The evolution of communication theory is about convey one form of thing and making it better , faster , and more reliable . USB 1 evolved into USB 2 ; FireWire 400 morphed into FireWire 800 ; 10 Mbps Ethernet move into 100 Mbps and then 1,000 Mbps . Where there ’s a option , it ’s between a worse , previous option and the belated and neat .
Not so with Wi - Fi , which has an interesting current trade-off with Apple ’s implementation in hardware and package . You ’re hand a significant pick as to which spectrum band to use or whether to let Mac OS X resolve for you . The choice you make has a huge impact on the distance , validity , and speed you could eke out of a meshing without wires .
Wi - Fi can work over one of two spectrum bands : 2.4GHz or 5GHz . The two bands have quite unlike belongings , and in the past Apple ’s AirPort Base Stations have only been able to use one band at a time . But the AirPort Base Station and Time Capsules released in March 2009 can operate at the same time overbothbands , removing some of the difficultness of build up Wi - Fi meshing that shape best for whatever gadget we attach to them .
The 2.4 GHz bands uses staggered, overlapping channels, which provides few clear options. The 5 GHz band reserves a full channel width without overlap.
Apple also supports both bands in Macs and the Apple TV as internet client . about all Macs with Intel processors work out in both bands , while nearly all Core 2 Duo Macs ( and Mac Pros with Wi - Fi ) also wield the late 802.11n Wi - Fi spec . ( First - coevals Intel Macs have dual - lot funding , but only for an older standard in 5GHz . )
With all this dual - band support , Apple has endeavor to keep you from having to make a determination about which ring to practice , automatically choosing the right oftenness for speed , eubstance , and range base on where your estimator is relative to a base post at any given sentence .
Often , taking Apple ’s suggestions make the most sense , but other times , you want to overrule machinelike choice and other options to produce better , more consistent throughput and range . I ’ll look at common problems and solutions that might plague you in the 2.4GHz and 5GHz band , and then put up advice for manually setting channels in both bands or creating two unparalleled networks with a concurrent dual - band base post .
Check the box to set a separate name for the 5 GHz network, allowing you to force which devices connect to which band.
Band tradeoffs
Wireless mesh work by stimulate a wireless home station transmit data on a given range of absolute frequency to another equipment . Both of the frequency bands used by Apple ’s base stations areunlicensed , which means any individual or governance can build up a machine that mail signals in the frequency compass covered by the band without obtain permission .
Unlicensed stripe require that devices generate no unneeded interference — meaning they expend as petty signal as is necessary to communicate . ( What we think of as interference turns out to be other signal that your finicky receiving gadget does n’t want to hear . ) Equipment that work in these bands must also be tolerant to interference , able to cope with unwanted signals for sort out the entropy it want to pull .
The tradeoffs between 2.4GHz and 5GHz have to do with interference ( almost only in 2.4GHz ) , range , and speed , three properties that all interrelate to one another . The more interference , the less hurrying and image ; the greater range you want , the less speed you could have ; the greater speed you want , the more you have to mitigate interference and work closer to an entree point .
Removing 802.11a compatibility from 5 GHz restricts 802.11a-only devices from slowing down your faster band.
lease ’s break down the band problem by these categories to see what you could do to bear upon each related property :
Interference in 2.4 GHz : The 2.4GHz band is a “ junk ” dance band — it ’s a frequency range that ’s to a great extent polluted . It ’s one of the most to a great extent usedindustrial , scientific , and aesculapian ( ISM ) bands , which have panoptic rules to allow equipment that require to let loose a signal to work in within its confines . ISM devices are n’t used for communication , but produce electromagnetic signaling as part of their operation . And those signal are hindrance .
The 2.4GHz band also has a legion of other competing United States of America ; 5GHz has the clear-cut benefit of have very lilliputian engineering that makes use of the band . Reducing noise lets networks forge at high speeds and greater ranges .
Let ’s look through vulgar 2.4 Gc interference problem . ( Also see “ Troubleshooting AirPort Interference , ” a 2007 article which is a fiddling out of date on some topics , but has more world-wide advice . )
Problem : Your home or office microwave oven oven . It uses the 2.4GHz band to heat water molecule , warming your intellectual nourishment . A microwave oven contains a gadget that generates a roughly 1,000 - W sign oscillating 2.4 billion times a second—2.4GHz . And there ’s your hitch . Microwaves are shielded from emission , but that only reduces the vast majority . There are tiny escape that , while near unmeasurable , are still enough to disrupt Wi - Fi , which practice very gloomy signal levels .
Solution : Stop stimulate popcorn already ! And move your basis post far from your kitchen or breakroom . Or utilize the 5GHz stria , which lack all these interference sources .
Problem : Networking hardware and the 2.4GHz dance orchestra . The dance band share utilize with common purposes , such as Bluetooth , cordless phones , baby monitors , and video cameras . Bluetooth has been harmonized and coordinated with Wi - Fi for years , but other devices are n’t so pleasant . The British spectrum regulator OFCOMjust released a studythat showed interference from competing devices , specially wireless television camera and sister monitor , appeared to be responsible for most Wi - Fi incumbrance , at least in London .
Solution : refresh your cogwheel , tack to 5.8GHz phone or comfortably behaved babe monitor ( some use Wi - Fi directly now ) , or force your Wi - Fi customer to apply 5GHz , if that ’s an option .
Problem : Few non - overlapping line . To make matters — and the potential for hinderance — worse , the 2.4GHz banding is part into overlap canal . The more intersection , the greater the preventive among web located intimately together . In the U.S. , that mean that only channel 1 , 6 , and 11 are mostly in the clear-cut when used in law of proximity . In an urban area or flat construction you might see dozens of networks all attempt to apply the same frequency , and all jar off each other — Wi - Fi does n’t give one exploiter ’s internet penchant to another — reduce throughput and sometimes causing the internet to neglect .
The 2.4 Gc bands uses staggered , overlapping channels , which offer few clear options . The 5 Gc lot reserves a full TV channel width without lap .
solvent : This will sound repetitive , but switching to 5GHz palliate the channel job . ( I ’ll talk about how to drive newer 802.11n hardware to use 5GHz by and by in this clause . ) That ’s because so many more channels are useable — and without any overlap — in the 5GHz band . ( Channel handiness variegate by country , more in 5GHz than 2.4GHz;Apple has a list . )
Range : The bountiful advantage 2.4GHz has over 5GHz is range . The unforesightful wavelengths used in the 5GHz band can not fall into place as well through on the face of it solid objects like bulwark , ceilings , desks , and the great unwashed . The flip side is that 5GHz has different rules about how much power a home post can practice to send signals .
trouble : 5GHz range seems quite small compare to 2.4GHz . you’re able to go one room away and not get a strong 5GHz signaling or see a meshing set to 5GHz .
Solution : In all likelihood , the base post automatically chose a low - numbered 5 gigacycle per second channel ( or you chose it manually ) . In the U.S. , the lower four uncommitted 5 GHz channel can only transmit at 5 percent of the power of the high channels . Apple ’s new foundation station now automatically choose a higher - count channel by default if there ’s one available . If your station is pick out a lower epithelial duct in the 5GHz banding , you may want to override that alternative and select a higher channel manually in monastic order to get the signaling strong suit you deserve .
you may override this by using AirPort Utility and forcing a choice :
( These education are for a simultaneous dual - band base station . For a one - band - at - a - time 802.11n nucleotide station , keep down the Option cay and then tap Channel in step 3 , and then select the transmission channel from the pop - up menu that appears . Radio Mode must be set to “ 802.11n ( 802.11a compatible ) ” or “ 802.11n only ( 5GHz ) ” for 5GHz channel option to look on those 802.11n base stations . )
With the distribution channel extract typeset to Automatic , the base station may be avoiding a higher - numbered channel because of encumbrance , although that should be unconvincing . If you choose 149 or higher and have problems with your internet , test the other three choice in ecological succession ( 153 , 157 , and 161 ) , and if you still have worry , switch back to robotlike and see if problems go away .
Speed : There ’s one more variable in the mixture — velocity , more properly measured as throughput , or the actual amount of data that can be carried over a medium whether radio waves or wire . Wi - Fi ’s speed drop by increments the further you are from a al-Qaeda place with a customer adapter in a computer or handheld , or when interference prevents signals from being cleanly received .
Problem : Slow link speeds . When checking with AirPort Utility ( see check over your Wi - Fi speed ) , an 802.11n gadget is connecting in 5 gigacycle per second at 130 Mbps or slower .
Solution : check that all-encompassing channels are enabled . With 802.11n , a Wi - Fi fundament place can create a connection over a wide channel , which utilise twice the frequency range as a regular groove . Apple and some other makers opted against permit wide-eyed channels in 2.4GHz , because there ’s already so much interference it might have only muddied signals further .
In 5GHz , however , where hinderance is much down in the mouth and channel more legion , Apple automatically enables wide channels . assure that this selection has been wrench on , if you ’re not seeing rates up to 270 Mbps , the highest raw information rate .
trouble : Low data rates . Specifically , when you search in AirPort Utility , you mark low data rates in either or both the 2.4GHz and 5GHz circle .
resolution : If your base station is far away from where your clients are connecting , see if you’re able to move it nearer , or add a 2nd Qaeda post that poke out the connection .
Also look into for hindrance . If removing potential sources or go the base station away from possible root improves speed , that ’s your problem ( and your solution ) .
Tweaking band choices
Apple does as much as possible to make good nonpayment choices with Wi - Fi , but there are cases where you need to pluck the options . You may need to set a communication channel manually , and you may desire to split your 2.4GHz and 5GHz web on a co-occurrent threefold - band base place into two unique networks .
By default option with its new simultaneous dual - band root word stations , Apple has both bands participating ( two separate radios sending freestanding electronic web signals ) using the same web name ( its SSID or servicing set identifier ) .
On the customer side , with Mac OS X 10.5.6 or by and by and theAirPort Client Update 2009 - 001installed , your Mac uses a diverseness of technique to evaluate whether it should plug in to the 2.4GHz or 5GHz interlingual rendition of the same net if the mesh ’s constitute the same .
Leopard looks at connection sign strength for the web it ’s on and same - named networks in the vicinity . When performance or signaling intensity drop , Leopard evaluates whether it ’s well off to go further with 2.4GHz or attempt to continue quicker with 5GHz .
This pairing of two circle and client hardware that picks the optimal band often works intimately . But there are three reasons that you might want to have singly - named networks for each band .
While the previous version of Leopard is smart about which band it take , quondam versions of Mac OS X and computer hardware from other companies that can work on either stripe expend less clever methodology . choose 2.4GHz might ensue in a very dull or erratic connection when the sign strength is strong , because mesh congestion and interference are n’t measured in 2.4GHz when Leopard chooses to switch over .
Another reason would be to keep some devices off of your 5GHz band , forcing 802.11n clients to utilise 5GHz solely . This frees up way in the 2.4GHz band and guarantees faster speeds for 802.11 machine . For case , most Intel Core Duo Macs can employ the 802.11a touchstone . ( The faster 802.11n standard come with Core 2 duette - based Macs . ) If you have an older 802.11a / b / g machine , you might want to sequester it on the 2.4GHz band in edict to keep it from reduce the fastness of your 802.11n - based 5GHz meshwork .
also , you might want to verify your newest appurtenance only utilize 5GHz and never duck down into 2.4GHz . Apple tries to flip to 2.4GHz only when it ’s necessary — say , the signal performance fades below an optimum level — but you might choose to see the stave and move closer rather than drop into a crowded circle .
Check the box to countersink a freestanding name for the 5 Gc web , allowing you to squeeze which gadget connect to which band .
To split the band in two :
There ’s an alternate manner to employ AirPort Utility to keep 802.11a / b / g gadget from connecting to your internet on the 5GHz band : In the Wireless tab ’s Radio Mode pop - up card , you may break surplus choices for what banner are supported in each spectrum banding by holding down the Option key and clicking on the card .
Removing 802.11a compatibility from 5 GHz throttle 802.11a - only devices from slowing down your faster circle .
By nonremittal , full rearwards compatibility is take : 802.11b / g / n for 2.4 gigacycle per second and 802.11a / n for 5GHz . alternatively , choose “ 802.11n only ( 5 Gc ) – 802.11b / g / n ” to disable 802.11a in 5GHz .
Clear signals ahead
take what makes each band check makes it more potential that you ’ll be able to create a web that ’s robust and fast , make systematically without dropout or drop in speed .
[ Glenn Fleishman writes always about networking , mostly wireless , and is the author ofTake Control of Your 802.11n AirPort connection(Take Control Ebooks ) . ]
