Wireless Network Implementation Tips

802.11n now ratified!

2009-09-13T09:37:00.001-04:00

The IEEE Standards Board recently ratified the 802.11n amendment to the 802.11 standard. This marks the final approval of a fairly long process. Of course many companies have been deploying 802.11n networks over the past couple years, and the Wi-Fi Alliance has already certified numerous products based on Draft 2 of 802.11n. You can likely upgrade products previously certified by Wi-Fi (802.11n, Draft 2) products to the ratified version.

By Jim Geier, Wireless-Nets, Ltd.

Solving Vista wireless connection problems

2008-12-04T08:11:00.000-05:00

By Jim Geier, Wireless-Nets, Ltd.

When beginning to use Vista, you may have troubles connecting to wireless / Wi-Fi networks. A problem is that Vista implements special functions that some access points don’t recognize. Sometimes connectivity will drop intermittently, especially if a Vista-based computer is connecting to a wireless access point that is not fully Vista compatible. If you’re having connection problems, check with the access point vendor, and see if newer firmware versions for the access point include Vista support.

If updating the access point firmware doesn’t solve the problem, try disabling Vista’s autotuning (which isn’t supported by some access points):
1. Click Start.
2. Type cmd in the search box.
3. Type CTR+SHIFT+ENTER. This opens the command prompt with elevated privileges.
4. The command prompt window will appear. You’ll know this is the correct privilege level if system32 shows up in the directory path
5. Type netsh int tcp set global autotuninglevel=disable, and hit Enter
6. After the command prompt window displays OK, restart your computer, and autotuning will be disabled.

If this doesn’t help, reactivate autotuning by following the same steps as above, but type netsh int tcp set global autotuninglevel=normal in the command window.

How to: Get the most from 802.11 multicasting

2008-12-02T21:01:00.000-05:00

By Jim Geier, Wireless-Nets, Ltd.

Multicasting over wireless LANs can make better use of capacity for some applications, but beware of the potential issues! Learn how to best satisfy performance and battery life when using multicast applications referring to a tutorial I just posted at http://www.wireless-nets.com/resources/tutorials/802.11_multicasting.html.

How to: Define wireless network security policies

2008-11-25T14:55:00.000-05:00

By Jim Geier, Wireless-Nets, Ltd.

Because of the use of radio waves, a wireless network is not secure unless you take special precautions. Learn what you need to consider when defining the wireless network security policies for your company by referring to a tutorial I just posted at http://www.wireless-nets.com/resources/tutorials/define_wireless_security_policies.html.

Wireless site survey tips

2008-11-19T08:30:00.000-05:00

By Jim Geier, Wireless-Nets, Ltd.

I recently completed a webinar titled “Wireless Site Survey Tips,” and you can view its audio/visual recording on my website at http://www.wireless-nets.com/training/wireless_survey_tips.html. In the webinar, I explain tips on preparing for a survey, performing testing, choosing tools, and determining optimum installation locations for access points (including coverage for elevators and multiple floors).

How to: Choose the right spectrum for 802.11n deployments

2008-11-12T14:51:00.000-05:00

By Jim Geier, Wireless-Nets, Ltd.

With 802.11n, you have a choice of using 2.4 GHz or 5 GHz spectrum. Gain a better understanding of what you should take into account when deciding which spectrum to deploy by referring to a tutorial I just posted at http://www.wireless-nets.com/resources/tutorials/choose_802.11n_spectrum.html.

How to: Sniff wireless packets with WireShark

2008-11-05T14:47:00.000-05:00

By Jim Geier, Wireless-Nets, Ltd.

WireShark is free software that sniffs packets on wireless networks. You can learn tips on configuring and using this tool when analyzing and troubleshooting 802.11 wireless networks by referring to a tutorial that I just posted at http://www.wireless-nets.com/resources/tutorials/sniff_packets_wireshark.html.

Looking for certified WiMAX products?

2008-10-30T08:23:00.000-04:00

By Jim Geier, Wireless-Nets, Ltd.

Many of my clients often ask which companies are offering WiMAX products that have actually gone through certification testing and have valid WiMAX certificates. The best place to find this information is on the WiMAX Forum website at http://www.wimaxforum.org/kshowcase/view.

WiBro and mobile WiMAX confusion

2008-10-28T09:20:00.000-04:00

By Jim Geier, Wireless-Nets, Ltd.

Based on conversations with some of my associates, there seems to be some confusion between WiBro, the wireless network being deployed in Korea, and mobile WiMAX. Some think that WiBro is something completely different than WiMAX. Actually, WiBro is based on the same IEEE 802.16e-2005 standard as Mobile WiMAX. WiBro has functionality defined by the Mobile WiMAX system profile, with identical PHY, MAC and Power Classes to Mobile WiMAX. Also, WiBro will be certified using the Mobile WiMAX certification processes and laboratories. For more details on relationship between WiBro and mobile WiMAX, refer to the following document: http://www.wimaxforum.org/news/WiBro_and_Mobile_WiMAX_Backgrounder.pdf

Wireless middleware important for mobile systems

2008-10-24T09:02:00.000-04:00

By Jim Geier, Wireless-Nets, Ltd.

Wireless middleware software resides between client software and the application server or databases and offers intermediate communications that elevate wireless issues, such as coverage holes. The middleware, which generally runs on a dedicated gateway platform attached to the wired network, processes the packets that pass between the wireless client and the server. As a result, middleware offers efficient and reliable communications over the wireless network, while maintaining appropriate connections to application software and databases on the server via the more reliable wired network.

For example, wireless middleware has store-and-forward messaging that queues traffic to ensure delivery to client devices that lose connections with the network. This is often referred to as session persistence. The middleware is able to act as a proxy of the client. In fact, most applications have no idea that the middleware server is maintaining the connection with the host. Once the client gains wireless connectivity again, the middleware lets the client resume communications. This is especially beneficial when servers and applications can’t tolerate the loss of connectivity, such as with public safety applications in municipalities.

If transmissions are unexpectedly cut at midstream, “intelligent restart” is a middleware recovery mechanism that detects the premature end of a transmission. When the connection is reestablished, the middleware resumes transmission from the break point instead of at the beginning. This not only enables wireless clients to easily reestablish connectivity, it also helps with improving performance and reducing battery drain due to fewer packet retransmissions.

Common wireless network deployment risks

2008-10-21T13:50:00.000-04:00

By Jim Geier, Wireless-Nets, Ltd.

In the past years, I’ve been involved with wireless networks for many different venues, including hospitals, airports, universities, and enterprises. I’ve been seeing a trend of mistakes that companies deploying wireless networks make. Unclear requirements, RF interference, security weaknesses and non-optimal application interfaces are leading problems. You can view more details about these types of deployment risks in a tutorial I just posted at the following URL: http://www.wireless-nets.com/resources/tutorials/identify_wireless_lan_deployment_risks.html

Beacon transmission rate impacts range

2008-10-16T12:21:00.000-04:00

By Jim Geier, Wireless-Nets, Ltd.

I’ve been testing the range of various radio cards in a laptop against an 802.11b/g access point. I found that the access point vendor (Proxim) changes the beacon transmission rate, depending on whether the access point is configured for mixed b/g mode or b-only mode. In mixed b/g mode, the beacon transmission rate is 2Mbps. In b-only mode, the transmission rate is 1Mbps. I consistently found that b-only mode offered better range (about 20%) compared to mixed b/g mode. This occurs because the lower beacon data rate allows the radio cards to maintain connections at greater ranges (receive sensitivity at 1Mbps is about 3dB better than at 2Mbps). When deploying wireless LANs for greater range, consider operating in b-only mode. Of course this will keep b/g radio cards from operating above 11Mbps.

Defining security policies for wireless networks

2008-10-14T12:17:00.002-04:00

By Jim Geier, Wireless-Nets, Ltd.

Security of wireless networks is certainly important. I’ve recently posted an updated tutorial that gives an overview of wireless network security policies that you should take into consideration when deploying and managing a wireless network. You can view the tutorial at the following URL: http://www.wireless-nets.com/resources/tutorials/define_wireless_security_policies.html

Choosing the right mobile user device

2008-10-09T10:45:00.000-04:00

By Jim Geier, Wireless-Nets, Ltd.

The selection of the right mobile devices significantly impacts the usability of the application and the corresponding ROI. You need to think about application requirements and choose devices having the optimum weight, keypad, screen, battery longevity, and ruggedness. User devices in warehouses, for example, will probably undergo more physical abuse than one in use in a typical office setting. Thus, in this scenario, you’d need rugged user devices that will withstand an industrial environment. Before rolling out hundreds of mobile devices to users, undergo testing of pilot sites with a reprehensive group of users. That way, you’ll be sure that the device you propose to use will best fit requirements and maximize ROI. Also, involve upper management in the trials to receive adequate levels of buy-in, which of course is sometimes necessary to continue funding for the project.

Tips for developing wireless software

2008-10-07T09:44:00.000-04:00

By Jim Geier, Wireless-Nets, Ltd.

Whether you’re starting from scratch with a wireless mobile application development project or converting an off-line application to operate in the wireless world, keep the following points in mind:
1. Always consider what will happen if wireless connectivity is lost, and have appropriate recovery mechanisms in place.
2. Look at your application from the viewpoint of a hacker, and design-in security elements, such as encryption and authentication, that significantly reduces or eliminates the security threat.
3. Minimize the transmission of data and overhead packets in order to increase battery longevity.

Wireless nay sayers

2008-10-02T10:43:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

In past wireless LAN deployments, I've encountered some people in companies who are totally against the implementation of mobile wireless solutions. The trouble is that these "nay sayers" can cause other users to become negative regarding the implementation. This often deteriorates the benefits of the system. As a result, I highly recommend, early in the deployment project, to promptly handle those against the deployment. One counter measure is to try including these people in the early phases of the project, such as when defining requirements and when considering design alternatives. If they're left out of the deployment process, negative feelings will intensify.

Keep firmware up-to-date

2008-09-30T10:41:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

I've been seeing a lot of companies with access point firmware that's not up-to-date. This means that these companies are not taking advantages of security and performance patches offered by the vendor. Take a look at your firmware and download updates as needed. Be certain to read over the vendor's notes, however, to ensure that installing the new firmware will not introduce any known issues that will adversely impact your network.

Use WireShark instead of Ethereal

2008-09-25T10:39:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

Many of you may be still using Ethereal for obtaining packet traces of Wi-Fi networks. About a year or so ago, Gerald Combs, Ethereal's lead developer, left his company and couldn’t keep the name "Ethereal." As a result, Gerald renamed the software "WireShark" and has been supporting WireShark since then. Instead of using Ethereal, which I don't believe is being supported anymore, I recommend downloading the latest version of WireShark at www.wireshark.org. WireShark is still free and provides the same (and better) functionality as Ethereal.

Watch your back!

2008-09-23T15:46:00.002-04:00

By Jim Geier, Wireless-Nets, Ltd.

You can implement the most effective encryption and authentication in the World, but someone can easily look over your shoulder and read your emails along with you. Airports are fairly open, making it easy for a hacker to also see your passwords as you type them in. So, keep this in mind as you utilize public Wi-Fi hotspots.

Wipe those mobile devices

2008-09-18T15:45:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

I've found that more and more companies are beginning to deploy device wipe functions to ensure that wireless hand held devices are secure in case they are lost or stolen. For example, an employee who's lost their device can inform a system administrator that the device is gone, and the administrator can issue a command to the device to wipe the memory and applications from the device. In case the device is out of range of the wireless network, functions on the device itself will automatically perform the wiping if someone mistakenly enters the wrong user name / password too many times. I don't believe that Windows natively supports the wiping functions, but I think that it's under development. Regardless, the device wiping seems to be a good security mechanism. Just be sure to do a good job of replicating data on a server!

Elevation makes a difference

2008-09-16T15:43:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

I've found that many Wi-Fi hotspots in outdoor areas have very poor signal strength because the access point antennas are mounted relatively low to the ground, such as near the edge of roofs. The antennas propagate radio waves that must slice through people, buildings, and other obstacles to reach the users. Because of the resulting attenuation, it's generally better to install the access points (or just the antennas) higher up on light poles if they are available. The problem, however, is that it's difficult to run cabling to these higher mounting places. That’s when mesh network technology comes in handy.

Inter-access point interference sometimes not a problem

2008-09-11T15:41:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

The common design rule for installing 802.11b/g access points is to set adjacent ones to non-overlapping channels (1, 6, and 11). This avoids the access points from competing for the same part of the spectrum, such as when transmitting beacons, data frames, and acknowledgements. When analyzing existing wireless LANs, however, I often find adjacent access points set to the same channel. In addition, it's common to have neighboring wireless LANs set to the same channels as yours. For example, a quick scan of my residential area shows several homes having access points all set to channel 6, the typical vendor default channel.

I've been analyzing various wireless LAN issues recently and ran some throughput tests between a wireless client and a particular access point - with and without the presence of another nearby ("interfering") access point set to the same channel. In fact, I measured degradation of a few percent in throughput when the interfering access point was active as compared to when it was not. This indicates that there's not much impact from the beacons of a neighboring access point set to the same channel. The problem, however, is when multiple clients are utilizing the interfering access point. That can take away a large portion of the bandwidth on your network.

Wireless Network Implementation Guide

2008-09-09T15:39:00.004-04:00

By Jim Geier, Wireless-Nets, Ltd.

I just started a newsletter titled the Wireless Network Implementation Guide. I focus each edition of the newsletter on a particular aspect of wireless networking. For example, the August edition of the newsletter discusses migration to 802.11n networks in enterprises. You can view past editions of the newsletter and subscribe to receive future editions at the following link: http://www.wireless-nets.com/resources/newsletter.html

Wi-Fi robots on the run

2008-09-04T15:38:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

As part of some research I'm doing, I came across a website (Dr. Robot) advertising Wi-Fi robots. You can develop some pretty interesting systems with these devices. I've seen rather extensive use of Wi-Fi for robot communications in hospitals, but you have to ensure good coverage, or the robot gets lost!

Defining requirements for wireless networking critical

2008-09-02T08:00:00.001-04:00

By Jim Geier, Wireless-Nets, Ltd.

Before implementing a wireless network, you must define requirements to ensure what you’re deploying is based on the right things. Understand what constitutes valid requirements and learn about requirements that you might have overlooked by reading my latest tutorial.