Develop A Mission-Critical Wireless Strategy

No longer just a data network serving a small percentage of workers relegated to warehouses or retail stores, Wi-Fi is growing at a rapid pace. Additionally, WLANs (wireless LANs) are becoming mission-critical networking infrastructures. I recently spoke with three industry experts from Meru Networks, Proxim Wireless, and Xirrus who offered their advice regarding what VARs need to know — and pitfalls they should avoid — to sell mission-critical WLANs.

Know The Challenges Of Outdoor Wi-Fi
According to a recent study by MuniWireless.com, outdoor Wi-Fi deployments have surpassed previous growth predictions and are continuing to grow faster than originally expected. This year, municipal wireless network spending is expected to reach $460 million, and in 2008 U.S. spending will grow 105% to $940 million. "Since September 11, 2001, there is an increased focus on using wireless technology for public safety, including first response, building inspection, and public works," says Milind Bhise, director of product and channel marketing at Proxim Wireless. "The education vertical also offers a lot of promise for Wi-Fi solutions, enabling campus mobility, guest access, campus WANs, wireless video surveillance, and even Wi-Fi telephony."

VARs that have experience deploying WLANs indoors have an advantage over VARs with no wireless experience, but there are still quite a few differences that need to be understood before selling outdoor WLANs. An outdoor site survey is much different from an indoor site survey, and it requires VARs to invest in additional site survey tools and consider new variables. "For example, you will need to use topographic maps in conjunction with RF [radio frequency] planning tools to account for any physical barriers to the RF signal," says Bhise. "Also, if you're rolling out an outdoor WLAN in a cold climate, you'll need to select APs [access points] with built-in heaters."

Another consideration is how portable the WLAN needs to be. For instance, public safety workers, construction workers, and building inspectors may work in one location for a short period and then move on to the next. "Setting up a traditional WLAN with a wired backhaul isn't practical in these circumstances," says Michael Tennefoss, VP of marketing at Meru Networks. "Instead, VARs need to use wireless APs with wireless backhaul capabilities that can be set up and taken down very quickly." Beyond temporary WLANs, Tennefoss sees a trend toward using wireless network backbones — both within and outside the four walls of an enterprise, thereby eliminating expensive Ethernet cable runs.

Tennefoss also strongly advises VARs to consider the capacity of the APs they use for outdoor deployments. "For mission-critical deployments, VARs should use only high-capacity APs that can support more than 100 clients per AP and feature multiple Wi-Fi channels built into the AP," he says. "If this step is overlooked in the beginning, the system cost and complexity will dramatically increase, because several additional APs and channel planning surveys will be necessary."

Another reason to choose APs with multiple radios, according to John DiGiovanni, director of marketing at Xirrus, Inc., is to enable maximum wireless security without compromising throughput. "APs are often deployed in time-sharing mode, which means the APs transfer data, and then when they're not in use, they scan the airwaves for security threats," he says. "By using APs with multiple radios, security functions such as IPS/IDS [intrusion prevention system/intrusion detection system] are possible without interruption and without compromising WLAN performance."

One other point to keep in mind with outdoor wireless deployments is power consumption. Two APs may have exactly the same throughput ratings, security features, and other specs, but one may consume up to 200% more power than the other. What's the big deal, you wonder? "For large campus/metropolitan deployments, this can translate to significant costs for the customer," says Bhise. "Also, high-power-consumption APs make disaster recovery options such as solar panel/battery backup impractical."

Bhise also advises VARs that want to sell outdoor WLANs to learn how to design mesh configurations, which allow APs to communicate with one another and feature built-in redundancy. "Wireless mesh networks work with wireless gateways to enable self-forming and self-healing networks," he says. "If one mesh link goes down, the network automatically reconfigures to maintain connectivity."

Implement Wireless Mesh With Caution
It's important to point out, however, that mesh is not without its drawbacks. Of significant importance, VARs need to take into account latency and end-to-end QoS (quality of service) issues that can occur if there are too many hops between APs. In a mesh environment, this occurs if there aren't enough gateway controllers. This is especially problematic for voice applications, which require minimal latency (i.e. no more than 60 milliseconds). The upside, according to Bhise, is that VARs that learn how to properly calculate the number of gateways necessary for a mesh wireless network can charge up to 50% more for the implementation compared with a traditional WLAN architecture.

Because of the complexity involved with implementing mission-critical WLANs, VARs have an opportunity to differentiate themselves by providing a total solution, including site surveys, network implementations, hardware and software sales, and postsale support. Additionally, VARs should build WLANs with future applications in mind. For instance, even though a customer may want a data-only wireless network now, it doesn't mean it won't want to add voice applications next year. If the network is built with voice (and other applications such as video) capability now, it won't require a rip-and-replace scenario when the time comes to add more communication protocols.