Wi-Fi offload for mobile networks: 20% of traffic and counting
Judging by the number of carrier-grade Wi-Fi equipment announcements during this year's Mobile World Congress trade show in Barcelona, Spain, offloading smartphone mobile data traffic onto Wi-Fi networks is becoming a key network requirement for operators around the world as they grapple with heavy data traffic. But interestingly enough, those operators that have embraced the offload concept have difficulty quantifying its ability to reduce 3G network congestion or solidly demonstrate its cost advantages. They just know it works.
"We've had the same question," said Steven Glapa, senior director of marketing with Ruckus Wireless, when asked how operators measure the effectiveness of Wi-Fi offload strategies.
Ruckus Wireless had an early jump on the data offloading trend. The company started working Hong Kong operator PCCW in 2007, when the operator began deploying Wi-Fi hotspots around the city and offering seamless roaming between its mobile network and the hotspots.
Glapa said the effectiveness of offloading for PCCW and other operators is difficult to measure primarily because the data traffic doesn't all end up in the same place. It may bounce between the Wi-Fi connection and the 3G connection and end up terminating on the 3G network again.
Moreover, operators cannot simply look at smartphone traffic traveling over Wi-Fi networks and conclude that the traffic would have moved over 3G had the hotspot not been available. The accessibility and the growing number of Wi-Fi enabled smartphones tends to drive up traffic on Wi-Fi networks, especially when a number of smartphone applications, such as FaceTime on the Apple iPhone, only work via Wi-Fi.
To wit: Last summer Towerstream, which recently announced it is getting into the Wi-Fi wholesale provider game to offload mobile traffic, threw up some access points in midtown Manhattan without telling anyone. It ended up seeing an average of 250,000 connections and more than terabyte of data transferred per day, primarily by mobile phones that simply stumbled across the free trial network.
Wi-Fi driving traffic
Not only does data traffic increase on Wi-Fi networks, but analysts say it drives up traffic on 3G networks as well.
"Wi-Fi has taken away congestion but generated more usage. But still, you need it," said Phil Marshall, head of Tolaga Research. "Wi-Fi offload will become a crucial part of an operator's network. ... It would be challenging for operators to carry everything on their networks."
Peter Jarich, service director with Current Analysis, agrees. "Wi-Fi causes people to use things they may not have otherwise," he said. "It may be generating more traffic, but it's likely taking more of that traffic off 3G. Wi-Fi offload is going to continue being part of the solution."
Testing the results
How are operators measuring the success of Wi-Fi offloading strategies today? Glapa said PCCW counts packets on both networks on a sample basis periodically. Others could try to quantify by measuring data usage on certain parts of their 3G networks before and after deploying a Wi-Fi hotspot or hotzone, Jarich said.
Generally speaking, those operators that have aggressively embraced a Wi-Fi offloading strategy, such as PCCW and AT&T Mobility, estimate that about 20 percent of their overall data traffic is riding over Wi-Fi networks.
"When you have Wi-Fi, you do more, and that effect is pretty hard to measure," Glapa said. "But nonetheless, I would say network traffic on PCCW's network would be 20 percent higher than if it didn't have Wi-Fi." In some of the dense traffic areas of Hong Kong, some 80 percent of data traffic is traveling over Wi-Fi, he said.
Marshall estimates that about 20 percent of iPhone traffic on AT&T Mobility's network is landing on the public Wi-Fi network, and it's likely that another 60 percent is landing on home Wi-Fi networks now that the operator has instituted tiered data plans, he said.
Offloading in the USA
AT&T has been somewhat of a poster child for Wi-Fi offloading in the U.S. It recently expanded its Wi-Fi hotzone project as a measure to ease the burden on its 3G mobile broadband network in areas of New York and San Francisco--two markets where the carrier has suffered from a deluge of data. Most of AT&T's smartphones now support auto-authentication at the carrier's AT&T-affiliated Wi-Fi hotspots, which number more than 23,000-- Wi-Fi usage does not count against a subscriber's monthly smartphone data usage plan.
In the third quarter of 2010, AT&T handled 106.9 million Wi-Fi connections on its network, exceeding the total 85.5 million connections made during the entire year of 2009.
T-Mobile USA markets Wi-Fi as a coverage enhancer rather than an offload technique. The carrier recently announced that 5 million of its 34 million subscribers route some of their cellular calls over a Wi-Fi network. Further, the carrier said its subscribers place around 40 million calls per month over Wi-Fi. This is possible via the company's Wi-Fi calling application, which works on some Google Android phones, BlackBerry phones and Nokia phones. The technology from Kineto Wireless allows users to route their calls and text messages through a Wi-Fi connection.
MetroPCS also recently embraced the Wi-Fi offload concept. The operator announced in December that its new Android-based smartphones--the new Huawei Ascend and LG Optimus M smartphones--will come preloaded with DeviceScape and Boingo clients, which can seek out and connect with Wi-Fi hotspots without user intervention.
Meanwhile, Verizon Wireless and Sprint Nextel have embraced Wi-Fi-enabled phones, but haven't actively pursued a smartphone Wi-Fi offload strategy--yet. They offer Wi-Fi plans for laptops via aggregators, but don't offer free Wi-Fi access for smartphones or auto-authentication on Wi-Fi networks. Their smartphone consumer offerings primarily revolve around using mobile hotspots that can connect multiple Wi-Fi-enabled devices and can also connect to Wi-Fi if a user subscribes to a broadband plan.
Going forward, operators that are embracing Wi-Fi offload strategies for smartphones should get a better handle on Wi-Fi data traffic by gaining more intelligence into these networks. Today's traffic running over Wi-Fi is a mystery when it comes to issues around QoS and the habits of subscribers since operators have no visibility into these networks. However, a number of vendors have now introduced carrier-grade Wi-Fi equipment capable of integrating into mobile networks--essentially creating a Wi-Fi extension of the mobile network.
Cisco, Nokia Siemens Networks and Ruckus are among the vendors that have recently announced such solutions. Cisco announced its service provider Wi-Fi solution that offers an 802.11n platform with authentication to enable roaming and service delivery. NSN introduced what it calls the Smart WLAN connectivity solution that is designed to selectively offload traffic onto Wi-Fi without any interruption in service. The solution allows operators to use existing services and functionality supported by their packet core networks such as authentication, charging, policy control and traffic management for both mobile and Wi-Fi traffic in a unified way.
Meanwhile, Ruckus Wireless, which is winning some big deals in China, introduced a product and technology roadmap that includes a new category of mobile Wi-Fi gateways designed to integrate Wi-Fi into mobile network infrastructures.
For public networks, WeFi announced a service called WeANDSF that allows operators to control where, when and under what circumstances their subscribers use Wi-Fi. Operators can essentially undergo a real-time evaluation of Wi-Fi networks vs. their 3G networks, taking into consideration parameters such as RSSI, battery time and the subscriber's monthly data capacity.
The solution uses the Access Network Discovery and Selection Function server that is defined by the 3GPP and is based on WeFi's global database of more than 80 million access points, the company said.
Whatever the future of Wi-Fi offload, it's clear that it's a technology and technique that operators will at least need to consider, if not implement.