Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Very good on hot mobile communication topics.

This is a very good book published right on-time. Covers hot mobile communications topics with good enough detail. Introduces mobile data communication concepts at first and explains mobile VPN's for 2.5G and 3G technologies. Although concentrated on CDMA2000 in stead of W-CDMA, this book is still useful on mobile data comunications and VPNs. Warmly recommended.