What is 802.11ac? IEEE 802.11ac is a wireless networking standard in the 802.11 family (which is marketed under the brand name Wi-Fi), developed in the IEEE Standards Association process, providing high-throughput wireless local area networks (WLANs) on the 5 GHz band.
This specification has expected multi-station WLAN throughput of at least 1 gigabit per second and a single link throughput of at least 500 megabits per second (500 Mbit/s). This is accomplished by extending the air interface concepts embraced by 802.11n: wider RF bandwidth (up to 160 MHz), more MIMO spatial streams (up to eight), downlink multi-user MIMO (up to four clients), and high-density modulation (up to 256-QAM). New technologies introduced with 802.11ac include the following.
Extended channel binding Mandatory 80 MHz channel bandwidth for stations (vs. 40 MHz maximum in 802.11n), 160 MHz available optionally (in future wave II).
More MIMO spatial streams
Support for up to eight spatial streams (four in SonicPoint AC/N2).
Higher Rate Modulation
Support 64-QAM, rate 5/6 and optionally 256-QAM, rate 3/4 and 5/6 (in future wave II).
MAC modifications (mostly to support above changes) .
Coexistence mechanisms for 20/40/80/160 MHz channels, 11ac and 11a/n devices.
Adds four new fields to the PPDU header identifying the frame as a Very High Throughput (VHT) frame as opposed to 802.11n's High Throughput (HT) or earlier. The first three fields in the header are readable by legacy devices to allow coexistence.
Beamforming with standardized sounding and feedback for compatibility between vendors (in future wave II) .
Downlink Multi-user MIMO (in future wave II) .
How about the backwards compatibility with 802.11n/a/b/g? IEEE 802.11ac operates only in 5GHz. SonicPoint ACe and ACi are capable of running 802.11n in 2.4GHz, and 802.11ac in 5GHz. 802.11ac is carefully designed to be maximally forward and backward compatible with 802.11a/n devices. In fact, the 802.11ac design is even simpler and more thorough than 802.11n compatibility with 802.11a devices.
An 802.11ac device must support all the mandatory modes of 802.11a and 802.11n. So an 802.11ac AP can communicate with 802.11a and 802.11n clients using 802.11a or 802.11n formatted packets. For this purpose it is as if the AP were an 802.11n AP. Similarly, an 802.11ac client can communicate with an 802.11a or 802.11n access point using 802.11a or 802.11n frames. Therefore, the emergence of 802.11ac clients will not cause issues with existing infrastructure.
What is the latest 802.11ac standard? IEEE 802.11ac-2013 standard was developed from 2011 through 2013 and approved in January 2014.
What standard is SonicPoint ACe and SonicPoint ACi based on? IEEE 802.11ac-2013 wave I.
Can all 802.11ac wireless clients work with SonicPoint ACe or SonicPoint ACi? All wireless clients that are fully compatible with IEEE 802.11ac and above can work with SonicPoint ACe and SonicPoint ACi.
When to Upgrade to 802.11ac? IT administrators are in the fortunate position to be able to pick between two great technologies 802.11n with A-MPDU, MIMO, and speeds from 65 to 450 Mbps within 40 MHz, and (2) 802.11ac with A-MPDU, MIMO, and speeds from 290 to 1300 Mbps within 80 MHz. 802.11n is available today and is sufficient for many customer use cases. 802.11ac will be the flagship of wireless LANs, which can provide full HD video at range to multiple users, higher client density, greater QoS, and higher power savings from getting on and off the network that much more quickly.
Most IT administrators deploy new APs at the same time as they fit out a building or retrofit a space. For these, we recommend installing SonicPoint N2 today, because of the sheer value of 802.11n. On the other hand, for investment protection and potential high throughput requirement, it is most desirable to install SonicPoint ACe/ACi, since the incremental value of 802.11ac exceeds any reasonable price differential. Also, IT administrators typically upgrade their APs on a three-, four-, or five-year schedule. These IT administrators should continue to upgrade their APs on schedule, since the capability of 802.11ac APs significantly exceeds the capabilities of previous generations of APs.
What is 80MHz and channelization? 802.11ac adopts a keep-it-simple approach to channelization. Adjacent 20-MHz subchannels are grouped into pairs to make 40-MHz channels, adjacent 40-MHz subchannels are grouped into pairs to make 80-MHz channels, and adjacent 80-MHz subchannels are grouped into pairs to make the optional 160-MHz channels. A BSS (that is, AP plus clients) uses the different bandwidths for different purposes, but the usage is principally governed by the capabilities of the clients.
In the United States, there are 20 to 25 20-MHz channels, 8 to 12 40-MHz channels, 4 to 6 80-MHz channels, and 1 or 2 160-MHz channels. These numbers are ranges because of the evolving regulatory issues surrounding the different spectrum noted in the figure.
What if most clients at a deployment are still 802.11n clients with 40 MHz maximum? Does deploying 802.11ac APs mean fewer channels and more interference? As you would expect from an IEEE standard, the answer is a resounding “no.” It is entirely allowed for two 80-MHz 802.11ac APs to select the same 80-MHz channel bandwidth but for one AP to put its primary 20-MHz channel within the lower 40 MHz and the other AP to put its primary 20-MHz channel within the upper 40 MHz. What this means is that 802.11n clients associated with the first AP can transmit 20 or 40 MHz as usual, at the same time that 802.11n clients associated with the second AP transmit 20 or 40 MHz in parallel. What is new in 802.11ac is the ability for any 802.11ac client that sees the whole 80 MHz as available to invoke a very high-speed mode and to transmit across the whole 80 MHz.
What’s the difference between SonicPoint N2 and SonicPoint N Dual Radio (NDR)? SonicPoint N Dual Radio only supports 2X2 MIMO, while new SonicPoint N2 can support 3X3 MIMO to reach theoretical throughput 450Mbps.
How far can 802.11ac signal transmit? It all depends on the environment. Another way to understand this is by asking the minimum RSSI required for 802.11ac. The graph below shows, for instance, that whereas -64 dBm was sufficient for the top rate (72 Mbps) of 802.11n in a 20-MHz channel, the requirement rises to -59 dBm for the top rate (86 Mbps) of 802.11ac, single-stream in a 20-MHz channel, and to -49 dBm for the top rate (866 Mbps) in a 160-MHz channel. Right now SonicPoint ACe and ACi support 80MHz channel, to achieve the top rate -52 dBm is required.
The following table shows theoretical throughput for single spatial stream in different modulation, short guard interval, and channel bonding settings.
Why my wireless client can not connect or can not stay connected? Please check the following things when wireless client doesn’t connect: We name SonicPoint ACe SonicPoint ACi, and all other SonicWall 802.11n capable wireless devices as SonicWall Wireless.
Download preference and TSR from the SonicWall Wireless and prepare for sending to us if you still have issues after going through the following steps.
Check if your wireless client adapter has the latest and valid driver installed. Old driver software or improper driver might generate miscellaneous connectivity and performance issue.
Check if the RF spectrum is the same for both SonicWall Wireless and wireless client. SonicPoint can operate in either 2.4GHz or 5GHz, or both at the same time. Some wireless client doesn’t support 5GHz.
Check if WLAN Radio is enabled and schedule is properly set up. If you are not sure about schedule, please set it to “Always on”.
Check if the Radio Mode is compatible between SonicWall Wireless and wireless client. “802.11ac Only” mode can merely support 802.11ac client, all legacy wireless clients can not work in this mode. If you have legacy 802.11 n/g/b wireless client, please select “802.11 n/g/b mixed mode”. If 802.11 ac/n/a mixed mode is chosen, please set Radio Band to Auto or standard - 20MHz Channel for legacy client.
Set the Channel to Auto or pick up the favorite one after you complete the RF survey in your open air environment. RF survey can provide more data regarding the noise and interference which will definitely affect the connectivity and performance. Setting the channel with the least interference is crucial to maintain good wireless connectivity and throughput.
Check if Authentication Type and Encryption Settings are matched between SonicWall and wireless client. Some legacy wireless clients can not support WPA or WPA2, if you configure SonicWall Wireless using these security settings, you will have to upgrade your wireless client to support these security settings as well.
Check if “Hide SSID in Beacon” is enabled. Wireless client may not be able to list your SonicWall SSID in site survey result with this setting on. And for wireless client which is managed by Windows Wireless Zero Configure, you also need to enable “Connect to SSID even it is not broadcasted” checkbox in Windows Wireless Zero Configure.
Check Transmit Power to make sure you get good signal strength from wireless client. Inadequate Transmit Power can cause serious connectivity and performance problem. However excessive Transmit Power may generate noisy or interference to other wireless devices.
Check Beacon Interval to make sure your setting can comply with the wireless client’s requirement. Usually 100ms works for most of wireless clients.
Check the distance and environment between your wireless client and SonicWall Wireless. The connectivity and throughput are impacted by these factors. Being too close is as bad as being too far to degrade the performance and link quality for some of wireless clients. And the media which blocks RF radiation can not be in the middle of clients and SonicWall Wireless.
Wireless communication is not one-way, but rather requires a solid round-trip connection with equal performance both to and from each client device. Many customers do not explicitly consider the available power, or signal strength, from the client back to the AP. AP-client power mismatches to be a major cause of many client device connectivity problems. The reason this is a problem is that client devices typically operate at lower transmitter power levels than APs. The worst combination is high power APs with low power clients. A symptom of this problem is having "5 bars" on the client device, but still having a poor connection. The client can hear the AP but the AP cannot hear the client. In this scenario, wireless client needs to move closer to AP to allow frame sent from client to reach APs.
Check if Maximum Client Association number has been reached.
Check MAC Filter list to make sure your client is not blocked by this feature. Please turn it off if you are not sure about your ACL setting. If you want this feature enabled, please make sure your client MAC address is added into ACL Allow Group.
Check if wireless client is in Power Saving mode, which can inhibit the wireless client to actively connect to any AP to save battery power.
Please make sure you only have one Wireless client utility to control your client. Windows Wireless Zero Configure and vendor’s specific utility can not work at the same time. For 802.11n high throughput support, vendor’s specific client utility works better than WZC generally since it usually provides high throughput options.
Please provide wireless RF site survey or packet sniffer result if possible to help us understand more.
How to configure Transmit Power and Channel? RF survey is always recommended before planning transmit power and channel setting. The whole idea of these two parameters is to provide the decent signal strength and coverage for the planned service area with the least interference. In 2.4GHz only channel 1, 6 and 11 are non-overlapped from each other. If any access point nearby has been operated in one of them, SonicWall Wireless should NOT reuse that.
Too low transmit power can not provide enough signal and coverage. However too strong transmit power will generate interference to your neighborhood. The careful measurement is required to determine the power level. For larger coverage deployment, the dedicated high gain antenna can be considered to replace the existing antenna.
Is there any settings I need to configure to get higher throughput? Apply channel bonding (40MHz for 2.4G, 80MHZ for 5G radio), enable frame aggregation, and short guard interval. These will take effect if the wireless client support IEEE802.11ac-2013 standard features. The wireless client should have the same option to be enabled to get high throughput.
Which spectrum band does SonicPoint ACe/ACi/N2 support? SonicPointACe/ACi/N2 supports both 2.4 GHz and 5 GHz bands. SonicPointACe/ACi has 802.11AC capability, while SonicPoint N2 doesn’t.
What is the difference between 2.4GHz and 5GHz spectrum band? SonicPoint ACe/ACi/N2 supports both 2.4 GHz and 5 GHz band. They are different RF band.
Which encryption algorithm can provide better throughput? RC4 based encryption algorithm including WEP and TKIP will degrade the throughput. WPA2 AES is highly recommended for secure wireless connection.
Why is the data throughput not good while wireless client’s signal strength is excellent? Throughput is possible not at the best level when there are many wireless devices contending for the radio environment. You can use SonicWall Wireless-N “Wireless > IDS”, “SonicPoint > IDS” or third party tools to determine whether there are too much interference nearby.
What is the requirement for SonicPoint deployment? Before deployment SonicPoint ACe/ACi/N2, it is very important to find a fair clean channel throughput site survey.
How to do a site survey? Besides SonicWall Wireless-N “Wireless > IDS” or “SonicPoint > IDS”, other wireless sniffers that can do site survey including NetStumber, AiroPeek, etc.
What information should I provide in order to get efficient support? Your detailed symptom report about the problem will be very helpful for us to solve it efficiently. Generally we expect to see TSR report and Preference file downloaded from your SonicWall firewall. Packet capture using site survey tools will be greatly useful. And the wireless client hardware model, OS version, managing utility as well as driver version are all required for connectivity issue. Another useful information is SonicPoint log. You can login in diag.html page, enable SonicPointN log, and download SonicPoint log from SonicPoint > SonicPoints page.
How to make my legacy 802.11n/a/g/b clients work with SonicWall 802.11AC radio? SonicPoint AC 2.4GHz radio supports five radio modes: 802.11g/b Mixed, 802.11g Only, 802.11b Only, 802.11n/g/b Mixed, and 802.11n Only. If you only have legacy 802.11g/b clients, you can select 802.11g/b Mixed, 802.11n/g/b Mixed, 802.11g Only, or 802.11b Only.
SonicPoint AC 5GHz radio can support 802.11n/a mixed, 802.11n Only, 802.11ac/n/a mixed and 802.11ac only modes. When 802.11ac/n/a mixed mode is selected, Radio Band must be Auto or Standard 20 MHz. Wide 40MHz/80MHz may not work for 802.11g/b clients. When 802.11n/a mixed is selected, Radio Band should be Auto or Standard 20MHz.
Can Short Guard Interval feature also work on 20MHz? No, SGI can only work on 40MHz/80MHz channel width.
Can Inter-wireless clients traffic achieve comparable high throughput as wireless-wired traffic? No, given the nature of half duplex mode of wireless RF radio, inter-wireless clients traffic has lower throughput than wireless-wired traffic.
I have an ASUS USB-AC56 802.11ac, but I’m only able to connect at 867Mbps. Why? The IEEE802.11ac maximum throughput (1300Mbps) requires all 802.11ac-2013 features to be supported by both Access Point and wireless client. The most important features include 80Mbps channel bonding, 3X3 MIMO spatial streams, frame aggregation, and short guard interval. SonicWall SonicPoint AC supports all of the above features in 5GHz band and is completely compatible with IEEE standard. The ASUS USB-AC56 AC NIC only supports 2X2MIMO spatial streams, so the max theoretical speed is 867M.
My laptop connectivity seems up and down. Why? Usually if you have both Windows WZC and Vendor’s specific managing utility working at the same time, both of them will try to control the wireless connection and conflict with each other. This will cause your connectivity up and down. You need to shutdown one of them to maintain the stability of wireless client. And you also need to check the power saving option on your wireless client, which will disassociate wireless client based on power consumption status on the laptop.
Noise and interference will also affect the connectivity. The mobile device such as hand held phone and microwave can all operate on 2.4GHz spectrum band, which can overwhelm the normal 802.11 wireless LAN traffic and cause connection loss. The nearby access point which is operating in the overlapped channel will generate interference and impact the connectivity as well as performance.
Another major reason to cause connectivity is wireless client driver. Please check the driver status of your wireless client from Vendor’s support web site and do upgrading to include their latest fixes as well. EXAMPLE: Intel 4965N driver has been upgraded to 188.8.131.52 by Intel on 1/5/2009 from http://downloadcenter.intel.com, if you are still holding old version of 11n driver, you may experience connectivity lost from time to time.
For wireless clients which are operated on Windows Vista OS, please find out the best driver version based on the vendor’s recommendation. For example Lenovo released stable driver 184.108.40.206 from http://download.lenovo.com for existing 802.11a/b/g WLAN NIC. Please keep using this stable version instead of upgrading to 220.127.116.11 since the new driver is released for 802.11n capable WLAN NIC only.
My wireless client can ping WLAN interface, but has trouble to access Internet. Is this a wireless issue? Most likely not a wireless issue if your wireless client can ping WLAN interface IP address (172.16.31.1). You may check your WAN setting, firewall rule and other customized configuration. System log will provide details if your packet gets dropped by SonicWall firewall.
My wireless client can only support WPA, can SonicWall Wireless-AC be set up as WPA2? WPA2 and WPA have different security criteria. If your wireless client can only support WPA, then SonicWall Wireless-N has to be configured as WPA or WPA2-AUTO.
Why does my 802.11ac card cannot get good throughput? Please make sure to review the driver properties to enable high throughput specific features, such as 80MHz/40MHz channel width, frame aggregation and short guard interval.
Why can my client only connect to non WPA/WPA2 SSID through Windows Zero Config? The windows zero config must be upgraded to have Windows Hot Fix KB893357 to be able to support WPA/WPA2. And another problem caused by WZC is when user initially sets SonicWall Wireless-N/AC as non-WPA/WPA2 SSID and connects to it, WZC will automatically create the profile in preferred wireless devices list with non-WPA/WPA2 authentication method. After SonicWall Wireless-N is changed to WPA/WPA2 authentication method, even WZC has already been upgraded to support WPA/WPA2, the existing preferred profile will still block wireless client to associate to SonicWall Wireless-N/AC until user removes the existing profile and reconnects.
Why does beacon happens later in 5GHz comparing with 2.4GHz? In 5GHz band, there are more available channels to be scanned and analyzed to prepare for operation. And DFS procedure also kicks in to prevent the current device from being conflicted with Radar Signal. All these processes postpone launching final beaconing in 5GHz band.
Why can’t I transfer large file over wireless when IPS/GAV is enabled? You may disable IPS/GAV at first to isolate if the failure is caused by IPS/GAV packet drop. If you still have problem after doing that, please check if wireless connectivity is not stable to cause TCP connection timeout.
Can I just import preference setting from previous SonicWall SonicPoint such as SonicPoint-N/Ni/Ne/N Dual Radio and assume it should work perfectly? In terms of wireless setting, you may check the transmit power, beacon interval and some other advanced radio configurations. The transmit power can be raised higher if you want the stronger signal strength. And the beacon interval can be adjusted to be smaller if you want the faster association. If you do not have the 802.11ac capable WLAN NIC installed on your wireless client, you can set the radio mode to be 802.11ac/n/g mixed or 802.11n/g only.
Why does my wireless client work better in legacy wireless access point? The reason may come from the following aspects.
Legacy wireless access point may have more favorable configuration to your wireless client, such as transmit power, channel setting and beacon interval. Therefore please double check your wireless access point configuration based on “Q: Why my wireless client cannot connect or cannot stay connected?” .
Current wireless client needs to upgrade the driver software to be able to work with the latest wireless technology.
In terms of signal strength, some legacy wireless access point may not be strictly conforming to FCC regulatory to generate illegally high power to provide strong signal strength to wireless client. However it is not allowed and should be risky in customer’s deployment.