Worldwide mobile data will grow at a 78-percent compound annual rate from .6 exabytes per month in 2011 to 10.8 exabytes per month in 2016 (an exabyte is one billion gigabytes), according to the Cisco Visual Networking Index. A real-world example of the problem and some of the current solutions are illustrated in this Bloomberg BusinessWeek article, "French Open Data Demand Spurs Network Congestion Fix."
One solution that wireless carriers rely on to handle exploding demand is offloading traffic to Wi-Fi networks. The Cisco Visual Networking Index indicates that, as a percentage of total mobile data traffic from all mobile-connected devices, mobile offload will increase from 11 percent (72 petabytes/month) in 2011 to 22 percent (3.1 exabytes/month) in 2016.
Since Wi-Fi networks are becoming extensions of cellular networks, they need to perform at similar levels to cellular networks to ensure seamless hand-offs and equal throughput. That requires the Wi-Fi network to offer carrier-grade performance. Wi-Fi networks remain in the spotlight, due in part to growth in the number of Wi-Fi hotspots, which today is an order of magnitude higher than just a year ago, and, according to research firm Informa, will reach 5.8 million by the end of 2015. That’s up from 800,000 in 2010. Today, eight of the world’s largest mobile operators are using Wi-Fi to offload their cellular data traffic, according to the New York Times. See "From London, a Lesson in the Benefits of Free Wi-Fi."
DSL Remains a Factor
But, as Wi-Fi removes some of the burden on cellular networks, another vital broadband technology, DSL, comes into play. Why? Because DSL networks are increasingly the source of massive volumes of traffic hitting Wi-Fi networks. Service providers are increasingly implementing VDSL and vectoring technologies – arguably the most groundbreaking development in DSL since its invention – which can deliver data rates exceeding 100 megabits per second (Mbps). Furthermore, DSL network management products are improving, providing network diagnostics and optimization to ensure that DSL networks perform at their best and provide optimal data rates.
DSL is evolving to support the high traffic and performance demands for carrier offload to Wi-Fi networks. Still missing is the ability to monitor, diagnose, and optimize the performance of the actual Wi-Fi signals that emanate from DSL networks. ASSIA estimates that Wi-Fi optimization will improve Wi-Fi data rates between 10 and 100 percent. Although it’s too early to tell, optimized DSL and Wi-Fi networks may continue to provide a solution for offloading data from cellular networks for years to come.
Tools for maximizing performance on DSL networks have been available for years, but the same cannot be said for Wi-Fi networks. While Ethernet performance is predictable – providing dedicated bandwidth and the ability to diagnose and optimize performance, Wi-Fi performance in the home was, until recently, virtually impossible to manage. The chief shortcoming has been the inability to measure wireless performance.
There are several factors to consider when evaluating Wi-Fi performance: RSSI (received signal strength indication), which is the radio signal strength indicated by bars on the home screen of most devices, could be a primary metric, but as an indicator of performance it is misleading. Signal strength and performance are different things; the number of bars indicating radio signal strength does not correlate with either throughput or quality of service.
However, residential Wi-Fi management products are addressing the issue by focusing on all the factors that affect performance – chief among them are throughput, latency, and connectivity. Throughput addresses the speed of delivery: how fast data travels to and from a device. Latency focuses on delays that may occur that especially impact online games. Connectivity is the ability of a device to maintain a connection rather than attempting to connect to a different channel or network when interference occurs.
The key missing piece is analysis: without data to analyze, it is impossible to diagnose network performance against ideal performance metrics. However, embedding a software agent in the customer-premises equipment (CPE) allows collection of performance data for storage, analysis, optimization, and reporting.
Wi-Fi is shaping up as the enabling technology for cellular offload. The technology is readily and widely available, and the management tools are now coming to the fore. And the timing is right: Wi-Fi offload is a highly viable alternative to re-architecting the cellular networks.