In Search of True 4G Mobile Backhaul: 3 Key Ingredients
You don’t have to look far these days to see the impact of the Mobile Internet on our personal and professional lives. Smartphones, tablets, WIFI, 3G … it seems every new electronic device has a way to connect to the Internet.
This chart from Visualizing Economics underscores the relatively rapid adoption of cellphones compared to other consumer technologies. And, as we look to the future with emerging machine-to-machine technologies like RFID and Smart Grid, it appears that the number of applications for the Mobile Internet will only continue to grow.
As I listen to our service provider customers around the world, I find them wrestling with the fact that revenue growth is increasingly driven by mobile services. Market research firm Infonetics reports that in 2010 the number of mobile broadband subscribers surpassed the number of fixed broadband (DSL, PON, Ethernet FTTH) subscribers. This opportunity is fueled by the availability of smartphone and tablets that enable high-speed mobile access to data-hungry applications.
Looking closer at the service provider networks that enable these mobile devices, a useful way to think about the architecture is to split the mobile network into two parts – the radio access network and the mobile backhaul network.
The radio access network provides wireless connectivity to mobile devices, in other words it connects the smartphone to the radio tower. Of course, the first generation of mobile phones were voice only, but as the industry progressed second generation (2G) and third generation (3G) radios were developed and deployed, adding data services to the basic voice service. These radios are part of the chips in your smartphone and on the towers that connect to the mobile backhaul network. In fact, as of this writing there are no 4G standards agreed upon, however a number of mobile operators have started marketing their 3G based networks as 4G.
The mobile backhaul network connects the radio to the mobile service core where phone calls are completed and data services originate. According to market research firm Heavy Reading, “The biggest cost challenges facing wireless service providers today is the backhaul network.
When 2G mobile networks were first deployed, mobile backhaul networks were built with time-division-multiplexing (TDM) based on T1/E1 and SONET/SDH. As 3G radios were deployed, mobile operators started by adding an overlay packet transport network alongside the SONET/SDH TDM transport network. As the amount of data traffic grows faster than the amount of voice traffic to smartphones, mobile operators have found the need to increase the capacity of the packet transport network while struggling with the cost and complexity of maintaining two transport networks. When we look to the future of themobile internet we see mobile operators planning all-packet next-generation mobile backhaul networks to mitigate the cost and complexity of running two networks for mobile backhaul
While the standards for 4G radios are still under development, there is consensus that the next generation of mobile backhaul networks will be packet-based, eliminating the overlay-network architecture of 3G backhaul. The challenge for network planners is that legacy 2G and 3G radios will need to be supported on this same backhaul network for decades to come. This means that true 4G mobile backhaul network needs to deliver many of the same capabilities of the legacy TDM network. Three key ingredients to true 4G mobile backhaul include performance, resiliency, and synchronization.
- Performance is easy to understand. The Global Mobile Suppliers Association estimates that 70% of commercially available services offer peak download data rates under 15Mbps and 30% are offering 42 Mbps peak download date rates. As radio data speeds continue to increase toward gigabit per second mobile access, the need for high-performance packet based mobile backhaul increases. The mobile backhaul network needs to support high speed gigabit Ethernet today and offer a migration path to 10GE without a fork-lift upgrade.
- Resiliency in the mobile backhaul network enhances the quality of the subscriber experience. Extreme Networks pioneered Ethernet Automatic Protection Switching in 2003 (IETF 3619), and now we are seeing the emergence of an International Standard for Ethernet ring protection switching – ITU G.8032.
- Synchronization in the mobile backhaul network is required for the delivery of quality voice services to 2G and 3G phones. In TDM networks timing is provided by the BITS (Building Integrated Timing System) network. In packet transport networks two approaches have emerged that enable synchronization of packet networks – The Institute of Electrical and Electronic Engineers has published the IEEE 1588 precision timing protocol and the ITU-T has published standards for synchronization over packet networks including G.8262 for synchronous Ethernet.