IEEE 802 Wireless Systems

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2 IEEE 802 Wireless Systems

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4 IEEE 802 Wireless Systems Protocols, Multi-hop Mesh/Relaying, Performance and Spectrum Coexistence Bernhard H. Walke ComNets, RWTH Aachen University, Germany Stefan Mangold Swisscom Innovations, Switzerland Lars Berlemann ComNets, RWTH Aachen University, Germany

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6 Contents Preface xvii 1 Introduction 1 Bernhard H. Walke, Guido Hiertz and Lars Berlemann 1.1 Standardization Next-generation Systems The IEEE 802 Project Motivation and Outline 5 2 Wireless Communication Basics 7 Bernhard H. Walke, Lars Berlemann, Guido Hiertz, Christian Hoymann, Ingo Forkel and Stefan Mangold 2.1 Radio Transmission Fundamentals Free-space Propagation Two-path Propagation Over Flat Terrain Attenuation Fading Shadowing Filtering and Transmit Spectrum Masks Propagation Models One-slope Model Hata Okumura Model Walfish Ikegami Model Dual-slope Model Berg Model Signal-to-Interference Ratio (SIR) Noise An Additional Source of Interference Signal to Interference and Noise Ratio (SINR) Interference Range Digital Modulation Modulation and Coding of Radio Signals 20

7 vi Contents 2.2 Duplexing Schemes Time Division Duplex Frequency Division Duplex Multiplexing Frequency Division Multiplex Time Division Multiplex Code Division Multiplex Space Division Multiplex Orthogonal Frequency Division Multiplex Pilot Tones and Preambles Fast Fourier Transformation (FFT) Cyclic Prefix Switching in Communication Networks Circuit Switching Packet Switching Channel Coding for Error Correction and Error Detection Forward Error Correction Automatic Repeat Request Protocols Send-and-Wait Go-back-N Selective-Reject Summary Hybrid Automatic Repeat Request Medium Access Control (MAC) Protocols ALOHA Pure ALOHA Slotted ALOHA Comparison of Pure and Slotted ALOHA Carrier Sense Multiple Access CSMA Variants CSMA/CD CSMA/CA Polling Summary 41 3 Radio Spectrum Regulation 43 Lars Berlemann and Bernhard H. Walke 3.1 Regulation Bodies and Global Institutions International Telecommunication Union Europe Germany Japan China United States Licensed and Unlicensed Spectrum Licensed Spectrum The Problem with Licensing 47

8 Contents vii Unlicensed Spectrum Europe United States Part 15 Regulation Tragedy of the Commons in Spectrum Regulation Open Spectrum Summary 52 4 Mesh Networks Basics 53 Guido Hiertz, Erik Weiss and Bernhard H. Walke 4.1 Introduction Classification of Wireless Mesh Networks General Problem Statement Path Selection Medium Access Control Exploiting the Capacity of the Radio Channel by Spatial Reuse Hidden Devices Potential Interferers Exposed Devices Unused Capacity Fairness and Congestion Avoidance Routing Routing Algorithms Ad-hoc On-demand Distance Vector Routing (AODV) Route Discovery Route Maintenance Local Repair Common Link Layer Behavior (Link Adaptation) Link Breakage Prediction Actions for Expected Link Break Early Route Rearrangement (ERRA) Early Route Update (ERU) Simulation Results Conclusions Summary 75 5 IEEE Wireless Local Area Networks 77 Stefan Mangold, Lars Berlemann, Matthias Siebert and Bernhard H. Walke 5.1 Scope of Reference Model, Architecture, Services, Frame Formats Reference Model Architecture Services Frame Formats Physical Layer Frequency Hopping, Direct Sequence Spread Spectrum, and Infrared B Complementary Code Keying, CCK A/G Orthogonal Frequency Division Multiplexing 83

9 viii Contents 5.4 Medium Access Control Protocol Distributed Coordination Function Listen Before Talk Timing and Interframe Spaces Collision Avoidance Recovery Procedure and Retransmissions Post-backoff Fragmentation Hidden Stations and RTS/CTS Synchronization and Cell Search Scanning Procedures in WLAN Passive Scanning Active Scanning Medium Access Control with Support for Quality-of-Service Point Coordination Function QoS Support with PCF QoS Support Mechanisms of E Improvements of the Legacy MAC Contention-based Medium Access EDCA Parameters Per AC Evaluation of Contention-based Medium Access Related Work EDCA throughput Capacity in an Isolated QBSS with Four Stations EDCA throughput with Increasing Number of Stations Controlled Medium Access QoS Guarantee with HCCA vs. EDCA The Superframe Block Acknowledgment Direct Link Protocol (DLP) Radio Spectrum Management Measurements in Information Transfer Specific Measurements in h Basic Report Clear Channel Assessment (CCA) Report Receive Power Indication (RPI) Histogram Report Specific Measurements in K Channel Load Report Noise Histogram Report Beacon Report Frame Report Hidden Station Report Medium Sensing Time Histogram Report STA Statistics Report LCI Report Measurement Pause Request 115

10 Contents ix 5.7 History and Selected Sub-standards, i.e., Amendments IEEE IEEE a IEEE b IEEE c IEEE d IEEE e IEEE f IEEE g IEEE h IEEE i IEEE k IEEE Wireless Personal Area Networks 119 Guido Hiertz, Yunpeng Zang and Bernhard H. Walke 6.1 Scope of Objectives Different Subgroups High-speed Wireless Personal Area Networks Task Group Medium Access Control Network Topology Medium Access Control Contention Access Period (CAP) Channel Time Allocation Period (CTAP) Data Transmission Network Security and Robustness Power Management Physical Layer Task Group 3a DS-UWB Proposal MB-OFDM Proposal Task Group 3b Task Group 3c WiMedia (Multiband OFDM) Alliance MAC Layer Overview Next Generation WPAN WiMedia MAC Medium Access Prioritized Contention Access Distributed Reservation Protocol Transmission Opportunities Acknowledgement Policies Minimum Interframe Space and Frame Aggregation Fragmentation and RTS/CTS Handshake Beacon Period and Beacon Frames Simulative Performance Analysis Conclusion 145

11 x Contents 6.8 Next-generation WPAN Technologies Market Perspective PHY Technology MAC Design IEEE Wireless Metropolitan Area Networks 147 Christian Hoymann and Bernhard H. Walke 7.1 Scope of Deployment Concept, Reference Model and Target Frequency Bands Deployment Concept Reference Model Target Frequency Bands History and Different Subgroups History IEEE Base Document IEEE /Conformance IEEE Coexistence IEEE e Mobility IEEE f/g/i Network Management IEEE h License Exempt IEEE j Mobile Multi-hop Relay Study Group ETSI BRAN HiperACCESS and HiperMAN WiMAX Forum Wireless Broadband (WiBro) Physical Layer Orthogonal Frequency Division Multiplexing in Randomizer Forward Error Correction Interleaving Medium Access Control Layer Service-Specific Convergence Sublayer Packet Convergence Sublayer ATM Convergence Sublayer MAC Common Part Sublayer Duplex Modes Frame Structure Frame Control Packet Data Unit Format Fragmentation and Packing Automatic Repeat Request Connection Identifier Network Entry Connection Management Bandwidth Requests and Uplink Scheduling Services Security Sublayer System Profiles MAC Profiles Physical Layer Profiles RF Profiles, Duplexing Modes and Power Classes 174

12 Contents xi 7.7 Space Division Multiple Access PHY Layer Comprising an Antenna Array Enhanced PHY Service Access Point SDMA Enhanced Medium Access Control Layer SDMA Scheduling Performance Evaluation of Multi-user Multi Phy Mode Scenario PHY Layer Configuration and PHY Mode Distribution MAC Layer Configuration and Performance Metric Performance Analysis System Performance of the Example Scenario Simulative Performance Evaluation IEEE Simulator Simulation Results Performance of SDMA Enabled Networks Scenario and Simulation Environment Downlink Cell Throughput Signal to Interference Plus Noise Ratio Conclusion IEEE , and for Mesh Networks 197 Guido Hiertz, Lars Berlemann, Harianto Wijaya, Christian Hoymann, Stefan Mangold and Bernhard H. Walke 8.1 Approaches to Wireless Mesh Networks in IEEE and Industry Differences between Mesh WPAN, WLAN and WMAN Mesh WLAN s Summary Mesh WPAN Status of Standardization in TG Mesh WMAN Mesh Option j Extensions to IEEE 802 MAC Protocols Homogeneous Multi-hop Networks IEEE Multi-hop Networks Multi-hop Operation in the Time and Frequency Domain MAC Subframe Embedding Hierarchical Beacon with Fixed Slot Allocation Time Sharing Wireless Router Time Sharing Wireless Router with Spatial Reuse IEEE e Multi-hop Networks Collision Avoidance through Channel Reservation Collision Avoidance by Channel Reservation with Spatial Reuse Performance Evaluation Results Scenario Description Mean Delay vs. Offered Traffic System Capacity vs. Distance between BS/HC and FRS Summary 223

13 xii Contents 8.3 Extensions to IEEE 802 MAC Protocols for Heterogeneous Multi-hop Networks Overview Medium Access Control in Heterogeneous Mesh Networks Mesh Network to Serve Stations Mesh Network to Serve Stations New Mesh Network Protocol to Connect BSs Interworking Control of and Scenario Medium Access Control BSHC and Legacy Stations Performance Evaluation Results Summary Conclusion Coexistence in IEEE 802 Networks 237 Lars Berlemann, Stefan Mangold and Bernhard H. Walke 9.1 Homogeneous Coexistence Spectrum Sharing e Networks Coexistence Scenario Overview Single Stage Game Quality-of-Service as Utility Utility under Competition Behaviors in Single Stage Games Cooperation through Predictable Behavior Classification of the Opponent s Behavior Equilibrium Analysis of Single Stage Game Multi Stage Game Strategies in Multi Stage Games Static Strategies Dynamic (Trigger) Strategies Grim and TitForTat RANDOM Strategy QoS Support in Multi Stage Games of Competing WLANs Coexistence Among Systems Heterogeneous Coexistence Unlicensed Operation of Coexistence Scenario Protecting the Beginning of MAC Frame Protecting the UL Subframe Shifting the Contention Slots Summary and Conclusion Broadband Cellular Multi-hop Networks 255 Bernhard H. Walke, Ralf Pabst and Daniel C. Schultz 10.1 Definitions Rationale Related Work 258

14 Contents xiii 10.4 Relay-based Deployment Concept for Cellular Broadband Networks Relaying Use Cases Relay to Increase Coverage Range Relay to Increase Cell Capacity Relay to Cover Locations Heavily Shadowed from Access Point Exploiting Spatial Separation of Subcells in REC Estimation of Subcell Capacity in a Relay Enhanced Cell Multi-hop throughput in Cellular Deployment Subcell Capacity served by an FRS Capacity of Multi-hop Links under Delay Constraint Conclusions Mutual Integration and Cooperation of Radio Access Networks 269 Matthias Siebert and Bernhard H. Walke 11.1 State-of-the-Art Overview ETSI BRAN/3GPP IEEE IEEE u: Interworking with External Networks Media Independent Handoff Working Group IETF ITU-T WWRF Mobility and Handover General Aspects of Mobility Handover Aspects Definition Reasons for Handover Types of Handover Handover Control Layer 2 Handover Higher Layer Handover Horizontal and Vertical Handover Trigger Definition and Classification Decision Criteria Future Mesh Technologies 289 Rui Zhao, Ole Klein, Bernhard H. Walke and Lars Berlemann 12.1 Facts on Medium Access Control State of the Art in Medium Access Control Protocols A Taxonomy HiperLAN 2 (H/2) DECT GPRS Potentials and Limitations of the State-of-the-art MAC Protocols Reservation per Packet TDMA in the Short TDMA in the Long 296

15 xiv Contents Key Methods for QoS Supporting Medium Access Control Protocols Single-hop Links Multi-hop Links Mesh Networking for WLAN Mesh Distributed Coordination Function TDMA Frame and Energy Signals Prioritized Channel Access Link Setup and Traffic Channel Reservation Transmission and On-demand-TCH Turnaround Packet Multiplexing and Multi-hop Operation Coexistence Performance Evaluation Results Simulation Tool Simulation Results QoS Performance in Mesh Networks Conclusion Cognitive Radio and Spectrum Sharing 311 Lars Berlemann, Stefan Mangold and Bernhard H. Walke 13.1 From Software-defined Radio to Cognitive Radio Software-defined Radio and Software Radio Composite Radio and Reconfigurable Radio Cognitive Radio Cognitive Radio Networks Essential Characteristics Spectrum Information Base Similar Approaches and Related Work Spectrum Sharing and Flexible Spectrum Access Spectrum Trading Underlay and Overlay Spectrum Sharing Opportunistic Spectrum Usage IEEE k Vertical and Horizontal Spectrum Sharing Coexistence, Coordination and Cooperation Coexistence-based Spectrum Sharing Dynamic Frequency Selection Transmit Power Control Ultra-wide Band IEEE IEEE h IEEE Coordination-based Horizontal Spectrum Sharing Common Spectrum Coordination Channel Dynamic Spectrum Allocation Brokerage-based Spectrum Sharing Inter-operator Spectrum Sharing IEEE y Spectrum Sharing Games 328

16 Contents xv 13.6 Coordination-based Vertical Spectrum Sharing Common Control Channel IEEE Spectrum Pooling Value Orientation Spectrum Load Smoothing Policies and Etiquette in Spectrum Usage Policy Framework Spectrum Navigation Reasoning-based Spectrum Navigation Reasoning Knowledge Representation Traceability of Decision Making Policy-defined Medium Access Control Summary and Conclusion Conclusions 337 Bernhard H. Walke, Lars Berlemann and Stefan Mangold Abbreviations 345 References 355 Index 375

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18 Preface In the mid-1990s cellular mobile radio was the only means for public wireless access on a large scale, apart from some company-specific solutions used to a very limited extent in niche markets. Since the late 1980s, researchers and developers started investigations on developing broadband wireless Internet access technology for personal computers (PCs), mainly driven at that time by Apple Corporation, taking the European Telecommunication Standards Institute (ETSI) as a platform. The first standard appeared in 1993 (ETSI, 1993) and the final version in 1995 (ETSI, 1995) specified a Wireless Local Area Network (WLAN), nowadays called HiperLAN 1, see also Walke (2001). This WLAN system was the first standard to provide a completely distributed control, able even to support differentiation of services of stations competing for the medium access. But it failed to reach market acceptance owing to its high complexity resulting from a channel bandwidth at 5 GHz of about 20 MHz using single-carrier GMSK modulation. It was not the time for such a highly sophisticated system. Overlapping this European activity, an initiative started in the US towards WLAN standardization in IEEE , aiming at broadband transmission in the 2 GHz band with a bit rate of 1 Mbit/s on a 1 MHz channel bandwidth (IEEE, 1997). Both standards were designed with an IEEE or ISO 8802 compatible interface, suitable as a replacement for a Local Area Network (LAN). In those days, Asynchronous Transfer Mode (ATM) had been introduced to wired (fiberbased) telecommunication networks and it was quite natural to think of a wireless extension of ATM. Accordingly, ETSI Broadband Radio Access Networks (BRAN) published its design of HiperLAN Type 2 (H/2) in 1997 (ETSI, 1997). At that time, IEEE had already progressed. The final HiperLAN2 standards was completed in 2000 (ETSI, 2000). Although H/2 with its OFDM-based 20 MHz wide channels, operating in the 5 GHz band had a much better throughput and delay performance than the WLAN specified in IEEE (with its then 2 Mbit/s throughput capacity), the made it to the market, owing to its simplicity and cost efficiency. From about 2002 on, wireless access, as well as cellular mobile access which in those days was mainly for voice communications, became widely accepted, and laptops started to have inbuilt WLAN access from 2003/4 onwards. Meanwhile, IEEE has greatly improved its performance and also covers operation in the 5 GHz band, using OFDM technology standardized earlier at ETSI BRAN for H/2. This technology has also been transferred to the 2.4 GHz band, where the first systems started operation and still operate as a majority. Today it is true that IEEE standardized WLAN technology has reached worldwide acceptance for wireless short-range Internet access, and similar to what the GSM (Global System for

19 xviii Preface Mobile Communications), GPRS (General Packet Radio Service) ETSI-Standards have reached for wide-range mobile Internet access. The interworking of these standard systems (besides others) is currently being standardized at IEEE The success of IEEE WLAN standards has also motivated initiatives to establish standards for Personal Area Networks (PANs) and Metropolitan Area Networks (MANs). And it is quite natural to also think of solutions on how to interwork these systems, not only on the network layer but also when operating on the same radio channel. Interworking of radio systems following different standards and coexistence of radio systems are big research themes today. The hype for an ever-increasing bit rate capacity supported by XAN standardized systems has also motivated researchers and developers to consider multi-hop communication-based solutions to extend the radio range of a Radio Access Point (RAP) beyond the range that can be covered using the transmit power permitted by the regulator. A Mesh network is the key research theme applied to improve the range of coverage and reliability of wireless technologies for private and public access. This book explores all these themes and related systems and proposals. Since the early 1990s, my research group at RWTH Aachen University, Communication Networks (ComNets) have specialized in the development of services and protocols for private and public mobile radio systems. It has produced an extensive set of tools for software design, modeling and stochastic simulation of wireless and mobile radio systems. By means of these tools, the mobile radio and wireless systems now being used worldwide or under discussion, or in the process of being introduced, and described in this book, have been reproduced in a highly accurate form as large simulation program packages. These tools allow us to study the existing or forthcoming systems in their natural environments with the appropriate radio coverage and channel characteristics modeling, representing mobility and typical traffic volumes of the users, and, based on this, to test our own approaches to the improvements and introduction of new services and protocols. The proposals by ComNets and the results of our work have substantially influenced the standardization of systems such as ETSI-GSM/GPRS, ETSI H/2, IEEE e/s, , and others, especially multi-hop Mesh networks and system coexistence. This book has its focus on existent and forthcoming IEEE 802 wireless systems, including presentation of traffic performance. It would not have been possible to present a description of the systems with the desired degree of detail without having implemented the services and protocols of all of these systems in realistic models for stochastic, event-driven simulation. The text and many of the figures in this book are based on the input of many Diploma and Master students at ComNets whose names it would not be possible to mention individually. All I can do is convey my gratitude to all of them for their enthusiasm and for the thoroughness of their work in this collaboration. Their contribution was in modeling and implementing as software the different systems and their modifications for performance evaluation, and their input has helped my research assistants and myself to develop a deep understanding of the characteristics of the systems considered. The individual chapters of the book have been written in close cooperation with the research assistants responsible for the respective system models and they have been named. The chapters reflect the results of extensive research and development and in many cases incorporate material from PhD theses performed at ComNets. I would like to take this opportunity to give my warmest thanks to those involved for the thoroughness of their contributions on the respective topics, for their assistance in dealing with the relevant Diploma/Master s theses that they have supervised and for their role in creating such an excellent working atmosphere. I should particularly like to mention Stefan Mangold, who proposed writing this book and provided the nucleus of IEEE work in Chapter 5 around which the book crystallized by integrating existing work based

20 Preface xix on other PhD theses performed at ComNets. It turned out that Stefan was not able to take responsibility for establishing the book and Lars Berlemann stepped in to take the load of editing and harmonizing large parts of the book, in close cooperation with myself. Without his devotion, this book would never have come together. Contributions to individual sections of the book have been made by the following members of the ComNets research group: Lars Berlemann (PhD), Chapters 1, 2, 3, 5, 8, 12 and 13 Ingo Forkel (PhD), Chapter 2 Guido Hiertz, Chapters 1, 2, 4 and 6 Christian Hoymann (PhD), Chapters 2, 7 and 8 Ole Klein, Chapter 12 Stefan Mangold (PhD), Chapters 2, 5, 8 and 13 Ralf Pabst, Chapter 10 Daniel Schultz, Chapter 10 Matthias Siebert (PhD), Chapters 5 and 11 Erik Weiss, Chapter 4 Harianto Wijaya (PhD), Chapter 8 Yunpeng Zhang, Chapter 6 Rui Zhao, Chapter 12 May this book prove useful to you! Bernhard H. Walke Stefan Mangold Lars Berlemann Aachen