MIMO, 'draft n' gear blazes near 100Mbps, but vendor interoperability remains an issue

Two years after the first multiple-input multiple-output-based wireless LAN products appeared, we're finally at a point where a wide array of systems are available for residential and small and midsize business markets.

How we tested MIMO

Testing results

The 'draft n' controversy

A MIMO primer

Why buy a MIMO PC card?

Archive of Network World tests

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Six vendors - Asus, Belkin, Buffalo, D-Link, Linksys and Netgear - submitted a total of nine products. SMC Networks also makes MIMO-based equipment, but we were unaware of its products at the time of testing. Bluesocket was not ready to send us its BSAP-1700 system for testing. During our tests of the Belkin system, we encountered a bug that prevented us from running our tests; a fix by Belkin was not completed until after our testing was finished.

Although the products tested are aimed at residential or SMB applications, it's important for enterprise IT managers to stay on top of MIMO-based offerings, because they point the way to tomorrow's enterprise-class systems.

Today's MIMO-based clients also can improve throughput and especially the range of existing 802.11g-based connections: Longer range is often desirable and even necessary (see "Why buy a MIMO PC card now?").

Asus wins the Clear Choice Award for its stellar performance and outstanding client-configuration features. Buffalo's WZR-G240 family and the Linksys WRT300N router also earn high marks for performance.

View from the lab: Testing MIMO gear

Keith Shaw and Craig Mathias go inside our testing of MIMO/pre-N router technology. View videos showing how the tests were done and what methods were used to get the more accurate results.

MIMO performance
Short-rangeThroughput (Mbps)
Asus93.33
Buffalo 24085.75
Netgear 24074.92
Netgear 85468.68
Linksys66.03
Buffalo 30060.60
Netgear 83457.22
D-Link47.18
Long-rangeThroughput (Mbps)
Asus69.42
Buffalo 24064.12
Netgear 24054.87
Linksys52.10
D-Link49.52
Netgear 83446.65
Buffalo 30043.28
Netgear 85441.77

Performance tests

When we tested homogeneous systems (with client card and router from the same vendor and product family), the results did not surprise us. The three top-performing products (from Asus, Buffalo and Netgear) were all models that had been on the market for some time, and all are based on the third-generation MIMO chipset from Airgo Networks. Earlier tests we performed showed the superiority of Airgo's products, which makes sense, considering the length of time the company has been building MIMO chips. Among the newer products, the Linksys router-client pair performed quite well.

Netgear's WNR-854T-WN511T product pair showed great promise with a record-setting (for this test, anyway) 120.1Mbps upstream (from access point to client) data rate, but a strange 18Mbps (an 802.11g rate) in the other direction. Subsequent discussions with staff at Marvell (the vendor of the MIMO chipset in these products) didn't yield a satisfactory explanation. Marvell says it has achieved performance in excess of 100Mbps in both directions but did not produce documentation for this claim. Nonetheless, we were impressed with the great performance in one direction.

The top performer in the short- and long-range tests was the Asus WL-566gM/WL-106gM pair. Asus also wins a truth-in-advertising award for achieving almost 100Mbps, just as it says on the boxes.

ProductAsus WL-566gM router, WL-106gM adapterBuffalo WZR-G240 router, WLI-CB-G240 adapterBuffaloWZR-G300N router, WLI-CB-G300N adapterD-Link DIR-635 router, DWA-645 adapter
VendorAsusBuffalo TechnologyBuffalo Technology D-Link
PriceRouter, $125; adapter, $87 .Router, $130; adapter, $86.Router, $130; adapter, $86.Router, $135; adapter, $86.
ScoreRouter, 4,05; adapter, 4.55.Router, 3.95; adapter, 3.73.Router, 3.05, adapter, 3.0.Router, 3.35; adapter, 2.95.
ProductLinksys WRT300N router, WPC300N adapterNetgear RangeMax 240 (WPNT834) router, WPNT511 adapterNetgear WNR-834B router, WN511B adapterNetgear WNR-854T router, WN511T adapter
VendorLinksysNetgearNetgearNetgear
PriceRouter, $130; adapter, $100 .Router, $120; adapter, $80 .Router, $130; adapter, $97.Router, $144; adapter, $97.
ScoreRouter, 3.55; adapter, 3.33Router, 3.4; adapter, 3.53Router, 3.0; adapter, 3.13Router, 2.9; adapter, 3.03

Routers 

The breakdownAsus WL-566gMBuffalo WZR-G240Linksys WRT300NNetgear RangeMax 240D-Link DIR-635Buffalo WZR-G300NNetgear WNR-834BNetgear WNR-854T
Performance 40%54.53.543333
Config./features 25%44333333
Mgmt./ease of use 15%33434333
Set up 10%333332.533
Documentation 10%34535432
TOTAL SCORE4.053.953.553.43.353.053.02.9

Client cards  

The breakdownAsus WL-106gMBuffalo WLI-G240Netgear WPNT511Linksys WPC300NNetgear WN511BNetgear WN511TBuffalo WLI-G300ND-Link DWA-645
Performance 40%54.543.53333
Config./features 25%53.53.523.53.532
Mgmt./ease of use 15%4333.5333.53
Set up 10%33343333
Documentation 10%43353255
TOTAL SCORE4.553.733.533.333.133.033.02.95
Scoring Key: 5: Exceptional; 4: Very good; 3: Average; 2: Below average; 1: Subpar or not available

Fun with interoperability

Absent a Wi-Fi Alliance interoperability test (or one of equivalent nature), our expectations for interoperability were fairly low, and the testing did not disappoint. There was a significant problem with the connectivity of several product combinations, all related to security settings (our tests required Wi-Fi Protected Access 2 security to be turned on). Several vendors noted upcoming firmware upgrades, but basic interoperability remains a challenge in many cases.

Overall performance levels in interoperability tests were typically in the 20Mbps range (what you'd see with 802.11g), but we also saw fine interoperability between products based on the same WLAN chipsets.

Other features

Performance counted for only 40% of the total score; we also evaluated configuration, features, management, ease of use, setup and documentation. We liked the set of client functionality included in the Asus product. While Asus' performance impressed us, we feel a little more attention should be paid to the wording of messages shown during the installation process.

We were confused by the nearly identical packaging and industrial design of Netgear's WNR-834B and -845T routers. We would caution buyers to carefully match respective clients when purchasing these (the boxes also look alike), as performance will clearly be below expectations if an error is made here.

D-Link and Linksys scored high for fine user manuals.

We also liked the automatic check for firmware upgrades that Buffalo's equipment performs, as well as the similar functionality on the Linksys WRT300N (along with its easy-to-use interface and diagnostic features). We weren't crazy about the industrial design of the otherwise stylish Buffalo WZR-G300N router. In addition, some of the indicator lights are on the front and some are on the back, making shelf placement problematic. We found the D-Link products easy to use.

Asus router

Asus adapter
The Asus router and adapter performed best in our Clear Choice Test.

Implications for the enterprise

We remain convinced that MIMO will be key in future WLANs. The technology is proven and clearly can be produced in cost-effective, easy-to-use products. We would be hard pressed to recommend a WLAN product that was not based on MIMO, at least in residential or SMB applications.

While absolute throughput and capacity are not very important in most residential applications (the fastest Internet connections available to most people are 6M to 8Mbps, and wireless high-definition TV distribution remains rare), range is far more often an issue. We frequently see situations where a MIMO-based product could easily deliver a usable - and sometimes great - signal to locations where a typical residential wireless system could not.

Enterprise applications increasingly rely on the opposite approach, installing more access points with less coverage, and therefore have less of a requirement for range. These dense deployments offer much more capacity because of the decrease in range (and thus stronger signals), as well as fewer users per microcell at any given time. Careful centralized management and control, particularly of radio-frequency parameters, is essential to make this strategy work.

MIMO in the enterprise, therefore, likely will be used to improve throughput beyond the 22M to 25Mbps maximum of 802.11g and 802.11a. Indeed, we expect 100Mbps effective throughput to be on the lower end of 802.11n performance, exceeding by a wide margin the 100Mbps (signaling rate, not application throughput) of typical wired Ethernet.

Our tests also showed enterprises are almost certainly better off waiting for the 802.11n standard to be completed before installing MIMO-based products. While we still recommend using MIMO to deliver an 802.11g waveform with improved range and reliability, we don't expect most of the enterprise-class WLAN vendors to roll out MIMO access points until the 802.11n standard is much further along.

Airgo, for example, says it intends to produce an 802.11n chipset by year-end, and the standard should be mostly ironed out by then. We expect it to be completed no later than mid-2007. We expect lots of MIMO products to come out then and become ubiquitous by early 2009. The standard will almost certainly allow backwards compatibility to earlier 802.11 physical-layer signaling rates, but we expect a rapid and massive upgrade to 802.11n - again, when it's done.

Until then, expect to see rapidly evolving chipsets, drivers, firmware and many more MIMO-based WLAN products. Despite some of the quirkier test results, we remain encouraged that wireless will become the default LAN connection for almost everyone in the not-too-distant future.

Mathias is a principal at Farpoint Group, a wireless advisory firm in Ashland, Mass. He can be reached at craig@farpointgroup.com.

NW Lab Alliance

Mathias is also a member of the Network World Lab Alliance, a cooperative of the premier reviewers in the network industry, each bringing to bear years of practical experience on every review. For more Lab Alliance information, including what it takes to become a member, go to www.networkworld.com/alliance.

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