February 13, 2006, 9:12 AM — One of the key challenges in wireless is range. While limiting range is often desirable so that spectrum can be re-used over a given distance, sometimes you just want and need more. A good example is in residential wireless LAN applications: often the signal just can't make it from where the router is to the back bedroom, attic, or den. This is because the signal emanating from the wireless router's antennas is quite weak, and fades with the square of distance (i.e., exponentially) as it moves through space. Moreover, going through walls, the typical case in the residence, really does a number on signal strength, as can interference. Anyway, now you know why WLAN equipment is often returned to the store - it's really working just fine, but not in the particular geometry of a given home.
Repeaters have been used for many years in a variety of applications, including cellular systems. While they don't add capacity (and often detract from it), they can extend the range of a signal without adding another expensive base station. There are even a number of Wi-Fi repeaters on the market today, but they tend to be expensive and add latency to the connection. The reason for this is that a typical Wi-Fi repeater is really two radios - one to receive the signal, and another to re-transmit it. The packet must be decoded, decrypted if secured, and then processed for retransmission. This architecture is acceptable in some applications, but as we begin to demand more capacity from our WLANs, as well as lower latency to handle voice and video, we need more speed.
Fortunately, a new development, the physical-layer (PHY) repeater, will shortly address the challenges inherent in the architecture and design of traditional Wi-Fi repeaters. The PHY repeater has very low latency (nanoseconds), and doesn't decode packets or otherwise have any knowledge (including of security) of their contents. This means they can work with any brand of wireless router or access point, and are simple to install and transparent in use. They'll even prove popular with public-access Wi-Fi systems, bringing neighborhood Wi-Fi signals indoors, and perhaps replacing cable and DSL connections (and traditional wireless routers) over time. This is big.
So big, in fact, that we've written a new whitepaper on this subject which you can find here. I expect to see the first PHY repeater products on the market shortly. If you've got a coverage problem, give them a look. And even if you don't, I think you'll be hearing much more about this fascinating new technology shortly.