Editor's note: This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.
With the barrage of data traffic hitting corporate and mobile networks from Wi-Fi-enabled smartphones, iPads and other bandwidth-hungry devices, enterprises and carriers must contend with data volumes that often exceed network capacity and a crowded RF spectrum that is impossible to navigate.
Enterprises and carriers must now rethink their infrastructure architectures from the outside in - with an eye on managing RF spectrum resources (the new wire), and latency and delay that effectively kill multimedia transmissions.
According to industry analysts, data traffic continued to increase across all networks in 2010. Some so-called "superphones" routinely average more than 1GB per month, and by the end of 2010, it's expected that the average U.S. consumption per smart device will be approximately 325MB per month, up 112% from 2009.
Additionally, Cisco's mobile data trends research estimates that 66% of the world's mobile data traffic will be video by 2014 and that mobile video will grow at a compound annual growth rate of 131% over the next five years. If this pans out, it will be a looming problem for networkers.
Meanwhile millions of Blackberry and iPhone users already know that mobile operators have a real problem on their hands from painful first-hand experience. Even where 3G networks are highly developed, demand for connectivity is outstripping supply at an unprecedented rate. The cost of transporting data is rising faster than revenue, and poor user experiences resulting from network congestion raise churn. Now these devices are being brought into the enterprise.
Doesn't 802.11n address the data tsunami?
IT departments must now deal with how to provide secure, fast and reliable access to a whole new class of devices that don't have Ethernet ports. The only way into and out of these devices is 3G or Wi-Fi - neither of which have a strong history of performing well.
802.11n dramatically increases potential bandwidth and seems ideal for wireless access. The problem is realizing this "potential."
802.11n is predicated on MIMO technology that leverages multiple antennas to coherently resolve more information than possible with a single antenna. One technique is spatial multiplexing, where multiple independent data streams are transferred simultaneously within one spectral channel of bandwidth, significantly increasing data throughput as the number of resolved spatial data streams is increased.
802.11n also doubles the channel width from 20MHz in previous 802.11 PHYs to 40MHz. So-called "channel bonding" can be enabled in the 5GHz mode or 2.4GHz if it won't interfere with any other 802.11 or non-802.11 (such as Bluetooth) systems using those same frequencies.
But without explicit knowledge of and control over the RF domain, these techniques are rendered useless. Concurrent Wi-Fi signals can be corrupted during transmission by interference or obstacles, thereby increasing retransmissions, packet loss and delays. If the Wi-Fi system can't select clean channels, bonding becomes hit or miss.
Because the majority of 802.11n implementations use standard di-pole, omni-directional antennas, they transmit and receive in all directions. If something goes wrong, conventional wireless systems can only decrease their power or change their RF channel assignment - a highly ineffective and problematic approach for IT managers in an increasingly noisy RF spectrum.
To address these issues, most WLAN vendors advocate adding more access points, lowering access point transmit power or steering clients to a less-crowded band. Adding access points can actually make things worse by causing more noise and creating co-channel interference that desecrates spectrum capacity.
And steering clients to the "channel-rich" 5GHz band (with 24 non-overlapping channels) isn't much better. DFS channels used for military radar systems are unavailable, and when channels are bonded into 40MHz-wide lanes to realize higher performance, network managers are left with only four non-overlapping channels - not much more than the 2.4GHz band used in the 802.11a/b/g world.
Dramatically increasing 802.11n wireless throughput and reliability requires learning about the RF spectrum as it changes, and adapting Wi-Fi transmissions to the fastest and cleanest signal path for each packet to reach a given client.
Managing Wi-Fi spectrum
Essential to faster and more reliable Wi-Fi performance is achieving a higher signal to noise and interference (SINR) ratio. A higher SINR means a better signal delivered to clients, faster data rates and more network capacity. But how do you deliver a stronger signal to clients while decreasing interference?
Transmit beamforming is one approach. An option defined within the 802.11n standard, beamforming makes use of the Wi-Fi chip to control the phase and relative amplitude of the signal at each transmitter to create a stronger signal to clients, up to 2dB in some cases.
Chip-based beamforming is almost always implemented using omni-directional antennas that transmit signals in 360 degrees. Yet because the Wi-Fi chip is busy beamforming, it can't perform spatial multiplexing functions that are vital to achieving higher data rates. Therefore most beamforming implementations will only provide minimal performance and range gains to legacy 802.11a/b/g clients.
More importantly, chip-based beamforming provides no client feedback, so the system doesn't know if beamforming is actually working. Additionally, there's no way for these systems to deal with interference.
Emerging dynamic beamforming and beamsteering implementations use intelligent antenna arrays (a collection of high-gain, directional antennas that are controlled by software) to overcome these issues by focusing Wi-Fi signals where they are needed while simultaneously avoiding and rejecting other RF noise (interference) that other systems can't. These smart antenna systems operate independently from the underlying wireless chips and perform beamforming in isolation. This enables concurrent support for beamforming, spatial multiplexing, channel bonding and other essential 802.11n techniques.
These systems also provide a client feedback mechanism that tells them if the directed beam is achieving the highest data rate, best signal-to-noise ratio and lowest amount of packet loss.
Dynamic beamforming and beamsteering are the backbone of systems that can adapt to environmental changes, and give enterprises the muscle they need to deal with the influx of multimedia traffic hitting their networks from mobile devices while delivering more reliable wireless access. These innovations are now grabbing the attention of carriers looking to solve their own set of problems.
Smarter Wi-Fi for 3G Offloading
Serious traffic overloads are increasingly choking mobile networks as more smartphones and other handhelds come online. Operators must quickly find new ways to economically increase capacity and extend network coverage. Brute force network expansion, requiring a doubling of 3G/4G capacity, isn't an option.
As more reliable forms of Wi-Fi are proven to handle offload of data traffic from 3G networks, operators are taking a more strategic view of the technology. They want to utilize it beyond simple hotspot operation and fully integrate it into the mobile infrastructure. To do so requires a complete collection of products that includes customer premise equipment, access points, point-to-multipoint wireless backhaul, network gateway services and remote management - all of which can work seamlessly with existing core cellular network services.
Because Wi-Fi networks introduce many new nodes, seamless integration with and the services provided through the existing cellular core must work flawlessly, without increasing the load on the 3G/LTE infrastructure.
Recent innovations in this area include advanced capabilities that enable transparent interactions between core services, such as HLR/HSS, PCRF and AAA, and the Wi-Fi network. For instance, using the IEEE 802.1X standard and its EAP-SIM variant for secure, automatic authentication between smartphones, access points and the 3GPP 23.234, or I-WLAN, helps govern how authentication and policy implementation is handled at the mobile operator's core network without any adjustments.
Beyond data offloading with smart Wi-Fi systems, operators can quickly deploy reliable wireless coverage and capacity at the lowest possible cost per bit and address the massive opportunity for high-speed data services that alternatives such as WiMAX cannot due to deployment costs and complexities.
In India, Tikona Digital Networks has built the world's largest outdoor Wi-Fi mesh network - having installed over 45,000 outdoor Wi-Fi mesh access points in under 24 months. Tikona's Smart Wi-Fi network is used to offer tiered broadband Wi-Fi services over the unlicensed 2.4GHz band to hundreds of thousands of subscribers in dozens of cities - something many thought impossible.
To achieve the full promise of Wi-Fi, operators need a well-conceived, carrier-built architectural approach that spans the radio access network, backhaul and core cellular infrastructure — addressing issues such as provisioning, seamless authentication and IP mobility. With a controlled and cooperative Wi-Fi/cellular infrastructure, operators can offer a high quality service to subscribers while monetizing services that travel over Wi-Fi.
Ultimately, for carriers and enterprise to adequately support the data onslaught hitting their networks from a flood of wireless devices, they must think about their networks from a radio perspective first, looking at technologies that can deliver the reliability and performance needed to deliver consistent services. Dynamic beamforming is one technology ready to transform Wi-Fi from a technology of convenience into a ubiquitous utility -- good news that comes at just the right time to deliver a positive mobile experience to iPad-toting end users over the next decade.
Ruckus Wireless has shipped more than a million Ruckus Wi-Fi systems and a million access points equipped with its patented BeamFlex technology.