Improved WiFi Performance

One of the more notable changes in the 2011 MacBook Pro lineup is a completely different WiFi chipset and subsequent RF design. The previous 2010 MacBook Pro included 802.11a/b/g/n support using a BCM4322 which included full 2x2 MIMO support, meaning two spatial streams were supported. Bluetooth 3.0 was provided by a BCM2070, and the whole solution was simply a BCM954224HMB reference design.


2011 MacBook Pro WiFi+BT Module—Courtesy iFixit

Back when the new Airport Extreme (Simultaneous Dual-Band II) launched, it included one little-hyped feature. One of the most notable improvements over the previous design was inclusion of a full 3x3 radio—again 3 spatial stream support. At the time, there were no Apple products that could actually use 3 spatial streams, and as a result many assumed the feature was completely locked down.


My wall-mounted Airport Extreme (Simultaneous Dual-Band II)

The Airport Extreme has had 3 spatial stream support for a long time to little fanfare. The Airport Extreme still only allows 20 MHz channels on 2.4 GHz spectrum. Other WiFi AP vendors ship firmware which will automaticaly selects 40 MHz channels on 2.4 GHz spectrum per WiFi Alliance rules, but Apple uniformly uses 20 MHz channels on 2.4 GHz. It's a design choice Apple made a while ago which still exists to this day – for two reasons. The first is that it prevents you from being, well, less than courteous and eating up to over 80% of spectrum on the already crowded 2.4 GHz ISM band with one AP. Apple's rationale for disabling 40 MHz channel support on the 2.4 GHz spectrum (for both clients and APs) is that Bluetooth needs lots of bandwidth to hop around on, and already a wide variety of Apple desktop and notebook products come by default with Bluetooth peripherals. Maintaining a good A2DP stereo stream for example requires considerable 2.4 GHz bandwidth. Instead, if you really want 40 MHz channels Apple recommends using 5 GHz, which Apple clients and Apple APs both allow to work with 40 MHz channels.


2011 MacBook Pro WiFi+BT Module—Courtesy iFixit

The 2011 MacBook Pro refresh is the first line of Apple products to bring 3x3 radios that can finally enable faster transfer rates and better performance at the edge of WiFi range. 3x3 MIMO support is starting to become relatively common in the PC notebook space, but this is the first for Apple. Inside the 2011 MacBook Pro is a BCM4331 and three clearly U.FL antenna connectors (on the left) for WiFi, as opposed to two in the previous design.

The fourth on the right is for Bluetooth, which remains 3.0 and provided by the same BCM2070 as previous models. Interestingly enough, though the Bluetooth controller is the same, the 2011 MacBook Pro includes newer firmware (37 vs 20), and software (2.4.3f1 vs 2.3.8f7). Hopefully at some point the older design will see a firmware update and bring whatever changes and improvements were made. Though the software versions are different, we couldn't detect any notable differences between the two in practice.


Left: 2010 MBP Bluetooth Hardware, Right: 2011 MBP Bluetooth

However, there's a dramatic improvement in both WiFi range and performance between the 2010 and 2011 refresh. With 400 ns guard intervals 40 MHz channels, 64-QAM modulation, each spatial stream adds n*150 Mbps. With 20 MHz channels, it's 72.2*n Mbps. For example, 1 spatial stream has a data rate of 150 Mbps, 2 has 300 Mbps, 3 has 450 Mbps, and so forth all the way up to 4 spatial streams and 600 Mbps as defined in the 802.11n specification. The reality of the matter is that what physical layer rate you'll see depends on the modulation and coding scheme and how many streams are going. You can look those up at any time by holding option and clicking the WiFi indicator, and looking them up in a table.

We tested a 15" 2011 MacBook Pro alongside a 15" 2010 MacBook pro connected to an Airport Extreme (Simultaneous Dual-Band II) running latest firmware. I originally suspected that 3 spatial stream support wasn't enabled, and that Apple would push a firmware update out right after their first 3 spatial stream products started shipping. Interestingly enough, it's always been there, enabled, this is just the first client I've gotten my hands on that does it. I'm not a huge fan of the Airport Extreme (I use a WRT54G-TM with Tomato and a WRT-600N with DD-WRT), but it's the only thing on hand with 3x3 MIMO. I tested in four different locations in my house—in my office, living room, kitchen, and outdoor patio. The base station is in my office mounted on the wall close to the ceiling, and those locations are subjectively ordered from best to worst.

To test, I initiated a large transfer over SMB (from a Windows Server 2008 R2 install with a 5 TB RAID5 array connected over gigabit ethernet) on each client, continually pinged AT, and at each location checked the reported transmit rate and RSSI. What we're reporting here is again the physical layer link. I'll show in a second that real-world transfers also improved, this just gives some perspective for what raw link rates are being negotiated at each location.

WiFi Transfer Rate Differences—802.11n
  2011 MacBook Pro 2010 MacBook Pro
  RSSI Transfer Rate (Mbps) RSSI Transfer Rate (Mbps)
Location 1—Office -44 450 -42 300
Location 2—Living Room -61 130 -64 117
Location 3—Kitchen -69 117 -68 78
Location 4—Outdoor Patio -85 20 -84 13

In most cases, RSSI is within the margin of error. RSSI is generally not something you can compare, but since both wireless chipsets are Broadcom and the numbers are so close, it seems they're reported the same way and probably just dBm. Just know that generally it doesn't work that way unless you're lucky. What's important, however is that the negotiated link speed is noticeably better in essentially all locations on the new 2011 MBP. Even when the extra antenna isn't being used for a spatial stream of its own, it's actively improving link quality and helping the new MBP negotiate higher physical layer speeds.

So how much of a difference does 450 Mbps 3x3 make over 300 Mbps 2x2? With both in the exact same spot in my office, I saw throughput of 98.1 Mbps on the 2010 MBP compared to 113 Mbps on the 2011 MBP. The modest 15% improvement over the previous generation's wireless chipset isn't dramatic, instead the dramatically improved range is.

110.28 Megabits/s over WiFi. I later saw sustained 113 Megabits/s.

Subjectively, I found many more APs visible with the new MBP. I was able to cling onto my AP all the way out to the curb (just like smartphones) when connected on 2.4 GHz, something the old generation just couldn't do.

The only complaint I have about the new wireless chipset is that it seems to hunt around for what rate it wants negotiated. I saw a number of different MCS (modulation coding scheme) values with the 2011 MBP in the exact same place. Link rates from just below 300 Mbps all the way up to the expected 450. It seems to settle out at the expected 450 Mbps in the same room as the AP, it just takes a while, whereas other 2x2 stacks I've seen always lock onto 300 Mbps and stay there in the same room and position.

Display Quality Thunderbolt
POST A COMMENT

197 Comments

View All Comments

  • brettski - Thursday, November 10, 2011 - link

    Total NYC sales tax is 8.875%.
    NY state tax is only 4.5%
    Reply
  • brettski - Thursday, November 10, 2011 - link

    i'm sorry... state is 4%, city is 4.5%, plus Metropolitan Commuter Transportation District surcharge of 0.375%= 8.875% sorry... mixed up the city and state rates. Reply
  • gstrickler - Thursday, March 10, 2011 - link

    What are you talking about? Most of us non-gamers don't even need a dedicated GPU, much less 256MB of graphics memory. I'm currently running on a late 2007, 15" MBP which has an 8600M GPU with 128MB of graphics RAM, and I only use it because there is no IGP on this machine. Once you get to the level of the Nvidia 9400M, IGP is plenty for a non-gamer, and even 32MB allocated to graphics RAM is more than adequate. The exception is if you need OpenCL support, since Intel's IGPs don't support OpenCL.

    I wish Apple offered a 13" MPB with a higher resolution (1440x900) matte display or a 15" with AES-NI and without a dGPU. I could use the faster CPU and HT, but I don't really need quad-core (but it's nice to have it available when on AC power), and battery life is far more important to me than a GPU or maximum CPU speed.

    In fact, what I would really like is a 15" with matte display, no dGPU, Core i7-2720QM (for AES-NI support) with the ability to disable 2 cores/4 threads when on battery power. The 2011 15" lets me get close, if I use gfxcardstatus to disable the dGPU. If I can get software to disable 2 cores when on battery, it'll give me everything I'm asking for, but at a fairly hefty premium ($+150 for the matte display, $+400 for the Core i7-2720QM and Radeon 6750M + 1GB that I'll never use). Of course, what that means is that I'll either get the entry level 15" without AES-NI support and use gfcardstatus to disable the dGPU, or I'll wait for the next update and see if the options are any better.

    Notes to Apple:
    1. Make a matte screen an option on all machines, for no more than a $50 premium (no forced upgrade to a higher resolution)
    2. Offer a 15" without a dGPU (e.g. make the dGPU a separate plug-in module)
    3. Offer a 1440x900 screen for the 13" MPB.

    I doubt I'll see any of those, but it doesn't hurt to ask.
    Reply
  • tipoo - Thursday, March 10, 2011 - link

    "Most of us non-gamers don't even need a dedicated GPU"

    Most people don't need a truck, that doesn't mean no one does. This is branded as a pro machine, and at nearly 2 grand the GPU doesn't fit the bill.
    Reply
  • alent1234 - Friday, March 11, 2011 - link

    MAcbooks are thin, long battery life, nice screen and good build quality first. specs second. until sandy bridge came out laptops with long battery life cost just as much as a macbook or more.

    a lot of the people that buy these are mobile pro's who need to use a laptop for hours while away from a power source
    Reply
  • sync216 - Thursday, March 10, 2011 - link

    256MB is fine for the 64xxM series GPUs. The performance improvement going to GDDR5 and a faster GPU is much higher than the improvement from 256 to 512 would have given. For customers who really need the additional graphics performance (and corresponding graphics memory) apple is offering the very fast 6750M with 1GB. Reply
  • Demon-Xanth - Thursday, March 10, 2011 - link

    ...Apple is more like Sony than Acer? Their core buisness is no longer computers, but gadgets. Reply
  • michael2k - Friday, March 11, 2011 - link

    Um, this was evident in 2001 when the Titanium PowerBook was first unveiled, then the iPod later that year, then the music store in 2004, etc.

    Also, you have it backwards, their core business is computers, they just happen to know how to turn computers into gadgets. They treat the iPod like a computer (firmware updates on a regular basis), which means they aren't disposable. Contrast that to the average phone OEM with Android who won't see updates for longer than 6 months, where Apple pushes updates to their iPhone for over 29 months.
    Reply
  • jameskatt - Friday, May 06, 2011 - link

    Nearly all of Apple's products are computers:

    Mac Pro = desktop expandable computer running OS X
    iMac = all-in-one desktop computer running OS X
    Mac Mini = non-expandable desktop computer running OS X
    MacBook Pro = high end laptop computer running OS X
    MacBook Air = high end netbook computer running OS X
    MacBook = basic laptop computer running OS X
    iPad = tablet computer running OS X
    iPhone = handheld tablet computer with phone running OS X
    iPod Touch = handheld tablet computer running OS X
    AppleTV = multimedia appliance computer running OS X

    OS X has two variations - Mac OS X and iOS. The core operating system is the same for both.

    Apps for both are written using Apple's XCode Development System.
    Reply
  • quiksilvr - Thursday, March 10, 2011 - link

    I'm surprised SSD isn't standard to begin with. $1199 for a 13" laptop and you don't even get dedicated graphics? Seriously? The HDDs aren't even 7200rpm. This is insulting to the nth degree.

    If you want a solidly built, well-spec'd, thin and fairly priced system, get the Envy 14. You get 7200rpm HDD, dedicated graphics, an HD webcam with TWO microphones (necessary for sound cancelling), a backlit keyboard and even Photoshop and Premiere.

    Until Apple drops their prices to a realistic and reasonable level, avoid it completely.
    Reply

Log in

Don't have an account? Sign up now