Broadband Myths

"Faster, Better, Cheaper" Broadband Wireless Product Myths

Lynda Partner

I bought a new car last month and a big selling feature to me was fuel economy. I compared the stats carefully to others and was really pleased with what my selected car manufacturer claimed. However my actual fuel economy wasn’t anything close to what the data sheet said it would be. When I called the dealer to ask, he gave me a long lecture about how fuel consumption stats were calculated under very specific conditions - in other words “results may vary”.

When it comes to broadband wireless, it seems there aren’t many commonly accepted definitions for the attributes we use to compare radios. Many attributes are open to interpretation. Some vendors are aggressive in their numbers, others less so, but that makes it really difficult for prospective customers to compare one radio to another or to believe you’ll realize exactly what the data sheet is promising.

So before you end up buying a radio that doesn’t perform exactly as the data sheet said it would, you might want to ask a few questions, especially in the areas of speed, environmental certifications and open standards - three areas that are very open to interpretation.

Myth 1: Our radio delivers high capacity (FASTER) You’ve heard it before- “Our radio delivers lots of Mbps”. Claims like this would lead you to believe the product can actually deliver the stated Mbps of data payload. However, for radios that operate in unlicensed bands many factors contribute to lower effective bandwidth, such as:

• Protocols. If a CSMA protocol is used to manage access to the air interface, it will consume about 50% of the available bandwidth, leaving at best 50% of the promised Mbps under ideal link conditions (excellent line of sight, no interference... etc.)
• Channel Size. Super high Mbps can only be achieved if you were able to use the full 40 MHz channel. This is an unrealistic expectation as a 40 MHz channel represents 90% of the bandwidth available in the unlicensed 5.4 GHz and 5.8 GHz bands. Since other users will be using these bands, you will never get full use of a 40 MHz channel.
• Distance - radios have their highest capacity at short distances but as the distance increases the capacity of some radios drops quickly.

All this taken into account, you may see a real payload delivery of less than one third the stated Mbps - a huge difference! For unlicensed band radios, the truth is that interference, excess demand, distance, and packet sizes can all contribute to a lower effective bandwidth. How the radio is designed in terms of the air interface, protocol and error correction is critical for optimal performance.

Your takeaway: Ask the vendor for test cases that include interference, distance and packet sizes and other test conditions to get a real picture of payload capacity.

Myth 2: Our radio is “ABC” Certified (BETTER) A product may be compliant, certified or both. A product is “compliant” when it meets certain minimum standards or measures but it may not be “certified”. Product certification involves processes to prove a product meets minimum standards. Wikipedia goes on to say “Product certification is provided by an authority that accredits the performance or constituents of products, systems, or components. Examples of these authorities are national standards, standards writing organizations, certification organizations, and testing organizations.” In other words, product certification is a lengthy, sometimes costly process.
However there is nothing to stop anyone from stating that their product is, for example, “ABC-compliant” even if they haven’t received independent verification. A good example is environmental certification - where the data sheet says the radio is IP67 / NEMA-6X certified to operate in harsh outdoor environments, will work over an industrial temperature range of -40 to +60 degrees C and meet ASTM-B928 to work in salt-laden marine environments. The truth is that the radio must be independently certified (not simply designed) to meet these standards to ensure the radio works as you hoped it would.

Your takeaway: Ask what certifications a product has earned and ask for proof of independent certification.

Myth 3: Our radio supports open standards (CHEAPER) Open standards is one of the most ill-defined terms in our industry. To many, this statement would lead you to believe the radio will work seamlessly with radio accessories such as cables and power supplies from other manufacturers giving you the option to source alternative components and to minimize your inventory. NEVER ASSUME. A radio that is specified to be open standards may mean the radio meets the open standards (i.e. WiFi, OFDM...etc) but it may also mean you are required to buy the radio accessories and network accessories from the radio manufacturer. As the total cost of the radio includes cables, power supplies, switches and routers, it’s important to consider the price and availability of all components. A lower cost radio may end up being more expensive if your only option is proprietary cables, proprietary power supplies and proprietary Ethernet switches and routers. So don’t assume - ask.

Your takeaway: Don’t assume - ask what they mean by support of open standards. Ask if the radio supports standard cables, power supplies and networking gear from third parties.

Conclusion:

You have probably heard the saying “Faster, Better, Cheaper- Pick Two”. Radio vendors are notorious for saying their radios can reach incredible speeds (faster), environmentally certified (better), and meet open standards (cheaper). However, take a moment to think critically about the statements your radio vendor is making and don’t be afraid to ask questions.

Reprinted from the Redline Communications Blog