Jim Geier

Many of the larger municipalities have installed or are planning to install Wi-Fi networks for creating city-wide wireless coverage. In some cases, such as Philadelphia, the coverage area is over a hundred square miles. These deployments have had ups and downs in terms of signal coverage and performance, and they are very costly. As an […]

This is excerpt is from Chapter 7: Designing a VoWLAN Solution, pp. 147-150 Deploying Voice over Wireless LANs, by Jim Geier, from Cisco Press. Roaming Because of the mobile aspect of wireless voice telephony, ensure that the VoWLAN system architecture you select supports effective roaming . The voice user must be able to move about the […]

In a typical wireless LAN, a wireless client connects to an AP, and communication takes place between the client and the access point (AP) as the user browses the Internet, sends and receives e-mail, or talks to someone on a wireless IP phone. This communication includes an uplink path from the client to the AP […]

Many municipalities, including big cities such as Philadelphia and San Francisco, are in the midst of deploying Wi-Fi networks that provide connectivity throughout most outdoor areas. With signal coverage over dozens and even hundreds of square miles, these systems are expected to serve a diverse set of applications, such as wireless meter readers, public safety, […]

One extremely beneficial aspect of Wi-Fi networks is mobility. For example, a person can walk through a facility while carrying on a conversation over a Wi-Fi phone or downloading a large file from a server. The Wi-Fi radio inside the user device automatically roams from one access point to another as needed to provide seamless […]

After installing a wireless LAN, you might find that it doesn’t support applications as expected. Users may complain of erratic connections and slow performance, which hampers the use and benefits of applications. When this happens, you’ll need to do some troubleshooting. Start by finding the root cause of the problems. The table below gives you […]

At some point, you’ll probably need to perform “RF mathematics” when installing or supporting a wireless LAN. In most cases, this will involve dealing with logarithmic relationships, which is a bit beyond what most of our brains can handle directly. So let’s take a look at what might make this pesky math a bit easier. […]

With traditional Wi-Fi networks, access points form radio cells that provide wireless connectivity to users, and these access points require cabling that interconnects them with Ethernet switches to enable roaming and connections to servers and the Internet. This is the most common wireless LAN configuration, but a problem for many applications is that it’s costly […]

Over the past few months, I’ve been testing Helium Networks’ new Wireless Recon system for performing radio frequency (RF) site surveys and engineering wireless LANs. Helium had been referring to this product as Rollabout during the beta development phase while I’ve been testing. The commercial release of the Wireless Recon system, which includes some enhancements, […]

A while ago, I completed a nine day road trip while working for one of my clients, a 2,500 mile journey by car throughout much of Ohio, Kentucky, Tennessee, Mississippi, Louisiana, Alabama, Florida, and Georgia. Since I generally fly while on business trips, this was a much different travel experience, but one that many sales […]

In the old days, frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS) were the only two radio-based 802.11 wireless LANs available. At one point, I remember FHSS being among the top choices when deploying a wireless LAN because FHSS access points were less expensive and more available than DSSS access points. Then, […]

When performing a radio frequency (RF) site survey, it’s important to define the range boundary of an access point based on signal-to-noise (SNR) ratio, which is the signal level (in dBm) minus the noise level (in dBm). For example, a signal level of -53dBm measured near an access point and typical noise level of -90dBm […]