This publication covers the latest advances in orthogonal frequency division multiplexing (OFDM), the modem of choice for high–profile wireless systems, including DVB–T, WiFi, WiMAX, and Ultra–wideband. The authors explore the technical concepts at the core of broadband air–interface design and implementation, then investigate advanced principles that open the door to significant improvements in network characteristics not realizable under the current wireless infrastructure.
The publication begins with a comprehensive look at OFDM its history, principles, and applications. Next is a discussion of the various types of enabling techniques for OFDM modems (e.g., carrier offset estimation, channel estimation, and phase noise and I/Q imbalance compensation), followed by an in–depth treatment of MIMO and smart antennas and their integration with OFDM. Coverage includes both current design methodologies as well as those proposed for future generation systems, including WiMAX and WiFi. The last three chapters examine MAC functionalities and present system considerations for OFDMA–based cellular networks. The authors address the problem of radio resource management through multiple access control, cross–layer optimization, and frequency planning. Finally, appendices are provided for IEEE 802.11a/g and IEEE 802.16e, offering readers the latest developments in WiFi and WiMAX standards.
Key features include:
- An emphasis on design concepts and algorithms for the air interface of OFDM–based broadband wireless access networks
- Protocols that can capture the full potential of OFDM by jointly optimizing link–level and system–level performance metrics
- Cutting–edge research results and articles that deal with OFDM modem and OFDMA–based multiple–access schemes
With detailed design examples provided throughout, this is an excellent hands–on tool for design engineers and professionals as well as graduate students in the fields of wireless and mobile communications.
1.1 OFDM–based wireless network overview.
1.1.1 Digital broadcasting and DVB–T.
1.1.2 Wireless LAN and IEEE 802.11.
1.1.3 WiMAX and IEEE 802.16.
1.2 The need for "cross–layer" design.
1.3 Organization of this text.
2. OFDM Fundamentals.
2.1 Broadband radio channel characteristics.
2.1.1 Envelope fading.
2.1.2 Time dispersive channel.
2.1.3 Frequency dispersive channel.
2.1.4 Statistical characteristics of broadband channels.
2.2 Canonical form of broadband transmission.
2.3 OFDM realization.
3. PHY Layer Issues – System Imperfections.
3.1 Frequency synchronization.
3.1.1 OFDM carrier offset data mode.
3.1.2 Pilot–based estimation.
3.1.3 Non–pilot based estimation..
3.2 Channel estimation.
3.2.1 Pilots for 2D OFDM channel estimation .
3.2.2 2DMMSE channel estimation.
3.2.3 Reduced complexity channel estimation.
3.3 I/Q imbalance compensation.
3.3.1 I/Q Imbalance Model.
3.3.2 Digital compensation receiver.
3.3.3 Frequency offset estimation with I/Q imbalance.
3.4 Phase noise compensation.
3.4.1 Mathematical models for phase noise.
3.4.2 CPE estimation with channel state information.
3.4.3 Time domain channel estimation in the presence of CPE.
3.4.4 CPE estimation without explicit CSI.
4. PHY Layer Issues – Spatial Processing.
4.1 Antenna array fundamentals.
4.2 Beam forming.
4.2.1 Coherent combining.
4.2.3 MMSE reception (optimum linear receiver).
4.2.5 Broadband beam forming.
4.3 MIMO channels and capacity.
4.4 Space–time coding.
4.4.1 Spatial multiplexing.
4.4.2 Orthogonal space–time block coding.
4.4.3 Concatenated ST transmitter.
4.4.4 Beam forming with ST coding.
4.4.5 ST beam forming in OFDM.
4.5 Wide–area MIMO beam forming.
4.5.1 Data model.
4.5.2 Uncoded OFDM design criterion.
4.5.3 Coded OFDM design criterion.
4.7 Appendix I: Derivation of Pe.
4.8 Appendix II: Proof of Proposition 5.
4.9 Appendix III: Proof of Proposition 6.
5. Multiple Access Control Protocols.
5.2 Basic MAC protocols.
5.2.1 Contention based protocols.
5.2.2 Non–contention based MAC protocols.
5.3 OFDMA advantages.
5.4 Multiuser diversity.
5.5 OFDMA optimality.
5.5.1 Multiuser multicarrier SISO systems.
5.5.2 Multiuser multicarrierMIMO systems.
5.7 Appendix I: Cn(p) is a convex function in OFDMA/SISO case.
5.8 Appendix II: C(p) is a convex function in OFDMA/MIMO case.
6. OFDMA Design Considerations.
6.1 Cross layer design introduction.
6.2 Mobility–dependent OFDMA traffic channels.
6.2.1 OFDMA traffic channel.
6.2.2 System model.
6.2.3 Channel configuration for fixed/portable applications.
6.2.4 Channel configuration for mobile application.
6.3 IEEE 802.16e traffic channels.
7. Frequency Planning in Multi–cell Networks.
7.1.1 Fixed channel allocation.
7.1.2 Dynamic channel allocation.
7.2 OFDMA DCA.
7.2.1 Protocol design.
7.2.2 Problem formulation for the RNC.
7.2.3 Problem formulation for BSs.
7.2.4 Fast algorithm for the RNC.
7.2.5 Fast algorithm for BSs.
7.3 Spectrum efficiency under different cell/sector configurations.
7.3.1 System configuration and signaling overhead.
7.3.2 Channel loading gains.
8.1 IEEE 802.11 and WiFi.
8.1.1 802.11 overview.
8.1.2 802.11 network architecture.
8.1.3 The MAC layer technologies.
8.1.4 The physical layer technologies.
8.2 IEEE 802.16e and Mobile WiMAX.
8.2.2 The physical layer technologies.
8.2.3 The MAC layer technologies.
8.3 Performance analysis of WiMAX systems.
8.3.1 WiMAX OFDMA–TDD.
8.3.2 Comparison Method.
Notations and Acronym.
About the Authors.
GUOQING LI, PhD, is a Research Scientist in the Communication Technology Lab of Intel, where she works on broadband wireless technologies. Previously, Dr. Li worked as a senior system engineer at UTStarcom, developing algorithms for physical, multiple access control, radio link control, and radio resource control layers for 3G–WCDMA and IS–95 networks. Dr. Li has published more than twenty journal articles and conference papers.