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Tuesday, October 02, 2012

802.11a 5 Times Faster Than 11b

802.11a 5 Times Faster Than 11b
By  John Taschek           January 14, 2002

eWEEK Labs' tests of some of the first 802.11a-based equipment out of the gate show that the new specification makes wireless networks better, stronger and faster—up to five times as fast as 802.11b-based systems.
This increase in throughput will not only boost users' productivity but will also make wireless LANs an acceptable conduit for applications such as video and streaming media.
802.11a has a maximum stated throughput of 54M bps (vs. 11M bps for 802.11b), and products based on the specification are more secure and far easier to set up and manage than the first batch of 802.11b devices. In our tests of 802.11a-based access points and network cards from SMC Networks Worldwide and Proxim Inc., it took no more than 15 minutes to set up an 802.11a network.
Typical 802.11b performance is about half of the claimed 11M bps, and our performance tests of SMC's EZ Connect and Proxim's Harmony show the same is true of 802.11a: Average throughput was about 28M bps.
To test the EZ Connect and Harmony devices, we used Intel Corp.'s Iometer to generate a series of 2KB packets. Iometer places a transactional load on the network and mimics what a user performing intense file I/O might see.
We also tested both systems' performance in "turbo" mode, an engineered performance increase that makes use of channel aggregation in the 802.11a standard. Performance in turbo mode should have delivered throughput of about 36M bps but in tests yielded only about 30M bps.
Although SMC's EZ Connect and Proxim's Harmony are similar (they both use the same Atheros Communications Inc. 802.11a chip set), they are not competitors. SMC's EZ Connect is designed for small to medium-size businesses, while Harmony is geared toward enterprise organizations.
EZ Connect costs $365 per access point and $145 per adapter. Harmony costs $500 for each access point and $210 for each card.
Harmony also requires an extra device, the $1,495 Controller, for managing all access points on the network. The Controller is extremely useful for configuring an entire batch of access points in an organization, but it can manage only Proxim devices.
802.11a access points and cards can cost twice as much as 802.11b-based devices. However, bandwidth is shared, so 802.11a's greater density will allow the same number of users per access point (64) to get better throughput than with 802.11b.
Uncertain standards
Although their performance, manageability and security make 802.11a-based systems a viable alternative to wired networks, early adopters face the stress of uncertain standards.
Products based on the IEEE's 802.11a standard cannot interoperate with the slower 802.11b units because they run on different bands. (802.11a runs on the 5GHz band while 802.11b runs on the more polluted 2.4GHz band).
Some vendors have stated their intention to add dual transceivers to future devices, but both SMC and Proxim officials said that they are only considering the possibility.
Further complicating matters is the IEEE's 802.11g specification, which was approved last November after much debate. 802.11g has the same performance potential as 802.11a and can interoperate with 802.11b-based systems because it also runs on the 2.4GHz band.
Vendors including Texas Instruments Inc. and Intersil Corp. have thrown their weight behind 802.11g, but products based on the specification are expected no earlier than late spring and are more likely to appear in the second half of the year.
Organizations that have widely deployed 802.11b-based networks should keep their eye on g-based products, but 802.11a-based systems are ready for prime-time deployment.
Additional testing by Francis Chu, Henry Baltazar and Cameron Sturdevant