Draft N Router Coverage: When the "n" in 802.11n really means "not yet"

Current Thoughts

We will be reviewing additional Draft N routers from Buffalo, NETGEAR, and D-Link in the near future along with verifying compatibility between not only the Draft N products but also the other wireless standards in mixed mode operations. We do not expect to see any great differences in performance with our new review units. We understand from NETGEAR their Marvell TopDog chipset products should have better overall throughput than the Broadcom Intensi-fi chipset. Both Linksys and NETGEAR now provide Draft N routers with four-port Gigabit Ethernet switches and we expect the other manufacturers to release like products shortly.

After reviewing the performance results we are generally disappointed in the current Draft N technology as it does not exceed the previous generation Pre-N MIMO products powered by the third generation Airgo chipset. While the Airgo based products contain proprietary technology and will never be upgradeable to 802.11n, they perform just as well or better than the current Draft N products whose manufacturers cannot guarantee full compatibility with the eventual 802.11n standard.

Perhaps it's something of a given, but we think it's important to stress that even in the best case scenario current Draft N equipment can only match wired 100 Mb performance, and the theoretical wireless networking performance is nowhere near what you actually get. Perhaps more importantly, any decently wired Fast Ethernet network will offer very consistent performance in all situations without dropping to below 1 Mb speeds due to interference or other conditions. For those that need Gigabit Ethernet levels of performance, wireless networks are still a long way off from coming anywhere close to that kind of sustained throughput.

With this in mind we need to review a few issues before drawing a conclusion. The 802.11n standards process is back in full swing after the initial shock of the Draft 1.0 failure (meltdown) and resulting fallout from the 12,000 plus comments from the IEEE membership. From all indications progress has been made in creating a new draft and most of the bickering between competing suppliers has subsided. It appears voting on Draft 2.0 of 802.11n has been set for January 2007 and could possibly be ratified as a final draft. However, several insiders expect a third and final draft to appear in the spring of 2007, followed by ratification with certified products hitting the shelves in early 2008.

The final 802.11n standard will provide numerous enhancements over the current 802.11g standard with the most noticeable being theoretical data speeds up to 600 Mbps along with full standards support for MIMO (multiple-input, multiple-output) antenna technology that Airgo introduced a couple of years ago. The 802.11n standard will also apply to a wide range of devices from PDAs to dual-band routers so creating a standard has been a very complex task.

In our preliminary mixed mode testing we experienced the "bad neighbor" effect several times. Not only with our own internal 802.11g network but also visits from actual neighbors who were upset with having to constantly reboot their systems during our testing phase. As we stated earlier, the current 802.11n Draft 1.0 products utilize channel bonding to combine two 20MHz channels into a one wide 40MHz channel. Without proper fall-back techniques, this type of channel bonding can basically take over the entire 2.4GHz band that these products utilize. While the current 802.11n draft states that routers should not interfere with other networks in the area there are not any specifics as to how this will occur. At this time it is left up to the individual manufacturers to determine a "good neighbor" policy.

As an example our Broadcom based routers would continually blast our neighbors off the air during testing sequences if we did not manually change our channel selection. While throughput performance was best on auto settings, we typically would receive a phone call or knock on the door during unencrypted testing. We contacted Broadcom and found out that routers based on their Intensi-fi chipset will continuously scan for other networks and will drop down to single channel (channel selection varies) 20MHz as required. That sounds great until you realize the router will not change bandwidth or channels if a client is attached. Unless you notice neighboring networks on the same channel in the control panel settings you will potentially be a bad neighbor until you disconnect, change the channels manually, or hope the auto-sensing algorithm corrects the issue when you reconnect. We believe this is the main reason why the Atheros based Belkin N1 only allows mixed mode operation although we are still confirming the process they utilize.

We believe the final 802.11n will provide an actual specification for this issue and it will require additional hardware on the router or a change in silicon. In the meantime, the long term solution will be dual band routers that offer single 20MHz channel compatibility for mixed mode operation while channel bonding (dual or quad) for bandwidth hungry applications such as HD movie streaming will occur on the 5GHz band. The 802.11a standard currently operates on the 5GHz band so suppliers do have prior experience in this area.

While this subject matter will be covered in our next article we need to state that mixed mode performance and compatibility of the current Draft N equipment is currently dismal. We also noticed that using clients in WEP security mode could hamper performance up to twenty percent and compatibility was never a guarantee. We do not recommend using the WEP security protocol but it is still widely used and can be found in everything from NAS devices to phones so there is a great chance you will have to operate in mixed mode settings for some time to come. WPA2-PSK is our preferred security protocol for home and small office environments. This protocol works best with 802.11n Draft 1.0 products and although our testing found some significant performance hits at the longer ranges it was not noticeable at the typical 10 and 40 foot test ranges except on the Belkin N1.

In order to reach the throughput results we reported your network will have to be free of legacy devices and utilizing the recommended wireless adaptor for the router. This requirement also holds true for the Pre-N equipment we tested and will add on average at least $99 per client for the Draft N user. Most of the new adaptors are primarily for notebooks, although desktop PCI based cards are being offered by D-Link, Belkin, and Linksys now.

The Draft N routers we tested today had excellent maximum and very good average throughput in the same room tests and also at the 40 foot mark in a typical home setting without encryption enabled. We are concerned with the minimum throughput capability of the Belkin and Linksys routers in all distances along with their performance hits when enabling encryption. The NETGEAR Draft N router faired better in this area but none of our units could match the overall consistency of the NETGEAR RangeMax 240 based on the third generation Airgo chipset.

During testing we found our Draft N routers to be particularly sensitive to antenna positioning and the wireless adaptor cards to be very sensitive to placement. If we placed our notebook next to a window at the 40 foot range we could expect our signal strength to drop upwards of 15% and watched minimal throughput scores almost hit zero several times.

During general usage we found ourselves constantly repositioning our notebook when sitting on a chair as movement on any axis would create a signal drop. When utilizing a desk, we found it best to position the notebook or adjust the router antenna first before we started working. While we did not lose signal connectivity in these instances we would notice stutters when saving large files to the network or trying to stream compressed (DivX) video from our server. This is something that did not occur with our Pre-N equipment in the same test situations.

Our Draft N products also required numerous firmware and driver upgrades along with replacement hardware from one particular vendor. In fact, it took several weeks of testing and constant technical support questioning before we felt comfortable enough to present our numbers today. We expect future firmware updates to the routers and driver improvements to the PC cards to further improve the performance and compatibility of our test units, but only on a very small scale.

We just cannot help but think this product was rushed to market and for reasons we can only speculate about. We understand there will be issues in the early release of products but all of the suppliers highly touted the benefits of their Draft N products with claims of better performance than previous products. These claims are largely untrue. This Draft N product release and the resulting situation where the customer base would become beta testers for the manufacturers is unacceptable.

However, it appears the marketing of the product has been successful as it is still for sale even though no guarantees can be made about its future compatibility with the final 802.11n standard. We are just now to the point of being able to test the equipment without it failing consistently and can now start discussing mixed mode performance and cross-compatibility with other Draft N equipment. Up until a few weeks ago this was not possible.

If the lure of the short range performance is enticing enough to purchase Draft N equipment then we highly recommend purchasing the router and client cards from the same supplier. If you require added range along with consistent throughput performance, consider the NETGEAR RangeMax 240 series of product or others featuring the third generation Airgo chipset. Although eventually this is a dead end solution, we believe the same is true of the current Draft N products as well. Even though we have not finished our testing, we have to strongly recommend that users wait if possible until 802.11n is ratified and approved.