When Apple Inc.'s new iPad with Long Term Evolution (LTE) support goes on sale Friday, March 16, it is expected to unleash a surge in data signaling traffic on next generation mobile broadband networks, particularly in North America.

The big question is: Will the networks cope with that traffic?

"The impact of the new iPad on networks from a signaling point of view could be larger than regular smartphones ... [It's] a bigger challenge to prepare for," says Ben Volkow, VP of product development at signaling system vendor Traffix Systems, which was recently acquired by F5 Networks Inc.. (See F5 Sends LTE Signal With Acquisition.)

Signaling in LTE networks is handled by the Diameter protocol, a Service Provider Information Technology (SPIT) element defined by the 3rd Generation Partnership Project (3GPP) for authentication, authorization and accounting (AAA) on HSPA+, LTE and IP Multimedia Subsystem (IMS) networks.

The protocol touches just about every part of a mobile operator's network, from the core to the back-end billing systems. As Heavy Reading Senior Analyst Jim Hodges wrote in a recent white paper, "Optimizing Diameter Signaling Networks," there are "approximately 50 3GPP and 3GPP2 defined interfaces which utilize Diameter signaling."

"You can't do anything in the LTE core network without Diameter," says Doug Suriano, CTO of signaling vendor Tekelec Inc.

So just how well operators have designed their Diameter signaling systems and how they can manage that traffic will be put to the test with the new LTE iPad, as they have been with the introduction of other new LTE devices. (See LTE Signaling Woes Ahead?)

"Any [LTE device] launch generates lots of Diameter signaling," said Suriano. "[The new iPad] is the next challenge, the next wave of new devices ... It's the first iconic device to hit the LTE network. Multiple millions of new subscribers are going to hit these networks in the next few months."

For Tekelec, the ability to cope with an LTE signaling surge is a matter of scale.

"These networks are not designed for scale yet, and they can't scale without a Diameter [system]," says Suriano.

Generally, tablets are more data hungry than smartphones. According to Jan Hellman, head of mobile broadband program at Nokia Siemens Networks, the global average for smartphone data use is 150 Megabytes per user per month, while the average for tablets is 400 MB.

There are only five operators that potentially could be affected by a surge in LTE signaling because the new iPad only supports the technology in the frequency bands operated by AT&T Inc. and Verizon Wireless in the U.S., and BCE Inc. (Bell Canada), Rogers Corp. and Telus Corp. in Canada, according to Apple's website. But mobile operators worldwide will undoubtedly pay attention as the experiences of the North American carriers will provide valuable lessons in designing and scaling Diameter signaling systems in LTE networks.

Of those operators, though, Verizon may have the most to be worried about when it comes to LTE signaling because it has already suffered several outages on its new mobile broadband network. (See Verizon Investigating LTE Outage, Verizon Says That LTE Is Back, Analyst Fingers NSN Server for Verizon's 4G Fail, Verizon Suffers an LTE Outage? and Verizon: LTE Is Back.)

— Michelle Donegan, European Editor, Light Reading Mobile