Smartphones are the hottest area of consumer technology right now, and billions of dollars are being spent upgrading worldwide networks to handle 4G, the next generation of mobile Internet technology.

How can investors take advantage of this trend?

Well, I don’t recommend buying the cell phone companies like AT&T (NYSE: T), Verizon Communications (NYSE: VZ) and Sprint (NYSE: S). These companies are basically going to kill each other over fees.

The real opportunity lies in a number of lesser-known companies that have hands in building the new information superhighway, doing things like laying optical cable to the cell phone towers and optimizing networks to make them faster.

Here are four of my favorite 4G winners:

Alliance Fiber Optic Products (AFOP)

Alliance Fiber Optic Products Inc. (NASDAQ: AFOP), as the name suggests, manufactures fiber-optic components. The company makes optical path integration and optical fiber amplifier components (attenuators, couplers, depolarizers, multiplexers and splitters). Alliance sells directly to telecom equipment makers and 50% of its sales come from North America.

F5 Networks (FFIV)

F5 Networks Inc. (NASDAQ: FFIV) is on the cutting edge of an emerging trend in business–telecommuting. The company’s application delivery controllers and software programs help make networks run faster and more efficiently. This allows companies to conduct business over great distances. F5 also develops file virtualization, WAN optimization and remote access products that further help customers “decentralize” their businesses. I travel a lot so I know firsthand the value of a reliable network. The ability to conduct business in real-time from even the furthest stretches of the world is becoming a necessity in our modern age.

Radcom Ltd. (RDCM)

Radcom Ltd. (NASDAQ: RDCM) is an Israel-based company that makes test equipment and software used in the creation, installation and maintenance of corporate computer networks. The company’s equipment identifies, diagnoses, isolates and resolves network problems. Radcom sells to telecom carriers, Internet service providers and communications equipment developers.

Acme Packet (APKT)

Acme Packet Inc. (NASDAQ: APKT) makes communications equipment that helps Internet-based networks communicate with each other better. It has a suite of products, called session board controllers (SBCs), which are used to connect networks operated by Internet service providers as well as business clients. These SBCs handle interactive services, including telephone calls made over the Internet. Acme Packet also provides multi-service security gateways and routers for ISPs to help them manage their Internet traffic flow. The company markets directly and through distribution partnerships with vendors including cellular phone maker Ericsson and Sonus Networks.