While weak signals and overloaded cells usually take the blame for slow mobile data, the way packets are handled on a carrier's network can also affect performance, and vendors of network management tools are finding new ways to reduce bottlenecks.
A collection of components called the EPC (Evolved Packet Core) was introduced along with the LTE (Long-Term Evolution) standard and has also been extended to 3G networks, bringing new capabilities such as shaping traffic according to carrier policies. Management appliance vendor Sandvine announced Tuesday at the CTIA Wireless trade show that it is now working with Citrix to reduce delays in both types of networks.
Using Citrix's NetScaler technology, Sandvine will allow carriers to send mobile data traffic directly to the Internet, bypassing their traditional core networks. Doing so will break a logical link between the subscriber's device and "home" network that can force Web pages, video streams and other data to needlessly traverse a national or international backbone. This capability could cut latency, or delay, by 20 percent or more on LTE networks and even more dramatically on 3G, according to Sandvine Chief Technology Officer Don Bowman.
At CTIA on Tuesday, carrier network executives said EPC is a critical tool for delivering good services while conserving capacity.
"If you look at the promise of an LTE network, it doesn't reside in downlink speed exclusively," said AT&T Chief Technology Officer John Donovan. Reducing latency is AT&T's foremost goal in deploying its EPC, he said.
EPC systems from most other vendors also include tools to shift IP (Internet Protocol) data traffic directly onto the Internet, a capability called mobile IP offload, said analyst Chetan Sharma of Chetan Sharma Consulting. The technology is all fairly new, and different vendors offload data to the Internet at different points in the carrier network, he said. Using NetScaler, Sandvine will offload the data between the cellular base station radio and the serving gateway, an aggregation router, according to Bowman.
Cellular networks are designed on the assumption that subscribers will need to maintain a continuous connection with the network so voice calls won't be interrupted. To ensure this, cell phones usually keep the same IP address even when the user has traveled far from home, though the phone drops the address when it is shut down, Bowman said. Because that IP address is associated with the mobile operator's local network in the user's hometown, packets need to go through that network before arriving at the phone in whatever remote location the user may be visiting.
In addition to unnecessarily delaying packets going to and from the subscriber, these detours take up precious capacity on the carrier's core network, Bowman said.
NetScaler will provide network address translation to change the home-based IP address to another one associated with a local network. In addition, it will find the most economical Internet route for the traffic and will coordinate with content delivery networks (CDNs) so data is directed to the phone from the most nearby cache operated by the CDN, Bowman said. Using the NetScaler-Sandvine solution will eliminate all network latency except the delays caused by the radio access network, Bowman said.
Sandvine's EPC system will allow carriers to deliver the benefits of mobile IP offload selectively based on service plan, handset or application, Bowman said. The types of mobile data sessions that require a continuous connection, such as voice over IP calls, will not be offloaded from the traditional back-end network of the operator, he said. The NetScaler-based system is in trials and available now, the company said.