Handbook of Information Security, Volume 1, Key Concepts, Infrastructure, Standards, and Protocols

Wireless Channels

P. M. Shankar, Drexel University

Introduction

Propagation of Signals

Power Loss

Signal Variability and Fading

Interference in Cellular Architecture

Concluding Remarks

Glossary

Appendix (Power Units)

Cross References

References

Further Reading

INTRODUCTION

Wireless systems have become part of everyday life. In addition to their use in cell phones, they are used inside the homes for networking computers and peripherals, cordless phones, baby monitors, and so on. They are used in factories to ferry information between locations without the use of wires. Medical informatics commonly use wireless systems to exchange vital information between practitioners. These systems have unique operating frequency bands. The choice of the frequencies is often determined by the range of operation (a few meters for a cordless phone to thousands of kilometers for satellite communication systems), the medium through which the signal traverses (from urban areas with tall structures, vast empty spaces in rural areas, and multilevel–multistructure environments in factories and malls), the amount of data to be transmitted (low volume of data in maritime mobile systems to Gbits/s in satellite systems). Other factors that are equally important are the sizes of the transmitting and receiving antennas and the cost and maintenance of installations. Table 1 shows a classification of various frequencies used in wireless communications along with information on antenna sizes and achievable information ...