Independent Analyst Confirms Siemens’ Power-over-Ethernet 802.11n Claims

Test results by Craig Mathias of Farpoint Group verify that the HiPath Wireless Access Points (APs) recently announced by Siemens Communications, Inc. deliver dual-radio, 3×3 MIMO 802.11n functionality while remaining compliant with the wattage limitations of industry-standard 802.3af Power-over-Ethernet (PoE). Farpoint Group confirmed this innovative capability in just-published results of comprehensive lab testing of the Siemens HiPath Wireless AP3620. Siemens also today announced that its new 802.11n HiPath Wireless AP has received the Wi-Fi CERTIFIED(r) seal of approval for 802.11n draft 2.0 from the Wi-Fi Alliance(r).

The HiPath Wireless AP3620 was awarded the certification after successfully passing a rigorous sequence of qualification testing, which ensures the compatibility of WLAN products based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11n WLAN specifications.

The HiPath Wireless AP is certified for adhering to industry standard tests for interoperability, the latest in security protection, and backward compatibility with previous generations of Wi-Fi gear.

Farpoint Group, a leading independent analyst firm of mobile technologies based in Massachusetts, performed its own tests aimed to verify if Siemens had met the difficult challenge of addressing both the physical power delivery constraints of the IEEE 802.3af PoE and the needs of power-hungry, dual-radio 802.11n APs. The 3×3 MIMO technology at the heart of 802.11n relies on the use of six transmitter/receivers (three for each radio) – compared with just two for 802.11a/b/g APs.

Depending on the implementation, this additional hardware could consume significantly more power than the 12.95 Watts that 802.3af PoE is designed to deliver across a 100-meter Ethernet cable. Many other WLAN vendors have introduced 802.11n solutions with workarounds to address this problem, which underscores the significance of Siemens’

“We were sceptical of Siemens’ claim that .3af power would be sufficient for dual-radio, 3×3 MIMO operation,” said Craig Mathias, a Principal with Farpoint Group and author of its published Technical Note. “It’s ferociously difficult from an engineering standpoint, so we jumped at the chance to verify Siemens’ claims.”

Details of Farpoint Group’s lab tests are available in its published Technical Note (Document FPG 2008-61.1, February 2008), entitled 802.11n Access Points and Power over Ethernet: Key Considerations. Mathias tested the HiPath Wireless 802.11n solution within a test network environment that consisted of both integral and add-on .11n clients, PoE switching infrastructure, and benchmarking software. “We saw outstanding performance with both radios running simultaneously at expected 3×3 MIMO throughput levels,” Mathias said. Tested throughputs ran as high as 143 Mbps – far faster than the typical 25 Mbps maximums of 802.11a/b/g wireless standards. This all took place while the AP drew power across 100m Ethernet cables connected to 802.3af PoE switch ports or .3af-compliant power injectors.

“The test results prove that Siemens has clearly achieved the feat of providing full dual-radio 3×3 MIMO 802.11n while being powered by 802.3af PoE,” Mathias said. “This accomplishment is clearly very difficult, and we expect Siemens to gain some real market advantage from this for some time.”

The Siemens HiPath Wireless APs’ compliance with the PoE 802.3af standard makes installation of 802.11n AP deployments much simpler and much more economical than competing approaches. HiPath Wireless APs only need to be plugged in to existing PoE-enabled Ethernet ports, while other 802.11n solutions could require pulling AC power, additional Ethernet cables, or adding completely new PoE infrastructure like switches or port injectors – all of which are costly and time-consuming.

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