by Platon Scheblykin
04/10/2007 | 11:31 AM
WLAN users have long been looking forward to the release of the new-generation IEEE 802.11n standard. The related workgroup was established over three years ago and the new standard has been discussed from time to time in computer-related press.
The discussion reached a peak in 2006 as the IEEE commission finally ratified a draft version of the standard. Some manufacturers of network equipment and chips rose to the occasion and introduced a number of devices with support for 802.11n draft.
Being highly interested in this WLAN standard ourselves, we want to check out one of such devices in our labs. We have picked up the WRT300N router from Linksys for that purpose.
Before getting closer to the Linksys router, we’d want to talk about the 802.11n standard in general. This is indeed a very exciting and important topic at the moment.
The story began in September 2003 when the Institute of Electrical and Electronics Engineers (IEEE) established a workgroup with the n index to develop a new wireless communication standard within the 802.11 family of standards. Why? Because the recently ratified (as of June 2003) 802.11g could not fully meet users’ requirements in terms of speed or coverage. The new standard was expected to make wireless networks as fast as wired ones and to ensure transmissions at a distance of 6 times that of the previous standard. Besides that, 802.11n was to provide compatibility with the earlier shorter-distance wireless communication standards (802.11a/b/g). As might have been expected, the budding standard became the subject of a hot argument right after the establishment of its workgroup. The companies that took part in developing the specification couldn’t come to a compromise and split into two conflicting camps, each with its own vision of what 802.11n was to be. One camp was called WWiSE (World-Wide Spectrum Efficiency) and comprised such firms as Broadcom, STMicroelectronics, Texas Instruments, Airgo Networks, France Telecom, Motorola, etc. It was opposed by TGn Sync (Task Group “n” synchronization) that combined such companies as Agere, Atheros, Intel, Qualcomm, Philips, Panasonic, Sony, and others. The project proposed by WWiSE dominated the discussions of the new standard at first, but it could not gather enough votes in the voting held in January 2005 on Hawaii to be accepted as a first official 802.11n draft. The opposing parties had to join forces eventually to create a unified project. However, in October 2005 some companies (Intel, Broadcom, Cisco, and others) made another attempt to split up the workgroup. They established the Enhanced Wireless Consortium with the presumable goal of speeding up the development process, but which was actually busy developing its own version of the project. As a result, Dell, Motorola, Nokia, Samsung and other companies protested against the EWC and the alternative version of the project was brought up for public discussion. After introducing about 50 amendments, the IEEE commission accepted it as an official version 1.0 draft of the 802.11n standard in January 2006. In January 2007 the same commission approved draft version 1.1 after introducing 3000 corrections into version 1.0 (as many as 12,000 corrections had been proposed at first). The new draft version doesn’t yet introduce any fundamental changes into the specification of the standard. If this goes on, it will only take a firmware or driver update for a device which supports the draft version to begin to support a final version of the 802.11n standard. We should just keep an eye on the ratification process. The final version of the standard is expected to appear in the second half of 2008, some sources even specifying the month, November. But the Wi-Fi Alliance which is responsible for the certification of new wireless equipment does not wan to wait for so long and is planning to begin the certification process as soon as the second quarter of this year.
So what is IEEE 802.11n, technically speaking? Its full draft version is not available to the public, but the fundamentals can be found at websites of some of its developers, e.g. Intel. We’ll use the publicly available information to talk about the technicalities of the new standard.
What benefits is 802.11n going to bring us? First of all, the developers put a focus on the effective bandwidth of the communication channel. That is, the nominal bandwidth is now calculated for the MAC level rather than for the physical level as before. For example, the nominal bandwidth of the 802.11g standard is 54Mbps whereas its effective bandwidth is not higher than 20-25Mbps. For the new standard the effective bandwidth must equal the nominal one or be very close to it at least. And second, the coverage area is increased in the new standard. It is all made possible by utilizing the Multiple Input Multiple Output technique (MIMO) which has been around for a while already. As a matter of fact, the developers of 802.11n didn’t try to invent some revolutionary technologies, but picked up the already available ones instead. This is going to reduce the price of finished solutions and solve the problem of compatibility with such standards as 802.11a and 802.11g/b. It is however clear that MIMO alone cannot increase the channel bandwidth to the declared level. The next speed-improving measure is the twofold expansion of the earlier 20MHz communication channel. Draft version 1.1 specifies that a wide 40MHz channel is formed by two adjacent 20MHz channels. This ensures compatibility because there is no need to introduce a 40MHz channel besides the existing 20MHz one. On the other hand, old network devices, e.g. 802.11g-compliant ones, will be able to communicate with 802.11n equipment.
The performance growth provided by the 40MHz channel is illustrated by the diagram that shows performance depending on the signal-to-noise ratio.
The resulting picture of performance – a wide channel plus MIMO – is shown in the next diagram:
It shows the bandwidth growth dynamics for different “Number of Channels x Number of Data Streams – Channel Frequency Bandwidth” configurations. The 2x2-40 configuration is superior to the others. Comparing the 2x2-40 and 4x4-20 configurations, you can see that the use of a 40MHz channel is optimal not only in performance but also in the cost of implementation because a system with two antennas is going to be much cheaper than a system with four antennas. The 2x2-40 configuration is taken as the basis for building wireless communication systems in the draft version of the standard while the maximum number of streams is limited to four as yet. However, the final version will describe some means to increase performance of an 802.11n device in case of emergency. Currently, most manufacturers that produce draft 802.11n-compliant devices install three antennas on them.
Besides the changes on the physical level, the MAC level was revised in the 802.11n standard as well. This level is important for reliability and performance of network equipment. As we wrote above, the declared bandwidth used to be measured for the physical level, but the effective speed of data transfers between network devices was much lower than specified due to auxiliary information, like the headers of physical-level packets, which was useless for the information user. The speed was reduced even more by various latencies that resulted from signal reflections, etc. The most annoying thing was that the speed reduction didn’t depend much on the overall connection speed. The most obvious way to increase the effective bandwidth is to minimize the overhead on the MAC level. The main approach to increasing the efficiency of communication in the future standard is the use of so-called aggregate exchange sequences . It means combining several MAC Protocol Data Units (MPDUs) into a single PHY Protocol Data Unit (PPDU). Aggregate exchange sequences allow to increase the effective bandwidth to the level of the theoretical one. Without them, a physical speed of 500Mbps would be required to reach a speed of 100Mbps on the MAC level.
Another method to make communication more effective is the new MAC-level data transfer mechanisms that allow transferring data in both directions without the need to initiate transmission. They minimize the time it takes to reverse transmission between the initiator and the responder. Besides that, the new standard is expected to introduce a new MPDU format that will allow sending physical-level packets to several recipients at once. Finally, error-correction algorithms have been improved to increase the coverage and Quality-of-Service mechanisms – this should have a positive effect on such services as high-quality streaming video and Voice over IP.
The problem of backward compatibility with the older Wi-Fi standards has been taken care of, too. First, the 5GHz range, necessary for 802.11a, has become a standard feature, instead of optional, in the new draft version of the standard. Second, the mechanism of operation of devices with 40MHz and 20MHz channels has been clearly defined. If a 20MHz device connects to an 802.11n access point, data transfers between them will utilize one of the two channels that make up a wide 40MHz channel. Third, the new standard will surely inherit all the modulation methods employed earlier in 802.11a/b/g.
Compatibility of different 802.11n devices between each other is important, too, but it’s all right here. Chipsets from Broadcom and Atheros are quite friendly to each other. Other manufacturers’ chipsets have a high degree of compatibility, too, which is determined by the connection speed only. Serious problems can only occur on the level of drivers and firmware, which is not critical.
Now that we’ve started talking about available chipsets, we should name a couple of them here.
As soon as the next day after the ratification of the first draft version of the 802.11n standard Broadcom announced that it was ready to begin shipments of its new Intensi-fi chipset. This chipset combines three pieces: a BCM2055 radio module, a BCM4321 MAC-controller, and a BCM4705 processor. The processor is not directly related to 802.11n. For the other two chips we can give you a general specification taken from the manufacturer’s product brief:
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The specification suggests that the chips are universal in terms of connection interface and antenna configuration.
Atheros, another world leader in manufacturing wireless communication chipsets, was catching up with Broadcom by releasing the xspaN AR5008. Unlike Broadcom’s, this chipset may contain a lot of different chips because each interface and antenna configuration is supported by a separate chip. Thus, the following versions of the chipset are available: AR5008-2NG, AR5008-2NX, AR5008-3NG, AR5008-3NX, AR5008E-2NG, AR5008E-2NX, AR5008E-3NG, and AR5008E-3NX. These versions are combinations of a total of six chips. The letter E in the first part of the marking denotes the AR5418 MAC-controller that supports a miniPCI Express interface. Otherwise, the AR5416 with a miniPCI/CardBus interface is employed. The digits 2 and 3 in the second part of the marking stand for an RF module with two (AR2122 and AR5122) or three (AR2133 and AR5133) antennas, respectively. The letter G at the end means that the RF module works in the 2.4GHz range only (AR2122 and AR2133) whereas the letter X means both 2.4GHz and 5GHz ranges (AR5122 and AR5133). We won’t publish the specification of the xspaN chipset because its versions are very similar and the parameters of one of them will be reflected in the specification of the WRT300N router.
Marvell has released its TopDog chipset, too, but there’s little information about it yet. It consists of an 88W8360 MAC-controller and an 88W8060 RF module that supports both 2.5GHz and 5GHz ranges.
The AGN400 chipset that is expected to arrive in the first quarter of 2007 has been announced by Qualcomm that has recently acquired the assets of Airgo Networks Inc. This chipset consists of an AGN403BB MAC-controller and an AGN403RF RF module and features True MIMO Gen-N technology. Here’s its specification taken from the manufacturer’s product brief:
PCIe 1.1, CardBus (PC Card 7.1), MiniPCI 1.0 , PCI 2.2, USB 2.0,
Frequency Band 2.400 - 2.485 GHz
4.920 - 5.825 GHz
Network Standard IEEE 802.11n, IEEE 802.11a, IEEE 802.11b, IEEE 802.11g
Orthogonal Frequency Division Multiplexing: BPSK, QPSK, 16 and 64 QAM
Direct Sequence Spread Spectrum: DBPSK, DQPSK, CCK
802.11b: 1 - 11 Mbps
802.11a: 6 - 54 Mbps
802.11g: 1 - 54 Mbps
802.11n: 24 -144 Mbps (20 MHz channel)
48 - 315 Mbps (40 MHz channel)
AGN403BB ™ Single-chip CMOS integrated MAC and baseband
AGN403RF ™ Single-chip SiGe 2.4/5 GHz transceiver
Encryption / Decryption
• 64 bit WEP
• 128 bit WEP
• CCMP (AES)
QUALITY OF SERVICE
802.11e, WMM & WMM-SA
And finally we can’t but acknowledge Intel’s having played an active part in promoting the new standard, too. The company has released a miniPCI Express adapter Next-Gen 4965AGN which will be installed into Intel Centrino Duo notebooks.
IEEE 802.11n draft, IEEE 802.11b/g
WEP (64, 128, 256 bit), WPA, WPA2
- 2 external dipole antennas
OFDM with BPSK, QPSK, 16 QAM, 64 QAM; DBPSK, DQPSK, CCK
2.3 - 2.5 GHz
Nominal data transfer rate
- 802.11g: 6-54Mb/s
11 for N. America, 14 Japan, 13 Europe (ETSI)
1 RJ-45 (10/100 BaseT) Fast Ethernet 10/100 Mb/s port
4 RJ-45 (10/100 BaseT) Fast Ethernet 10/100 Mb/s ports
External 12V power supply
188 x 176 x 40 mm
There actually exist two versions of the WRT300N router. One version is meant for the United States and Japan (at least that’s what you can infer after exploring the database of Linksys drivers for different countries). The second version is meant for the countries of Europe (and other regions of the world except the mentioned above). The specifications of main parameters are identical for both versions of the router. They only differ in their hardware components as we’ll show you shortly. We’ve got a second version and will be talking about it from now on.
The box contains, besides the router:
Linksys must have set a goal of creating a product that would be new and would also look new. That’s why they developed a completely new case design for this model with all its variations. This design differs from all other company products. The designers must have tried to make the device ergonomic and functional, but also elegant and appealing so that the WRT300N could fit well into the room interior. And they have succeeded. Just like a TV-set or a DVD recorder, this device won’t look out of place in a living room. The router’s innards are packed into a small passively ventilated stylish case with three antennas. One antenna is shaped like a locator. Combined with the other antennas and the overall case design, this makes the router look like some spaceship component.
Inside the plastic casing there is a card with a dual-sided planar antenna. The spring-loaded feet on the router’s case can be turned around by 180 degrees. If the router stands horizontally, they stick out sideways, providing more support. If the router is positioned vertically, you can turn the feet around to hide them from view.
There is one peculiarity in the product’s color scheme. The color of the top and bottom panels (or side panels if the router is positioned vertically) tells you which version of the router you are dealing with. If the color is blue, it is the American version. Silver indicates the European version. The WRT300N doesn’t have too many indicators and connectors. All of its indicators are gathered on the front panel. Here they are, from left to right:
The leftmost and rightmost indicators are based on dual-color SMD LEDs. The others use single-color LEDs. The light from the diodes is transferred to the front panel through plastic light pipes.
The front panel is made of translucent dark plastic. Indicator labels are painted on this panel in white.
This looks stylish for sure, but is not very practical. The lights in the front panel are too small and are rather dull (especially if viewed at an angle). By the way, there are excess light pipes in the front panel which are not used at all. Perhaps other versions of the router will have some additional indicators.
The router’s back panel offers Fast Ethernet connectors for local and external networks. Here you can also see a power supply connector and a reset button.
There should have been another button under the front panel:
Its purpose should have been to quickly set up security settings for the wireless connection. But there is only a small hole in the case which is sealed with a “Reserved” sticker. A button can be found under the sticker, but it doesn’t do anything when pressed.
The quality of the case is high, just as you can expect from such a respectable firm as Linksys, but we were surprised to find the router very difficult to take apart. Well, most users won’t ever do that, especially while the router’s warranty is in effect, but those enthusiasts who’ll try to get inside their WRT300N, will have some troubles doing that. Externally, it is perfectly unclear what to start with. It’s only after some scrutiny that you notice that you should first lift up the panels with the vent holes. This will call for a screwdriver and some effort on your side.
To take the PCB out after that, you’ll have to unblock four locks simultaneously to release the translucent front panel. And you also have to unfasten the four screws on the case to take it apart into two pieces and extract the PCB. By the way, the state of things inside the router is somewhat disappointing. There are loops of cables going to the antennas that are just stuck to the case panels with sticky tape.
You expect something more elegant from a device of that class. The wiring and layout of the two cards you can find inside the case is good, however. Every detail is placed logically and not too close to others.
The PCB is wired neatly and cleverly. All the main components are placed on one side of the PCB while the other carries a miniPCI slot for a wireless interface card.
You can notice a few empty seats for more components on the PCB:
Particularly, there is a seat for a PCMCIA slot and for an appropriate controller with accompanying elements. The engineers must have had doubts as to what interface the wireless module would be connected with. There are no unsoldered components here, although there is plenty of room. The new PCB design must have been developed for later models like the WRT350N.
Now let’s take a closer look at the components installed in the WRT300N:
Let’s start with the router’s heart. Here, it is the IXP420 network processor from Intel. Its 32-bit XScale core is clocked at a frequency of 266MHz consuming a maximum of 1.9 watts of power. It has separate data and instruction caches, 32KB each. The integrated memory controller supports up to 256 megabytes of SDRAM. The IXP420 also supports a lot of external interfaces such as USB 1.1, PCI 2.2, UART, a special 16-bit expansion bus, etc.
The router has 16 megabytes of memory in two 8MB 6ns A2V64S40CTP SDRAM chips from Powerchip Semiconductor. The router’s firmware is written into an 8MB flash memory chip with an access time of 70ns.
This chip from Macronix is marked as MX29LV320C. By the way, a closer look at the place with the flash memory chip can tell you that the PCB provides for installation of a larger chip.
There are two more chips on board that should be mentioned. Both are Fast Ethernet switches. The router’s four LAN ports are based on the Marvell 88E6060 switch from the LinkStreet family.
This switch offers five Fast Ethernet ports (but only four of them are employed by the router), and a MII port that is connected to the network processor. The frame buffer of the switch is 512KB large. The MAC address buffer is 1024KB large. The WAN port is based on the Realtek RTL8201CP chip which is connected to the network processor via MII, too. Both switches can automatically recognize crossover connections.
The WLAN card carries the AR5008-3NX version of the Atheros xspaN chipset. It means we’ve got two chips here: AR5416 and AR2133.
We’ve got nothing to add to that because we’ve described the chipset above. By the way, this is the most significant difference between the American and European versions of the router. The American version is equipped with a chipset from Broadcom whereas the European version comes with a chipset from Atheros.
There is no final version of the 802.11n standard yet, so the firmware of the WRT300N router is going to be updated. Right now the Linksys website offers only one official version of firmware (2.00.17). We don’t know anything about alternative firmware for this router. The official firmware is rich in options (we’ll discuss them shortly), but we were mostly interested in checking out the router’s support of the Point-to-Point Tunneling Protocol. Many modern routers have poor implementation of PPTP, so what about this one? It turned out that the WRT300N provided limited options for setting up a VPN tunnel by means of PPTP. The router cannot establish connection if the VPN server is on another subnet. Moreover, it doesn’t support an alternative address for the PPTP server. In fact, the router only allows to set up a PPTP tunnel if the server has the same address as the main network gateway. Alas, this is not a common thing for many providers that work via VPN (PPTP).
To learn what else the firmware can do, we should check out the options provided through the router’s Web-interface. To enter it, type 192.168.1.1 into your Web-browser’s address line. You’ll be asked to enter a login and password then. The login field should be left empty while the password is admin by default. The router’s GUI doesn’t look like an interface of a common SOHO-class router and may be somewhat unusual to deal with for a user who has never worked with Linksys products before. The interface seems to be overcrowded at first and it’s hard to make out anything among the options. But after you get used to the austere design without rounded-off corners, pretty buttons, etc, the interface turns to be quite comfortable, in our opinion. The menu is organized as a horizontal row of tabs each of which contains its own submenus which are listed horizontally below the main list. Each page contains options divided into groups whose names are located on the left of the list and opposite the corresponding group. A short description of the current page is given on the right. To get detailed help on the necessary page, you should click the appropriate button below the brief description. The Save Settings button in the bottom right corner of each page does what its name suggests. An Abort button is placed next to it.
You don’t have to open up a special page to learn the firmware version of the router. It can be seen in the top right corner of each page.
We’ll now describe briefly the options offered by the WRT300N’s web-interface.
The Setup tab goes first. On this tab you can change basic parameters of wired networking and routing. The first page is called Basic Setup.
Here you can configure the WAN port, particularly the way it is connected to the Internet. The next group of settings belongs to the router’s DHCP server, including the router’s address on the local network. At the end of the page you can set up the router’s internal time.
On the DDNS page you can choose a service the user host will be registered with if you have enabled the dynamic DNS feature.
This is the MAC Address Clone page. You can specify a MAC address the router will be identified on the external network by.
The Advanced Routing page is the last one on the Setup tab. Easy to guess, it contains settings of routing parameters.
You can enable/disable NAT, specify the type of routing (static or dynamic), and manage entries in the routing table.
The Wireless tab contains wireless communication options. The Wireless Basic Settings page offers parameters any wireless network begins to be set up with.
First of all, you can disable the wireless interface altogether, assign the SSID and enable/disable its broadcasting. You can also manage communication channels here. If you select a channel width of 20MHz, there will be no special features which only appear when you select a 40MHz wide channel. If you do, then besides the 40MHz channel you will also have to choose one 20MHz channel for initializing communication and for operation of 802.11b/g equipment.
On the Wireless Security page you can choose the method of encrypting wireless connections and the encryption algorithm.
To filter access to the router via the wireless network, you should go into the Wireless MAC filter page.
This filtering works by allowing/prohibiting devices whose MAC addresses is on the appropriate list to access the router. The list contains up to 50 addresses.
Few users will tamper with the options of the Advanced Wireless Settings page.
These are fine wireless network settings. For example, you can unite all wireless devices connected to the router into an isolated virtual network. You can also specify such parameters as speed of different connections, sync packet transfer frequency, maximum packet size within packet aggregates, etc.
The Security tab is needed to specify various limitations for the external connection.
The Firewall page contains basic settings of the SPI Firewall. On the VPN Passthrough page you can limit the passing of traffic through different types of VPN channels.
There is only one page with settings on the Access Restrictions tab. It is called Internet Access Policy.
Here you can find settings pertaining to security and restrictions of the connection to the outer world. You can either limit the access to the external network or prohibit it altogether (this can all be done by a schedule or for individual machines).
The next tab is called Applications and Gaming. It is needed to set up certain applications so that they could work with the network correctly.
The Single Port Forwarding and Port Range Forwarding pages contain editable lists of applications that demand forwarding of individual ports or port ranges.
The Port Range Triggering page also contains an editable list of applications that need port forwarding.
As opposed to the previous two lists, packets received to certain ports are forwarded only to the recipient that has requested them.
On the DMZ page you can make all ports of a certain machine open.
The QoS page contains traffic priority parameters.
The Administration tab contains settings directly related to the router itself.
Particularly, the Management page allows to specify the parameters of remote router administration, change the password for the Web-interface, enable/disable the use of the UPnP protocol, and save/restore the router’s settings in/from a file.
Enabling/disabling logging is done on the Log page.
Pressing the View Log button will open up a separate window for you to choose the necessary log.
On the Diagnostics page you can do the same as the commands ping and tracert do.
On the Factory Defaults page you can reset the router’s settings to their defaults.
The router’s firmware can be updated using the Firmware Upgrade page.
The last page of the Web-interface is called Status. It consists of informational fields that reflect the status of the router at large as well as of its individual interfaces.
Thus, the router’s options cover virtually all of its areas of application. Each area is quite fully represented in the settings, which is just what you want from a device like the WRT300N.
Now it’s time to check out the router in action. The new wireless communication standard, even in its draft version, is going to have a higher speed than 802.11g, but by how much? Considering that the declared speed of the wireless interface is higher than 100Mbps, the router’s using a Fast Ethernet switch sounds somewhat alarming. It may become a bottleneck for an 802.11n connection. Well, we’ll see soon if it will really be. We’ll also test the router’s bandwidth in other key operation modes and will measure its coverage area.
Here is a list of equipment and software we used for this test session:
We’ll first publish the results of the wired connection.
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The wireless connection in draft 802.11n mode was tested using WPA2 PSK encryption with the AES algorithm. These security settings are the default ones in the draft version of the new standard and are likely to remain such in the final version, too. We offer you test results for both unidirectional and bidirectional connections.
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So, what about the results? The WRT300N router surely does not meet our expectations. Contrary to our apprehensions, the 100Mbps wired interface proved to be enough to reveal the full potential of the wireless communication module. Well, if you calculate the total bandwidth of the bidirectional data transfer, the 100Mbps barrier may be considered as overcome. But we are more interested in the speed of a unidirectional connection and the WRT300N performs somewhat worse here. The speed of 90Mbps is surely high by itself, but does not meet the requirements of the standard. Besides that, the speed of the LAN-WAN connection is low as well.
It’s hard to pinpoint the reason for the low speed of the wireless connection. It could be the chipset or imperfect firmware. We should test at least one more device on the Atheros chipset to make sure. As for the low speed of routing (the low result of the LAN-WAN test), it is indicative of low performance of the router’s processor. The router has more than enough of memory, so its memory subsystem cannot be the reason for that.
Finally we tested the router’s coverage at different distances and with different obstacles. We measured the signal level in five points:
Point 1: Near the WRT300N
Point 2: At a distance of 4 meters without obstacles
Point 3: At a distance of 5 meters + two thin gypsum wallboards
Point 4: At a distance of 6 meters + one brick wall, about 30cm thick
Point 5: At a distance of 17 meters + one thin gypsum wallboard and one 30cm brick wall
Here are the results:
There’s nothing particularly remarkable in the diagram. The speed degenerates as soon as there is an obstacle like a blank brick wall in the path of the signal. It’s sad it degenerates so greatly.
The Linksys WRT300N is a well-made device that is a pleasure to work with. Its original case design will surely appeal to the user, except for people who don’t care at all about how their hardware looks.
The router disappointed us somewhat with its poor implementation of PPTP connection, but this is not the main thing about this model, after all. Its key feature is the wireless interface that supports the draft version of the 802.11n standard. Unfortunately, the WRT300N did not provide the declared bandwidth of 802.11n in our tests. Hopefully, this will be corrected with the release of new firmware which is almost sure to appear.
But generally speaking, there is an uncertainty as to the future of the new communication standard and the already released devices that support it. Although the manufacturers of network equipment claim their devices will all work normally with the final version of the 802.11n standard, they do not offer any warranties. There can be only one warranty, Wi-Fi Alliance’s certification, but this organization is still waiting. And even if the final version will not differ fundamentally from the draft, you still should not hurry with purchasing a new wireless router right now. We are sure there will be a lot of certified models with higher functionality and quality than the existing ones by the time the 802.11n standard has been officially ratified. That is why we cannot recommend the tested router (its version on the Atheros chipset) as an optimal purchase for all users.