Special Considerations When Planning a Wireless Network
A Wireless Access Point or WAP (pronounced "whap") is wireless equivalent of a wired Ethernet switch. (Technically, it's closer in operation to a hub, but since we haven't talked about either of those two in detail yet, you really probably don't care.) It receives data from one wireless device and retransmits it for all the other wireless devices to hear, so it effectively ties them together. However, it uses radio waves to send and receive data rather than electrical signals on wires. The strength of the radio signal diminishes with the distance traveled - at an almost alarming rate. With wired networks, the placement of the switch can be fairly arbitrary. The goal is to keep the length of the cable runs as short as possible, but if it makes life convenient, you can put the switch on the other side of the room and add 10 or 15 feet to the cables without causing any problems in most cases. This isn't true with wireless networking. Putting the WAP across the room may make that bedroom at the opposite end of the house just out of range. Putting a wired switch next to a big metal filing cabinet has no effect on its functionality. Putting the WAP next to the same filing cabinet (or steel computer case or any other large metal object) may kill the radio signals to a whole section of your house. Having a WAP isn't a requirement for a home network, but it may be beneficial. WAPs are often included in the router supplied by your ISP, so you may have it regardless if you plan to use it.
Mentally survey the rooms are areas you are likely to use wireless connected devices in. If you're thinking of roaming your around your home with a laptop using a wireless connection, will you want to use it on the deck? The bedroom? Garage? How about in the living room? Once you have the area of coverage in mind, place the WAP accordingly. If the area of coverage is fairly small - such as a 30 or 40 foot diameter - you can usually place your WAP where is it convenient. If the area is any greater than that, try to pick a location roughly in the center of that area. On the first floor of a two story home, placing the WAP up high such as on top of a tall bookcase where is above the influence of metal desks, chairs and filing cabinets can often help get a good signal to the second floor. However, if the WAP is on the second floor and the majority of the wireless devices are on the first floor, you may want to place the WAP on the floor instead. As already mentioned, try to avoid placing the WAP near large metal objects like (metal) computer cases, filing cabinets and refrigerators. Metal objects in your walls that you can't see will also affect the signal. This includes things like steel I-beams, electrical wiring, copper plumbing, and duct work. Since it may be hard to tell where these items are, you should experiment by moving the WAP to different spots to maximize its signal to the areas you want covered. If you're using a combination router/switch/wireless access point, you should place it with the largest consideration given to its function as a WAP.
Distance is the enemy of wireless networks. Manufacturers of wireless networking equipment state operating ranges for their equipment in hundreds of feet. The only scenario I can think of where that might work is if they test their equipment outdoors on a very flat wide-open field without a single metal object within 100 miles. My experience is that the maximum practical usable distance from a typical WAP to a wireless device is more on the order of 50-75 feet. If you are planning on a bigger wireless network, you may need to use a wireless range extender or more than one WAP.
A range extender is a device that acts as a signal repeater. Whatever signals it receives, it retransmits (and in the process, amplifies). The upside is that the range is extended as desired. The downside is that is sends the signal in all directions including back at the source, so it increases the traffic that the WAP sees and also the traffic to wireless Ethernet adapters within range of both the WAP and repeater. Also, the extra "hop" from the WAP to the extender and then on to the destination wireless device adds a delay or lag. Still, a delayed signal is better than no signal or a signal too weak to use. Finally, repeaters aren't standardized among manufacturers. That means, if you have a Linksys WAP, get a Linksys range extender (repeater) and so on. (I personally have not used a range extender, so this is only my "working knowledge" on the subject.) The section on networking equipment includes an example of a wireless range extender.
Another WAP (in addition to the one built in to the router) can sometimes help. If, for example, you have a wired network on one floor, but can't easily get that to the second floor then wireless networking is one solution. However, if the second floor is long or parts of it are too far away from the router/WAP, the signal may be too weak to be usuable. In this case, buying a dedicated WAP and placing it on the first floor on the opposite end of the house from the original WAP may fix the problem. (The WAP will be set up to look identical to the one built into the router.) The wireless devices will tend to connect to whichever WAP signal is the strongest. The section on networking equipment includes an example of a dedicated WAP.
Wireless networks can operate in two modes named "infrastructure" and "ad-hoc." When a WAP is used, the wireless network operates in infrastructure mode. The WAP acts as a controller for the wireless traffic. In ad-hoc mode, there is no WAP. Instead, every card transmits as needed and all cards within range get the data. Therefore, every wireless Ethernet adapter needs to be within range of all the other adapters it needs to talk to, so the effective range of the entire network is roughly a 50-100 foot diameter circle. Since a WAP retransmits the signals it receives, it effectively doubles that range to having a 50-100 foot radius or 100-200 foot diameter. This is another reason why having a WAP can be beneficial.
If you would like to use wireless connections with a broadband connection sharing type of network, a WAP is more-or-less required. The WAP functions to bridge the wired network (where the Internet connection is) to the wireless devices. (This bridging can also be done using a PC that has both a wired and a wireless Ethernet adapter. Windows 98 and beyond supports sharing an Internet connection through a PC. However, we're not going to cover that just yet. See Windows Internet Connection Sharing.) It may be that the only wired portion of your network is from the cable/DSL modem to your router/switch/WAP device. Everything else can then be wireless if that's what works best. Some combination of wired and wireless devices is more typical.