Signals and Communication Technology For furthervolumes: http://www.springer.com/series/4748 Yifei Yuan LTE-Advanced Relay Technology and Standardization 123 Yifei Yuan Standards Department ZTEInc. Beijing People’s Republic ofChina ISSN 1860-4862 ISBN 978-3-642-29675-8 ISBN 978-3-642-29676-5 (eBook) DOI 10.1007/978-3-642-29676-5 SpringerHeidelbergNewYorkDordrechtLondon LibraryofCongressControlNumber:2012938204 (cid:2)Springer-VerlagBerlinHeidelberg2013 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purposeofbeingenteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthe work. Duplication of this publication or parts thereof is permitted only under the provisions of theCopyrightLawofthePublisher’slocation,initscurrentversion,andpermissionforusemustalways beobtainedfromSpringer.PermissionsforusemaybeobtainedthroughRightsLinkattheCopyright ClearanceCenter.ViolationsareliabletoprosecutionundertherespectiveCopyrightLaw. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. While the advice and information in this book are believed to be true and accurate at the date of publication,neithertheauthorsnortheeditorsnorthepublishercanacceptanylegalresponsibilityfor anyerrorsoromissionsthatmaybemade.Thepublishermakesnowarranty,expressorimplied,with respecttothematerialcontainedherein. Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface Why I Wrote this Book LTE-Advanced becomes a truly global standard for 4G cellular communications. Relay, as one of the key technologies of LTE-Advanced, can significantly extend the coverage, and improve the system throughput. LTE-A standards and tech- nologiesweredescribedinseveral recent bookswhere the limitedpages for relay feature prevent the detailed explanations of the technology. Inthis book, we tried toprovideanin-depthdescriptionofLTE-Arelaydevelopment.Morespecifically, significantportionsarespentonrelaychannelmodelingandpotentialtechnologies during the study item phase of the development, although some of those tech- nologies,suchasType2cooperativerelay,multi-hoprelay,relaywithbackhaulof carrier aggregation, were not standardized in Release 10 LTE. The purpose of those discussions was to offer some insights of relay research in future LTE releases. For Type 1 relay which was standardized in Release 10, our focus is to describe the design principles and rationales of key features, rather than literally explaining the specifications. By doing so, we hope that readers can get the intuitions of major candidate techniques for Release 10 relay, regardless of whe- ther they were adopted in the specifications. Besidesthestandardizationofrelay,someimplementationaspectsofrelaywere also discussed with the aim to provide a high-level view on how to build a relay node and deploy the relay systems. Structure of this Book Thearrangementofthechaptersfollowsnaturallythestandardizationprocessand implementationsteps.Itstartswiththeapplicationscenarioandchannelmodeling, followed by the open study on technology and system performance evaluations, v vi Preface then narrowed down to a short list of techniques that would ultimately be standardized,beginningfromphysicallayer,thenupperlayerworkinggroups,and then in performance working groups. Once the performance requirements are set, theimplementationaspectscomenext.Intheend,weprovidetheoutlookoffuture relay study. • Chapter 1: Introduction • Chapter 2: LTE-A Relay Scenarios and Evaluation Methodology • Chapter 3: LTE-A Relay Study and Related Technologies • Chapter 4: Physical Layer Standardization of Release 10 Relay • Chapter 5: Higher Layer Aspects and RAN4 Performance Aspects • Chapter 6: Implementation Aspects of Release 10 Relay • Chapter 7: Outlook of Relay in Future LTE Releases How to Use this Book This book is written for researchers and engineers working on wireless commu- nications, in particular, in the field of 3G and 4G cellular communications. Chapters 2 and 3 target for researchers with broader interest in relay and related technologies. Chapters 4–6 would be more useful for engineers specialized in designingandimplementingthe relay systems. Thediscussions inChaps. 1and7 are more general and suitable for both researchers and engineers. Acknowledgments TheauthorfirstwouldliketothanktherelayphysicallayerteamatZTEfortheir contributions to relay study and specifications in 3GPP RAN1. The team, led by Feng Bi, includes Feng Liang, Shuanshuan Wu, Ming Yuan, Jin Yang, Yunfeng Li, and Xumin Yu. Their original research constitutes a significant portion of this book. The author also thanks his RAN2/3 colleagues, Mary Chion and Si Chen, and RAN4colleagueYiqingCaoatZTE,fortheirhelponsomeofthechaptersinthis book. RelaydiscussionsinthisbookalsotouchotherkeyLTE-Atechnologiessuchas downlink reference signals, carrier aggregation, heterogeneous networks, etc. HegreatlyappreciatesthevaluablesuggestionsbyhisRAN1colleaguesRuyueLi, Wenfeng Zhang, Shupeng Li, Huaming Wu, Zhisong Zuo, Junfeng Zhang in the corresponding sections. Input from ZTE’s product teams is quite appreciated with regard to the implementation aspects of relay. Finally, the author thanks Professor Hequan Wu, the former vice president of theChineseAcademyofEngineering,forhisencouragementinwritingthisbook. vii Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 LTE-A Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 LTE-A Relay Standardization. . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 IEEE Relay Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 Book Objectives and Outline . . . . . . . . . . . . . . . . . . . . . . . . . 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 LTE-A Relay Scenarios and Evaluation Methodology . . . . . . . . . . 9 2.1 Relay Scenarios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.1 Rural Area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.2 Urban Hot Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.1.3 Dead Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1.4 Indoor Hot Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.1.5 Group Mobility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.1.6 Emergency or Temporary Network Deployment. . . . . . . 17 2.1.7 Wireless Backhaul Only. . . . . . . . . . . . . . . . . . . . . . . . 17 2.2 Channel Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.2.1 Large Scale Fading Modeling for RN–UE Connection. . . . . . . . . . . . . . . . . . . . . . . . 20 2.2.2 LOS Probability of RN–UE Connection. . . . . . . . . . . . . 22 2.2.3 Large Scale Fading Modeling for eNB–RN Connection . . . . . . . . . . . . . . . . . . . . . . . 24 2.2.4 LOS Probability eNB–RN Connection. . . . . . . . . . . . . . 26 2.3 Impacts of Relay Site Planning. . . . . . . . . . . . . . . . . . . . . . . . 28 2.3.1 Less Attenuation from Donor eNB . . . . . . . . . . . . . . . . 28 2.3.2 Improvement of LOS Probability in Donor eNB–RN Connection. . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.4 Large Scale Fading Parameters. . . . . . . . . . . . . . . . . . . . . . . . 33 2.5 Small Scale Fading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.6 Other Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 ix x Contents 3 LTE-A Relay Study and Related Technologies . . . . . . . . . . . . . . . 39 3.1 Relay Categorization Based on Protocol Architecture . . . . . . . . 39 3.1.1 L1 Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.1.2 L2 Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.1.3 L3 Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.2 Operating Band. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 3.2.1 Brief Description of LTE-A Carrier Aggregation . . . . . . 44 3.2.2 Relay with Carrier Aggregation . . . . . . . . . . . . . . . . . . 46 3.3 Number of Hops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.4 Type 1 Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.4.1 Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 3.4.2 Technology Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.4.3 Semi-Analytical Evaluations. . . . . . . . . . . . . . . . . . . . . 57 3.4.4 Downlink Performance Evaluation with Uniformly Distributed Relay Nodes . . . . . . . . . . . . . . . . . . . . . . . 59 3.4.5 Downlink Performance Evaluation with Relay Nodes Placed Near Cell Edges. . . . . . . . . . . . . . . . . . . 63 3.4.6 Uplink Performance Evaluation with Relay Nodes Placed Near Cell Edges. . . . . . . . . . . . . . . . . . . 67 3.5 Type 2 Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 3.5.1 Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 3.5.2 Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 3.5.3 Performance Evaluations . . . . . . . . . . . . . . . . . . . . . . . 82 3.6 Other Related Technologies in LTE-Advanced . . . . . . . . . . . . . 86 3.6.1 Downlink Reference Signals. . . . . . . . . . . . . . . . . . . . . 86 3.6.2 Enhanced ICIC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 3.6.3 CoMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 4 Physical Layer Standardization of Release 10 Relay . . . . . . . . . . . 91 4.1 Scenario. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 4.2 Physical Layer Control Channel Specification. . . . . . . . . . . . . . 92 4.2.1 Relay Downlink Frame Timing. . . . . . . . . . . . . . . . . . . 94 4.2.2 Configuration of Start Symbol of R-PDCCH and PDSCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 4.2.3 Relay Uplink Frame Timing. . . . . . . . . . . . . . . . . . . . . 97 4.2.4 Relay Node Synchronization . . . . . . . . . . . . . . . . . . . . 100 4.2.5 R-PDCCH Multiplexing. . . . . . . . . . . . . . . . . . . . . . . . 103 4.2.6 Reference Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 4.2.7 Cross-Interleaved and Non Cross-Interleave R-PDCCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 4.2.8 PUCCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Contents xi 4.3 Backhaul Subframe Configuration and HARQ Timing. . . . . . . . 120 4.3.1 FDD systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.3.2 TDD Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 5 Higher Layer Aspects and RAN4 Performance Aspects. . . . . . . . . 135 5.1 Relay Architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 5.2 C-Plane Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 5.3 U-Plane Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 5.4 S1/X2 Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 5.5 Release 10 Relay Performance Aspects . . . . . . . . . . . . . . . . . . 143 5.5.1 RF Requirements in General . . . . . . . . . . . . . . . . . . . . 144 5.5.2 RF Requirements for Backhaul Link. . . . . . . . . . . . . . . 145 5.5.3 RF Requirements for Access Link. . . . . . . . . . . . . . . . . 146 5.5.4 Baseband Requirements. . . . . . . . . . . . . . . . . . . . . . . . 146 5.5.5 Synchronization Requirements . . . . . . . . . . . . . . . . . . . 148 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 6 Implementation Aspects of Release 10 Relay. . . . . . . . . . . . . . . . . 149 6.1 General Consideration of PHY Layer Implementation . . . . . . . . 149 6.2 Baseband Realization of Relay Node. . . . . . . . . . . . . . . . . . . . 150 6.2.1 Channel Characteristics of Backhaul and Access Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 6.2.2 Common Reference Signal Demodulation . . . . . . . . . . . 153 6.2.3 DL DMRS Demodulation . . . . . . . . . . . . . . . . . . . . . . 154 6.2.4 Search Space for R-PDCCH Without Cross-Interleaving. . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 6.2.5 Choice for Relay Timing. . . . . . . . . . . . . . . . . . . . . . . 156 6.3 Radio Modules and Antennas of Relay Node . . . . . . . . . . . . . . 157 6.3.1 Power Amplifier and Filters. . . . . . . . . . . . . . . . . . . . . 157 6.3.2 Clock Synchronization. . . . . . . . . . . . . . . . . . . . . . . . . 158 6.3.3 Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 6.4 Relay Node Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 6.4.1 Deployment Scenarios. . . . . . . . . . . . . . . . . . . . . . . . . 160 6.4.2 Relay Frame Timing. . . . . . . . . . . . . . . . . . . . . . . . . . 160 6.4.3 Access Link HARQ. . . . . . . . . . . . . . . . . . . . . . . . . . . 161 6.4.4 Uplink Power Control for UEs in RN Cell. . . . . . . . . . . 162 6.4.5 Data Buffering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 6.5 Baseband Implementations in Donor eNB . . . . . . . . . . . . . . . . 163 6.6 Scheduler at Donor eNB . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 6.6.1 Resource Allocations for R-PDCCH . . . . . . . . . . . . . . . 164 6.6.2 Transport Block Size Determination and MCS Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . 166 6.6.3 Configurations of CSI Feedback and SRS . . . . . . . . . . . 168 xii Contents 6.6.4 Resource Scheduling for PDSCH . . . . . . . . . . . . . . . . . 169 6.6.5 Open Loop Uplink Power Control for RNs . . . . . . . . . . 171 6.7 Relay Network Planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 6.7.1 Number of RNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 6.7.2 RN-to-RN Interference . . . . . . . . . . . . . . . . . . . . . . . . 172 6.7.3 Cell Range Expansion and ABS Configuration. . . . . . . . 173 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 7 Outlook of Relay in Future LTE Releases. . . . . . . . . . . . . . . . . . . 177 7.1 Some Trends in Mobile Communications. . . . . . . . . . . . . . . . . 177 7.1.1 Trends at Terminal Side . . . . . . . . . . . . . . . . . . . . . . . 177 7.2 Cooperative Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 7.3 Relay Backhaul for High Speed Mobility. . . . . . . . . . . . . . . . . 183 7.4 Cooperative Mobile Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 7.5 Local Server. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185