Last year was the first time that Wi-Fi carried more mobile traffic than cellular did, according to Cisco’s Visual Networking Index Global Mobile Data Traffic Forecast (2015 to 2020), which cites Maravedis’ research. That trend is fundamentally changing the telecom market in a variety of ways.
For example, the more that mobile operators and their customers rely on Wi-Fi, the more important it is for 802.11 to provide good quality of service experience (QoS/QoE). (One way to define “good” is a connection that’s at least as fast, reliable and low latency as what cellular offers.) Otherwise, many customers will choose cellular, and mobile operators will pay the price in terms of having to buy additional base stations, backhaul and spectrum – if there’s even any spectrum available for them to buy. Hotspot owners and aggregators also will pay the price in terms of less revenue, both from end users and from their mobile operator partners.
To avoid those problems, the Wi-Fi industry has spent the past couple of years developing “carrier-grade” 802.11, which aims to provide a better user experience than traditional “best-effort” Wi-Fi. By the end of 2017, carrier-grade access points will start to outnumber best-effort ones, Maravedis predicts. By 2020, more than 90 percent of hotspots will be carrier grade.
The Business Case for LTE Coexistence
When it comes to Wi-Fi QoS/QoE, one looming wild card is LTE’s use of the same 5 GHz band that many hotspots inhabit. LTE Licensed Assisted Access (LTE-LAA) technology aggregates signals across licensed and unlicensed bands in order to deliver more bandwidth than the licensed spectrum alone could support.
Note that “support” doesn’t refer only to the maximum amount of bits that a slice of spectrum can handle. Support also can be viewed in financial terms. For example, a mobile operator might configure LTE-LAA so that the LTE “anchor” carrier is used for minimal traffic because that licensed spectrum is scarce and expensive. The bulk of the traffic then would go over the unlicensed carrier(s), thus reducing the operator’s cost of delivering service and in turn increasing its ability to achieve a profit.
Whatever the scenario, LTE-LAA also highlights why mobile operators – and their vendors – have a vested interest in finding ways to ensure that their traffic coexists peacefully alongside Wi-Fi. If LTE-LAA pollutes the unlicensed spectrum, then the interference will undermine Wi-Fi’s QoS/QoE, making offload less attractive to customers. That would shift more traffic back into licensed spectrum, which is already crowded in urban areas.
For example, Qualcomm and Verizon Wireless are among the companies developing “listen before talking” (LBT) technologies, which enable LTE-LAA devices and infrastructure to check to see if a nearby Wi-Fi application is already sending traffic on a particular frequency. If there is, LBT would look for another, clear frequency before transmitting.
Time and real-world deployments will show whether LBT is a viable way to enable coexistence. In urban and suburban areas, unlicensed spectrum is already crowded, so there will be times and places where LBT inevitably struggles to find clear frequencies. Many of those times and places also are when and where cellular spectrum is overloaded, such as city centers during the workday. The likely result is that there will be times and places where mobile operators and their customers would benefit the most of LTE-LAA offload, but LBT will be unable to broker it.
Offloading to Other Bands, Including New Ones
The good news is that other technologies are emerging to help shoehorn more traffic into unlicensed spectrum. Some of these technologies also complement one another to maximize their benefits. For example, self-optimizing Wi-Fi networks (SON) can identify when a dual-band Wi-Fi device could and should move to just one of those bands, thus freeing up the other band for other users. That alone would help reduce congestion, which could be further reduced if LBT devices also are active in that area.
Another example is WiGig, which uses unlicensed 60 GHz spectrum. If it achieves significant market share, that would mean less traffic clogging up the 2.4 GHz and 5 GHz bands. The 802.11ah and 802.11ax standards could have similar effects by shifting some traffic into new bands between 900 MHz and 6 GHz.
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By Caroline Gabriel, Research Director, Maravedis-Rethink
The latest R&D project in 60GHz spectrum comes from Samsung, which can transfer a 1Gbyte movie in three seconds. However, as the speed wars heat up in WiFi, all these data rates are going to need backhaul support, an issue Broadcom and others are seeking to address through new Ethernet standards.
The race to break speed records in WiFi is almost as intense as it is in cellular, and Samsung is a prominent name in both. The Korean firm has been demonstrating ‘5G’ prototypes hitting gigabit speeds, but WiFi can support even higher data rates, and the company says it has achieved up to tenfold increase on current speeds.
In both WiFi and cellular R&D, the key to blistering speeds is usually the combination of techniques such as advanced MIMO, with high frequency spectrum. Samsung says it has developed a version of WiGig (the WiFi-like standard for the 60GHz band) which boosts the current maximum theoretical data rate for a consumer device fivefold – and in terms of real world average speeds, the gap is 10 times.
The prototype system enables a 1Gbyte movie to be transferred in under three seconds and uncompressed high definition video to be streamed in real time. Like other next generation WiFi efforts, Samsung says its technology removes the gap between theoretical and actual speeds, and of course it will hope that its breakthrough will give it an influential position in emerging standards, as well as differentiation for its own future products.
“Samsung has successfully overcome the barriers to the commercialization” of the 60GHz WiFi technology, claimed Kim Chang Yong, head of a Samsung R&D center, in a statement. “New and innovative changes await Samsung’s next generation devices, while new possibilities have been opened up for the future development of WiFi technology.”
Amid rising competition in its heartland smartphone business, Samsung is investing in R&D in many areas which could extend its business model, including software and media platforms, enterprise platforms and cutting edge infrastructure for ‘5G’, which is expected to include technologies derived both from LTE and WiFi. The first products to be targeted with 60GHz WiFi are likely to be audiovisual home and mobile media devices, telecoms infrastructure and medical systems, said Samsung.
Samsung’s rivals are all working on enhancing WiFi for higher speed and better quality of experience in future. For instance, Huawei recently demonstrated 10Gbps connections in conventional 5GHz spectrum.
However, the faster WiFi gets, the more challenging its backhaul issues will be. With that in mind, Broadcom, HP and Cisco are drumming up interest in dramatically speeding up gigabit Ethernet, to keep up with the pace of change in WiFi.
The two giants claim there is a growing need for standard physical layers running at 2.5Gbps and 5Gbps, to fit between the current Gigabit Ethernet standard and the high end 10Gbps platform. The standard would cover ranges of 100 meters over Cat E twisted pair cabling, so that changes to cable infrastructure would not be required as they would for 10Gbps and above.
The main reason is the rapid increase in the speed of WiFi. Enterprise and hotspot WLANs are adopting the latest 802.11ac iteration, and its gigabit speeds are threatening to drown the access points’ wired Ethernet backhaul links.
The two companies are proposing the formation of a study group within the IEEE 802 effort, focused on a Next Generation Enterprise Access Base-T PHY. This will get its first hearing at the IEEE 802 plenary in San Antonio, Texas on November 3-6. The initiators of the would-be study group are Yong Kim, senior technical director at Broadcom, and David Law of Hewlett-Packard, chair of the 802.3 working group, and Cisco has also lent its support.
They say in their invitation: “This is a call for interest to initiate a Study Group to explore the need for one or more new Ethernet speed(s) between 1Gbps and 10Gbps over balanced twisted pair cabling. We believe there is a market need, driven by IEEE 802.11ac wireless access points, to support higher than 1Gbps Ethernet rates at a 100m reach. Higher performance end devices like desktop and laptop PCs, as well as other enterprise applications for Ethernet, will also benefit from the new data rates provided by this work.”
John D'Ambrosia, a Dell fellow and veteran of Ethernet standards efforts, told EETimes there was significant interest and the study group was likely to be approved. "I wouldn't be surprised to see a dual-rate effort come out of this," he commented.
There is also work going on far higher up the Ethernet performance scale, in the area which feeds into Carrier Ethernet and mobile backhaul platforms. A de facto standards alliance was formed in July to look at 25G and 50G Ethernet, but the IEEE quickly responded with its own study group, focused on the same data rates, a few days later. These different efforts highlight the diversity of applications for Ethernet these days, requiring a faster development cycle and a wider variety of speeds. "People have removed the barriers of traditional 10x Ethernet upgrades,” said d’Ambrosia.
Meanwhile, Ethernet PHY specialist Aquantia is getting in early, and in time-honoured fashion seeking to create a technology in advance of an IEEE standards effort, which could then form the basis for that standard. Its new AQrate range supports 2.5G and 5G rates over 100m of Cat E twisted pair cable. The 28nm parts are based on Aquantia's existing 10G Ethernet PHY, which is in production and work in conjunction with FPGAs and IP from Xilinx.
Confirms purchase of 60GHz specialist Wilocity and announces integrated Snapdragon platform
The purchase has been discussed for a couple of months, but is now complete, giving Qualcomm significant technology and IPR in the 802.11ad standard, branded WiGig. Once a separate activity from WiFi, the WiGig Alliance was brought under the wing of the WiFi Alliance last year and the 60GHz platform is now positioned as complementary to the 802.11ac gigabit WiFi offering.
Qualcomm also unveiled a family of triband chipsets combining WiGig with dual-band WiFi, integrated with its Snapdragon 810 mobile system-on-chip. WiGig's initial commercial applications have been in the PC community, with backers like Intel and Dell deploying it as a high speed PC connectivity system. However, while this was a relatively simple way to prove the technology's multi-gigabit (up to 7Gbps), short distance capabilities, all the big names have had a far grander vision for 11ad - in enterprise and hotspot WiFi, where cells are getting ever-smaller to create density; and in supporting high end multimedia in smartphones.
With Qualcomm's solution, mobile devices will be able to transmit 4K video directly to larger screens from next year, says the firm, potentially replacing HDMI ports and other methods. The first WiGig handsets will appear in the second half of 2015, according to Cormac Conroy, VP of product management and engineering at Qualcomm Atheros, the firm's WiFi and multimode division. 4K video has a resolution of 3840 x 2160 pixels, four times that of 1920 x 1080 HD.
Qualcomm did not disclose the purchase price, though it is rumored to be about $300m, which sounds very reasonable, given this puts Qualcomm in the technology and patents vanguard for mobile WiGig, outwitting Intel - which has its own visions for the technology - into the bargain.