GlobespanVirata 11g vs. Atheros 11g
Source: Tom's Guide US | Keywords: atheros, super
- 1. Introduction
- 2. GlobespanVirata 11g vs. Atheros 11g
- 3. GlobespanVirata 11g vs. Super-G
- 4. Super-G and 11b
2. GlobespanVirata 11g vs. Atheros 11g
| My previous tests with Broadcom 11g clients seemed to validate Broadcom's assertions that Super-G was a "bad neighbor" technology. But something didn't sit right with me.
For Atheros to ship technology that was by design virtually guaranteed to interfere with an installed base of hundreds of thousands, if not millions of products, would be either incredibly stupid, arrogant, or both. Since my experience with Atheros tells me that the people there are neither, I felt something else was going on. Also bothering me was the fact that during my initial look at the NETGEAR WG511T and WGT624, I ran some quick WLAN vs WLAN tests using an 802.11b client, and didn't see any "bad neighbor" effects. |
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Streaming So I decided to repeat my tests, this time using 11g equipment based on GlobespanVirata's PRISM chipset. Drawing from the products I had on hand, I chose NETGEAR's WG121 11g / USB2.0 adapter and WG602 access point and the following setup: Atheros-based test pair set to "normal" 802.11g, channel 6 GlobespanVirata-based 11g test pair on channel 11 2.048Mbps, UDP NetMtgv.scr running on both WLANs 10 feet maximum between WLANs (both APs and STAs [clients]) GlobespanVirata-based WLAN started first, followed by Atheros-based WLAN 10 seconds later. Data sent from STA to APFigures 1 and 2 show throughput and lost data plots, with the results showing no measurable interaction between the two wireless LANs. Note that the glitch in the throughput plot - according to Broadcom - is due to a scan done by WinXP's Zero Configuration utility. Although interesting, these results weren't that surprising, since the same test done with a Broadcom-based client also showed little interaction between WLANs. |
Figure 1: Throughput for Atheros 11g vs GlobespanVirata 11g - 2Mbps streams - 10ft
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Maximum Throughput So I next moved on to run maximum throughput tests on both 11g WLANs, using this setup: Atheros-based test pair set to "normal" 802.11g, channel 6 GlobespanVirata-based 11g test pair on channel 11 Throughput.scr running on both WLANs. TCP protocol, 200,000 Byte file size, no delay between sends, unlimited data rate 10 feet maximum between WLANs (both APs and STAs) GlobespanVirata-based WLAN started first, followed by Atheros-based WLAN 10 seconds later. Data sent from STA to APAgain, results in Figures 3 and 4 were similar to the Broadcom-client tests with noticeable interference between the WLANS at 10 feet, but gone by 30 feet. (I didn't run 50 foot tests, since I knew they wouldn't provide additional insight. |
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Mixed Streaming and Throughput I wrapped up this round of tests with a mixed streaming / throughput run, set up as: Atheros-based test pair set to "normal" 802.11g, channel 6 GlobespanVirata-based 11g test pair on channel 11 Throughput.scr running on the Atheros-based WLAN. TCP protocol, 200,000 Byte file size, no delay between sends, unlimited data rate 2.048Mbps, UDP NetMtgv.scr running on GlobespanVirata-based WLAN 10 feet maximum between WLANs (both APs and STAs) GlobespanVirata-based WLAN started first, followed by Atheros-based WLAN 10 seconds later. Data sent from STA to APOnce again, not a lot of insight gained, since the results were similar to my previous tests. Time to move on to Super-G testing. |
Figure 5: Throughput for GlobespanVirata 11g 2Mbps stream vs Atheros 11g throughput - 10ft
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