC via the S1 interface. When the UE connects to the network, the eNB performs call control and resource allocation required for service. When the UE is disconnected from the network, the eNB collects and releases the allocated resources.

Handover

The eNB supports intra-frequency or inter-frequency handover between intra-eNB cells, X2 handover between eNBs, and S1 handover between eNBs. It also processes signaling and bearer for handover. At intra-eNB handover, handover-related messages are transmitted via internal eNB interfaces; at X2 handover, via the X2 interface; at S1 handover, via the S1 interface. To minimize user traffic loss during X2 and S1 handovers, the eNB performs the data forwarding function. The source eNB provides two forwarding methods to the target eNB: direct forwarding via the X2 interface and indirect forwarding via the S1 interface. The eNB allows the UE to receive traffic without loss through the data forwarding method at handover.

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Handover Procedure

For more information on the handover procedure, see the ‘Message Flow’ section

below.

Admission Control (

AC)

The eNB provides capacity-based admission control and QoS-based admission control for a bearer setup request from the EPC so that the system is not overloaded.

 Capacity-based admission control

There is a threshold for the maximum number of connected UEs (new calls/handover calls) and a threshold for the maximum number of connected bearers that can be allowed in the eNB. Call admission is determined depending on whether the connected UEs and bearers exceed the thresholds.

 QoS-based admission control

The eNB determines whether to admit a call depending on the estimated PRB usage of the newly requested bearer, the PRB usage status of the bearers in service, and the maximum acceptance limit of the PRB (per bearer type, QCI, and UL/DL).

RLC ARQ

The eNB performs the ARQ function for the RLC Acknowledged Mode (AM) only. When receiving and transmitting packet data, the RLC transmits the SDU by dividing it into units of RLC PDU at the transmitting side and the packet is retransmitted (forwarded) according to the ARQ feedback information received from the receiving side for increased reliability of the data communication.

QoS Support

The eNB receives the QoS Class Identifier (QCI) in which the QoS characteristics of the bearer are defined and the GBR, the MBR, and the Aggregated Maximum Bit Rate (UEAMBR) from the EPC. It provides the QoS for the wireless section between the UE and the eNB and the backhaul section between the eNB and the S-GW. V ia the air inte rface, it per f orm s retransmission GBR/MBR/UE-AMBR values, priority of bearer defined in the QCI, and scheduling considering packet delay budget, and the Packet Loss Error Rate (PLER). V ia the back haul in terfac e, it per form s QCI -based packet classification, QCI to DSCP mapping, and marking for the QoS. It provides queuing depending on mapping results, and each queue transmits packets to the EPC according to a strict priority, etc. In the Element Management System (EMS), in addition to the QCI predefined in the specifications, operator-specific QCI and QCI-to-DSCP mapping can be set.

to satisfy the rate control according to the

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2.2.3 IP Processing

IP QoS

The eNB can provide the backhaul QoS when communicating with the EPC by supporting the Differentiated Services (DiffServ). The eNB supports 8 class DiffServ and mapping between the services classes of the user traffic received from the MS and DiffServ classes. In addition, the eNB supports mapping between the Differentiated Services Code Points (DSCP) and the 802.3 Ethernet MAC service classes.

IP Routing

Since the eNB provides multiple Ethern et int erface s, it stor es in the rout ing table the information on which Ethernet interface the IP packets will be routed to. The routing table of the eNB is configured by the operator. The method for configuring the routing table is similar to the standard router configuration method. The eNB supports static routing settings, but does not support dynamic routing protocols such as Open Shortest Path First (OSPF) or Border Gateway Protocol (BGP).

CHAPTER 2. System Overview

Ethernet/VLAN Interface

The eNB provides Ethernet interfaces and supports the static link grouping, Virtual Local Area Network (VLAN), and Ethernet CoS functions that comply with IEEE 802.3ad for Ethernet interfaces. The MAC bridge function defined in IEEE 802.1D is not supported. The eNB allows multiple VLAN IDs to be set for an Ethernet interface. To support Ethernet CoS, it maps the DSCP value of the IP header to the CoS value of the Ethernet header for Tx packets.

2.2.4 SON Function

The SON function supports the self-configuration, se lf-establishment and self-optimization function.

Self-Configuration and Self-Establishment

Self-configuration and self-establishment enable automatic setup of radio parameters and automatic configuration from system ‘power-on’ to ‘in-service’, which minimizes the effort in installing the system. The detailed functions are as follows.

 Self-Configuration

− Self-configuration of Initial Physical Cell Identity (PCI)

− Self-configuration of initial neighbor information

− Self-configuration of initial Physical Random Access Channel (PRACH)

information

 Self-Establishment

− Automatic IP address acquisition

− Auto OAM connectivity

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− Automatic software and configuration data loading

− Automatic S1/X2 setup

− Self-test

Self-Optimization



PCI auto-configuration The SON server of the LSM is responsible for allocating the initial PCI in the selfestablishment procedure of a new eNB, detecting a problem automatically, and selecting, changing, and setting a proper PCI when a PCI collision/confusion occurs with the neighbor cells during operation.

 Automatic Neighbor Relation (ANR) optimization

The ANR function minimizes the network operator’s effort to maintain the optimal NRT by managing the NRT dynamically depending on grow/degrow of the neighbor cells. This function automatically configures the initial NRT of each eNB and recognizes environment changes, such as cell grow/degrow or new eNB installation during operation to maintain the optimal NRT. In other words, the ANR function updates the NRT for each eNB by automatically recognizing topology changes such as new neighbor cell or eNB installation/uninstallation and adding or removing the Neighbor Relation (NR) to or from the new neighbor cell.

 Mobility robustness optimization

The mobility robustness optimization function is the function for improving handover performance in the eNB by recognizing the problem that handover is triggered at the incorrect time (e.g. too early or too late) before, after, or during handover depending on UE mobility, or handover is triggered to the incorrect target cell (handover to the wrong cell) and then by optimizing the handover parameters according to the reasons for the problem.

 Random Access Channel (RACH) optimization

The RACH Optimization (RO) function minimizes the access delay and interference through dynamic management of the parameters related to random access. The RO function is divided into the initial RACH setting operation and the operation for optimizing parameters related to the RACH. The initial RACH setting operation is for setting the preamble signatures and the initial time resource considering the neighbor cells. The operation for optimizing parameters related to the RACH is for estimating the RACH resources, such as time resource and subscriber transmission power required for random access, that change depending on time, and for optimizing the related parameters.

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