Radio Resource Management for Wireless Networks

From the Book: The development in the field of wireless communications has been nothing short of astonishing in the past decades. We now are witnessing the transition between the mobile telephone era and the era of wireless computing. With the breakthrough advances of digital signal processing high data rate, many of the technical problems associated with the adverse and changing propagation conditions in mobile radio communication have been solved. Multimegabit data rates to portable mobile terminals are no longer science fiction, but reality. As the engineer seems to have the upper hand in this struggle against nature, very much of the development efforts are concentrated on the social struggle for scarce resources, such as the frequency spectrum and terminal battery power. The question is not only if we, as engineers, can provide wideband wireless communication everywhere, but rather, if we can afford it. These issues, the Radio Resource Management (RRM) problem are addressed in this book. Chapter 1 provides a brief introduction to the problems in resource management and an historical outlook over the field and its relations to adjacent disciplines. In Chapter 2, a refresher of multi-user communication theory is given. Readers with a solid background in this area may omit the first section of this chapter. The last section of Chapter 2 introduces the analysis model used throughout the book. In Chapter 3, the radio resource management problem is defined in a more stringent way. Chapter 4 is probably the core chapter of the book where static resource management and cellular system design is introduced and the RUNE tool is put to work for the first time. In Chapters 5-7, various elements of resource management, such as handoffs, dynamic channel allocation, and transmitter power control are treated. Whereas the treatment in Chapters 1-7 mainly has been focused on F/TDMA type (orthogonal) waveforms, Chapters 8 and 9 deal with spread spectrum waveforms and the special problems in RRM for these systems. In particular Chapter 9, where resource management issues in CDMA systems are dealt with, is an important chapter in the book. Chapter 10 brings the focus on to RRM for data communication systems and the special characteristics and problems related to management of packet traffic. In Chapter 11, various aspects of system planning are investigated, in particular so-called "hierarchical cell structures" (HCS). The last chapter, Chapter 12, widens the scope of RRM to consider resources other than the frequency spectrum. Here also other resources are taken into account, mainly the infrastructure of fixed networks and wireless access ports. Throughout the book, examples from the application of RRM techniques, current 2G systems, as well as future 3G systems are provided. The book is intended as a textbook for a second graduate course in wireless networks. The student and reader should be familiar with the fundamentals of radio communications, communication theory, and some queuing theory basics. Wireless networks are complicated systems, which makes the design and performance analysis inherently difficult. Several approaches are taken in the book. Classical analysis involves highly simplified models but renders easily tractable results. Slightly more elaborate models are analyzed by means of numerical analysis. The most interesting results, however, are those derived from the more realistic models for propagation and traffic conditions. Here, stochastic simulation has been the tool of choice in the field. For this purpose, RUNE, a MATLAB-based software tool for performance analysis in wireless networks, has been included in the book. This tool was originally developed at Ericsson, but has been developed by the software authors for pedagogical use. Most of the examples in the book that require simulations have been solved using this tool. The software solutions for these examples have been provided on the CD, enabling the reader to repeat and modify the experiments in the book. In addition, a number of problems are provided for each chapter. Some of the problems are marked with an asterisk and require simulation solutions with the RUNE tools. Most of the material has been used in courses given by the authors at the Royal Institute of Technology (KTH) in Stockholm, Sweden, and in various in-house courses at Ericsson. The authors would like to thank the software authors, Magnus Almgren at Ericsson, who is the original architect of RUNE, and Olav Queseth at KTH, who made RUNE "student friendly," for their valuable contributions and discussions around the simulation examples in the book. We would also like to acknowledge the help received in the development of the course material and early versions of the manuscript. In particular we are grateful for the contributions of Magnus Frodigh, Hakan Olofsson, Anders Furuskar, and Sverker Magnusson at Ericsson Radio Systems. Thanks to all graduate students at the Radio Communication Systems laboratory at KTH that have been instrumental in solving and designing many of the problems. Last but not least, we would like to extend our gratitude to the anonymous reviewer whose valuable comments have helped us to clarify some of the more intricate concepts in the book. Jens Zander Seong-Lyun Kim