Samsung SMM BMAA022001 User Manual

Ver.

1.0

L TE Smart MBS

System Description

This description 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.

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This description may be changed for the system improvement, standardization and other technical reasons without prior notice.

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INTRODUCTION

Purpose

This description introduces characteristics, features, and structure for Smart MBS

Document Content and Organization

This description consists of 4 Chapters and Abbreviation as follows.

CHAPTER 1. Overview of Samsung MBS System

LTE/CDMA Smart MBS System Description

 Samsung Smart MBS Introduction  Samsung Smart MBS Network Configuration  Samsung Smart MBS System Feature

CHAPTER 2. Overview of Smart MBS

 Smart MBS System Introduction  Smart MBS Main Feature  Smart MBS Specification  Interface between the Systems

CHAPTER 3. Smart MBS System Structure

 Hardware Structure  Software Structure

CHAPTER 4. Message Flow

 LTE Call Processing Message Flow  Loading flow

ABBREVIATION

Provides definition for acronyms used in this description.

INTRODUCTION

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 History

EDITION DATE OF ISSUE REMARKS

1.0 2012. 02. First Edition

LTE/CDMA Smart MBS System Description

TABLE OF CONTENTS

INTRODUCTION I

Purpose ........... ................ ............ ............... ................ ............... ............... ............... .......... ..... ..... ... ..... ...I

Document Cont en t and Orga niz at ion ....... ........ ....... ........ ....... ........ ........ ..... ....... ........ ....... ........ ...... .... ...I

Conventions............... ...... ..... ..... ..... ..... ..... ..... ..... ... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... .. . ..... ..... ..... ..... ..II

Revision Hist or y...................... ........ ....... ........ ........ ....... ........ ....... ........ ........ ....... ........ ..... .. ..... ..... ...... ....II

CHAPTER 1. Overview of Samsung MBS System 오류! 책갈피가 정의되어 있지 않

습니다.

1.1 Introduction to Samsung MBS System...................오류! 책갈피가 정의되어 있지 않습니다.

1.2 Samsung MBS System Network Configuration .................................................................. 1-1

1.2.1 System N etwork Configu r at ion.......................... ..... .오류! 책갈피가 정의되어 있지 않습니다.

1.2.2 LTE System Network Co nf igu r at io n....................... ..... .. ..... ..... ...... ..... ..... ..... ..... ..... ..... ..... ....1-1

1.3 Samsung MBS System Feature............................................................................................1-5

1.3.1 System F e at ur e............................... ..... ..... ..... ..... ....오류! 책갈피가 정의되어 있지 않습니다.

1.3.2 LTE System Feature.......................................... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ... ..... ....1-5

CHAPTER 2. Smart MBS Abstract 1-1

2.1 Smart MBS System Introduction..........................................................................................1-1

2.1.1 System F e at ur e............................... ..... ..... ..... ..... ....오류! 책갈피가 정의되어 있지 않습니다.

2.1.2 LTE System Feature.......................................... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ... ..... ....1-3

2.2 Smart MBS Main Feature..................................................................... ...... ..... ..... ..... ...... ..... .. 1-6

2.2.1 Physic al Lay er P roces s ing Fun ctio n........................ ........ ........ ....... ........ ....... ........ ....... ..... ..1-6

2.2.2 Call Pr o c ess in g F u nc ti on.............................. ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ...... .1-8

2.2.3 IP P roc ess ing Func ti on...................... ........ ........ ....... ........ ....... ........ ..... ........ ....... ........ .......1-10

2.2.4 Operation and Maintenance Function................................................................................1-10

2.3 Specifications ......................................................................................................................1-13

2.4 Interface between Systems................................................................................................. 1-15

2.4.1 Interf ace Structure................................. ........ ....... ....오류! 책갈피가 정의되어 있지 않습니다.

2.4.2 LTE Interface St ru ct u re............................................. ..... ..... ..... ... ..... ..... ..... ..... ..... ..... ..... .....1-15

2.4.3 Physic al Inter f ace Op er atio n M etho d........................................................ ........ ....... ........ ..1-20

III

TABLE OF CONTENTS

CHAPTER 3. Smart MBS Structure 2-1

3.1 Smart MBS Hardware Structure ..............................................................................................2-1

3.1.2 Interna l C on f ig ura t io n o f Sy s te m (LTE) ...................................................... ..... ..... ..... ..... ..... .2-4

3.1.3 UADU................................... ..... ..... ..... ...... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... .. . ..... ...2-6

3.1.4 LRU.............................................. ..... ..... ..... ..... ... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... .............. 2-11

3.1.5 Power D ev i ce................ ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ... ..... ..... ..... ..... ..... ..... ..... ..... ..... . .. .2-13

3.1.5 Enviro nme nt Dev ic es................ ........ ....... ........ ..... ........ ....... ........ ........ ....... ........ ....... ........ .2-15

3.1.6 Interf ac e s tr u ct ure.......................................... ..... ..... ..... ..... ..... ..... .. ..... ...... ..... ..... ..... ..... ... .. .2-17

3.2 Smart MBS Software Structure...........................................................................................2-21

3.2.1 Software S tru ct ur e....................... ..... .. ..... ..... ...... ....오류! 책갈피가 정의되어 있지 않습니다.

3.2.2 LTE Software Stru ctu re............................ ........ ........ ....... ..... ........ ........ ....... ........ ....... ........ .2-21

CHAPTER 4. Message Flow 3-1

4.1 Call Processing Message Flow.............................................................................................3-1

4.1.1 Call Pro ces sin g Me ssa ge F low.......... ........ ........ ....오류! 책갈피가 정의되어 있지 않습니다.

4.1.2 LTE Call Processing Messa ge Fl ow................... ....... ........ ....... ........ ........ ....... ........ ....... ......3-1

4.2 Loading Flow........................................................................................................................3-13

ABBREVIATION I

A ~ C................................................ ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ... ..... ..... ..... . .... ... ..... ..... ..... ..... ..I

D ~ F......................... ........ ....... ........ ....... ........ ....... ........ ........ ....... ........ ....... ........ ...... .. ..... ..... ..... ..... ..... .II

G ~ M..................... ........ ........ ..... ....... ........ ....... ........ ........ ....... ........ ....... ........ ........ .... ... ..... ..... ..... ...... ..III

N ~ P.......................................................... ....... ........ ........ ....... ........ ..... ....... ........ ...... .... ..... ..... ..... ... .....IV

Q ~ S........................................ ........ ....... ..... ........ ....... ........ ........ ....... ........ ........ ....... . ....... ..... ..... ..... ..... .V

T ~ W..................................... ....... ........ ....... ........ ........ ....... ........ ....... ........ ........ ....... ... ..... ..... .. ..... ...... ..VI

LIST OF FIGURES

Figure 1.1 Network Configuration of Samsung MBS System오류! 책갈피가 정의되어 있지 않습

니다.

Figure 1.3 LTE System Network Configuration..................................... ..................................1-1

Figure 1.4 System Functional Structure......................오류! 책갈피가 정의되어 있지 않습니다.

Figure 1.5 Functions of E-UTRAN and EPC...........................................................................1-5

Figure 2.1 Protocol Stack between BTS and MS........오류! 책갈피가 정의되어 있지 않습니다.

Figure 2.2 Protocol Stack between BTS and BSC......오류! 책갈피가 정의되어 있지 않습니다.

Figure 2.3 Protocol Stack between BTS and BSM......오류! 책갈피가 정의되어 있지 않습니다.

LTE/CDMA Smart MBS System Description/Ver.1.0

Figure 2.4 LTE Interface Structure........................................................................................1-15

Figure 2.5 Protocol Stack between UE and eNB.................................................................. 1-16

Figure 2.6 Protocol Stack between eNB and EPC................................................................ 1-17

Figure 2.7 Protocol Stack between eNB and MME............................................................... 1-17

Figure 2.8 Protocol Stack between eNBs (User Plane)........................................................ 1-18

Figure 2.9 Protocol Stack between eNBs (Control Plane).................................................... 1-18

Figure 2.10 Protocol Stack between eNB and LSM..............................................................1-19

Figure 3.1 Smart MBS Configuration......................................................................................2-2

Figure 3.4 LTE 6 Sector Configuration................................................................................... 2-3

Figure 3.6 Internal Configuration of System (LTE) .................................................................2-4

Figure 3.7 UADU Configuration..................................오류! 책갈피가 정의되어 있지 않습니다.

Figure 3.8 Cooling Structure of the UADU (FANM-C4)......................................................... 2-10

Figure 3.9 Power Device Configuration................................................................................ 2-13

Figure 3.10 Power Structure.................................................................................................2-14

Figure 3.10 Configuration of Environment Devices.............................................................. 2-15

Figure 3.12 Hardware Interface structure of UADU (LTE) .................................................... 2-19

Figure 3.13 Hardware Interface structure of LRU-C2........................................................... 2-20

Figure 3.18 LTE Software Structure ..................................................................................... 2-21

Figure 4.15 Attach Process....................................................................................................3-2

Figure 4.16 Service Request Process by UE.........................................................................3-4

Figure 4.17 Service Request Process by Network................................................................. 3-5

Figure 4.18 Detach Process by UE........................................................................................ 3-6

Figure 4.19 Detach Process by MME..................................................................................... 3-7

Figure 4.20 X2-based Handover Procedure........................................................................... 3-8

Figure 4.21 S1-based Handover Procedure......................................................................... 3-10

Figure 4.22 Smart MBS’ Loading Message Flow.................................................................3-14

LTE/CDMA Smart MBS System Description

1.2 Samsung MBS System Network Configuration

Samsung MBS system plays a role as LTE base station in a network where LTE systems co-exist. Samsung MBS System is configured as follows:

1.2.2 LTE System Network Configuration

LTE network of Samsung MBS system incorporates base station (eNB), packet core (EPC), LSM. The LTE system consists of multiple base stations (eNB: Evolved UTRAN Node-B) and EPC(MME, S-GW/P-GW) provides functionality for UE to connect to external network as subnet of PDN. In addition, LTE system provides LSM and self-optimization function for operation and maintenance of eEB.

LTE network architecture of Samsung MBS system is as follows:

EMS

LSM-C

EMS

LSM-R

MSS

RMI

TL1

SNMP/FTP/UDP

PDN

EPC

S10

P-GW

S5/S8

S11 S6a

S-GW

S1-U

Smart MBS Smart MBS

MME

S1-MME

X2-C

X2-U

OCS

PCRF

HSS/SPR

Figure 1.3 LTE System Network Configuration

Evolved UTRAN Node-B (eNB)

eNB is a system located between mobile terminal (User Equipment, UE) and EPC, and it handles the packet calls by connecting to UE wirelessly in accordance with LTE air standard. eNB executes various functions including Tx/Rx of wireless signal, modulation/demodulation of packet traffic, packet scheduling for efficient use of RF resources, Hybrid Automatic Repeat request (HARQ) and Automatic Repeat request (ARQ) process, Packet Data Convergence Protocol (PDCP) of compressed packet header,

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CHAPTER 1. Smart MBS Abstract

and wireless resource control. Also, it synchronizes with EPC to execute handover.

Evolved Packet Core (EPC)

EPC is a system between eNB and PDN. It incorporates MME, S-GW/P-GW.

 MME: MME handles control message with eNB via Non-Access Stratum (NAS)

signaling protocol, and performs management of mobility for UE, management of tracking area list, control plane function such as bearer and session management.

 S-GW: S-GW plays role as anchor on user plane between 2G/3G access system and

LTE system. S-GW manages/processes packet transmit layer of downlink/uplink data.

 P-GW: P-GW allocates IP address to UE, plays role as anchor for mobility between

LTE system and non-3GPP access systems, manages accounting for different service levels, and handles management/modification of the throughput rate.

LTE System Manager (LSM)

LSM provides the following functions.

 LTE System Manager-Radio (LSM-R)

The LSM-R provides an operator interface which the operator can use for operation and maintenance of the eNB. It also provides functions for software management, configuration management, performance management and fault management, and Self Organizing Network (SON) server.

 LTE System Manager-Core (LSM-C)

The LSM-C provides an operator interface which the operator can use for operation and maintenance of the MME, S-GW and P-GW.

Home Subscriber Server (HSS)

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 and supplementary services, and provides a routing function to the called subscriber.

Master SON Server (MSS)

MSS is a higher node of local SON server. MSS interworks with local SON server to optimize the interworking in regards to Multi-LSM. MSS is a function that is interworking with the operator Operations Support System (OSS), and the availability of this optional function will be decided after discussion with operator.

Policy Charging & Rule Function (PCRF)

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

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LTE/CDMA Smart MBS System Description/Ver.1.0

PCRF server to each service flow.

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CHAPTER 1. Smart MBS Abstract

Online Charging System (OCS)

If subscribers (with online accounting information) makes call, subscriber’s accounting information is sent/received.

Offline Charging System (OFCS)

OFCS stores the offline accounting data, and provides accounting data per each subscriber.

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LTE/CDMA Smart MBS System Description/Ver.1.0

1.3 Samsung MBS System Feature

1.3.2 LTE System Feature

The eNB manages UEs which are in connected mode at the Access Stratum (AS) level. The MME manages UEs which are in idle mode at the Non-Access Stratum (NAS) level, and the P-GW manages user data at the NAS level as well as working with other networks.

The functional architecture of E-UTRAN eNB, MME, S-GW, and P-GW according to the 3GPP standard is shown below. The eNB is structured in layers while the EPC is not.

eNB

Inter Cell RRM

RB Control

Connection Mobility Control

Radio Admission Control

eNB Measurement

Configuration & Provision

Dynamic Resource

Allocation (Scheduler)

RRC

PDCP

RLC

MAC

PHY

E-UTRAN

MME

NAS Security

Idle State Mobility

Handling

EPS Bearer Control

S-GW

Mobility Anchoring

P-GW

UE IP address allocation

Packet Filtering

EPC

Internet

eNB

The eNB serves the Evolved UTRAN (E-UTRAN), a wireless access network in the LTE system. The eNBs are connected via the X2 interface whereas the eNB and EPC are connected via S1 interface. The eNB’s wireless protocol layers are divided into Layer 2 and Layer 3. Layer 2 is subdivided into the Media Access Control (MAC) layer, Radio Link Control (RLC) layer, and PDCP layer, each operating independently. Layer 3 has the RRC layer.

The MAC sublayer distributes wireless resources to each bearer according to its priority, and carries out the multiplexing function and the HARQ function for the data received from the multiple upper logical channels.

The RLC layer performs the following functions.

Figure 1.5 Functions of E-UTRAN and EPC

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CHAPTER 1. Smart MBS Abstract

 Segmentation and reassembly on the data received from the PDCP sublayer into the

size specified by the MAC sublayer

 Restoration of the transmission by resending in case of transmission failure at lower-

level layers (ARQ)

 Re-ordering of the HARQ operation of the MAC sublayer

The PDCP layer carries out the following functions.

 Header compression and decompression  Ciphering and deciphering of the user plane and control plane data  Integrity protection and verification of the control plane data  Data transmission of data, including serial numbers  Removing timer-based and duplicate data

The RRC layer is responsible for managing mobility in the wireless access network, keeping and controlling the Radio Bearer (RB), managing RRC connections, and sending system information.

Mobility Management Entity (MME)

The MME works with the E-UTRAN (eNB), handling S1 Application Protocol (S1-AP) signaling messages in the Stream Control Transmission Protocol (SCTP) base to control call connections between the MME and eNB as well as handling NAS signaling messages in the SCTP base to control mobility and call connections between the UE and EPC. The MME also works with the HSS to obtain, modify and authenticate subscriber information, and works with the S-GW to request assignment, release and modification of bearer paths for data routing and forwarding using the GTP-C protocol. The MME can work with the 2G and 3G systems, SGSN, and MSC to provide mobility, Handover (HO), Circuit Service (CS) fallback, and Short Message Service (SMS). The MME is also responsible for managing mobility between eNBs, idle-mode UE reachability, Tracking Area (TA) list as well as for P-GW/S-GW selection, authentication, and bearer management. MME supports the handover between MMEs and provides the mobility for the handover between the eNBs. It also supports the SGSN selection function upon handover to a 2G or 3G 3GPP network.

Serving Gateway (S-GW)

The S-GW performs the mobility anchor function upon inter-eNB handover and inter-3GPP handover as well as routing and forwarding of packet data. The S-GW allows the operator to set a different charging policy by UE, PDN or QCI, and manages the packet transport layer for uplink/downlink data. The S-GW also works with the MME, P-GW, and SGSN to support the GPRS Tunneling Protocol (GTP) and Proxy Mobile IP (PMIP).

PDN Gateway (P-GW)

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LTE/CDMA Smart MBS System Description/Ver.1.0

The P-GW works with PCRF to carry out charging and bearer policies, and manage the charging and transmission rate based on the service level. It also provides packet filtering per subscriber, assigns IP addresses to UEs, and manages the packet transmission layer of the downlink data.

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CHAPTER 1. Smart MBS Abstract

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LTE/CDMA Smart MBS System Description

CHAPTER 1. Smart MBS Abstract

2.1 Smart MBS System Introduction

Smart MBS is the Samsung MBS system. It is managed by packet core (BSC, EPC), and makes call to terminal to create LTE links. It is controlled by the BSC, DPC(LTE)for connecting LTE calls to the mobile terminal.

To this end, the Smart MBS provides the following functions: modulation/demodulation of packet traffic signal, scheduling and radio bandwidth allocation to manage air resources efficiently and ensure Quality of Service (QoS), Automatic Repeat request (ARQ) processing, ranging function, connection control function to transmit the information on the Smart MBS and set/hold/disconnect the packet call connection, handover control, control station such as BSC/EPC interface function, power control function and system operation management function.

The Smart MBS securely and rapidly transmits various control signals and traffic signals by interfacing with the BSC/EPC via the Fast Ethernet/Gigabit Ethernet backhaul.

Physically, the Smart MBS consists of an Universal platform type A Digital Unit (UADU), which is a DU, and Local Radio Unit (LRU), which is a combined RF unit. UADU and LRU are mounted on the outdoor cabinet with rectifier. UADU is a digital part, which is a type of 19 in. shelf. It can be mounted onto outdoor 19 inch commercial rack, and one UADU can provide the following maximum capacity. Based on operator’s setup, it can be operated as omni type or sector type.

 LT E: 5 MHz 1 Carrier/6 Sector

LRU cab be operated as follows as RF part.

 Advanced Wireless Services (AWS) band, 1Tx/2Rx RF path

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CHAPTER 2. Smart MBS Abstract

Smart MBS also provided the following features:

Common Platform

Digital boards of each wireless technology, to be mounted in Smart MBS, share the common DU platform. Therefore, different boards (for multiple technologies) may be mounted in a single DU, and operator can mount up to 2 UADUs in outdoor cabinet to implement various configurations. LRU of Smart MBS can simultaneously support multiple technologies in the same duplexing type with the same bandwidth.

Loopback Test

Smart MBS provides the loopback test function to check whether communication is normal on the baseband I/Q interface line between the UADU and LRU.

Remote Firmware Downloading

The operator can upgrade the LRU and its service by replacing its firmware. Without visiting the field station, the operator can download firmware to the LRU remotely using a simple command from the BSM/LSM-R. In this way, operators can minimize the number of visits to the field station, reducing maintenance costs and allowing the system to be operated with greater ease.

Monitoring Port

Operators can monitor the information for an LRU using its debug port.

Smooth Migration

The UADU of the Smart MBS supports migration from 4G mobile communication such as LTE by adding traffic processor card/channel cards and upgrading the software. The LRU of the Smart MBS, on the other hand, only requires software upgrade for evolving into 4G mobile communication in the same frequency range or even simultaneous operation of 3G and 4G mobile communications.

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LTE/CDMA Smart MBS System Description/Ver.1.0

2.1.2 LTE System Feature

OFDMA/SC-FDMA Technology

Smart MBS can handle downlink OFDMA/uplink SC-FDMA channel processing that supports the Physical Layer of LTE standard. Downlink OFDMA can use sub-carrier, which are assigned to each subscriber, to simultaneously send data to multiple users. Also, in accordance with the requested data transfer rate, it can assign single (or multiple) sub-carrier to particular subscriber for data transmission. Also, when entire sub-carriers are shared by multiple subscribers, OFDMA can dynamically determine well-matched sub-carrier for each subscriber, so that resource can be assigned efficiently to enhance data throughput.

Uplink SC-FDMA is basically similar to Mod/Demodulation algorithm of OFDMA. However, Discrete Fourier Transform (DFT) process is handled per each subscriber during Tx Modulation, then on contrary, Inverse Discrete Fourier Transform (IDFT) process is handled during Demodulation to minimize potential Peak to Average Power Ratio (PAPR) that can occur during the transmission. Also it is responsible for assigning the particular frequency resource to particular subscriber continuously. As a result, it will reduce the power that is dissipated by terminal.

Support for Broadband Channel Bandwidth

Smart MBS provides multiple bandwidth of 5 MHz high speed/high capacity packet service.

QoS Support

Smart MBS provides QoS for the EPS bearer/E-RAB based on the standard QCI and operator-specific QCI of the 3GPP TS. 23.203 specifications. Detailed techniques to provide QoS are:

 QoS-based radio scheduling

 The scheduler allocates resources to provide the GBR based on QoS characteristics

(resource type, priority, PDB and PLER).

 The scheduler supports the Aggregate Maximum Bit Rate (AMBR) for non-GBR

bearers.

 Backhaul QoS

 QoS mapping between the QoS class and DSCP  IP DSCP and Ethernet COS markings are used to satisfy the carrier’s backhaul

requirements.

 Transmission is controlled according to the priority by QoS classes, such as

signaling, user traffic and O & M traffic.

 QoS-based CAC

The CAC algorithm accepts calls only when the requested bit rate and QoS can be satisfied.

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CHAPTER 2. Smart MBS Abstract

SON

SON provides functions such as self-configuration, self-establishment and self-optimization.

Self-Configuration & Self-establishment

Self-configuration and the self-establishment allow system to configure radio parameters automatically, and to be powered up and have backbone connectivity without human interventions. This will reduce the cost of eNB installation and management. The detailed functions are as follows:

 Self-configuration

 Initial Peripheral Component Interconnect  Initial neighbor information self-configuration  Initial Physical Random Access Channel

 Self-establishment

 Auto OAM connectivity  Software and configuration data loading  Automatic S1/X2 setup  Self-Test

Self-Optimization

 PCI auto-configuration

The local SON server of the LSM provides the function for allocating the initial PCI in the self-establishment procedure of a new system, and the function for detecting a problem automatically and setting a proper PCI when a PCI collision/confusion occurs during operation with the adjacent cells.

 Automatic Neighbor Relation (ANR) optimization

The ANR function dynamically manages the Neighbor Relation Table (NRT) according to neighbor cells growing/degrowing reduced so as to minimize the network operator’s efforts to maintain the optimal NRT. To maintain the optimal NRT, SON server is required to self-configure initial NRT of each system and to detect environmental changes during operation, such as cell growing/degrowing or new system installation. In other words, the ANR function updates the NRT for each eNB by automatically recognizing the topology change such as installing or removing a new adjacent cell or adjacent system and by adding or removing the Neighbor Relation (NR) to or from a new adjacent cell.

 Mobility robustness optimization

Based on the moment before, after, or during handover caused by mobile terminal mobility within the system, the mobility robustness optimization function is to improve handover performance by recognizing problems that trigger handover at the incorrect time (e.g., too early or too late) or to the incorrect target cell and by optimizing the handover parameters according to the causes of the problems.

 RACH optimization

The RACH Optimization (RO) function can minimize the network operator’s efforts to minimize access delay and interference by managing dynamically the parameters related to random access. The RO function is divided into the initial RACH setting

(PCI) self-configuration

(PRACH) information self-configuration

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LTE/CDMA Smart MBS System Description/Ver.1.0

operation and the operation for optimizing parameters related to the RACH.

 The initial RACH setting is to set the preamble signatures and the initial time

resource considering the neighbor cells.

 The parameter optimization related to the RACH is to optimize the related

parameters by estimating the RACH resources, such as time resource and subscriber transmission power required for random access that changes by time during operation.

 Load balancing

The Load balancing feature in a multi-carrier environment selects and hands over mobile terminal from a high-loaded carrier and to a low-loaded carrier. If all carriers in the same sector are highly loaded, it selects a low-loaded neighbor cell and the mobile terminal in the cell edge to perform handover. The mobile terminal selection algorithm tries to minimize the QoS degradation. Idle UE distribution function among carriers ensures that mobile terminals are camped in a way that they are distributed to low-loaded carriers, considering the active UE load distribution among the carriers in the same sector.

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

this system description, please refer to separate documentations.

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CHAPTER 2. Smart MBS Abstract

2.2 Smart MBS Main Feature

Smart MBS is a base station that supports LTE technology which provides physical layer, and call processing feature. Regardless of the operated technology, IP processing feature and operation/maintenance feature are integrated.

2.2.1 Physical Layer Processing Function

2.2.1.2 LTE Physical Layer Processing Function

Downlink Reference Signal Generation and Transmission

Reference Signal is used for demodulation of downlink signal at mobile terminal, and also utilized for measuring the channel characteristic for scheduling, link adaptation, and handoff. In case of sending Non-MBSFN (Multimedia Broadcast multicast service over a Single Frequency Network), there are two reference signals.

 Cell-specific reference signal: Cell-specific reference signals are used to measure the

quality of the channel, calculate the MISO rank, perform MISO precoding matrix selection, and measure the strength of the signals for handover.

 UE-specific reference signal: UE-specific reference signals are used to measure the quality

of the channel for data demodulation which is located in the PDSCH block of the specific mobile terminal in the beamforming transmission mode.

Downlink Synchronization Signal Generation and Transmission

Synchronization signal is used by mobile terminal when obtaining the initial synchronization before communicating with base station. It has two signals, namely Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS). Cell identity information can be identified by synchronization signal. Mobile terminal can obtain additional information (other than cell information) via Broadcast Channel. Synchronization signal and Broadcast channel are transmitted through the exact center of channel bandwidth of the cell, which is 1.08 MHz band. This is to allow mobile terminal to identify cell’s basic information such as cell ID regardless of base station’s transmission bandwidth range.

Channel Encoding/Decoding

Smart MBS executes channel encoding/decoding function which is designed to correct the error generated on wireless channel environment. LTE uses turbo coding and 1/3 tail-biting convolutional coding. Turbo coding is generally used to send relatively large data of downlink/uplink, while convolutional coding is used for control data transmission (downlink and uplink) or used as broadcast channel.

Modulation/Demodulation

In case of downlink, Smart MBS receive data from upper layer, process it with baseband of

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LTE/CDMA Smart MBS System Description/Ver.1.0

physical layer, and sends it out onto wireless channel. At this time, baseband signal is modulated to higher bandwidth in order to transmit it to longer distance. Also, in case of uplink, base station receives the data via wireless channel, demodulate it into baseband signal, and decodes it.

Resource Allocation & Scheduling

With LTE, Smart MBS uses multi link scheme. OFDMA is used for downlink while SCFDMA is used for uplink. Both schemes allocate 2-dimensional (time & frequency) resources into multiple terminals (without overlapping to each other) that communication link is allocated to multiple terminals. In exceptional case of MU-SISO mode, same resource can be shared among multiple terminals. Such allocation of resources onto multiple terminal, is referred to as scheduling, and individual scheduler of each cell can process this. LTE Scheduler of Smart MBS can analyze channel environment of each terminal, demanded data transfer rate, and various QoS to optimize the resource allocation to maximize the cell’s total throughput. Also, in order to reduce the interference with other cells, it can exchange information with other cell’s scheduler via X2 interface.

Link Adaptation

Wireless channel condition can change either rapidly or slowly, either improve or deteriorate. When channel’s condition can be expected, it can be used to increase the data transfer rate, or maximize the entire cell’s throughput. This is called ‘Link Adaption’. Particularly, MCS (Modulation and Coding Scheme) can adjust modulation scheme and channel coding rate at different channel’s conditions. For example, good channel environment will utilize high-order modulation (such as 64 QAM) to enlarge the number of transmitted bit per unit symbol, but bad channel environment will utilize low-order modulation and low coding rate to minimize the channel error. In channel environment where MISO is supported, MISO Mode is utilized to either increase the user’s peak data rate or cell throughput. In cases when channel condition is incorrectly reported, or if higher ordered modulation or coding rate is used, error can occur. This can be efficiently corrected by Hybrid-ARQ feature.

H-ARQ

H-ARQ is a physical layer retransmission scheme which utilizes stop-and-wait protocol. Smart MBS executes H-ARQ to minimize the potential impact due to change in either wireless channel environment or noise signal level. It improves throughput by retransmitting or combining the frame in physical layer. LTE uses H-ARQ technique based on Incremental Redundancy (IR), and considers Chase Combining (CC) scheme as one specific method of IR. In case of Downlink, Smart MBS uses asynchronous scheme, but uplink uses synchronous scheme.

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Inter-Cell Interference Coordination (ICIC)

Since mobile terminals within a cell in LTE use orthogonal resources with no interference between the mobile terminals, there is no intra-cell interference. However, if different mobile terminals in neighboring cells use the same resource, interference may occur. This happens more seriously between the mobile terminals located on the cell edge, resulting in serious degradation at cell edge. The technique used to relieve such inter-cell interference problem on the cell edge is InterCell Interference Coordination (ICIC). ICIC allows interference signals to be transmitted to other cells in the cell edge area in as small an amount as possible by allocating a basically different resource to each mobile terminal that belongs to a different cell and by carrying out power control according to the mobile terminal’s location in the cell. Smart MBS uses the X2 interface for exchanging scheduling information with one another for preventing interferences by resource conflicts at cell edges. If the interference of a nearby cell is too strong, the system informs the other system to control the strength of the interference system. Therefore, the ICIC function is used for enhancing the overall cell performance.

2.2.2 Call Processing Function

2.2.2.2 LTE Call Processing Function

Cell Information Transmission

In the cell area being served, the Smart MBS periodically broadcasts a Master Information Block (MIB) and the System Information Blocks (SIBs), which are system information, to allow the mobile terminal that receives them to perform proper call processing.

Call Control and Air Resource Assignment

Smart MBS allows the mobile terminal to be connected to or to be released from the network. When the mobile terminal is connected to or released from the network, the Smart MBS sends and receives the signaling messages required for call processing to and from the mobile terminal via the Uu interface, and to and from the EPC via the S1 interface. When the mobile terminal connects to the network, the Smart MBS carries out call control and resource allocation required for service. When the mobile terminal is released from the network, it collects and releases the allocated resources.

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Execution of Handover

Smart MBS supports intra-frequency or inter-frequency handover between intra-eNB cells, X2 handover between eNBs, and S1 handover between eNBs, and carries out the signaling and bearer processing functions required for handover. At intra-eNB handover, handoverrelated messages are transmitted via internal eNB interfaces; at X2 handover, via the X2 interface; at S1 handover, via the S1 interface. Smart MBS carries out the data retransmission function to minimize user traffic disconnections at X2 and S1 handovers. The source eNB provides two methods of using the X2 interface for direct retransmission to the target eNB and using the S1 interface for indirect retransmission. Smart MBS uses the data forwarding function to ensure that the UE receives the traffic without any loss at handover.

Admission Control (AC) Function

Smart MBS 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 AC

There is a threshold for the maximum number of connected mobile terminals (new calls/handover calls) and a threshold for the maximum number of connected bearers that can be allowed in the Smart MBS. When a call setup is requested, the permission is determined depending on whether the connected mobile terminals and bearers exceed the thresholds.

 QoS-based AC

Smart MBS provides the function for determining whether to permit a call depending on the estimated Physical Resource Block (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 Function

Smart MBS carries out the ARQ function for the RLC Acknowledged Mode (AM) only. When receiving and sending packet data, the RLC transmits the SDU by dividing it into units of RLC PDU in the sending end and the packet is forwarded according to the ARQ feedback information received from the receiving side for increased reliability of the data communication.

QoS Support Function

Smart MBS should receive QCI (QoS Class Identifier) which defines QoS characteristics, GBR, Maximum Bit Rate (MBR), Aggregated Maximum Bit Rate (AMBR) from EPC. Also, it should provide QoS between wireless interface between mobile terminal and Smart MBS, and on the backhaul between Smart MBS and S-GW. Wireless interface should perform retransmission in order to satisfy rate control based on GBR/MBR/AMBR values, bearer priority defined in QCI, and scheduling considered packet delay budget, and Packet Loss Error Rate (PLER). For QoS in Backhaul, packet classification based on QCI, QCI to DSCP mapping, and marking should be executed. Queuing should be provided in accordance with the result of the mapping, and each Queues should send the packets to EPC per strict priority. In case of EMS, other than the previously defined QCI, configuration for operator specific QCI and QCI-to-DSCP mapping can be configured.

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2.2.3 IP Processing Function

IP QoS Feature

Since Smart MBS supports Differentiated Services (DiffServ), it can provide the backhaul QoS in the communication with ACR. It supports 8-class DiffServ and supports the mapping between the DiffServ service class and the service class of the user traffic received from an MS. In addition, Smart MBS supports the mapping between Differentiated Services Code Point (DSCP) and 802.3 Ethernet MAC service class.

IP Routing Function

Since Smart MBS provides multiple Ethernet interfaces, it maintains a routing table to route IP packets to different Ethernet interfaces. Smart MBSs. routing table is configured by the operator similar to a standard router configuration. Smart MBS only supports static source routing, and does not provide routing feature for traffic received from external network and does not support any IP routing protocols.

Ethernet/VLAN Interface Feature

The TD-LTE Flexible system provides the Ethernet interface and supports the static link grouping function, Virtual Local Area Network (VLAN) function and Ethernet CoS function under IEEE 802.3ad for the Ethernet interface. At this time, the MAC bridge function defined in IEEE 802.1D is excluded. The TD-LTE Flexible system enables several VLAN IDs to be set in one Ethernet interface and maps the DSCP value of IP header with the CoS value of Ethernet header in Tx packet to support Ethernet CoS.

2.2.4 Operation and Maintenance Function

Smart MBS interworking with the management system carries out the following maintenance functions: system initialization and restart, management for system configuration, management for the operation parameters, failure and status management for system resources and services, statistics management for system resources and various performance data, diagnosis management for system resources and services and security management for system access and operation.

Graphic and Text based Interface

BSM/LSM-R manages the each LTE system by using Database Management System (DBMS) and Smart MBS interworks with this BSM/LSM-R. For operator’s convenience and working purpose, graphic-based and text-based interface is provided. The operator can carry out the retrieval and setup of the configuration and the operation information and monitoring about faults, status and statistics via this interface. Also, the operator can carry out grow/degrow of resources and setting of the neighbor list and paging group which have correlation between several NEs only via the BSM/LSM-R.

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