A WIRELESS WANS 101 PUBLICATION
      Wireless WANs 101 - Making Sense of the Wireless WAN Hype
wireless wan intro
 It's Wireless Wanarchy! Save Yourself!
by David Theodore
INTRODUCTION

There are as many forms of "wireless" as there are itchy skin rashes. That's part of the problem and so I'll start by qualifying that this article - and my expertise, extends to wireless that's used to connect one corporate network (LAN) to another, typically building to building and for bandwidths of 10 megabits or more. That's where the highest telecom costs are and where phone companies and fiber providers charge the big bucks.

Applications for point to point wireless can be for primary, backup or last-mile connections to bypass local telco lines en route to a long-distance provider or collocation facility. For the sake of consistency, I'll use "wireless WAN" as the catch-all term, since whatever your wireless application, if you're extending your data network outside your building then you're creating a wireless wide area network.


WIRELESS WAN ANARCHY

"Wild West" is a metaphor so often used to describe the wireless WAN business. But it's worse than that. In the Old West everyone had a gun. In the wireless WAN business customers are completely unarmed. What's going on?

Well, for one, vendors are playing fast and loose with terminology that should mean something. For instance, "carrier-class" used to mean a licensed microwave product with such exacting specifications that it's suited for the most demanding of all users, the telephone companies (aka, "common carriers"). Now "carrier-class" is stamped on radios you can buy for $800 that carriers wouldn't touch with a ten foot (telephone) pole. The problem is further compounded by the big network players - far from wireless experts, who see wireless as a necessary evil and offer only instant out-of-box solutions so as not to complicate the larger sales of their mainstay products; switches, routers, servers, etc.

Where are the wireless manufacturers in all this? Out to lunch, literally, wining and dining the big telecom carriers and leaving end user (enterprise) business to resellers who are hard pressed to shoulder the job of customer marketing and education.

Wireless is compelling, but who do you trust and how do you decide what's best for you? There's certainly no lack of information out there, but the more you read the more you encounter conflicting information and outright false advertising. What else do you call it when vendors blaze bandwidth claims like "45 Mbps!" all over their marketing literature when they know full well that their product doesn't come anywhere near that throughput?

For one, the throughput of many wireless products (unlicensed) is dynamically adjusted for distance, increasing transmit gain at the expense of bandwidth. Then there's software overhead that saps performance. But the best ruse of all is the term "aggregate", which means that whatever speed a vendor boasts is doubled, meaning that an aggregate 100 megabits is really only 50 in each direction. Would you buy any other network device or even an automobile that's marketed that way? How about selling cars with aggregate gas mileage claims? If a car gets 30 miles to the gallon, why not just say that it gets 60 aggregate miles to the gallon? Maybe then U.S. auto makers can better compete against the imports.


TRUST COMMON SENSE

Should you be looking at Wi-Fi, 802.11a, b?, unlicensed or licensed, wireless or microwave? What's WiMax? How do you decide between the different frequencies, 2.4, 5.8, etc.? Well, let's cut to the crux of the matter. First, let's understand that, excepting free space optics ("laser"), the "wireless" you're be looking at will be "microwave radio" and it's either going to be unlicensed or licensed.  (Continue with page 2 - below)
Meridian Microwave specializes in point-to-point microwave for enterprise wireless WANs. Call us at (781) 413-5661.
A Wireless WANs 101 Publication. Copyright © 2005 by David S. Theodore. All rights reserved.
       A WIRELESS WANS 101 PUBLICATION
      Wireless WANs 101 - Making Sense of the Wireless WAN Hype
Deciding between the two is what matters most. Once you've made that decision then the rest is all about comparing features like remote management or interface options.

Unlicensed microwave means that it operates in one of the commonly used radio frequency bands, which is shared by lots of other consumer devices such as cordless phones, baby monitors and PC cards. Since there's no FCC licensed required, you can buy the product and pop it up on your roof on the day it arrives.

Licensed microwave means that it operates in an exclusively assigned FCC licensed frequency band and in order to install it your vendor needs to licensed your microwave path. The process takes up to 90-days and so instant gratification would not be a feature.

Unlicensed microwave is low in cost but the downside is that it's susceptible to interference, depending on how much congestion there is in the particular frequency band that the product operates in. The choices are 2.4 GHz, 4.9 GHz (public safety band), 5.3-5.8 GHz, 60 GHz and 70 GHz. Of these, you can forget the 2.4 band. It's a nightmare. The 5.8 band is a pretty safe bet for the time being, because it offers more sub channels to mitigate congestion.

I have no trouble recommending 5.8 products, particularly as they're relatively small investments that won't break anyone's budget. Vendors make strong statements, but none will GUARANTEE interference free performance for any length of time. The only exception are the 60 and 70 GHz products, which are absolutely immune from interference, however restricted to path distances of under half a mile.

By contrast, licensed microwave is absolutely immune from interference, however that protection doesn't come cheap. Expect to pay upwards of $30,000 to $50,000 or more for a licensed microwave connection as opposed to about $3,000 to $20,000 for an unlicensed solution.

Whether this is worth the cost difference depends on how critical your application is. If you can afford the risk, then you'll save a fortune by purchasing an unlicensed product. On the other hand, if your application is mission critical, then $30,000 of up front savings on an unlicensed solution can be wiped out in minutes, along with your job.

Deciding on a point to point wireless solution as simple as that, and the only other thing you need to make sure of is that whatever bandwidth you need is supported by the microwave product you choose. Be more careful to understand the REAL throughput of an unlicensed microwave product based on your distance, the product overhead and whatever you get in each direction - and not the "aggregate" throughput. By contrast, licensed microwave has no product overhead and the bandwidth is maintained in toto, regardless of distance.

Trust your common sense. In the end, if you're comparing a $200,000 fiber run or a $3,000 a month telco bill, then don't believe that a wireless solution for pennies on the dollar is going to give you the same performance. If a $3,000 wireless link could truly supplant a $36,000 a year telco connection, then phone companies would need to hold bake sales to stay afloat.

And one final piece of advice. If you're in the market for a wireless WAN solution, then you'll be better served by a firm that specializes in wireless and not an all-purpose network vendor.
Note from the author:

I hope you enjoyed this article. If you're interested, read my bio or visit me at my day job, Meridian Microwave LLC. We offer unlicensed as well as licensed microwave - with no bias other than to properly match the solution to each customer application.  
Meridian Microwave specializes in point-to-point microwave for enterprise wireless WANs. Call us at (781) 413-5661.
A Wireless WANs 101 Publication. Copyright © 2005 by David S. Theodore. All rights reserved.