Wray Castle - UMTS Air Interface

Full text

(1)UMTS Air Interface Course Code: VFT2800. Duration: 2 days. Technical Level: 3. UMTS courses include: . essential UMTS. . UMTS System Overview. . UMTS Air Interface. . HSPA Principles and Application. . UMTS Core Network. . 3G Indoor Coverage Planning. . Cell Planning for UMTS Networks. . Introduction to UMTS Optimization. . Long Term Evolution (LTE). Specially prepared for. www.wraycastle.com.

(2)

(3) UMTS Air Interface. UMTS AIR INTERFACE. First 2008 Last updated December 2008 WRAY CASTLE LIMITED BRIDGE MILLS STRAMONGATE KENDAL LA9 4UB UK. Yours to have and to hold but not to copy The manual you are reading is protected by copyright law. This means that Wray Castle Limited could take you and your employer to court and claim heavy legal damages. Apart from fair dealing for the purposes of research or private study, as permitted under the Copyright, Designs and Patents Act 1988, this manual may only be reproduced or transmitted in any form or by any means with the prior permission in writing of Wray Castle Limited. © Wray Castle Limited.

(4) UMTS Air Interface. ii. © Wray Castle Limited.

(5) UMTS Air Interface. UMTS AIR INTERFACE. CONTENTS Section 1 Section 2 Section 3 Section 4 Section 5 Section 6. UMTS Structure and Aims UTRAN Protocol Structure UMTS Physical Layer Layer 2 Operation RLC and MAC Radio Resource Control (RRC) Air Interface Procedures and NAS Interactions. © Wray Castle Limited. iii.

(6) UMTS Air Interface. iv. © Wray Castle Limited.

(7) UMTS Air Interface. SECTION 1. UMTS STRUCTURE AND AIMS. © Wray Castle Limited. i.


(9) UMTS Air Interface. CONTENTS 1. General Service Aims for UMTS 1.1 Introduction 1.2 General Aims 1.3 Fixed and Mobile Differentiation. 1.1 1.1 1.1 1.1. 2. Service Definition 2.1 Service Capabilities 2.2 Efficient Use of the Resource 2.3 UMTS Bit Rates 2.4 Factors Limiting Bit Rate. 1.3 1.3 1.3 1.5 1.5. 3. UMTS Main Elements 3.1 Core Network (CN) 3.2 UMTS Terrestrial Radio Access Network (UTRAN). 1.7 1.7 1.7. 4. UMTS Core Network Architecture 4.1 Required Connections 4.2 The Evolution of Core Architecture. 1.9 1.9 1.11. 5. UE Capabilities 5.1 Baseline Capabilities 5.2 UE Service Capabilities. 1.13 1.13 1.13. 6. Standard Voice Service 6.1 Adaptive Multi-Rate (AMR) Speech Codec 6.2 Wideband AMR Codec. 1.15 1.15 1.17. 7. Multimedia Service Capabilities 7.1 Introduction. 1.19 1.19. 8. UE Radio Characteristics 8.1 Radio Spectrum 8.2 Basic UE Transmitter Characteristics 8.3 Basic UE Receiver Characteristics. 1.21 1.21 1.23 1.23. © Wray Castle Limited. iii.


(11) UMTS Air Interface. OBJECTIVES At the end of this section you will be able to: • • • • • •. state the general service aims for UMTS define the service capabilities and factors affecting the bit rate used identify the network elements and interfaces within UMTS outline User Equipment (UE) requirements and characteristics outline the use and basic action of the Adaptive Multi-Rate (AMR) voice coder state the need for video coding standards. © Wray Castle Limited. v.

(12) UMTS Air Interface. 1. GENERAL SERVICE AIMS FOR UMTS 1.1. Introduction. The key aim for UMTS is that it should provide a platform to carry the services and features that are generally associated with fixed networks into the mobile and roaming environments. UMTS should provide an integrated telecommunication system that is able to support a wide range of applications. The throughput should be variable, to provide a range of capability from narrowband to wideband. The user should experience true personal communication, regardless of location. 1.2. General Aims. All aspects of service provision need to be considered, including the need for types of services to be applicable to probable applications, and the ease with which these services can be utilized. 3rd Generation Partnership Project (3GPP) Specification TS 22.101 ‘UMTS Service Principles’ details many of these considerations. In many cases they are not specified as requirements, but set out as design aims for manufacturers and operators. The reason for the relaxation of rigid service specification is to enable more flexibility for operators to differentiate their services from those of their competitors. Despite this, services should be accessed in a uniform and easy to understand way; this impacts on the design of both the service and the User Equipment (UE). It is also intended that a user should experience a constant level of service, irrespective of location. In particular, attention should be paid to the roaming environment. 1.3. Fixed and Mobile Differentiation. The user should be able to access a range of services in the mobile environment that offer similar rates and reliability to those normally associated with fixed networks. The practical limitations of the radio resource and radio characteristics will probably mean that this will not be possible in all environments. However, in the localized business and residential environments, full emulation of Private Branch Exchange (PBX) and Local Area Network (LAN)-type services should be available.. 1.1. © Wray Castle Limited. VFT2800/S1/v1.

(13) UMTS Air Interface. neral Service A e G ims TS M U Integrated Telecommunication System Personal Communication Regardless of Location Differentiation of Operators’ Offerings Narrowband or Broadband Simple to Operate Continuity of Service while Roaming PBX and LAN Emulation. Fixed. Mobile. Figure 1 UMTS General Service Aims VFT2800/S1/v1. © Wray Castle Limited. 1.2.

(14) UMTS Air Interface. 2. SERVICE DEFINITION 2.1. Service Capabilities. For most telecommunication systems, including the first- and second-generation mobile systems, it is common to define rigidly the bearer and teleservices that should be provided by an operator. However, it was felt that this approach would be too restrictive for third-generation systems. With this in mind, it is only service capabilities that have been defined for UMTS rather than a full set of teleservices. The teleservices that were defined for second-generation systems remain in place, and in addition to these are the service capabilities. These imply the definition of bearers, resource control mechanisms and Quality of Service (QoS) parameters. This allows operators to define more advanced teleservice types for themselves, based on the standard set of service capabilities. These non-standard services may include those used for alternative speech services: video, multimedia, messaging, and other data applications. 2.2. Efficient Use of the Resource. Most applications, and in particular multimedia applications, exhibit some degree of asymmetry and are discontinuous. For example, applications involving Internet access would be both discontinuous and asymmetric; streaming video or audio would be completely asymmetric, but continuous. It is intended that UMTS, both in the Core Network (CN) and in the Access Network (AN), should take full advantage of these characteristics to promote resource utilization efficiency.. 1.3. © Wray Castle Limited. VFT2800/S1/v1.

(15) UMTS Air Interface. Video Streaming Multimedia. Customized Supplementary Services. Access to an Enterprise Server Audio/Video Messaging Database Access. Video Telephony. File Transfer. High Quality Audio. Undefined Services. Defined Service Capabilities Figure 2 Service Capabilities VFT2800/S1/v1. © Wray Castle Limited. 1.4.

(16) UMTS Air Interface. 2.3. UMTS Bit Rates. An application requesting a bearer service will specify it with regard to the variables mentioned on the previous pages. It is possible for a single UE to have several active bearers in operation simultaneously: these may be a mixture of connection-oriented and connectionless services. The actual bit rate available for a particular application will depend on the radio environment and on operator-determined limitations. In general, the aims for UMTS based upon service aims set out by the International Telecommunication Union (ITU) in documents relating to International Mobile Telecommunications 2000 (IMT-2000) are summarized as: • at least 144 kbit/s – rural outdoor • at least 384 kbit/s – urban/suburban outdoor • at least 2,048 kbit/s – indoor/low range outdoor 2.4. Factors Limiting Bit Rate. Two important factors limit the ultimate bit rate available to the user. The first is related to the radio characteristics applicable to the user’s physical location, including factors such as interference, Doppler shift and fading characteristics. These affect the performance of the channel and, in general, more hostile radio conditions will limit the achievable throughput in the channel. The second limiting factor relates to radio carrier capacity. The number of channels available on a UMTS radio carrier is inversely proportional to the bit rate provided in each channel. Thus, the higher the bit rate allocated to a user, the fewer other users will have access to the cell. It is possible that one bearer at 2,048 kbit/s could represent the entire capacity of one radio carrier, which would represent a significant drain on network resources if allocated in a rural or suburban environment. However, it may be acceptable if allocated in the indoor pico cell environment. For Phase 1 of UMTS (Release 99), circuit-switched services are limited to 64 kbit/s due to Mobile-services Switching Centre (MSC) capability. Higher bit rates are only applicable to packet-switched services.. 1.5. © Wray Castle Limited. VFT2800/S1/v1.

(17) UMTS Air Interface. Target. User. Environment. Bit Rate. Mobility. Rural Outdoor. 144 kbit/s. 500 km/h. 384 kbit/s. 100 km/h. 2,048 kbit/s. 10 km/h. Operating. Urban/Suburban Outdoor Indoor/Low Range Outdoor. Figure 3 Bearer Types for UMTS VFT2800/S1/v1. © Wray Castle Limited. 1.6.

(18) UMTS Air Interface. 3. UMTS MAIN ELEMENTS. A UMTS network can be considered as three interacting domains. These are the CN, the UMTS Terrestrial Radio Access Network (UTRAN) and the UE. Interfaces are defined within and between these systems, providing standardization and, in many cases, inter-vendor compatibility. 3.1. Core Network (CN). The main function of the CN is to provide switching, routing and transit for user traffic. There are many possible implementations for the CN, but a general requirement is flexible high bandwidth capability, provided as real-time or non-realtime services. This may be initially provided by a combination of circuit and packet switching. By Release 5/6 the core network becomes wholly packet switched with QoS mechanisms to support real-time services. The CN also contains the databases and network management functions. 3.2. UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is concerned with the provision of radio coverage across the operating area and the provision of services across the air interface. Included in this is the handling of macro diversity through the provision of soft handover. Soft handover may take place within the UTRAN, or between UTRANs. The UTRAN contains the base stations, referred to as Node Bs, and Radio Network Controllers (RNCs), which provide the control functionality for one or more Node Bs. The description of Node B and RNC functions is logical rather than physical. Although there is a defined interface between Node B and RNC, the logical nature of their definition means that this does not necessarily correspond to a physical interface in a particular vendor’s equipment. A single RNC and its associated Node Bs is known collectively as Radio Network Subsystem (RNS). An UTRAN may contain one or more RNS.. 1.7. © Wray Castle Limited. VFT2800/S1/v1.

(19) UMTS Air Interface. Core Network. Iu. Iu. UTRAN RNS. RNS Iur. Iub. Node B. Iub. Iub. Node B. Node B. Iub. Node B. ser wray castle Brow .. Internet Search: http//www. xXX XXXXXXXXxx X XXXxXXXX XX XXXXXXXXXX XX XXXXxxxxxXX XXX XxXX XXX X XXX XXX. UE. Figure 4 UMTS Main Elements VFT2800/S1/v1. © Wray Castle Limited. 1.8.

(20) UMTS Air Interface. 4. UMTS CORE NETWORK ARCHITECTURE. The basic architecture for UMTS is based on that of the GSM incorporating GPRS. At R99 and Release 4, switching is a combination of circuit switching provided by the MSC/VLR, and packet switching provided by the Serving and Gateway GPRS Support Nodes (SGSN/GGSN). These GSM elements are modified for UMTS operation and service provision. A UMTS MSC will need to support a new interface in order to communicate and exchange traffic with the UTRAN. Similarly, a 3G-SGSN also needs to support the new interface. In both cases these elements need to be able to supply the bearer types required to provide UMTS multimedia services. The GSM databases Visitor Location Register (VLR) and Home Location Register (HLR) are present in UMTS. The VLR is a temporary distributed database assumed to be integrated into the MSC. The HLR is a permanent store for subscriber data within an operator’s system. 4.1. Required Connections. There are four defined logical interfaces that interconnect the functional elements of the UTRAN and connect the UTRAN to other network domains. Two of these interfaces, the lu and Uu, are external interfaces. The lub is internal only, and the lur will usually be internal, but could be external for some network architectures. The interfaces used are as follows: lu. – RNC to CN. Uu – Node B to UE lub – RNC to Node B lur – RNC to RNC. 1.9. © Wray Castle Limited. VFT2800/S1/v1.

(21) UMTS Air Interface. Uu wray castle Browser Internet Search: http//www.. xxxXX XXXXXXXX X XXXxXXXX XXXX XXXXXXXX XX XX XXXXxxxxx. Radio Access Network. XXX XxXX XXXX XXX XXX. RNC. lu-CS. PSTN. UE lu-PS. C HLR. lu-CS lur. Gs. EIR. Gr. AuC. Gc. Uu lu-PS wray castle Browser Internet Search: http//www.. xxxXX XXXXXXXX X XXXxXXXX XXXX XXXXXXXX XX XX XXXXxxxxx XXX XxXX XXXX XXX XXX. UE. RNC Radio Access Network. Gn. Gi. IP Network or X.25 Network. Signalling Connection Traffic and Signalling Connection. Figure 5 General UMTS Architecture VFT2800/S1/v1. © Wray Castle Limited. 1.10.

(22) UMTS Air Interface. 4.2. The Evolution of Core Architecture. From Release 4 onwards the GSM/GPRS based UMTS core network evolves into an all-packet-switched IP-based architecture. This provides both economy and flexibility for service delivery. 4.2.1. Circuit-Switched Core. The UMTS circuit-switched core network still provides circuit-switched connectivity for voice and circuit-switched data, but with alterations to the nodes. The traditional MSC, with its 64 kbit/s group switch, may be replaced with a soft switch. This new node will consist of an MSC server, in essence a Media Gateway Controller (MGC), and a Media Gateway (MG). This approach means minimal impact on the radio access network, as signalling towards the MSC server is unchanged. The traffic will be converted from circuit switched to packet switched by the media gateway. This means that the transport of traffic through the core can make use of the efficiencies of packet switching. Interworking with legacy networks such as the Public Switched Telephone Network (PSTN) can be facilitated by using media gateways and signalling gateways. 4.2.2. Packet-Switched Core. The packet-switched core will have fewer architectural changes, with connectivity still being provided by GPRS. The main additional architecture is defined at Release 5 of the standards. The IP Multimedia Subsystem (IMS) can be accessed via the packet switched core, providing a variety of services and applications based on a packet-switched bearer. These will include peer-to-peer applications such as Voice over Internet Protocol (VoIP), video and audio streaming and Push-to-talk over Cellular (PoC).. 1.11. © Wray Castle Limited. VFT2800/S1/v1.

(23) UMTS Air Interface. IMS. CSCF. Other IMS or IP Networks. Mw Mm. HSS. Cx. CSCF Mg MGCF. Gr Gi. Gi. PS Domain Gn. TCP/IP. Mc Iu. UTRAN Gi r. wray castle Browse Internet Search: http//www.. XXXXXXXXxxxXX X XXXxXXXX XXXXXXXXXXXX xXX XX XXXXxxxx XXX XxXX XXXX XXX XXX. Iu. PSTN/ Legacy CS Domain MGW. Nb. Mc. MGW Mc. MSC Server. Nc. SGW. GMSC Server. HSS. Figure 6 Release 5 Architecture VFT2800/S1/v1. © Wray Castle Limited. 1.12.

(24) UMTS Air Interface. 5. UE CAPABILITIES. UMTS is intended to be capable of supporting a wide range of services, either individually or in combination. It cannot be expected that all UEs will support all types of service. In order to allow for UE capability variation, while maintaining compatibility between UEs and all UMTS networks, many options are included in the 3GPP specifications. As a consequence, there are many different physical forms for the UE, depending on its intended function. 5.1. Baseline Capabilities. The baseline capability describes the basic capabilities required by a UE to enable worldwide roaming within all 3GPP networks. The baseline capabilities include functions relating to scanning, cell and Public Land Mobile Network (PLMN) selection and registration, including authentication. 5.2. UE Service Capabilities. To make a UE marketable, the manufacturer has to add UE service capabilities. There is no requirement for any particular combination of service capabilities to be supported but a number of standardized UE service capabilities are described in the 3GPP specifications. These provide for services such as speech and text messaging as well as bearers for video and data services. This does not preclude the provision of other service capabilities. There are six categories of standardized service capabilities: • teleservices • bearer services • supplementary services • service capabilities • system features • other UE service capabilities The UE may also support service capabilities suitable for additional nonstandardized teleservices such as multimedia services.. 1.13. © Wray Castle Limited. VFT2800/S1/v1.

(25) UMTS Air Interface. Bearer services. Teleservices Voice calls Emergency calls SMS. Symmetry Point-to-point/multipoint Delay characteristics Bit Error rate Bit rate. Service Capabilities. Other UE service capabilities. USIM Application Toolkit MExE LCS. Multimedia services Fax service. Supplementary services. System Features. Standardized GSM Non-standardized. NITZ USSD. UE Service Capabilities Baseline Capabilities. Scanning PLMN selection Cell selection/reselection Registration Authentication LA/RA updating. Figure 7 UE Capabilities VFT2800/S1/v1. © Wray Castle Limited. 1.14.

(26) UMTS Air Interface. 6. STANDARD VOICE SERVICE. 6.1. Adaptive Multi-Rate (AMR) Speech Codec. Because of bandwidth limitations on the air interface, a low-rate voice-coding scheme is required. In addition, the voice coder must offer the user good quality in a variety of situations. The AMR speech codec is designed to allow dynamic adaptation of the bit rate for source and channel coding. The overall speech quality is improved by increasing the amount of error protection while reducing the bit rate for source coding if the radio link quality degrades. To realize rate adaptation, the decoder needs to signal the mode it prefers to receive to the encoder. The AMR codec consists of eight source codec bit rate modes. For codecs that support variable rate operation, the UE can be allowed by Radio Resource Control (RRC) in the UTRAN to reduce transmission rate independently without requesting a new codec mode from the network, within limits defined by the network in the current transport format set for the impacted Radio Bearer (RB).. 1.15. © Wray Castle Limited. VFT2800/S1/v1.

(27) UMTS Air Interface. Codec Mode. Source Codec Bit Rate. AMR_12.20. 12.20 kbit/s (GSM EFR). AMR_10.20. 10.20 kbit/s. AMR_7.95. 7.95 kbit/s. AMR_7.40. 7.40 kbit/s (IS-641). AMR_6.70. 6.70 kbit/s (PDC-EFR). AMR_5.90. 5.90 kbit/s. AMR_5.15. 5.15 kbit/s. AMR_4.75. 4.75 kbit/s. AMR_SID. 1.80 kbit/s. SID – Silence Descriptor Frame. Figure 8 Source Codec Bit Rates for the AMR Codec VFT2800/S1/v1. © Wray Castle Limited. 1.16.

(28) UMTS Air Interface. 6.2. Wideband AMR Codec. Traditionally in telecommunications networks speech has been limited in bandwidth with the highest modulating frequency set to 3.4 kHz. This has always been considered good commercial or toll quality. The introduction of a wideband speech service in Release 5 will provide improved voice quality by allowing the highest modulating frequency to extend to 7 kHz. The Adaptive Multi-Rate – Wideband (AMR-WB) speech coder is a development of the existing AMR speech coder offering nine source rates from 6.6 kbit/s to 23.85 kbit/s. The coder also includes a low bit rate background encoding scheme to support Discontinuous Transmission (DTX). The bit rate can be changed under instruction from the network every 20 ms.. 1.17. © Wray Castle Limited. VFT2800/S1/v1.

(29) UMTS Air Interface. Codec Mode. Source Codec Bit Rate. AMR_WB_23.85. 23.85 kbit/s. AMR_WB_23.05. 23.05 kbit/s. AMR_WB_19.85. 19.85 kbit/s. AMR_WB_18.25. 18.25 kbit/s. AMR_WB_15.85. 15.85 kbit/s. AMR_WB_14.25. 14.25 kbit/s. AMR_WB_12.65. 12.65 kbit/s. AMR_WB_8.85. 8.85 kbit/s. AMR_WB_6.60. 6.60 kbit/s. AMR_WB_SID. 1.75 kbit/s. Figure 9 Source Codec Bit Rates for the AMR-WB Codec VFT2800/S1/v1. © Wray Castle Limited. 1.18.

(30) UMTS Air Interface. 7. MULTIMEDIA SERVICE CAPABILITIES. 7.1. Introduction. For Release 99, 3G-324M has been agreed as the default standard for UEs supporting multimedia capabilities. 3G-324M is based upon the ITU H.234 standard. H.234 was developed to support video telephony over fixed networks. 3G-324M can be viewed as an umbrella standard for the support of real-time, multimedia services over circuit-switched networks. The standard includes several other protocols that handle multiplexing and demultiplexing of speech, video, control data and in-band call control. 7.1.1. H.223 Multiplexing and Demultiplexing. Multimedia transmission will require mechanisms to mix different information streams together. This mixing process is one of the tasks of H.323. Additionally, H.223 provides a number of degrees of resilient transport ranging from Level 0 with limited protection through to Level 3 which defines the most robust delivery scheme including both Forward Error Correction (FEC) and Automatic Repeat Request (ARQ) mechanisms. 7.1.2. H.245 Call Control. When two devices need to exchange information they may have different H.223 multiplexing and demultiplexing capabilities as well as different audio and video codecs. H.245 supports mechanisms for exchanging capability information as well as negotiating which end is to be master or slave. The master–slave relationship is necessary to resolve any conflicts. To provide reliability H.245 employs a Simple Retransmission Protocol (SRP) which can optionally be Numbered (NSRP). Media and data flows are organized into logical channels and H.245 provides logical channel signalling allowing logical channels to open and close. Finally, H.245 provides a range of call control commands to support flow control, codec control and user input indications. 7.1.3. H.263 and MPEG-4. The 3G-324M standard specifies H.263 as mandatory and MPEG-4 as a recommended video codec. H.263 is a legacy codec that is used with existing H.323 systems and has been kept for compatibility. MPEG-4 is more flexible than H.263 and offers advanced error detection and correction schemes.. 1.19. © Wray Castle Limited. VFT2800/S1/v1.

(31) UMTS Air Interface. 3G-324M. ITU H.324. H.223. H.245. Multiplexing speech, video control data. Call control Organizes data flows into logical channels, provides logical channel signalling. Provides different degrees or error resilient transport. Speech codecs AMR. G.723.1. Video codecs H.263. MPEG-4. Figure 10 Multimedia Capabilities VFT2800/S1/v1. © Wray Castle Limited. 1.20.

(32) UMTS Air Interface. 8. UE RADIO CHARACTERISTICS. The physical layer of the UMTS air interface is very complex and thus there are many detailed requirements for the UE. These are divided into those that relate to transmitter performance and those that relate to receiver performance. Some of these requirements are described here. 8.1. Radio Spectrum. The 3GPP specifications describe the requirements for UMTS operation in nine bands for Frequency Division Duplex (FDD) operation and a further three bands for Time Division Duplex (TDD) operation. The key FDD bands are Band I, which represents UMTS operation in 3G spectrum in Europe, Africa and Asia, and Band II, which represents UMTS operation in the Personal Communications System (PCS) spectrum in North and South America. The key TDD band is Band A, for which many operating licenses have been awarded in Europe.. 1.21. © Wray Castle Limited. VFT2800/S1/v1.

(33) UMTS Air Interface. UMTS FDD Defined Operating Bands (Rel-7). I. Uplink (MHz) 1920–1980. Downlink (MHz) 2110–2170 MHz. Nominal duplex spacing (MHz) 190 MHz. II. 1850 –1910. 1930–1990 MHz. 80 MHz. III. 1710–1785. 1805–1880 MHz. 95 MHz. IV. 1710–1755. 2110–2155 MHz. 400 MHz. V. 824–849. 869–894 MHz. 45 MHz. VI. 830–840. 875–885 MHz. 45 MHz. VII. 2500–2570. 2620–2690 MHz. 120 MHz. VIII. 880–915. 925–960 MHz. 45 MHz. IX. 1749.9–1784.9. 1844.9–1879.9 MHz. 95 MHz. Band. UMTS TDD Defined Operating Bands (Rel-7) Spectrum blocks Band (MHZ) a. 1900–1920 and 2010–2025. b. 1850–1910 and 1930–1990. c. 1910–1930. d. 2570–2620. Figure 11 UE Spectrum Capabilities VFT2800/S1/v1. © Wray Castle Limited. 1.22.

(34) UMTS Air Interface. 8.2. Basic UE Transmitter Characteristics. There are four power classes defined for UMTS UEs. These are outlined in terms of maximum transmit power. The minimum transmit power for all classes needs to be better than –50 dBm. This suggests a dynamic range in the order of 70 dB. Power step size needs to be switchable between 1, 2 and 3 dB. When the transmitter has to ramp for packet mode transmission, compressed modes of operation and discontinuous transmission, the ramping is required to be completed within 50 µs centred on the transition point. The UE has to maintain a frequency stability of 0.1 ppm in respect of the received signal from the Node B (Node B stability is 0.05 ppm). Stability for generated radio frequencies and codes is derived from the same source, and is subject to the same stability requirement. 8.3. Basic UE Receiver Characteristics. The receiver characteristics are complex, and quoted in terms of performance in a range of different test conditions. Some of these tests are designed to assess absolute performance capability in sanitized conditions; some are designed to simulate more hostile and realistic radio conditions. The absolute sensitivity level for all classes of UE is defined in terms of energy per chip in the Dedicated Physical Channel (DPCH_Ec) when the Bit Error Rate (BER) is better than 0.001. Thus DPCH_Ec = –117 dBm/3.84 Mcps.. 1.23. © Wray Castle Limited. VFT2800/S1/v1.

(35) UMTS Air Interface. Power Class. Max O/P Power. Tolerance. 1. +33 dBm. 2W. +1 dB / –3 dB. 2. +27 dBm. 0.5 W. +1 dB / –3 dB. 3. +24 dBm. 0.25 W. +1 dB / –3 dB. 4. +21 dBm. 0.125 W. ±2 dB. Minimum power better than –50 dBm Step size 1 dB, 2 dB and 3 dB. Receiver sensitivity for BER better than 0.001 DPCH_Ec = –117 dBm/3.84 Mcps. Figure 12 Radio Characteristics VFT2800/S1/v1. © Wray Castle Limited. 1.24.

(36) UMTS Air Interface. 1.25. © Wray Castle Limited. VFT2800/S1/v1.

(37) UMTS Air Interface. SECTION 2. UTRAN PROTOCOL STRUCTURE. © Wray Castle Limited. i.


(39) UMTS Air Interface. CONTENTS 1. Air Interface Structure 1.1 Aims of the Air Interface 1.2 Air Interface Modes of Operation. 2.1 2.1 2.3. 2. Access Stratum (AS) and Non-Access Stratum (NAS) 2.1 Introduction 2.2 NAS 2.3 AS 2.4 AS on the Air Interface 2.5 NAS on the Air Interface 2.6 Logical, Transport and Physical Channels. 2.5 2.5 2.5 2.5 2.7 2.7 2.7. 3. Protocol Termination within the UTRAN 3.1 Termination Nodes 3.2 Variations for Protocol Termination. 2.9 2.9 2.9. 4. Logical Channels 4.1 Logical Channel Types. 2.11 2.13. 5. Transport Channels 5.1 Transport Channel Types. 2.15 2.17. 6. Downlink (DL) Physical Channels 6.1 Introduction 6.2 Physical Channel Types 6.3 Physical Channels for CPCH Access. 2.19 2.19 2.21 2.23. 7. Uplink (UL) Physical Channels 7.1 Introduction 7.2 Physical Channel Types. 2.25 2.25 2.25. 8. FDD Mode Channel Mapping 8.1 Logical to Transport Channel Mapping 8.2 Transport to Physical Channel Mapping 8.3 Mapping for the Uu Interface. 2.27 2.27 2.27 2.27. © Wray Castle Limited. iii.


(41) UMTS Air Interface. CONTENTS 9. UTRAN Architecture 9.1 Key Components of the UTRAN 9.2 Node B 9.3 Radio Network Controller (RNC) 9.4 Radio Network Subsystem (RNS). 2.29 2.29 2.29 2.29 2.29. 10. General UTRAN Protocol Structure 10.1 Control and User Planes 10.2 ATM in the UTRAN 10.3 IP in the UTRAN. 2.31 2.31 2.33 2.33. 11. Iub Interface 11.1 Iub Location and Capabilities 11.2 Iub General Structure. 2.35 2.35 2.37. 12. Iur Interface 12.1 Iur Location and Capabilities 12.2 lur Radio Network Layer. 2.39 2.39 2.41. 13. lu Interface 13.1 lu Location and Capabilities 13.2 lu Radio Network Layer User Plane 13.3 Radio Network Layer Control Plane. 2.43 2.43 2.45 2.45. 14. Summary. 2.47. © Wray Castle Limited. v.

(42) UMTS Air Interface. vi. © Wray Castle Limited.

(43) UMTS Air Interface. OBJECTIVES At the end of this section you will be able to: • • • • • • • • • • • •. describe the structure of the air interface in terms of the different modes of operation, i.e. CDMA and Time Division – CDMA (TD-CDMA) describe the two areas of functionality in relation to the isolation of radio and telecommunication access requirements list the protocols used within the UTRAN and state the relevance of the terminations when accessing the network state what is meant by logical, transport and physical channels in UMTS outline the use and functions of logical, transport and physical channels explain the mapping of logical to transport channels and ultimately transport to physical channel mapping identify the basic functions and the termination point of the physical layer explain the functionality of the UTRAN network elements: Node B and Radio Network Controller (RNC) explain the general UTRAN protocol structure common on all three terrestrial interfaces describe the use of Asynchronous Transfer Mode (ATM) on the Iu interface in terms of the adaptation layer functions identify the extension of the transport channels to the RNC describe the use of the Iu and Iub interfaces in terms of their structure in relation to both user and control planes. © Wray Castle Limited. vii.

(44) UMTS Air Interface. 1. AIR INTERFACE STRUCTURE 1.1. Aims of the Air Interface. The air interface forms the link between the UE and the UTRAN. The aim of this interface is to provide a reliable conduit through which user data and signalling can be transferred. It is a radio interface and must provide seamless mobility over a wide area and in varying conditions. Yet it should require minimal modification of the higher-layer protocols that are used to provide the wide range of UMTS teleservices, services and features. The establishment and efficient operation of this radio link should be hidden from the user. There are thus two distinct transport requirements for the UMTS air interface: control of the radio link itself, and provision of the supported telecommunication functions. The name given to the UMTS air interface is the Uu interface.. 2.1. © Wray Castle Limited. VFT2800/S2/v1.

(45) UMTS Air Interface. UE Telecommunication Service ser. wray castle Brow Internet Search: http//ww. Core Network. w.. xxxXX XXXXXXXX X XXXxXXXX XXXX XXXXXXXX XX XX XXXXxxxxx XXX XxXX XXX X XXX XXX. Iu Air Interface (Uu). Node B Iub. Iub Node B. UTRAN. Figure 1 Air Interface VFT2800/S2/v1. © Wray Castle Limited. 2.2.

(46) UMTS Air Interface. 1.2. Air Interface Modes of Operation. The UMTS specifications describe two different technology modes for the air interface. These are allocated to each of the two types of duplexed radio spectrum: CDMA used for the paired spectrum, and Time Division CDMA (TD-CDMA) used for the unpaired spectrum. The CDMA part of UMTS is used in the paired radio spectrum, i.e. FDD. As such, it is referred to as FDD mode 1. Mode 1 distinguishes it from the other technologies that are part of the 3GPP family. It may also be referred to as Direct Sequence (DS) mode. The TD-CDMA part of UMTS is used in the unpaired radio spectrum, i.e. TDD. It is simply referred to as TDD mode, although there are two variants known as High Chip Rate (HCR) and Low Chip Rate (LCR). The HCR variant is designed to operate in the European TDD spectrum and the LCR variant is a Chinese-defined 3G technology.. 2.3. © Wray Castle Limited. VFT2800/S2/v1.

(47) UMTS Air Interface. UMTS Core Network. w. Internet Search: http//ww. xxxXX XXXXXXXX X XXXxXXXX XXXX XXXXXXXX XX XX XXXXxxxxx. i s ion Time D iv. ser. wray castle Brow. TD-C DMA. Dupl ex M ode. M A CD. Fr eq. ue. nc. y. Di vi si on. Du pl ex. M od e. UMTS Terrestrial Radio Access Network (UTRAN). XXX XxXX XXX X XXX XXX. User Equipment FDD Mode. ser wray castle Brow Internet Search: http//ww. w.. xxxXX XXXXXXXX X XXXxXXXX XXXX XXXXXXXX XX XX XXXXxxxxx XXX XxXX XXX X XXX XXX. User Equipment TDD Mode Figure 2 Air Interface Modes VFT2800/S2/v1. © Wray Castle Limited. 2.4.

(48) UMTS Air Interface. 2. ACCESS STRATUM (AS) AND NON-ACCESS STRATUM (NAS) 2.1. Introduction. To facilitate the isolation of radio-related functions from telecommunication-related functions, the UMTS air interface is divided into two clear areas of functionality. These are known as the Access Stratum (AS) and the Non-Access Stratum (NAS). These coarse divisions can be described in terms of their relationship to UMTS functional elements and the Open Systems Interconnect (OSI) Seven-Layer Model. 2.2. NAS. The NAS represents communication directly between the UE and the CN. With regard to the OSI Seven-Layer Model, it can be considered as constituting layers 3–7. The UMTS specifications describe layer 3 functionality relating to signalling for connection establishment and routing of calls. In general, this is to be structured as it would be in a fixed network, with minimal modification adapting it to the radio environment. The NAS acts transparently through the UTRAN, and it can be considered as being carried by, rather than actually being, the air interface. 2.3. AS. The AS represents communication between the UE and the UTRAN. The functionality of the AS encompasses the entirety of layers 1 and 2 of the OSI SevenLayer Model, and in addition there is some layer 3 functionality. In general terms, AS functions include: • provision of physical channels • control of physical channels • link establishment and clearing • various types of channel coding • some security functions Interaction may take place between the UE and the CN in the AS, but it will occur indirectly via relay in the UTRAN.. 2.5. © Wray Castle Limited. VFT2800/S2/v1.

(49) UMTS Air Interface. OSI Layers. UE. Core Network Non-Access Stratum. L7. Relay. L3 L3. Access Stratum. L1 UTRAN. Uu. Iu. Figure 3 Access Stratum (AS) and Non-Access Stratum (NAS) VFT2800/S2/v1. © Wray Castle Limited. 2.6.

(50) UMTS Air Interface. 2.4. AS on the Air Interface. At layer 1, signalling and traffic data are carried across the air interface in physical channels that are defined in terms of either code set and frequency for FDD mode, or code, timeslot and frequency for TDD mode. Layer 2 is divided into two sublayers. The lower sublayer is the Medium Access Control (MAC) layer. It is responsible for a wide range of functions including random access procedures, physical link control, ciphering, multiplexing and channel mapping to the physical layer. The upper sublayer is the Radio Link Control (RLC) layer, which is responsible for logical link control, and acknowledged and unacknowledged data transfer. Layer 3 in the AS provides only the lower part of layer 3 in the control plane. This is known as Radio Resource Control (RRC) layer. It is responsible for the coordination and control of a range of functions including bearer control, monitoring processes, power control processes, measurement reporting, paging and broadcast control functions. 2.5. NAS on the Air Interface. The upper part of layer 3 is part of the NAS. It contains layer 3 signalling protocols that have peer entities in the UE and the core network. These include Call Control (CC) and Mobility Management (MM), that relate to the CS domain, and Session Management (SM) and GPRS Mobility Management (GMM), that relate to the PS domain. 2.6. Logical, Transport and Physical Channels. There is a complex array of user and signalling requirements. In order to define a process for each type of information, sets of logical channels mapping into transport channels and ultimately physical channels are defined. Logical channels are defined between RLC and MAC. Transport channels are defined between MAC and the physical layer. Logical channels define what type of data is transferred. Transport channels define how and with which type of characteristics the data is transferred over the air interface. Physical channels define the exact physical characteristics of the radio channels, i.e. specific carrier frequency, code-set, relative phase (Uplink (UL)) and timeslot (TDD mode).. 2.7. © Wray Castle Limited. VFT2800/S2/v1.

(51) UMTS Air Interface. L3 (NAS). CC MM SMS SM GMM. L3 (AS). Radio Resource Control RRC. User Plane Information. Radio Link Control RLC. Logical Channels. L2. Medium Access Control MAC. Transport Channels. Physical Layer L1. Physical Channels Figure 4 Air Interface AS VFT2800/S2/v1. © Wray Castle Limited. 2.8.

(52) UMTS Air Interface. 3. PROTOCOL TERMINATION WITHIN THE UTRAN 3.1. Termination Nodes. The UTRAN contains two logical functions, the Radio Network Controller (RNC) and the Node B. The NAS is transparent to both of these node types, but the protocols of the AS will terminate at either the RNC or the Node B. In general, the Node B is concerned only with physical layer functions, thus the layer 2 protocols MAC and RLC will terminate at the RNC. RRC, which represents the AS part of layer 3, also terminates at the RNC. However, protocols in the NAS part of layer 3 will terminate in the appropriate core network node. Messages relating to these protocols are carried transparently through the UTRAN and are encapsulated in RRC messages as they traverse the air interface. 3.2. Variations for Protocol Termination. The precise arrangements for protocol termination are subject to some variation. One factor resulting in variation is the logical channel type in use. For some types of system information being broadcast on the Broadcast Channel (BCH), rapid update may be required. This update period may be in the order of fractions of a second. Since it is considered unlikely that such a rapid update rate would be available from the RNC, it is permitted for the AS to terminate in the Node B. Basic system information is then transported transparently to the Node B and the rapidly updated system information is added locally for transmission. For High-Speed Downlink Packet Access (HSDPA) operation some MAC layer functionality is moved from the RNC to the Node B. This is because the adaptive nature of HSDPA operation requires a very fast control loop.. 2.9. © Wray Castle Limited. VFT2800/S2/v1.

(53) UMTS Air Interface. CC MM SMS SM GMM. RRC. RLC. CN. MAC Iu. CC MM SMS SM GMM RRC Iub. Physical. RLC. Node B. MAC. Physical Uu. User Equipment wray castle Brow. ser. .. Internet Search: http//www. xXX XXXXXXXXxx X XXXxXXXX XX XXXXXXXXXX XX XXXXxxxxxXX XXX XxXX XXX X XXX XXX. Figure 5 Protocol Termination VFT2800/S2/v1. © Wray Castle Limited. 2.10.

(54) UMTS Air Interface. 4. LOGICAL CHANNELS The MAC layer provides transfer services via a set of logical channels. A logical channel is defined for each different transfer requirement. Each logical channel relates to particular kinds of information that need to be transferred. Some relate to signalling information, and some to traffic information. The following logical channels are used for the transfer of signalling information: • Broadcast Control Channel (BCCH) • Paging Control Channel (PCCH) • Common Control Channel (CCCH) • Dedicated Control Channel (DCCH) • Shared Channel Control Channel (SHCCH) The following logical channels are used for the transfer of user information: • Dedicated Traffic Channel (DTCH) • Common Traffic Channel (CTCH). 2.11. © Wray Castle Limited. VFT2800/S2/v1.

(55) UMTS Air Interface. Control Channels from RLC. BCCH. PCCH. CCCH. DCCH. (TDD only) SHCCH. Traffic Channels from RLC DTCH. CTCH. Medium Access Control (MAC). Figure 6 Logical Channel Types VFT2800/S2/v1. © Wray Castle Limited. 2.12.

(56) UMTS Air Interface. 4.1. Logical Channel Types. Broadcast Control Channel (BCCH) The BCCH is a downlink (DL) broadcast channel carrying system information. There are two types, known as BCCH-Constant (BCCH-C) and BCCH-Variable (BCCH-V). The first carries information that does not change on a regular basis; the second carries information that may be constantly updated. Paging Control Channel (PCCH) The PCCH is a DL channel carrying paging messages. It is used when the network does not know the location cell of the UE, or the UE is using sleep mode procedures. Common Control Channel (CCCH) This is a bidirectional channel carrying control information between the network and the UE. It is used when the UE has no RRC connection with the network. Dedicated Control Channel (DCCH) This is a point-to-point bidirectional channel carrying dedicated control information between the network and the UE. It is used when a dedicated connection has been established through RRC connection set-up procedures. Shared Channel Control Channel (SHCCH) The SHCCH is a bidirectional channel carrying control information for UL and DL shared channels. Dedicated Traffic Channel (DTCH) The DTCH is a dedicated point-to-point channel carrying user information between the network and the UE. It may be used in both the UL and DL directions. Common Traffic Channel (CTCH) The CTCH is a point-to-multipoint unidirectional channel carrying user information for a specified group of UEs.. 2.13. © Wray Castle Limited. VFT2800/S2/v1.

(57) UMTS Air Interface. Control Channels from RLC. BCCH. PCCH. CCCH. DCCH. (TDD only) SHCCH. Traffic Channels from RLC DTCH. CTCH. Medium Access Control (MAC). Figure 6 (repeated) Logical Channel Types VFT2800/S2/v1. © Wray Castle Limited. 2.14.

(58) UMTS Air Interface. 5. TRANSPORT CHANNELS Information is transferred from the MAC layer and mapped into the physical channels via a set of transport channels. Transport channels can be classified into two groups: common channels and dedicated channels. Information in common channels will require inband identification of the UE. For dedicated channels the UE’s identity is associated with the channel allocation. The common transport channels are: • Random Access Channel (RACH) • Common Packet Channel (CPCH) (FDD mode only) • Forward Access Channel (FACH) • Downlink Shared Channel (DSCH) • High Speed Downlink Shared Channel (HS-DSCH) • Uplink Shared Channel (USCH) (TDD mode only) • Broadcast Channel (BCH) • Paging Channel (PCH) The dedicated transport channel is the Dedicated Channel (DCH).. 2.15. © Wray Castle Limited. VFT2800/S2/v1.

(59) UMTS Air Interface. Common Channels from MAC. RACH. * CPCH. * FACH DSCH HS-DSCH USCH BCH PCH (TDD only). (FDD only). Dedicated Channels from MAC DCH. Physical Layer. * These channels are removed from Release 5 onwards. Figure 7 Transport Channel Types VFT2800/S2/v1. © Wray Castle Limited. 2.16.

(60) UMTS Air Interface. 5.1. Transport Channel Types. Random Access Channel (RACH) A contention-based channel in the UL direction, the RACH is used for initial access or non-real-time dedicated control or traffic data. Common Packet Channel (CPCH) This channel is only used in FDD mode. It is a contention-based channel used for the transmission of bursty traffic data in a shared mode. Fast power control is used. This channel is removed from the standards from Release 5 onwards. Forward Access Channel (FACH) The FACH is a common DL channel without power control. It is used for relatively small amounts of data. Downlink Shared Channel (DSCH) A DL channel used in shared mode by several UEs, the DSCH is used to carry control or traffic data. This channel is removed from the standards from Release 5 onwards. High Speed Downlink Shared Channel (HS-DSCH) Similar to the DSCH but used to achieve very high downlink data rates as part of the HSDPA feature. Uplink Shared Channel (USCH) This channel is only used in TDD mode. It is a UL channel used in shared mode by several UEs. It is used to carry control or traffic data. Broadcast Channel (BCH) This is a DL broadcast channel used to carry system information across a whole cell. Paging Channel (PCH) The PCH is a downlink broadcast channel used to carry paging and notification messages across a whole cell. Dedicated Channel (DCH) The DCH is used in the UL or DL direction to carry user information to or from the UE.. 2.17. © Wray Castle Limited. VFT2800/S2/v1.

(61) UMTS Air Interface. Common Channels from MAC. RACH. * CPCH. * FACH DSCH HS-DSCH USCH BCH PCH (TDD only). (FDD only). Dedicated Channels from MAC DCH. Physical Layer. * These channels are removed from Release 5 onwards. Figure 7 (repeated) Transport Channel Types VFT2800/S2/v1. © Wray Castle Limited. 2.18.

(62) UMTS Air Interface. 6. DOWNLINK (DL) PHYSICAL CHANNELS 6.1. Introduction. In the DL direction there are a number of channels carrying higher-layer information and a large number having control and synchronization functions associated with layer 1. The DL physical channels carrying higher-level information are: • Primary Common Control Physical Channel (PCCPCH) • Secondary Common Control Physical Channel (SCCPCH) • Physical Downlink Shared Channel (PDSCH) • High Speed Physical Downlink Shared Channel (HS-PDSCH) • Dedicated Physical Data Channel (DPDCH) The DL channels carrying control and synchronization are: • Synchronization Channel (SCH) • Common Pilot Channel (Primary and Secondary) (CPICH) • Dedicated Physical Control Channel (DPCCH) • Acquisition Indicator Channel (AICH) • CPCH – Access Preamble Acquisition Indicator Channel (AP-AICH) • CPCH – Collision Detection/Channel Assignment Indicator Channel (CD/CA-ICH) • CPCH – Status Indicator Channel (CSICH) • Paging Indicator Channel (PICH). 2.19. © Wray Castle Limited. VFT2800/S2/v1.

(63) UMTS Air Interface. Transport Channels. Layer 2. * DCH. BCH. DPDCH. PCCPCH. FACH. PCH. DSCH. HSDSCH. PDSCH. HSPDSCH. Layer 1 Physical Channels. *. *. SCCPCH. *. CSICH CD/ AP-AICH AICH CPICH CA-ICH. SCH. PICH. DPCCH. DPCH. * These channels are removed from Release 5 onwards. Figure 8 Downlink Physical Channel VFT2800/S2/v1. © Wray Castle Limited. 2.20.

(64) UMTS Air Interface. 6.2. Physical Channel Types. Dedicated Physical Data Channel (DPDCH) and Dedicated Physical Control Channel (DPCCH) The DPDCH is a bidirectional channel used to carry higher-layer information from the transport channel DCH. It is multiplexed with the DPCCH that provides the layer 1 control and synchronization information. Once multiplexed, the two are referred to as a DPCH. One DPCCH may be associated with one or more DPDCHs Primary Common Control Physical Channel (PCCPCH) This is used in the DL direction to broadcast the BCH across a cell. There will be only one of these on each cell. Secondary Common Control Physical Channel (SCCPCH) The SCCPCH is used to carry the transport channels PCH and FACH in the DL direction. There may be one or more SCCPCHs, and if an SCCPCH is only carrying the FACH, it may be transmitted over only part of the cell using beamforming antennas. Physical Downlink Shared Channel (PDSCH) This is a DL channel used to carry the DSCH. It is shared by multiple users by way of code multiplexing. The PDSCH is always associated with one or more DL Dedicated Physical Channels (DPCHs). High Speed Physical Downlink Shared Channel (HS-PDSCH) This is a downlink channel that is used to carry the HS-DSCH for HSDPA operation. It is always associated with an existing dedicated channel and other physical signals. Paging Indicator Channel (PICH) This DL channel is used to carry Paging Indicators (PI). These are used to enable discontinuous reception of the PCH being carried on an associated SCCPCH. Synchronization Channel (SCH) This is a DL channel used during cell search. It consists of primary and secondary sub channels, and conveys information to the UE concerning the time alignment of a cell’s codes and frame structures.. 2.21. © Wray Castle Limited. VFT2800/S2/v1.

(65) UMTS Air Interface. Transport Channels. Layer 2. * DCH. BCH. DPDCH. PCCPCH. FACH. PCH. DSCH. HSDSCH. PDSCH. HSPDSCH. Layer 1 Physical Channels. *. *. SCCPCH. *. CSICH CD/ AP-AICH AICH CPICH CA-ICH. SCH. PICH. DPCCH. DPCH. * These channels are removed from Release 5 onwards. Figure 8 (repeated) Downlink Physical Channel VFT2800/S2/v1. © Wray Castle Limited. 2.22.

(66) UMTS Air Interface. Common Pilot Channel (CPICH) This channel is used to provide the phase reference for the SCH, PCCPCH, AICH and the PICH. It may also be the default phase reference for all the other DL channels. There will be only one Primary CPICH in a cell. It is an option to have one or more Secondary CPICHs in a cell. If present, the Secondary CPICHs would act as the phase reference for SCCPCH, and potentially DPCH. Acquisition Indicator Channel (AICH) This DL channel carries Acquisition Indicators (AI). These are used to acknowledge UE random access attempts, and grant permission for a UE to continue with its random access transmission. 6.3. Physical Channels for CPCH Access. These channels carry information used for the CPCH access procedure and do not carry transport channels. Since the CPCH is removed from Release 5, these channels are also no longer required. CPCH – Access Preamble Acquisition Indicator Channel (AP-AICH) This channel carries AP acquisition indicators which correspond with the AP signature transmitted by the UE. It is also used to acknowledge the random access preambles, which are then followed by a collision detection preamble. CPCH – Collision Detection/Channel Assignment Indicator Channel (CD/CA-ICH) The CD/CA-ICH is used to acknowledge the collision detection access preamble. CPCH – Status Indicator Channel (CSICH) The CSICH uses the unused part of the AICH channel to indicate CPCH physical channel availability so that access is only attempted on a free channel.. 2.23. © Wray Castle Limited. VFT2800/S2/v1.

(67) UMTS Air Interface. Transport Channels. Layer 2. * DCH. BCH. DPDCH. PCCPCH. FACH. PCH. DSCH. HSDSCH. PDSCH. HSPDSCH. Layer 1 Physical Channels. *. *. SCCPCH. *. CSICH CD/ AP-AICH AICH CPICH CA-ICH. SCH. PICH. DPCCH. DPCH. * These channels are removed from Release 5 onwards. Figure 8 (repeated) Downlink Physical Channel VFT2800/S2/v1. © Wray Castle Limited. 2.24.

(68) UMTS Air Interface. 7. UPLINK (UL) PHYSICAL CHANNELS 7.1. Introduction. In the UL direction there are four types of physical channel: • Physical Random Access Channel (PRACH) • Dedicated Physical Data Channel (DPDCH) • Dedicated Physical Control Channel (DPCCH) • Physical Common Packet Channel (PCPCH) Note that as in the downlink direction the DPDCH and DPCCH are combined to form a Dedicated Physical Channel (DPCH). 7.2. Physical Channel Types. Physical Random Access Channel (PRACH) This UL channel is a contention-based channel used to carry higher-layer information in the form of the RACH. Dedicated Physical Channel (DPCH) The DPCH is ultimately used to carry the transport channel DCH. However, it also carries layer 1 information in the form of the pilot, Transmit Power Control (TPC), and Transport Format Combination Indication (TFCI) bits. As such, the DPCH can be considered as two subchannels: the DPDCH, which is used to carry DCH; and the DPCCH, which is used to carry the layer 1 information. These two subchannels are time division multiplexed together to form the DPCH. Physical Common Packet Channel (PCPCH) The PCPCH carries the common packet transport channel, which comprises access preambles, collision detection preamble, power control preamble and a message part. This channel is removed from the standards from Release 5 onwards. High data rate uplink packet data will be provided through enhancement of the dedicated channel, sometimes called High Speed Uplink Packet Access (HSUPA).. 2.25. © Wray Castle Limited. VFT2800/S2/v1.

(69) UMTS Air Interface. Transport Channels Layer 2. * CPCH. DCH. RACH. Layer 1. Physical Channels DPCCH. PCPCH. DPDCH. DPCH. PRACH. * This channel is removed from Release 5 onwards. Figure 9 Uplink Physical Channel VFT2800/S2/v1. © Wray Castle Limited. 2.26.

(70) UMTS Air Interface. 8. FDD MODE CHANNEL MAPPING 8.1. Logical to Transport Channel Mapping. Before its transmission across the air interface, information presented in logical channels must be mapped into transport channels. This mapping process is very flexible, and for some logical channels there are several options, depending on the function and the type of information being transferred. 8.2. Transport to Physical Channel Mapping. The physical layer applies error protection and maps and multiplexes transport channels into physical channels. It should be noted that some unidirectional channels, i.e. PICH, CPICH and AICH, which perform some kind of indication to the receiving element, are derived at the physical layer, since the information carried in these channels is of no interest to higher layers. These channels are known as physical channels. 8.3. Mapping for the Uu Interface. The directions of arrows shown in the diagram reflect the mapping process as seen from the UTRAN side. For the channels carrying broadcast information, mapping is direct from BCCH to BCH and from PCCH to PCH. For the other control and traffic-carrying channels, mapping is more flexible. For example, DL DCCH can be mapped either to FACH or to DSCH, depending on information requirements. In the UL direction DCCH may take information from CPCH, RACH, USCH or DCH. The logical channel DTCH is similar, in that it has access to a range of transport channels. However, the CCCH is simple: it uses only RACH and FACH for bidirectional communication.. 2.27. © Wray Castle Limited. VFT2800/S2/v1.

(71) UMTS Air Interface. BCCH. PCCH. CCCH. DCCH. CTCH. DTCH. Logical Channels. MAC. BCH. PCH. FACH. *. RACH. CPCH. *. DSCH. HS-DSCH. Transport Channels. DCH. Physical Layer PCCPCH. SCCPCH. PRACH. *. PCPCH. *. PDSCH. HS-PDSCH. DPCH. Air Interface. *. These channels are removed from Rel-5 onwards. Figure 10 FDD Mode Channel Mapping VFT2800/S2/v1. © Wray Castle Limited. 2.28.

(72) UMTS Air Interface. 9. UTRAN ARCHITECTURE 9.1. Key Components of the UTRAN. The UTRAN constitutes the part of an operator’s network that enables users to access the services provided by the CN via radio in a mobile environment. In this context there will be two main roles: radio provision and the control of the radio channel resource. Two functional elements have been defined to carry out these roles: the Node B and the RNC. These functions and the interfaces between them are only logical descriptions; their physical implementations are open to vendors’ interpretations. However, a likely interpretation would be to implement them as physical elements. This would lead to an architecture similar to that used in second-generation systems, and therefore a potentially simpler migration route. 9.2. Node B. The Node B contains radio transmitters, receivers, baseband functions, antennas and feeders for one or more cells. The Node B acts only as a relay between the radio interface on the UE side and the terrestrial interface on the network side. In this role it only has lower-layer functionality. A Node B may be able to support one or more of the radio access modes. 9.3. Radio Network Controller (RNC). Control of functionality for a number of Node Bs is performed by the RNC. The RNC terminates signalling and control between the UE and the UTRAN. In this role it has functionality up to layer 3 of the air interface protocol stack. The RNC has control of the radio channel resource and handles local mobility in the context of macro diversity. 9.4. Radio Network Subsystem (RNS). Radio Network Subsystem (RNS) is a collective term for one RNC and its associated Node Bs. An UTRAN may contain one or more RNS.. 2.29. © Wray Castle Limited. VFT2800/S2/v1.

(73) UMTS Air Interface. Radio Network Subsystem (RNS). Node B modulation/demodulation. radio resource control. transmission/reception. admission control. CDMA physical channel coding. channel allocation. micro diversity. power control thresholds. error protection. handover control. closed loop power control. macro diversity segmentation/reassembly ciphering broadcast signalling open loop power control Figure 11 UTRAN Architecture. VFT2800/S2/v1. © Wray Castle Limited. 2.30.

(74) UMTS Air Interface. 10. GENERAL UTRAN PROTOCOL STRUCTURE 10.1. Control and User Planes. The UTRAN protocols employ a common architecture on all three terrestrial interfaces, Iub, Iur and Iu. The protocol architecture is divided horizontally into two key layers. The upper part is referred to as the Radio Network Layer, and the lower part is referred to as the Transport Network Layer. The Radio Network Layer constitutes the resource for data to be transferred across the interfaces; this data will be signalling or traffic. The Transport Network Layer provides the necessary transport mechanisms, based on Asynchronous Transfer Mode (ATM). The protocol architecture is also divided vertically into three planes, the control plane, which handles control information pertaining to the internal UTRAN interfaces, the user plane, and a transport network control plane. The control plane includes the application protocols, Radio Access Network Application Part (RANAP) on the lu interface, Radio Network System Application Part (RNSAP) on the lur interface and Node B Application Part (NBAP) on the lub interface. The User Plane (UP) includes the data stream(s) and the data bearer(s) for the data stream(s) which are characterized by one or more UP framing protocols specified for each interface. The user in this context means the application using the interface and does not refer to network subscribers. Thus for the Iub and Iur interfaces this includes both traffic and layer 3 signalling. On the Iu interface ‘user’ refers only to traffic. The Transport Network Control Plane includes Access Link Control Application Protocol (ALCAP), needed to establish, release and maintain point-to-point connections on the lu-CS, lub and lur interfaces.. 2.31. © Wray Castle Limited. VFT2800/S2/v1.

(75) UMTS Air Interface. Radio Network Layer. Control Plane. User Plane. Signalling. Traffic. Transport Network Layer. ATM-based. Figure 12a Simplified UTRAN Structure. Radio Network Layer. Transport Network Layer. Control Plane. User Plane. Application Protocol. Data Protocol. Transport Network User Plane. Transport Network Control Plane. Transport Network User Plane. ALCAP Signalling Bearers. Signalling Bearers. Data Bearers. Physical Layer. Figure 12b UTRAN Protocol Structure VFT2800/S2/v1. © Wray Castle Limited. 2.32.

(76) UMTS Air Interface. 10.2. ATM in the UTRAN. Up to and including Release 4, the use of ATM as the transport protocol in the UTRAN is mandatory. However, only parts of the functionality are used and on some interfaces they are used in a non-standard way. For normal ATM operation a set of ATM Adaptation Layers (AALs) have been defined to transport different types of user data having differing quality of service requirements. Within the UTRAN only AAL2 and AAL5 are used. AAL2 is designed to deal with synchronous, variable-bit-rate, delay-critical data flows. Typically, these characteristics would be associated with circuit-switched traffic flows. However, within the UTRAN these characteristics are used on the Iub and Iur interfaces to provide reliable bearers that carry layer 3 signalling and packetswitched traffic as well as circuit-switched traffic. On the Iu interfaces it is used in the conventional way to carry only circuit-switched traffic relating to the CS core network domain. AAL5 is designed to deal with asynchronous, non-delay-critical variable-length frames. Typically, these characteristics would be associated with packet data and signalling. On the Iub and Iur interfaces within the UTRAN the only function for AAL5 is the transport of internal interface signalling. Again, however, on the Iu interface AAL5 is used in the conventional way to carry packet data and signalling. 10.3. IP in the UTRAN. From Release 5 it becomes an option to use a private IP network as the transport layer within the UTRAN. It may either replace or simply supplement the current ATM structure. This change is not visible to the mobile and is independent of the IP backbone that may be operating in the core network (although some transmission links may be common). Any IP addresses supplied to the UE are relevant only to the services being accessed by the user and are not part of the private IP network in the UTRAN.. 2.33. © Wray Castle Limited. VFT2800/S2/v1.

(77) UMTS Air Interface. AAL2. AAL5. synchronous. asynchronous. variable bit rate. variable-length frames. delay critical. non delay critical. connection oriented. connectionless or connection oriented. Figure 13a AAL2 and AAL5. RNC Core network. IP (optionally with ATM). Figure 13b IP in the UTRAN VFT2800/S2/v1. © Wray Castle Limited. 2.34.

(78) UMTS Air Interface. 11. Iub INTERFACE 11.1. Iub Location and Capabilities. The Iub interface connects the RNC to a Node B. Since the Node B only performs a relay function between the terrestrial link, which is the Iub, and the radio link, which is the air interface, any higher-layer signalling between the UE and the UTRAN will be terminated at the RNC. This signalling will therefore be carried on the Iub interface. In addition, the Iub is carrying signalling directly between the Node B and the RNC. This signalling is used to control radio resource allocation, general control functions for the Node B, and for Operations and Maintenance (O&M) functions. Higher-layer signalling to and from the air interface must be carried over the Iub interface to terminate at the RNC. A key function of the Iub interface will be to allow multiplexing of data streams relating to transport channels on the air interface. The definition of the Iub interface is intended to enable interconnection of Node B and RNC irrespective of the manufacturer.. 2.35. © Wray Castle Limited. VFT2800/S2/v1.

(79) UMTS Air Interface. Signalling and Traffic to UE. ser. wray castle Brow Internet Search: http//ww. Control of Node B and its resources (NBAP). w.. xxxXX XXXXXXXX X XXXxXXXX XXXX XXXXXXXX XX XX XXXXxxxxx XXX XxXX XXX X XXX XXX. Iub UE. Node B. Figure 14 Iub Main Aims VFT2800/S2/v1. © Wray Castle Limited. 2.36.

(80) UMTS Air Interface. 11.2. Iub General Structure. On the lub interface the radio network layer provides signalling between the RNC and the Node B in the control plane, and signalling/traffic between the RNC and UE in the user plane. The transport layer is similar on all three interfaces (lub, lur and lu) in that it has common physical and ATM layers, although the use of AAL5 and AAL2 on the Iu interface differs slightly from that on Iur and Iub. 11.2.1. Radio Network Layer Control Plane. The control plane of the radio network layer contains the signalling protocol NBAP. This signalling entity represents all types of signalling and control between the RNC and a Node B. The main functions for this are: • radio channel management • radio resource management • radio network performance measurement • cell configuration management • Operations and Maintenance (O&M) • Iub link management 11.2.2. Radio Network Layer User Plane. The user plane of the radio network layer constitutes the higher layers of the air interface. It involves the transfer of dedicated and common channels that are used on the air interface. The content of these channels will be traffic and signalling between the RNC and UEs.. 2.37. © Wray Castle Limited. VFT2800/S2/v1.

(81) UMTS Air Interface. a) Iub User Plane. Iub Framing Protocols. Iub Framing Protocols. AAL2 Signalling Protocol Adaptation Layer AAL5. AAL2 Signalling Protocol Adaptation Layer AAL2. AAL5. AAL2. ATM. ATM. Physical Layer. Physical Layer. b) Iub Control Plane Node B. RNC. NBAP. NBAP. AAL5. AAL5. ATM. ATM. Physical Layer. Physical Layer. Figure 15 Iub User and Control Plane VFT2800/S2/v1. © Wray Castle Limited. 2.38.

(82) UMTS Air Interface. 12. Iur INTERFACE 12.1. Iur Location and Capabilities. The Iur interface exists between two RNCs. It is intended to enable the transport of air interface signalling and traffic between a Serving RNC (SRNC) and a Node B belonging to a Drift RNC (DRNC).. 2.39. © Wray Castle Limited. VFT2800/S2/v1.

(83) UMTS Air Interface. Signalling and Traffic to UE. Communication between SRNC and DRNC RNSAP ser wray castle Brow w.. Internet Search: http//ww. xxxXX XXXXXXXX X XXXxXXXX XXXX XXXXXXXX XX XX XXXXxxxxx XXX XxXX XXX X XXX XXX. UE. Iub. Iur. Node B. Figure 16 Iur Location and Aims VFT2800/S2/v1. © Wray Castle Limited. 2.40.

(84) UMTS Air Interface. 12.2. lur Radio Network Layer. There are two users in the radio network layer for the lur interface. These are the user plane framing protocols and the RNS Application Part (RNSAP). Since the lur interface is primarily providing a relay function for the SRNC to communicate with a UE via a remote Node B, the user plane framing protocols provide a similar function to those on the lub interface. They allow transfer of data streams relating to the common and dedicated channels used at layer 2 of the air interface. The function of the RNSAP is to provide the signalling between the SRNC and the DRNC that is necessary to establish transport for the user plane framing protocols.. 2.41. © Wray Castle Limited. VFT2800/S2/v1.

(85) UMTS Air Interface. a) Iur User Plane. Iur Framing Protocols. Iur Framing Protocols. AAL2 Signalling Protocol Adaptation Layer AAL5. AAL2 Signalling Protocol Adaptation Layer AAL2. AAL5. AAL2. ATM. ATM. Physical Layer. Physical Layer. b) Iur Control Plane DRNC. SRNC. RNSAP. RNSAP. AAL5. AAL5. ATM. ATM. Physical Layer. Physical Layer. Figure 17 lur User and Control Plane VFT2800/S2/v1. © Wray Castle Limited. 2.42.

(86) UMTS Air Interface. 13. lu INTERFACE 13.1. lu Location and Capabilities. The lu interface exists between an RNC and the CN and can have two physical implementations, lu-CS and lu-PS. The lu-CS interface provides a CS connection between an RNC and a 3G Mobile Switching Centre (3G MSC) in the CN, while the lu-PS interface provides a PS connection between an RNC and a 3G Serving GPRS Support Node (3G SGSN) in the CN.. 2.43. © Wray Castle Limited. VFT2800/S2/v1.

(87) UMTS Air Interface. Signalling and Traffic to UE. Communication between SRNC and 3G MSC/SGSN RANAP. ser wray castle Brow w.. Internet Search: http//ww. xXX XXXXXXXXxx X XXXxXXXX XX XXXXXXXXXX XX X XXXXxxxxxX. Iub. XXX XxXX XXX X XXX XXX. UE. Iur. Node B. Iu. 3G MSC/ SGSN. Figure 18 lu Location and Aims VFT2800/S2/v1. © Wray Castle Limited. 2.44.

(88) UMTS Air Interface. 13.2. lu Radio Network Layer User Plane. The UP contains the lu UP Protocol. This protocol provides the services required for presentation of user data for transport by lower layers. It offers two modes of operation: Transparent Mode (TrM), and Support Mode for predefined Service Data Unit (SDU) size (SMpSDU). TrM only provides segmentation of data into Protocol Data Units (PDUs), there is no peer-to-peer communication. It would be used for packet transfer or non-transparent CS transfer. For both of these, peer-to-peer communication occurs in other layers of the protocol stack. SMpSDU provides segmentation with communication peer-to-peer in headers on the Packet Data Unit (PDU). It would be used where additional communication peer-topeer is required of the lu UP layer, e.g. for AMR-coded voice. 13.3. Radio Network Layer Control Plane. The control plane contains a function referred to as RANAP. RANAP provides signalling between the CN and the UTRAN as well as the transport of signalling between the CN and the UE. Signalling between CN and UE will be call control or other general service-related functions.. 2.45. © Wray Castle Limited. VFT2800/S2/v1.

(89) UMTS Air Interface. a) Iu User Plane. TrM. SMpSDU. TrM. Iu Protocol. Iu Protocol. AAL2 Signalling Protocol Adaptation Layer AAL5. SMpSDU. AAL2 Signalling Protocol Adaptation Layer AAL2. AAL5. AAL2. ATM. ATM. Physical Layer. Physical Layer. b) Iu Control Plane RNC. CN. RANAP. RANAP. AAL5. AAL5. ATM. ATM. Physical Layer. Physical Layer. Figure 19 lu User and Control Plane VFT2800/S2/v1. © Wray Castle Limited. 2.46.

(90) UMTS Air Interface. 14. SUMMARY The use of ATM as a transport protocol in the UTRAN is mandatory for Release 99 and Release 4 of the 3GPP UMTS specifications. However, only the AAL2 and AAL5 ATM adaptation layers are utilized within the UTRAN. The diagram summarizes how AAL2 and AAL5 are applied on each UTRAN interface. On the Iu-CS interface AAL2 is used in the user plane to carry circuit-switched user data. In the control plane all signalling is carried in AAL5. Signalling on this interface consists of RANAP messages and NAS messages that are themselves encapsulated in RANAP messages. On the Iu-PS interface, AAL5 is used in the user plane to carry packet-switched user data and in the control plane to carry all signalling. Again, signalling on this interface consists of RANAP messages and NAS messages that are themselves encapsulated in RANAP messages. On the Iub and Iur interfaces the user plane utilizes AAL2. Here the user plane carries the transport channel framing protocols. Consequently this includes circuitswitched and packet-switched user data as well as RRC messages and RRCencapsulated NAS messages. AAL5 is used on the Iub and Iur interfaces to carry NBAP and RNSAP messages respectively.. 2.47. © Wray Castle Limited. VFT2800/S2/v1.

(91) UMTS Air Interface. Node B CN Node. Iub. Iur. Iu-CS/PS. AAL2 CircuitSwitched Domain. RANAP. AAL5. AAL2. NBAP. AAL5. NAS Signalling User Data RRC Signalling. RNSAP. AAL2. AAL5. RANAP. AAL5. PacketSwitched Domain. Figure 20 AAL within the UTRAN VFT2800/S2/v1. © Wray Castle Limited. 2.48.

(92) UMTS Air Interface. 2.49. © Wray Castle Limited. VFT2800/S2/v1.

(93) UMTS Air Interface. SECTION 3. UMTS PHYSICAL LAYER. © Wray Castle Limited. i.


(95) UMTS Air Interface. CONTENTS 1. The Physical Layer (L1) 1.1 Introduction 1.2 The UMTS Absolute Radio Frequency Channel Number (UARFCN). 3.1 3.1. 2. General CDMA Code Functions 2.1 Codes and Physical Channels 2.2 UL and DL Allocation 2.3 The Two-Stage Coding Process. 3.3 3.3 3.3 3.5. 3. UMTS Code Types 3.1 Introduction 3.2 Initial Synchronization Codes 3.3 Spreading Codes 3.4 DL Scrambling Codes 3.5 UL Scrambling Codes. 3.7 3.7 3.7 3.7 3.7 3.9. 4. Application of Codes to the Air Interface 4.1 DL Direction 4.2 Summation of DL Channels 4.3 UL Direction. 3.11 3.11 3.11 3.13. 5. Complex Scrambling 5.1 Justification for Complex Scrambling 5.2 Complex Scrambling Process. 3.17 3.17 3.17. 6. General Structure for Physical Channels. 3.19. 7. Dedicated Physical Channels (DPCH) 7.1 DPCH Functionality Split 7.2 Downlink DPCH Slot Structure 7.3 Downlink DPCH Slot Fields 7.4 Operation with Multiple DPDCHs 7.5 Uplink DPCH Slot Structure 7.6 Uplink DPCH Slot Fields. 3.21 3.21 3.23 3.25 3.27 3.29 3.31. © Wray Castle Limited. 3.1. iii.


(97) UMTS Air Interface. CONTENTS 8. Downlink Common Physical Channels 8.1 The Common Pilot Channel (CPICH) 8.2 The Synchronization Channel (SCH) 8.3 Primary Common Control Physical Channel (PCCPCH) 8.4 Secondary Common Control Physical Channel (SCCPCH) 8.5 Physical Random Access Channel (PRACH) 8.6 The Acquisition Indicator Channel (AICH) 8.7 The Paging Indicator Channel (PICH) 8.8 High Speed Downlink Packet Access (HSDPA) Channels 8.9 HSDPA Channel Organization and Timing. 3.33 3.33 3.35 3.39 3.41 3.43 3.49 3.51 3.53 3.55. 9. Physical Channel Time Alignments 9.1 General DL Timing within a Cell 9.2 General UL Timing within a Cell. 3.57 3.57 3.59. 10. Formats for Physical Layer Data Transfer 10.1 Transport Blocks 10.2 Transport Format 10.3 Transport Format Combination. 3.61 3.61 3.63 3.63. 11. Channel Coding and Multiplexing 11.1 General Structure for Transport Channel Coding and Multiplexing 11.2 FEC Channel Coding 11.3 Channel Coding and Multiplexing Examples. 3.65 3.65 3.67 3.69. Closed Loop Power Control 12.1 Inner Loop Power Control 12.2 Outer Loop Power Control 12.3 Closed Loop Power Control Commands for the Uplink 12.4 Processing TPC Bits from a Single Physical Channel 12.5 Processing TPC Bits from Multiple Physical Channels 12.6 Closed Loop Power Control Commands for the DL 12.7 DPCCH/DPDCH Power Difference Physical Layer TDD Operation. 3.81 3.81 3.81 3.83 3.85 3.87 3.89 3.91 3.97. 12. 1. © Wray Castle Limited. v.

(98) UMTS Air Interface. vi. © Wray Castle Limited.

No results found