Wcdma umts wireless networks
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This document provides an overview of 3rd generation WCDMA/UMTS wireless networks. It describes the evolution from 2G to 3G networks and the key aspects of WCDMA/UMTS architecture, including the air interface, radio access network, core network and radio resource management functions such as admission control, load control, packet scheduling, handover control and power control. The document also briefly discusses additional topics such as radio network planning issues, high speed data packet access, and a comparison of WCDMA and CDMA2000.
Wcdma umts wireless networks
- 1. 1 3rd Generation WCDMA / UMTS Wireless Network
- 2. 2 Outline Evolution from 2G to 3G WCDMA / UMTS Architecture Air Interface (WCDMA) Radio Access Network (UTRAN) Core Network Radio Resources Management Admission Control, Load Control, Packet Scheduler Handover Control and Power Control Additional Briefs Radio Network Planning Issues High Speed Data Packet Access WCDMA vs Ccdma2000
- 3. 3 Outline What will not be covered Antenna, RF Propagation and Fading Added Services, e.g. Location Services Certain Technical Aspects, e.g. WCDMA TDD Mode, Base Station Synchronization Detailed Protocol Structures Detailed Design Issues, Optimizations Performance Evaluation cdma2000
- 4. 4 Evolution : From 2G to 3G Source : Northstream, Operator Options for 3G Evolution, Feb 2003.
- 5. 5 Evolution : From 2G to 3G Fully specified and world-widely valid, Major interfaces should be standardized and open. Supports multimedia and all of its components. Wideband radio access. Services must be independent from radio access technology and is not limited by the network infrastructure. Primary Requirements of a 3G Network
- 6. 6 Standardization of WCDMA / UMTS The 3rd Generation Partnership Project (3GPP) Role: Create 3G Specifications and Reports 3G is standardized based on the evolved GSM core networks and the supporting Radio Access Technology Source : Overview of UMTS, Guoyou He, Telecommunication Software and Multimedia Laboratory, Helsinki University of Technology GSM
- 7. 7 Standardization of WCDMA / UMTS Introduction of GPRS / E-GPRS 3GPP Release ‘99 Source : Overview of UMTS, Guoyou He, Telecommunication Software and Multimedia Laboratory, Helsinki University of Technology
- 8. 8 Standardization of WCDMA / UMTS 3GPP Release 4 3GPP Release 5-6 All IP Vision Source : Overview of UMTS, Guoyou He, Telecommunication Software and Multimedia Laboratory, Helsinki University of Technology
- 9. 9 Standardization of WCDMA / UMTS Multiple Access Method DS-CDMA Duplexing Method FDD/TDD Base Station Synchronization Asychronous Operation Channel Separation 5MHz Chip Rate 3.84 Mcps Frame Length 10 ms Service Multiplexing Multiple Services with different QoS Requirements Multiplexed on one Connection Multirate Concept Variable Spreading Factor and Multicode Detection Coherent, using Pilot Symbols or Common Pilot Multiuser Detection, Smart Antennas Supported by Standard, Optional in Implementation WCDMA Air Interface, Main Parameters
- 10. 10 Outline Evolution from 2G to 3G WCDMA / UMTS Architecture Air Interface (WCDMA) Radio Access Network (UTRAN) Core Network Radio Resources Management Admission Control, Load Control, Packet Scheduler Handover Control and Power Control Additional Briefs Radio Network Planning Issues High Speed Data Packet Access WCDMA vs Ccdma2000
- 11. 11 UMTS System Architecture USIM ME Node B Node B RNC Node B Node B RNC MSC/ VLR GMSC SGSN GGSN HLR UTRAN CNUE ExternalNetworks Cu Uu Iu Iub Iur
- 12. 12 UMTS Bearer Services TE MT UTRAN CN Iu EDGE NODE CN Gateway TE End-to-End Service External Bearer Service Radio Access Bearer Service Backbone Network Service UTRA FDD/TDD Service TE/MT Local Bearer Sevice UMTS Bearer Service CN Bearer Service Radio Bearer Service Iu Bearer Service Physical Bearer Service UMTS
- 13. 13 UMTS QoS Classes Traffic class Conversational class Streaming class Interactive class Background Fundamental characteristics Preserve time relation between information entities of the stream Conversational pattern (stringent and low delay) Preserve time relation between information entities of the stream Request response pattern Preserve data integrity Destination is not expecting the data within a certain time Preserve data integrity Example of the application Voice, videotelephony, video games Streaming multimedia Web browsing, network games Background download of emails
- 14. 14 UMTS In Detail USIM ME Node B Node B RNC Node B Node B RNC MSC/ VLR GMSC SGSN GGSN HLR UTRAN CNUE ExternalNetworks Cu Uu Iu Iub Iur
- 15. 15 WCDMA Air Interface Wideband CDMA, Overview DS-CDMA, 5 MHz Carrier Spacing, CDMA Gives Frequency Reuse Factor = 1 5 MHz Bandwidth allows Multipath Diversity using Rake Receiver Variable Spreading Factor (VSF) to offer Bandwidth on Demand (BoD) up to 2MHz Fast (1.5kHz) Power Control for Optimal Interference Reduction Services multiplexing with different QoS Real-time / Best-effort 10% Frame Error Rate to 10-6 Bit Error Rate UE UTRAN CN
- 16. 16 WCDMA Air Interface UE UTRAN CN Direct Sequence Spread Spectrum User 1 User N Spreading Spreading Received Despreading Narrowband Code Gain ⇒ Frequency Reuse Factor = 1 Wideband Wideband ⇒ 5 MHz Wideband Signal allows Multipath Diversity with Rake Receiver Wideband Narrowband f f ff f f t t Multipath Delay Profile Variable Spreading Factor (VSF) User 1 Spreading : 256 Wideband f f User 2 Spreading : 16 Wideband f f ⇒ VSF Allows Bandwidth on Demand. Lower Spreading Factor requires Higher SNR, causing Higher Interference in exchange.
- 17. 17 WCDMA Air Interface UE UTRAN CN Mapping of Transport Channels and Physical Channels Broadcast Channel (BCH) Forward Access Channel (FACH) Paging Channel (PCH) Random Access Channel (RACH) Dedicated Channel (DCH) Downlink Shared Channel (DSCH) Common Packet Channel (CPCH) Primary Common Control Physical Channel (PCCPCH) Secondary Common Control Physical Channel (SCCPCH) Physical Random Access Channel (PRACH) Dedicated Physical Data Channel (DPDCH) Dedicated Physical Control Channel (DPCCH) Physical Downlink Shared Channel (PDSCH) Physical Common Packet Channel (PCPCH) Synchronization Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indication Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision Detection/Channel Assignment Indicator Channel (CD/CA-ICH) Highly Differentiated Types of Channels enable best combination of Interference Reduction, QoS and Energy Efficiency,
- 18. 18 WCDMA Air Interface UE UTRAN CN Common Channels - RACH (uplink) and FACH (downlink) • Random Access, No Scheduling • Low Setup Time • No Feedback Channel, No Fast Power Control, Use Fixed Transmission Power • Poor Link-level Performance and Higher Interference • Suitable for Short, Discontinuous Packet Data Common Channel - CPCH (uplink) • Extension for RACH • Reservation across Multiple Frames • Can Utilize Fast Power Control, Higher Bit Rate • Suitable for Short to Medium Sized Packet Data RACH FACH 1 2 1 3 3P 3 1P 1 CPCH 1P 1 2P 2
- 19. 19 WCDMA Air Interface UE UTRAN CN Dedicated Channel - DCH (uplink & downlink) • Dedicated, Requires Long Channel Setup Procedure • Utilizes Fast Power Control • Better Link Performance and Smaller Interference • Suitable for Large and Continuous Blocks of Data, up to 2Mbps • Variable Bitrate in a Frame-by-Frame Basis Shared Channel - DSCH (downlink) • Time Division Multiplexed, Fast Allocation • Utilizes Fast Power Control • Better Link Performance and Smaller Interference • Suitable for Large and Bursty Data, up to 2Mbps • Variable Bitrate in a Frame-by-Frame Basis DCH (User 1) DCH (User 2) DSCH 1 2 3 1 2 3 1 2 3 1 2
- 20. 20 WCDMA Air Interface UE UTRAN CN Summary • 5 MHz Bandwidth -> High Capacity, Multipath Diversity • Variable Spreading Factor -> Bandwidth on Demand RACH CPCH DCH (User 1) DCH (User 2) DSCH FACH 1 2 1 3 3P 3 1P 1 1P 1 2P 2 1 2 3 1 2 3 1 2 3 1 2
- 21. 21 UTRAN UE UTRAN CN USIM ME Node B Node B RNC Node B Node B RNC MSC/ VLR GMSC SGSN GGSN HLR UTRAN CNUE ExternalNetworks Cu Uu Iu Iub Iur
- 22. 22 UTRAN UE UTRAN CN Node B Node B RNC Node B Node B RNC Iub Iur UTRAN RNS RNS Two Distinct Elements : Base Stations (Node B) Radio Network Controllers (RNC) 1 RNC and 1+ Node Bs are group together to form a Radio Network Sub-system (RNS) Handles all Radio-Related Functionality Soft Handover Radio Resources Management Algorithms Maximization of the commonalities of the PS and CS data handling UMTS Terrestrial Radio Access Network, Overview
- 23. 23 UTRAN UE UTRAN CN Protocol Model for UTRAN Terrestrial Interfaces Application Protocol Data Stream(s) ALCAP(s) Transport Network Layer Physical Layer Signalling Bearer(s) Transport User Network Plane Control Plane User Plane Transport User Network Plane Transport Network Control Plane Radio Network Layer Signalling Bearer(s) Data Bearer(s) Derivatives : Iur1, Iur2, Iur3, Iur4 Iub Iu CS Iu PS Iu BC Functions of Node B (Base Station) • Air Interface L1 Processing (Channel Coding, Interleaving, Rate Adaptation, Spreading, etc.) • Basic RRM, e.g. Inner Loop Power Control
- 24. 24 UTRAN UE UTRAN CN Node B Node B RNC Logical Roles of the RNC Controlling RNC (CRNC) Responsible for the load and congestion control of its own cells CRNC Node B Node B SRNC Serving RNC (SRNC) Terminates : Iu link of user data, Radio Resource Control Signalling Performs : L2 processing of data to/from the radio interface, RRM operations (Handover, Outer Loop Power Control) Drift RNC (DRNC) Performs : Macrodiversity Combining and splitting Node B Node B DRNC Node B Node B SRNC Node B Node B DRNC UE UE Iu Iu Iu Iu Iur Iur
- 25. 25 Core Network UE UTRAN CN USIM ME Node B Node B RNC Node B Node B RNC MSC/ VLR GMSC SGSN GGSN HLR UTRAN CNUE ExternalNetworks Cu Uu Iu Iub Iur
- 26. 26 Core Network UE UTRAN CN MSC/ VLR GMSC SGSN GGSN HLR CN ExternalNetworks Iu Core Network, Overview Changes From Release ’99 to Release 5 A Seamless Transition from GSM to All-IP 3G Core Network Responsible for Switching and Routing Calls and Data Connections within, and to the External Networks (e.g. PSTN, ISDN and Internet) Divided into CS Network and PS Network
- 27. 27 Core Network UE UTRAN CN MSC/ VLR GMSC SGSN GGSN HLR ExternalNetworks Iu-cs Core Network, Release ‘99 CS Domain : Mobile Switching Centre (MSC) Switching CS transactions Visitor Location Register (VLR) Holds a copy of the visiting user’s service profile, and the precise info of the UE’s location Gateway MSC (GMSC) The switch that connects to external networks PS Domain : Serving GPRS Support Node (SGSN) Similar function as MSC/VLR Gateway GPRS Support Node (GGSN) Similar function as GMSC Register : Home Location Register (HLR) Stores master copies of users service profiles Stores UE location on the level of MSC/VLR/SGSN Iu-ps
- 28. 28 Core Network UE UTRAN CN MGW MGW SGSN GGSN External Networks Iu-cs Core Network, R5 1st Phase of the IP Multimedia Subsystem (IMS) Enable standardized approach for IP based service provision Media Resource Function (MRF) Call Session Control Function (CSCF) Media Gateway Control Function (MGCF) CS Domain : MSC and GMSC Control Function, can control multiple MGW, hence scalable MSG Replaces MSC for the actual switching and routing PS Domain : Very similar to R’99 with some enhancements Iu-ps MSC GMSCIu-cs MRF CSCF HSS MGCF Services & Applications Services & Applications IMS Function
- 29. 29 Summary • System Architecture, Bearer Services, QoS Classes • WCDMA Air Interface : Spread Spectrum, Transport Channels • UTRAN : Roles of RNCs and Node Bs • Core Network : Roles of Different Components of R’99 and R5 USIM ME Node B Node B RNC Node B Node B RNC MSC/ VLR GMSC SGSN GGSN HLR UTRAN CNUE ExternalNetworks Cu Uu Iu Iub Iur
- 30. 30 Radio Resources Management Evolution from 2G to 3G WCDMA / UMTS Architecture Air Interface (WCDMA) Radio Access Network (UTRAN) Core Network Radio Resources Management Admission Control, Load Control, Packet Scheduler Handover Control and Power Control Additional Briefs Radio Network Planning Issues High Speed Data Packet Access WCDMA vs cdma2000
- 31. 31 Radio Resources Management Network Based Functions Admission Control (AC) Handles all new incoming traffic. Check whether new connection can be admitted to the system and generates parameters for it. Load Control (LC) Manages situation when system load exceeds the threshold and some counter measures have to be taken to get system back to a feasible load. Packet Scheduler (PS) Handles all non real time traffic, (packet data users). It decides when a packet transmission is initiated and the bit rate to be used. Connection Based Functions Handover Control (HC) Handles and makes the handover decisions. Controls the active set of Base Stations of MS. Power Control (PC) Maintains radio link quality. Minimize and control the power used in radio interface, thus maximizing the call capacity. Source : Lecture Notes of S-72.238 Wideband CDMA systems, Communications Laboratory, Helsinki University of Technology
- 32. 32 Network Based Functions RT / NRT : Real-time / Non-Real-time RAB : Radio Access Bearer Source : Lecture Notes of S-72.238 Wideband CDMA systems, Communications Laboratory, Helsinki University of Technology
- 33. 33 Connection Based Function Power Control Prevent Excessive Interference and Near-far Effect Open-Loop Power Control Rough estimation of path loss from receiving signal Initial power setting, or when no feedback channel is exist Fast Close-Loop Power Control Feedback loop with 1.5kHz cycle to adjust uplink / downlink power to its minimum Even faster than the speed of Rayleigh fading for moderate mobile speeds Outer Loop Power Control Adjust the target SIR setpoint in base station according to the target BER Commanded by RNC Fast Power Control If SIR < SIRTARGET, send “power up” command to MS Outer Loop Power Control If quality < target, increases SIRTARGET
- 34. 34 Connection Based Function Handover Softer Handover A MS is in the overlapping coverage of 2 sectors of a base station Concurrent communication via 2 air interface channels 2 channels are maximally combined with rake receiver Soft Handover A MS is in the overlapping coverage of 2 different base stations Concurrent communication via 2 air interface channels Downlink: Maximal combining with rake receiver Uplink: Routed to RNC for selection combining, according to a frame reliability indicator by the base station A Kind of Macrodiversity
- 35. 35 Additional Briefs Evolution from 2G to 3G WCDMA / UMTS Architecture Air Interface (WCDMA) Radio Access Network (UTRAN) Core Network Radio Resources Management Admission Control, Load Control, Packet Scheduler Handover Control and Power Control Additional Briefs Radio Network Planning Issues High Speed Data Packet Access WCDMA vs cdma2000
- 36. 36 Radio Network Planning Issues Radio Link Power Budgets Interference margin (loading) + Fast fading margin (power control headroom) + Soft handover gain (macrodiversity) Cell Coverage is obtained Load Factor Estimation of Supported Traffic per Base Station Required SNR, Intracell Interference, Intercell Interference Orthogonality of Channels One of the example: Soft Capacity CDMA has no definite capacity limit Can always “borrow” capacity from other cell or decrease QoS Other Issues Network Sharing Co-planning Inter-operator Interference ( ) ( ) ( ) ( ) ( ) ( ) forward 0 reverse 0 1 Capacity 1 1 1 Capacity 1 1 b b W R p j E N dv s j f g h m W R p j h m E N dv j f g h = + + + + + + = + + − + + +
- 37. 37 HSDPA High Speed Downlink Packet Access Standardized in 3GPP Release 5 Improves System Capacity and User Data Rates in the Downlink Direction to 10Mbps in a 5MHz Channel Adaptive Modulation and Coding (AMC) Replaces Fast Power Control : User farer from Base Station utilizes a coding and modulation that requires lower Bit Energy to Interference Ratio, leading to a lower throughput Replaces Variable Spreading Factor : Use of more robust coding and fast Hybrid Automatic Repeat Request (HARQ, retransmit occurs only between MS and BS) HARQ provides Fast Retransmission with Soft Combining and Incremental Redundancy Soft Combining : Identical Retransmissions Incremental Redundancy : Retransmits Parity Bits only Fast Scheduling Function which is Controlled in the Base Station rather than by the RNC
- 38. 38 WCDMA vs cdma2000 Some of the Major Differences WCDMA cmda2000 Remarks Spread Sprectrum Technique 5Mhz Wideband DS-SS Multicarrier, 3x1.25MHz Narrowband DS-SS, 250kHz Guard Band Multicarrier does not requires a contiguous spectral band. Both scheme can achieve similar performance Chip Rates 3.84Mcps 3.6864Mcps (1.2288 per carrier) Chip Rate alone does not determine system capacity Frame Lengths 10ms 20ms for data, 5ms for control Response and efficiency tradeoff Power Control Rate 1.5kHz 800Hz Higher gives better link performance Base Station Synchronization Asynchronous Synchronized Asynchronous requires not timing reference which is usually hard to acquire. Synchronized operation usually gives better performance Adopted by Telecommunications Industry Association, backward compatible with IS-95, lately moved to 3GPP2 (in contrast to 3GPP for WCDMA) as the CDMA MultiCarrier member of the IMT-2000 family of standard
- 39. 39 Wrap Up and Key References What we have been talked about 2G to 3G Evolution WCDMA Air Interface UTRAN Core Network Radio Resources Management Network Planning Issues High Speed Data Packet Access WCDMA vs cdma2000 Key References WCDMA for UMTS, Radio Access for Third Generation Mobile Communications, 2nd Ed., Edited by Harri Holma and Antti Toskala Overview of UMTS, Guoyou He, Telecommunication Software and Multimedia Laboratory, Helsinki University of Technology Course materials from Course S-72.238 : Wideband CDMA systems, Communications Laboratory, Helsinki University of Technology
Editor's Notes
- #2: What do WCDMA / UMTS means? Wideband CDMA, Universal Mobile Telecommunications System, Standards
- #3: A very compact review of the very detailed standards
- #5: Roadmap of the Evolution of Wireless Network 2G Technologies -&gt; 2.5G -&gt; 3G Provides Intermediate Steps of Transitions Upper: GSM (EDGE: Enhanced Data for GSM Evolution) Lower: CDMA Focus on the Upper Stream -&gt; Introduce WHY WCDMA would be today’s focus
- #6: How can we position / define a 3G Network?
- #7: Let’s take a closer look of how 3G Network is evolved and standardized. Illustrate by connection path. MS -&gt; Access Network -&gt; Core Network -&gt; External Network Only CS Domain NMS: Network Management System BSS: Base Station System NSS: Network Support System
- #8: Later, in so call 2.5G, E-GPRS is introduced, BSS -&gt; Enhanced RAN -&gt; First PS Domain -&gt; Support new external networks connections In 3GPP Release 99, New name: UMTS E-RAN evolved into UTRAN (UMTS Terrestrial Radio Access Network) Upgrade of BTS, BSC to BS and RNC
- #9: After R99, there’s R4 and R5/6 (most updated) Goes all the way to an ALL-IP Network R4: Minor changes to the CS Domain -&gt; Separate control and data switching -&gt; More Scalable (MSC: Mobile Switching Center, MGW: Media Gateway) R5/6: Only PS Domain -&gt; Circuit Routing: Virtual Circuit Switching
- #10: 3G Requires a new Radio/Air Interface 3GPP’s UMTS adopted WCDMA -&gt; Illustrates briefly
- #12: -&gt; Brief network by network, and their Functions -&gt; Introduce the Concepts of Interfaces -&gt; CN : CS / PS Domain -&gt; Illustrates sample data paths (CS and PS) USIM: Universal Subscriber Identity Module VLR: Visitor Location Register HLR: Home Location Register
- #13: Services Point of View Connections is supported by different layers of bearer services. -&gt; All defined by the standard Elaborates some of the services
- #14: Elaborates briefly
- #15: Short conclusion : Architecture, Services, QoS Now, Drill into the detail of the UMTS 3 Item: Air Interface, UTRAN, CN
- #16: What is an Air Interface? What’s the Function? Following Slides -&gt; Principle and Advantage of the wideband technology -&gt; Different physical channels and how they operates
- #17: Introduce Spread Spectrum -&gt; In order to illustrates Multipath and VSF
- #18: Standard… Following slides: FACH, RACH, DCH, CPCH, DSCH Aim -&gt; Illustrates “Random Access, Schedule Access, Dedicated Access”
- #24: Protocol Model Independent Horizontal Layer and Vertical Panes Node B Brief
- #26: Last Part, Core Network
- #27: Following slides: Take 2 example for illustration, R99 and R5
- #29: Point out changes first HSS: Home Subscriber Server (Many Database Functions, e.g. HLR, DNS, Security, Network Access, etc)
- #32: Brief, Brief, Brief…
- #33: Introduces different States Introduces how AC, LC, PS reacts Admission Control (AC) Handles all new incoming traffic. Check whether new connection can be admitted to the system and generates parameters for it. Load Control (LC) Manages situation when system load exceeds the threshold and some counter measures have to be taken to get system back to a feasible load. Packet Scheduler (PS) Handles all non real time traffic, (packet data users). It decides when a packet transmission is initiated and the bit rate to be used.
- #34: Connection based function…
- #36: Additional Briefs: Make the presentation more complete Drive of some further study areas