The Big Picture
A network lets you connect multiple PCs and other devices together so that they can share resources such as printers, files, or an Internet connection. There are three major types of home networks: ethernet networks that make connections over special (Category 5) wiring; power-line networks that use existing electric wiring and outlets; and wireless (Wi-Fi) networks based on components that send data over the airwaves using radio frequencies.
A wireless home network offers more convenience than a wired one--there's no need to install cables, and notebook users can roam untethered. But wired networks are generally more secure and reliable (especially for multimedia streaming), and those that use existing electrical wiring eliminate the expense and hassle of installing new cables. Depending on your requirements for the location and mobility of networked devices, you might consider combining elements of wired and wireless networks; it's relatively easy if you plan ahead.
Networks based on the IEEE's family of 802.11 standards for wireless ethernet are commonly referred to as Wi-Fi.
Wi-Fi comes in several flavors. The newest and most common are based on draft 2 of the upcoming 802.11n standard. They are among the fastest wireless products available, with maximum theoretical speeds of up to 300 megabits per second (mbps); their range of coverage is also dramatically better than that of networks based on the earlier and slower 802.11a, b, and g standards described below.
Although the IEEE still hasn't finalized 802.11n (final ratification is expected later this year), the Wi-Fi Alliance--the industry group that certifies Wi-Fi products for compatibility--last year began a certification program for draft 2 products in order to address compatibility issues that had surfaced with earlier products based on the initial draft. Fortunately, most products based on the earlier draft are firmware-upgradable to the more recent draft, but shoppers should strive to find the newer products that the Alliance has certified for 802.11n draft 2 compatibility.
Unlike previous Wi-Fi standards, 802.11n covers operations on two different frequency bands: 2.4 GHz and 5 GHz. Most products operate only on the 2.4-GHz band, and are backward-compatible with products based on the previous 2.4-GHz Wi-Fi standards, 802.11g and 802.11b. A few recent high-end 802.11n products, however, also support the 5-GHz band, and are also backward-compatible with 802.11a products (which use the 5-GHz band). We'll discuss the benefits of such "dual-band" products later.
The Wi-Fi Alliance certifies 802.11n products for each of these frequencies; products from different vendors will be able to interoperate at high speed on the frequencies for which they are certified.
Draft-N vs. Pre-N
The 802.11n standard's superior speed and range derive in part from its use of multipath radio and antenna technology that first appeared a couple of years ago in products (including some labeled "pre-n") based on chips from a single vendor, Airgo Networks. These early products have been largely discontinued; you should avoid them, as they are compatible with 2.4-GHz draft-n products only at the speeds of older 802.11g products. One way of making sure that you are buying the most current technology is to look for Wi-Fi Alliance certification for 802.11n (draft).
Older and Slower Standards
Because prices on low-end draft-n gear have declined dramatically, we don't recommend buying products based on the older 2.4-GHz 802.11 standards (802.11g and 802.11b)--they're increasingly hard to find anyway. The 802.11g standard has a theoretical maximum throughput of 54 megabits per second, and 802.11b has a theoretical maximum off 11 mbps.
You may also see 802.11g gear promising speeds of up to 108 mbps, but such products use proprietary technologies, and you probably won't achieve those speeds if you mix and match 802.11g products from different vendors.
Note that if all you're sharing on your network is broadband Internet access, you might not notice any performance boost with faster Wi-Fi gear, since most cable and DSL hookups top out at 6 mbps. Though Wi-Fi connections never approach their theoretical maximum speeds, even 802.11g Wi-Fi networks can keep up with the fastest broadband.
Products based on the 802.11a standard also support theoretical maximum speeds of 54 mbps, but tend to have a slightly shorter range than 802.11g products do. Even so, 802.11a does not interoperate with b/g products because it works on a different radio band (5 GHz), and the standard never took off the way its siblings did. In the end, 802.11a was used primarily in some business environments.
2.4 GHz vs. 5.4 GHz
Why, then, do some 802.11n Wi-Fi products support both the 2.4-GHz and 5-GHz bands? For starters, dual-band support takes care of all older Wi-Fi products. And though many more 2.4-GHz legacy products are around, the 2.4-GHz frequency band has a serious limitation that has become increasingly problematic over time: It has just 11 channels, of which only 3 (1, 6, and 11) are nonoverlapping.
As 802.11b and g networks have proliferated--along with other devices that use the 2.4-GHz band (such as Bluetooth-equipped cell phones and headsets, microwave ovens, and some cordless phones)--channel overcrowding has grown to be a significant issue. If multiple users are trying to use the same 2.4-GHz channel, one will inevitably knock off others, resulting in brief service outages. Such interruptions may not be noticeable if you're downloading a file (your device will simply reconnect); but they can be very obvious if you're trying to conduct a phone conversation, play a game, or stream music or video.
The 5.4-GHz frequency range, in contrast, has more than a dozen nonoverlapping channels, and is therefore less prone to interference. For that reason, it's expected to appear in a coming generation of connected consumer electronics that will stream multimedia. Investing in a dual-band router will allow you to add such devices to your network while still supporting the more common 2.4-GHz legacy devices.
If you want support for network components that use both frequencies, however, make sure to buy a router that can handle them simultaneously--some dual-mode routers may be configured to support only one frequency or the other. Apple's dual-mode router, for example, supports either 5-GHz or 2.4-GHz traffic; it might be better suited for people who invested in an early 2.4-GHz draft-n router and now want to support 5-GHz traffic. Expect to pay more for routers that can support both frequency bands simultaneously.
On the wired side, power-line technologies that transfer data over your home's existing electrical lines are becoming increasingly attractive alternatives to ethernet, which requires special wiring that can be expensive to install.
HomePlug 1.1, the HomePlug Powerline Alliance's original, 14-mbps technology, delivers speeds on a par with those of 802.11b Wi-Fi. But in the last 18 months, several faster technologies, including the Alliance's own HomePlug AV, have eclipsed it. With a theoretical maximum throughput of 200 mbps and technology to optimize streaming multimedia, HomePlug AV is shaping up as a strong competitor to 802.11n as the best standard for moving video and music throughout a networked home. Linksys and Zyxel are among the U.S. vendors that have released HomePlug AV products; Belkin is expected to ship HomePlug AV products this fall.
HomePlug AV itself faces competition from other power-line technologies. One is the Digital Home Standard, based on 200-mbps technology from a Spanish company called DS2 and promoted by the Universal Powerline Association (the trade group backing Power Line Communications technology for delivering data services over electrical distribution lines). D-Link and Netgear are shipping products based on DS2 technology. Panasonic has also introduced its HD PLC power-line adapters, based on the company's own technology.
PC World tested early products based on all three power-line technologies in late 2006. All three proved speedy, but the HomePlug AV-based gear was the most resistant to line interference. We have not had a chance to look at more recent products, though, and while HomePlug AV would appear to have a leg up on its rivals, this standards story has not yet completely played out--in part because power-line networking in general has been lingering in the shadow of the more glamorous Wi-Fi. As streaming-media applications grow more ubiquitous, we expect power-line networking to become more popular, since it's generally more reliable for such tasks.
The Ethernet Option
Ethernet remains the gold standard for network connectivity because of its speed and reliability. But it requires special wiring between all network components, and installing ethernet cabling can be an expensive and messy proposition. In the past, 10/100-mbps ethernet was the norm, but in recent years more and more desktops and laptops have begun shipping with support for 1-gbps (1024-mbps, or "gigabit") ethernet.
The days when you had to buy an ethernet adapter for your system have long passed: Almost all now ship with integrated ethernet support.
No matter what type of network you use, you will need a network adapter or client for each device; most laptops these days ship with both ethernet and Wi-Fi adapters, but desktop systems may not have Wi-Fi. If you want a power-line network, however, expect to buy an adapter that will plug into your system's ethernet port at one end and into a free electrical outlet on the other.
You'll also need a router, which acts as a kind of switchboard that directs all data traffic between PCs on your network and between your network and your Internet connection.
If you're installing a wireless network, you will need either a router with a built-in wireless access point or, if you already have a router, a separate wireless access point to plug into it. Wireless access points connect wireless networks to wired ones (such as your Internet connection). The access point communicates with Wi-Fi adapters, sending and receiving the data in radio signals to and from the wired network, and then the Internet. All wireless networks involve one adapter connecting to one access point, and most wireless home gateways have built-in access points.
Power-line networks also require a router. Typically, a starter power-line network kit will have two power-line-to-ethernet adapters: one to plug into an available ethernet port on your router, and the other to plug into the ethernet port on a client device.