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UMTS Reference for RF Engineers and RNC Engineers UMTS Reference for RF Engineers and RNC Engineers Version 1.0 November 10, 2008 2100 Lakeside Blvd. Suite 300 Richardson, Texas 75082 Phone: +1.972.664.0727 Fax: +1.972.664.0729 If you have any questions, concerns or comments regarding this document please write to us at: www.awardsolutions.com friends@awardsolutions.com  2008 Award Solutions, Inc. All rights reserved. No part of this book shall be reproduced or transmitted by any means, electronic, mechanical, photocopying, recording or otherwise, without the express written consent from Award Solutions, Inc. UMTS Reference for RF Engineers and RNC Engineers Table of Contents 1.0 Scope of the Document 1 2.0 Introduction of UMTS 1 3.0 GSM/GPRS/EDGE Evolution to UMTS 1 4.0 UMTS Releases 2 Release 99 2 Release 4 2 Release 5 2 Release 6 2 Release 7 2 Release 8 2 5.0 The UMTS Core Network 3 MSC/VLR 3 Home Location Register (HLR) 3 SGSN 3 GGSN 3 6.0 The UTRAN 3 RNC 4 Node B 4 7.0 UMTS Interfaces 4 Access Stratum (AS) 4 Non Access Stratum (NAS) 4 Uu Interface 5 Iu Interface 5 Iub Interface- “The Backhaul” 5 Iur Interface 5 8.0 UE-UTRAN Protocol Stack 5 WCDMA Physical Layer (L1) 5 Medium Access Control (MAC) Layer (L2) 5 Radio Link Control (RLC) Layer (L2) 6 Radio Resource Control (RRC) Layer (L3-Control) 6 Packet Data Convergence Protocol (PDCP) Layer (L3-Data Traffic) 7 9.0 WCDMA 7 Forward Error Correction (FEC) Coders 7 Orthogonal Variable Spreading Factor (OVSF) Codes 7 Scrambling Codes 8 Data Rate Computation 8 10.0 Channels 9 Logical Channels 9 Transport Channels 9 Physical Channels 10 DL Dedicated Physical Channel 10 UL Dedicated Physical Channel 11 Modulation Schemes 11 11.0 Power Control 12 UMTS Reference for RF Engineers and RNC Engineers Eb/No 12 Ec/Io 12 Power Control in UMTS R99 12 Open Loop Power Control 12 Closed Loop Power Control 12 12.0 RRC Connection and RRC States 13 RRC Idle Mode 13 RRC Connected Mode 13 CELL_DCH sub-state 14 CELL_FACH sub-state 14 CELL_PCH sub-state 14 URA_PCH sub-state 14 13.0 UE Power Up and Initial Cell Selection 15 Synchronization 15 14.0 Voice Calls 15 Registration Procedure 15 Voice Call Setup 15 Channels for a Voice Call 16 15.0 R99 Data Calls 16 Attach Procedure 16 R99 Data Call Setup 16 Channels for a R99 Data Call 17 PDP Contexts 17 16.0 Handovers and Measurements 17 Soft Handovers 17 Hard Handovers 18 Measurements 18 Measurement Control and Measurement Reports 19 17.0 HSDPA Concepts 21 18.0 HSDPA Channels 21 High Speed – Downlink Shared Channel (HS-DSCH) 21 High Speed – Physical Downlink Shared Channel (HS-PDSCH) 22 High Speed - Shared Control Channel (HS-SCCH) 22 High Speed - Dedicated Physical Control Channel (HS-DPCCH) 23 19.0 HSDPA Traffic Operations 24 Basis for CQI Reporting 24 HSDPA DL Scheduler 25 HSDPA Hybrid ARQ 25 20.0 HSUPA Concepts 27 Rise over Thermal (ROT) Threshold: 27 21.0 HSUPA Channels 27 Enhanced Dedicated Channel (E-DCH) 27 Enhanced Dedicated Physical Data Channel (E-DPDCH) 28 Enhanced Dedicated Physical Control Channel (E-DPCCH) 28 E-DCH Absolute Grant Channel (E-AGCH) 28 UMTS Reference for RF Engineers and RNC Engineers E-DCH Relative Grant Channel (E-RGCH) 28 E-DCH HARQ Indicator Channel (E-HICH) 29 22.0 HSUPA Traffic Operations 30 Scheduling Request 30 Grants 30 HSUPA Hybrid ARQ 31 23.0 HSPA Data Calls 32 Attach Procedure 32 HSPA Data Call Setup 32 Channels for a HSPA Data Call 32 24.0 Acronyms 34 UMTS Reference for RF Engineers and RNC Engineers 1 1.0 Scope of the Document This document is a quick reference for RF Engineers and RNC Engineers for UMTS Release 99 (R99), Release 5 (R5) HSDPA and Release 6 (R6) HSUPA concepts and terms. It provides a summary of the important ideas and concepts in the courses which are part of the Bronze curriculum for RF Engineers and RNC Engineers at AT&T. The courses are: 1. FOT110 - Evolution from GSM to UMTS (eLearning) 2. FOT120 – Overview of UMTS (eLearning) 3. FOT121 – UMTS/WCDMA Air Interface Fundamentals (eLearning) 4. FOT123 – UMTS Signaling (eLearning) 5. AOT101 – HSDPA (R5) Overview (eLearning) 6. AOT103 – HSUPA (R6) Overview (eLearning) 7. ATN301 – UMTS Radio Network Protocols and Signaling (Instructor Lead Training) 8. ATN302 – HSPA Protocols and Signaling (Instructor Lead Training) It is intended to serve two purposes: • Serve as a quick reference document on the job for UMTS concepts and terms • Assist RF Engineers and RNC Engineers to prepare for their Bronze Assessment Test This document is designed to be used as a supplementary reference to the courses listed above and not as a stand-alone document . 2.0 Introduction of UMTS Second Generation (2G) cellular wireless systems, like GSM/GPRS/EDGE, introduced the use of digital radio techniques that employ digital transmission mechanisms, including digitized compressed speech signals, for wireless mobile telephony and low speed packet data services. Since the original intent of 2G systems was the delivery of high quality voice services, 2G systems can only provide low data rate packet radio services. In particular, GPRS/EDGE is an enhancement to GSM which adds a second domain to the existing circuit-switched domain of the GSM core network; specifically, a packet domain of routers is added to GSM’s circuit-switched core network. Though the packet-switched domain provides direct access to the Internet, the user’s access is constrained by the existing 2G radio technologies, which are highly optimized for circuit-switched voice services. Overcoming this 2G limitation was one of the driving factors for 3 rd Generation (3G) cellular wireless systems. Third generation (3G) cellular networks profoundly transform the radio access network to remove the 2G radio technology’s constraints imposed on so-called 2.5G systems (GPRS/EDGE), while leaving the dual-domain 2.5G core network intact. The key feature of 3G wireless systems is the concurrent support of both circuit-switched voice, and higher-rate packet data speeds that support a wide variety of packet data services. We call this wireless multimedia mobile network the UMTS (Universal Mobile Telecommunication System), which we declare to be a 3G Wireless System with the following key characteristics: • Theoretical Downlink (DL) and Uplink (UL) data rates as high as 2 Mbps in R99 • Practical DL and UL data rates in the range of 100 kbps – 384 kbps in R99 • Support of circuit-switched voice, packet-switched data, and SMS • Support of concurrent services (simultaneous voice and data calls on a UE for instance) • Defined by the 3 rd Generation Partnership Project (3GPP) 3.0 GSM/GPRS/EDGE Evolution to UMTS The GSM core network (GSM PLMN) provides voice and SMS services. The GPRS core network (GPRS PLMN) provides packet data services. Both kinds of services share the existing 2G, GSM-based radio technologies, which delivers either service in a non-concurrent way, i.e. one service or the other, but not both at the same time. The GSM Radio Access Network (RAN) includes the Base Station Controller (BSC) which controls several Base Transceiver Subsystem (BTS) and which also referred to as the “cell site”. There is no support for concurrent services in this kind of 2.5G network. • The Radio Access Network (RAN), the GSM RAN, connects to the two core networks, or what we call a “dual-domain” core network. • The GSM RAN connects to the GSM PLMN, which is the legacy circuit-switched domain, through the A Interface between the BSC and MSC. UMTS Reference for RF Engineers and RNC Engineers 2 • The GSM RAN connects to the GPRS PLMN, the newer packet-switched domain, using the Gb Interface between the BSC and SGSN. • The BSC connects to the BTS, or its BTSs, using the Abis Interface(s) within the RAN. • There is no interface defined to connect two BSCs within the RAN. 4.0 UMTS Releases UMTS Releases are listed in the chronological order of their formulations: Release 99 The first release of UMTS is called Release 99 which has the following characteristics: • Deploys the UMTS Terrestrial Radio Access Network (UTRAN) which is the UMTS-specific RAN. • Uses a Wideband Code Division Multiple Access (WCDMA) air interface. • Frequency Division Duplex (FDD) is the most commonly deployed mode of the WCDMA interface. • FDD deployment requires a total of 10 MHz of spectrum: 5 MHz for the DL and another 5 MHz for the UL. • Supports voice, packet data, SMS and multimedia services, and supports these as concurrent services. • Uses the GSM PLMN for voice services; the Circuit Switched Core Network (CS-CN). • Uses the GPRS PLMN for packet data services the Packet Switched Core Network (PS-CN). • UTRAN uses Asynchronous Transfer Mode (ATM) and Internet Protocol (IP) for transport services. • The mobile station and all its associated hardware is called the User Equipment (UE) in UMTS. Release 4 UMTS Release 4 (R4) introduces a new and important feature in the CS-CN with the introduction of Media Gateways (MGW) and MSC servers. • The MSC is replaced by MSC servers and some Media Gateways. • MSC Servers implement the control, billing, call processing, mobility management and Visitor Location Register (VLR) related functions as well as facilities for controlling its MGWs. • The MGW is responsible for processing and switching user traffic (media) as well the conversions between different formats of traffic (e.g., AMR to PCM). Release 5 UMTS Release 5 introduces High Speed Downlink Packet Access (HSDPA) as a UTRAN feature. • Enhances and builds on the R99 UTRAN while still requiring the R99 capabilities. • Theoretical Downlink (DL) data rates as high as 14 Mbps; UL data rates are the same as in R99. • Practical DL data rates depend on the HSDPA Category of the UE. IP Multimedia Subsystem (IMS) is also introduced in R5 as a new core network feature. Release 6 UMTS Release 6 introduces High Speed Uplink Packet Access (HSUPA), as a UTRAN feature. • Enhances and builds on the R99/R5 UTRAN while still requiring the R99 capabilities. • Theoretical Uplink (UL) data rates as high as 5.76 Mbps; DL data rates are the same as in R5. • Practical UL data rates depend on the HSUPA Category of the UE. Release 7 UMTS Release 7 introduces further improvements to the UMTS architecture and data rates. Release 8 UMTS Release 8 defines Long Term Evolution (LTE), which is comprehensive end-to-end enhancement to the entire UMTS architecture. The LTE air interface is based on Orthogonal Frequency Division Multiplexing (OFDM) and focuses on dramatic Packet Data Service enhancements. UMTS Reference for RF Engineers and RNC Engineers 3 5.0 The UMTS Core Network The Release 99 UMTS network includes the UTRAN, the CS-CN/GSM PLMN and the PS-CN/GPRS PLMN/UMTS PLMN as shown in the picture below. The GSM PLMN provides traditional voice services and SMS. The GPRS/UMTS PLMN provides packet data services. The UTRAN is composed of the Radio Network Controller (RNC) which controls one or more Node B’s. • The UTRAN connects to the two core networks. • The UTRAN connects to the GSM PLMN using the Iu Interface between the RNC and MSC. • The UTRAN connects to the GPRS PLMN using the Iu Interface between the RNC and SGSN. • The Iu Interfaces perform the functions of both the GSM A Interface and GPRS Gb Interface. The GSM PLMN provides connectivity to the 3G UTRAN via the evolved 3G MSC/VLR, while the GPRS/UMTS PLMN provides connectivity to the 3G UTRAN via the evolved 3G Serving GPRS Support Node (SGSN). MSC/VLR • The MSC anchors voice calls and provides SMS. • The MSC performs switching, mobility management, authentication, Quality of Service (QoS) approval and billing for all the UEs in its geographical area. • The MSC assigns a Temporary Mobile Subscriber Identifier (TMSI) to each UE to identify and track it. • The MSC is responsible for one or more Location Areas (LA). • The VLR is the local database associated with each MSC. • The VLR updates the HLR whenever subscribers attach to the MSC so the HLR knows the UEs location down to the MSC/VLR level. Home Location Register (HLR) • The HLR maintains a common UE subscription database for both CS and PS domains. • The HLR maintains separate location information for the two domains. • The HLR uses the International Mobile Subscriber Identity (IMSI) to track UE profiles. SGSN • The SGSN anchors packet data calls (often called “sessions”), and tunnels the UEs IP packets to their proper destinations. • The SGSN performs billing, mobility management, authentication, and QoS approval for all the UEs in its geographical area. • The SGSN assigns a Packet TMSI (P-TMSI) to each UE to identify and track it. • The SGSN is responsible for one or more Routing Areas (RA). • The SGSN connects to the Gateway GPRS Support Node (GGSN). • The SGSN updates the HLR whenever subscribers attach to it so the HLR knows the UEs location down to the SGSN level. GGSN • The GGSN is the gateway from the operator’s core network, specifically the PS-CN, to any of the external IP networks to which it provides connectivity. • The GGSN assigns IP addresses as required to UEs desiring packet-switched services. 6.0 The UTRAN The UTRAN consists of one or more Radio Network Subsystems (RNS). The RNC is the master of the RNS. A Node B is the radio transmission and reception unit within an RNS. UMTS Reference for RF Engineers and RNC Engineers 4 The UTRAN provides one unified set of radio bearers for both the PS domain and the CS domain. These radio bearers carry bursty traffic for the packet-switched domain and delay sensitive voice traffic for the circuit- switched domain. The UTRAN provides some distribution functionality to the two domains. In doing so, the UTRAN provides the UE with access to the basic services the two core networks provide, and provides both kinds of access concurrently, if desired, with equal ease. Unlike the case with 2G and 2.5G, the UTRAN’s radio bearers are not exclusively optimized for any service in particular; they can be dynamically configured for any kind of service. RNC The RNC handles all aspects of radio resource management within the RNS. The RNC interfaces with both the MSC and SGSN, each through their own Iu interfaces, to route signaling and traffic to/from the UE. Some RNC functions include: • Manage all radio resources and enforce QoS, which includes but is not limited to o Allocation of DL and UL OVSF Codes for UEs in UMTS R99 o Allocation of UL Scrambling Codes for UEs • Configuration of Node B • Forward messages between UE and MSC/SGSN • Power Control • Soft Handover • The RNC assigns a UMTS Radio Network Temporary Identifier (U-RNTI) to each UE in order to identify it and communicate with it. Node B The Node B is the radio transmission and reception unit within an RNS; there may be many Node Bs associated with a single RNC. Node B handles the radio transmission and reception duties for multiple sectors (or logical cells) within a cell (or coverage area). Some Node B functions include: • Implement WCDMA functions: digital coding, interleaving, spreading, scrambling, modulation • Power Control • Handling of logical cells • Node Bs are responsible for one or more cells (or sectors) on one or more radio carriers. 7.0 UMTS Interfaces UMTS defines open interfaces between all components. Each interface defines a set of protocols for exchanging traffic and signaling information. Access Stratum (AS) This is a functional layer in the UMTS protocol stack between the RNC and the UE that serves both traffic and signaling. AS signaling is used for establishment, modification and release Radio Links and associated functions. These functions are very specific to the UTRAN and its technologies. Non Access Stratum (NAS) This is a functional layer in the UMTS protocol stack between the Core Network and the UE that serves both traffic and signaling. NAS signaling is used for Mobility Management, Connection Management and Session UMTS Reference for RF Engineers and RNC Engineers 5 Management functions. These functions (authentication for instance) are independent of the radio access network and its technologies. Uu Interface • The interface between the UTRAN and the UE is known as the Uu Interface. • The Uu is a WCDMA-based air interface that allows the UE to connect to the UTRAN via code channels. • RRC (Radio Resource Control) is the main signaling protocol on the Uu Interface. Iu Interface • Each of the interfaces between the RNC and the two domains in the core network is known as the Iu Interface. • The Iu Interface between the RNC and SGSN is called the Iu-PS Interface. • The Iu Interface between the RNC and MSC is called the Iu-CS Interface. • Radio Access Network Application Part (RANAP) is the signaling protocol on the Iu Interface. • The Iu Interface is can be deployed with ATM at Layer 2 or with IP at Layer 3. • The Core Networks use their Iu Interfaces to request radio resources from the UTRAN. • The Iu Interface is used to carry UE traffic between the UTRAN and Core Networks. Iub Interface- “The Backhaul” • The interface between the Node B and its RNC is known as the Iub Interface. • The Iub Interface is an open interface, which is in sharp contrast to the somewhat proprietary Abis interface in GSM. • Node B Application Part (NBAP) is the messaging protocol on the Iub Interface. • The Iub Interface is can be deployed with ATM at Layer 2 or with IP at Layer 3. • The Iub Interface is used to carry common and dedicated signaling and user traffic. Iur Interface • The interface between two RNC’s is known as the Iur Interface. • The Iur Interface is an open interface which has no equivalent whatever in GSM/GPRS. • Radio Network Subsystem Application Part (RNSAP) is the signaling protocol on the Iur Interface. • Iur Interface is can be deployed with ATM at Layer 2 or IP at Layer 3 • The Iur Interface is used to carry common and dedicated signaling and traffic between RNCs. • It allows certain mobility procedures such as soft handovers between different RNSs. • It is an optional Interface. 8.0 UE-UTRAN Protocol Stack The UE-UTRAN Interface protocols are implemented on the UE, Node B and the RNC. There are five participating protocols (WCDMA-Physical, MAC, RLC, RRC, and PDCP) involving two functional layers (AS and NAS). WCDMA Physical Layer (L1) The WCDMA-based Physical Layer is used to transmit data over the air, it implements the following WCDMA functions: • Channel Coding • Interleaving • Repetition • Spreading • Scrambling • Modulation • Power Control • Macro-diversity Medium Access Control (MAC) Layer (L2) The MAC Layer is an elaborate traffic cop type of function that organizes multiple users and services in the WCDMA-Physical Layer. As such MAC is responsible for the following functions: • Logical to Transport Channel Multiplexing [...]... resources There are two types of Hard Handovers in UMTS: • One type is the UMTS- UMTS Hard Handovers o Intra-Carrier UMTS- UMTS Hard Handovers o Inter-Carrier UMTS- UMTS Hard Handovers • The other type is the Inter-RAT Hard Handovers; UMTS GSM Hard Handovers The only purpose of Hard Handovers is Mobility Measurements Several types of measurements have been defined in UMTS These are used to evaluate different aspects... due to the pilot If you prefer, you can express this in decibels, which in this case is -20log10(.25) which equals 12.04 Power Control in UMTS R99 Ec/Io and Eb/No are elements of power control and interference management in UMTS There are two types of Power Control in UMTS R99: • Open Loop • Closed Loop Open Loop Power Control Open Loop Power Control is used when the UE wants to transmit a message on... information being transported for? These are things like: o OVSF Code o Scrambling Code In UMTS, the WCDMA radio frame is 10 msec long (38400 chips) A radio frame is divided into 15 slots Each slot is 0.667 msec long (2560 chips) In GSM/GPRS the Physical Channel was identified by time slot and frequency The UMTS equivalent is the OVSF code, the OFSF code’s SF and the scrambling code Acronym CPICH PCCPCH... then transmitted as shifted streams with a half symbol duration This means that the UL requires half the SF for the same throughput that the DL can provide • UMTS R99 uses Modulation (2 bits are represented by each modulation symbol) on the DL 11 UMTS Reference for RF Engineers and RNC Engineers 11.0 Power Control Eb/No Energy per Bit over Noise Energy per Hertz (Eb/No) only applies to dedicated channels... the coded symbol rate, the longer the OVSF code Because of their mutual orthogonality, transmission to multiple users over the same channel is possible In UMTS R99, the allowed range of OVSF code lengths in the DL is - 4 bits through 512 bits In UMTS R99, the allowed range of OVSF code lengths in the UL is - 4 bits through 256 bits Length of the OVSF codes is also called the Spreading Factor (SF) of... the rate of the Inner Closed Loop and the options are based on whether it is for the UL or the DL UMTS deployments commonly use the default value of 1500 times a second When the UE or Node B receives a TPC command (Transmit Power Control) it changes the power of its transmission by a “Step Size” amount UMTS deployments commonly use the default value of 1 dB (decibel) 12.0 RRC Connection and RRC States... channel These secondary transmitter identification codes are called Scrambling Codes or Gold Codes The UMTS DL supports 512 different Scrambling Codes that uniquely identify a Cell These are downlink Cell-Specific Scrambling Codes and the planning of these codes is required at network deployment time The UMTS UL provides 224 (16,777,216) Scrambling Codes that uniquely identify a UE in the uplink Since... after a Handover to provide an updated list of Neighboring Cells that the UE should be monitoring 20 UMTS Reference for RF Engineers and RNC Engineers 17.0 HSDPA Concepts HSDPA is a Release 5 (R5) innovation, some key aspects and concepts of which include: • HSDPA is an enhancement of the UTRAN in UMTS R5, which is focused only on Packet Data services • HSDPA increases only the DL data rates • DL Data... versions of the packet No further redundant versions of the packet are sent to the UE 26 UMTS Reference for RF Engineers and RNC Engineers 20.0 HSUPA Concepts HSUPA • • • • • • • • • • • • • • • • is a Release 6 (R6) innovation, some key facts and concepts of which include: HSUPA is an enhancement of the UTRAN in UMTS R6, which focused only on Packet Data services HSUPA increases the UL data rates UL... in the DL and 64 bit OVSF code in the UL 384 kbps RAB (Radio Access Bearer) uses an 8 bit OVSF code in the DL and a 4 bit OVSF code in the UL 10.0 Channels Three types of channels have been defined in UMTS, and a Radio Bearer (RB) defines all three of these kinds of channels: • Logical Channels • Transport Channels • Physical Channels Logical Channels • • • The Logical Channel defines the services provided . Inc. UMTS Reference for RF Engineers and RNC Engineers Table of Contents 1.0 Scope of the Document 1 2.0 Introduction of UMTS 1 3.0 GSM/GPRS/EDGE Evolution to UMTS 1 4.0 UMTS. are part of the Bronze curriculum for RF Engineers and RNC Engineers at AT&T. The courses are: 1. FOT110 - Evolution from GSM to UMTS (eLearning) 2. FOT120 – Overview of UMTS (eLearning). connect two BSCs within the RAN. 4.0 UMTS Releases UMTS Releases are listed in the chronological order of their formulations: Release 99 The first release of UMTS is called Release 99 which has