Customer Reviews

OFDM for Wireless Multimedia Communications (Artech House Universal Personal Communications)

5 star:		(2)
4 star:		(0)
3 star:		(1)
2 star:		(2)
1 star:		(1)

 

 

If you are looking for a book that clearly explains the mysteries of OFDM and COFDM then, you will have to wait. This is not that book. Much is left to "as an exercise for the student." There is some generic stuff on coding but how it relates to multipath mitigation is not clear. There are no good pictures of spectrums. The effect of amplifier non-linearities is inadequately addressed. The concept of IFFT as applied to modulation is not explained in a way you can understand it quickly. The section on coherent and differential detection is uneven in the amount of detail and understandability. The whole book has in places either too much math or not enough. There is no section on performance that tells you what the end to performance might be. Good try but far from perfect.

Charan Langton

OFDM is not a new technology. It was firstly introduced in 1960s. But until recently, OFDM was largely unknown. As OFDM seems to be the only technology for wideband wireless transmission, it became the past one year. OFDM was used in digital audio/video transmission, wireless LAN and is currently under investigation for wireless fixed point transmission. This is book is one of the only two books about OFDM available now, and I think it is a good book. It gives a quite complete overview about wireless transmission, and also addresses the main techniques used in OFDM, including sychronization, channel equalization, peak-average power problems, etc.. It is the right book for starting OFDM. The only shortcome of this book is that I found the references given were not enough.

Artech House, the folks that brought us poorly edited-or non-edited books bring you yet another example of self-referencing, poorly-written, cut and paste job. A very expensive one this time.

Of particular note is Chapter 5: Coherent and Differential Detection. Authors were busy copying and pasting covariance matrix entries but they forgot to check whether their equations for channel coefficients make sense. They dont.

In general, no attempt was made to provide insight. Self-advertisement, major errors, confused descriptions, pigeon English rule the land here. I wonder whether van Nee set up the organization of the book, and Prasad filled in the blanks, since the second author appears to be producing (I would not call that writing) too many books in a short time period. Where else, at Artech House of course.

Recommendation: Avoid.

I suppose if you were already familiar with OFDM this book might be useful to you. It touches on most aspects of the modulation. However, this book is very poorly written. Throughout it introduces technical terms without defining them. For example in chapter 2 it talks about delay spread and cyclic prefixes with no description whatsoever of what those terms mean. Unless you already know the nature of an OFDM signal, the description is just a mish-mash of jargon. In a supposed numerical example, there is no math; just a rambling description of the math.

from page 47,

"The delay-spread requirement of 200ns suggests that 800ns is a safe value for the guard time. By choosing the OFDM symbol duration 6 times the guard time (4.8us), the guard time loss is made smaller than 1 dB. The subcarrier spacing is now the inverse of 4.8-0.8=4us which gives 250kHz. To determine the number of subcarriers needed, we can look at the ratio of the required bit rate and the OFDM symbol rate. To achieve 20Mbps, each OFDM symbol has to carry 96 bits of information (96/4.8us=20Mbps)......"

Prior to this "example" there is no justification, explanation, or even an equation that tells why the guard time should be 4 times the delay-spread. The same goes for the symbol time being 6 times the guard time. There is no explanation of guard time loss or why 1dB is good value for it. They don't even tell you that the requirement for subcarriers being orthogonal(the 'O' in OFDM) is that duration of the symbols and carrier spacing have a fixed mathematical relationship.

One really has to wonder what the point of this book is. It certainly wasn't written to teach the topic of the book.

Here's a note to technical book writers. Ask yourself who your audience is. Write assuming the reader is not as knowledgeable as you are. If they were, why would they need your book? The first time you use an important technical term clearly define it, or include a glossary. Have a knowledgeable peer proofread it and have someone from the target audience read it before publication. The authors of this book apparently did none of this.

I'm not sure how anybody who has read a book about OFDM can then claim that they don't understand how it deals with multipath. OFDM is designed specifically to deal with multipath so I doubt whether he/she has actually read this book properly. Also, the IFFT is a fundamental part of OFDM and if you don't understand this then you won't understand much else. I have not read the book but I have read papers by Ramjee Prasad and I don't believe that they have described OFDM so badly that a reader does not understand the basics concepts.

Actually, now I have read it I can confirm that it does describe how OFDM deals with multipath.
I would not say this is a particularly good book though. It is very short, especially for the price. There is so much research out there on OFDM and multicarrier CDMA that that you would expect a fair number of topics to be covered but it seems only the basics are covered and what's more this book is mainly just about the authors own research areas. For example, Prasad has published work on some variant of OFDM or MC-CDMA (I can't remember what it was because I borrowed the book from a library but I do know that this hasn't received much attention so I imagine it can't be that good) and there is a large proportion of the book on this and other topics that I wouldn't have expected to be covered when there is so much other material that could have been presented. This is unfortunate because there needs to be a decent OFDM book available (compare with the number of CDMA books out at the moment) and I have heard that the only other one isn't much better than this one.
All in all, if you're after useful OFDM or MC-CDMA material you only get about 40 or so pages worth. My advice would be to buy the other book if you have to have an OFDM book or if you have access to research papers stick to them ahead of buying this book. For example, if you are after material on MC-CDMA or its variants you won't learn anything (or very little) if you have read "Overview of Multicarrier CDMA" by Hara & Prasad.

This is one of the best book regarding OFDM technology on the market. Its description of the OFDM and its history is concise, accurate, and intuitive. Lots of articles are cited, which is helpful for further studies. Also, the related industrial standards are referred, which make it a very practical reference, especially for the engineers in this field. It is basically product-oriented without too much rigid mathematical derivations. Whereas, it is not a book for beginners.