![]() ![]() It was also used in the Samsung Galaxy S II. The iPhone 4S uses the Broadcom BCM4330 - at the time last year Broadcom's newest WLAN - Bluetooth, and FM combo chip. But historically, Apple has sourced the radio from Broadcom. We don't know exactly, yet, until the phone is released and it gets the "tear-down" treatment. The chip vendors will need to tweak their probing and selection algorithms to tighten this up, and there are some new standard features coming that will help. this is probably due to the larger number of channels that must be scanned. Higher-gain antennas and/or increased transmit power (though this is regulated by the Federal Communications Commission) can offset the 5GHz propagation.Īnother issue is how the phone will decide which band to use: Will it be set (or settable) to "prefer" 5GHz over 2.4GHz, so the choice is automatic? Or will you be prompted for your preference? Or do you have to manually select one or other?Ī June 2012 blog post at WLAN vendor Aruba Networks noted that the vendor's testing of 5GHz mobile devices found "that handover performance for a fast-moving device is not quite as good when both bands are enabled as it was for 2.4GHz only. From a client perspective, for example using a Starbucks hotspot or a well-designed hotzone or enterprise WLAN planned for 5GHz, users often may not be affected by either of those characteristics. That means it propagates shorter distances. "I have my fingers crossed that the iPhone 5 delivers similar results."Īt the same power level, a 5GHz signal has a shorter wavelength than a 2.4GHz signal. "60Mbps is a serious amount of throughput to a mobile device under real-world conditions!" he says. He speed-tested his Samsung Galaxy S III smartphone in the network: 60.33Mbps download, and 58.78Mbps upload. ![]() Kish was recently at the Time Warner Cable Arena in Charlotte, N.C., where a Ruckus Wi-Fi network had been installed, for a live event. ![]() In all cases the actual throughput users get is much less. 802.11a offers the same 54Mbps, but in theory its capacity is much larger due to the larger number of 5GHz channels.įor 802.11n, the numbers are even greater: 150Mbps per channel, for 450Mbps in the 2.4GHz band, and 3.45Gbps in 5GHz. "The higher aggregate capacity is mostly a function of the much larger amount of bandwidth (e.g., the number of channels) available in the 5GHz band as well as the more capacity-favorable propagation characteristics of the 5GHz spectrum," Kish says.įor example, an 802.11g network offers 54Mbps of capacity on each of three 2.4GHz channels, for a total capacity of 162Mbps. Kish defines aggregate capacity as "the total capacity available to all simultaneous users across all of the APs in a given area." "It increases aggregate capacity in challenging environments by something like a factor of 10-12 compared to 11n on 2.4GHz." "5GHz support on an iPhone is a wonderful thing for Wi-Fi," says William Kish, CTO and co-founder of Ruckus Wireless. This would mean using 802.11n, with a single data stream, and a 40MHz channel. Says that iPhone 5 will deliver a maximum 150Mbps data rate. In the 802.11n radio standard, one way that data rates increase dramatically is by combining (or "bonding") two of these channels into a wider 40MHz "pipe." In 2.4GHz, you only have the three channels, and can create only one 40MHz channel. And fewer channels means lower aggregate capacity on the network side.īy contrast, the 5GHz band has, for now, many fewer Wi-Fi clients, and 23 20MHz-wide, non-overlapping channels. Second, the 2.4GHz band has only three non-overlapping, 20MHz-wide channels: In crowded environments - lots of access points, lots of clients - that can make it hard to get a channel connection. Vendors and IEEE are working on various technologies to address this, including shifting more control over the connection, and optimizing it to the access point/network, instead of the client. 802.11n, which has much higher data rates, can run on either band but most smartphones today that have 11n, such as iPhone 4 and 4S, only run it on 2.4GHz.Īnd even when the client radio could run on either band, a lot of them today still "decide" to connect on 2.4GHz and stick with it, even when a better connection is available. ![]() 802.11a, which so far has not been widely used, runs on 5GHz. There are lots of devices are using it: Lots of other Wi-Fi devices, including embedded Wi-Fi radios, but also non-Wi-Fi radios like Bluetooth, cordless phones, baby monitors, and stuff like microwave ovens.Ĭlient Wi-Fi radios that support only 802.11g can only connect on 2.4GHz. First, because the 2.4GHz band is crowded, and therefore has a greater chance of interference. ![]()
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