5G telephones! How long ago was 4G? 4G long-term evolution (LTE)? It was introduced about eight years ago--eons in technology years--and is still being deployed in many areas. It also continues to evolve. This book discusses both sides of 5G: what we don’t know yet and what we do know has to be done. For the most part, though, what we don’t know is rather larger than what we do know.

We do know what some of the major problems are. In particular, it is quite clear that we’ll need more bandwidth to provide solid mobile web, video, and audio performance. It isn’t quite so clear where this will come from. Two chapters are devoted to spectrum/bandwidth issues.

The following chapters are included in the book:

“Introduction to Mobile Wireless Systems” covers the history of wireless systems and smartphones and has some information on the standards bodies involved.

“The Evolution and Technology Adaptations of 4G”: 4G isn’t a single technology, rather it’s a collection of related technologies; not all of these are created equal, and many have been added to smartphone technology along the way. 4G continues to evolve, and many of the newer technologies added to 4G will likely be the base for technologies in 5G.

“Evolving from 4G to 5G”: the requirements that are likely to drive the evolution of 5G.

“5G Technologies”: the crucial technologies used by and supporting 5G rollout, focusing mostly on spectrum and bandwidth and the different approaches to using it efficiently.

“Spectrum Sharing”: ways to share spectrum and bandwidth that may be only partially utilized. This is almost as much a regulatory problem as a technical one.

“The Disruptor: the Millimeter Wave Spectrum”: millimeter wave signals have some inherent problems, such as propagation losses and blockage by buildings and raindrops. On the other hand, millimeter waves can be high bandwidth enabling high-capacity information transmission.

“Conclusion” wraps it all up.

There are bibliographies for each chapter. Many--but not all--of the cited materials are online, which makes things a bit harder to find. There is a very short index, and for those not immersed in the field, this is likely to be frustrating. Almost every page introduces or references acronyms (sometimes rather more than a few), and the vast majority of these are not indexed and there is no glossary for them.

Another problem, at least with the print edition, is that many of the diagrams are quite small and hard to read. This is complicated in a few places because the diagrams are all grayscale and sometimes the descriptive text refers to color in them.

Much of this book may be worthwhile both to those with little experience in the area as well as experts. It does suffer a bit from a lack of real details in many sections. As the foreword says, “We just don’t know which technologies will define 5G.”