Wishing for 1XRTT T&M

With CDMA carriers racing to roll out 1XRTT networks, testing and measuring the performance of next-generation technology and devices while maintaining 2G system quality isn't just important; it's mandatory. But what testing solutions should CDMA carriers have on their Christmas lists?

“The important thing about 1XRTT is backward compatibility, so when you reconfigure your network or overlay, you want to make sure that the network they have on either side doesn't get degraded,” said Farhad Bassirat, Nortel Networks director of wireless networks engineering.

Bassirat said Nortel, which tests Western Wireless' 1XRTT network in Terry, MT, provides a benchmarking process, including data collection on the mobile side, for carriers before and after deployment to make sure the product delivers what it touts.

Verizon Wireless purchased two of Spirent Communications' performance-analysis solutions to test 1XRTT handset performance. Spirent's AirAccess C2K combines Windows-based application software with instruments to provide emulation of a multicell IS-95/1XRTT network, with emulation of up to six sectors. An intuitive GUI enables interactive device testing, and a real-time protocol-processing engine allows testing of multifrequency handoff scenarios and high-speed packet-data applications. The C2K-ATS combines Windows-based application software with instruments to enable automated, closed-loop device testing.

The solutions provide an integrated 1XRTT physical-layer and protocol-layer test solution, said Rob Van Brunt, Spirent director of product marketing. A carrier could, for example, benchmark brand A phone vs. brand B and brand C. Before deciding which phones to sell, it would use such solutions to benchmark in the lab, as opposed to drive testing brand A today and brand B tomorrow.

Van Brunt said carriers should benchmark against both 3G and 2G systems.

“When 3G service first rolls out, there will just be pockets of it, so you'll be handing back down to 2G services,” he said. “So when they do testing of the handsets now, they not only have to test all the brand new functionality, but also have to go back and make sure that they didn't break anything else.”

Testing services in both 3G and 2G modes is important, as well as measuring how well handsets make that handoff, Van Brunt said. A CDMA emulator that can imitate both 3G networks and older 2G networks is a key tool for carriers.

Gary Schulman, Verizon Wireless data & Internet division president, said measuring real-life data speed is key. During its 1XRTT Express Network preview, Verizon is measuring actual speeds attained by users. It expects to deliver between 40kb/s and 60kb/s consistently for commercial service.

“When it comes to real people using the actual network, the critical factor is speed,” Schulman said. “Hypothetical maximum throughput figures are interesting, but the proof is in the pudding.”

Wayne Newitts, Tektronix marketing manager, said he saw interest one year ago to provide cdma2000, 1XRTT and 3XRTT testing capabilities. Tektronix designed its NetTek YBT250 portable base station T&M field tool to meet those needs.

The YBT250 brings cdma2000 measurement capability to the platform to deliver common field-transmitter measurements for cdma2000 base-station installation and maintenance. Automated tests include a full set of signal-quality measurements, pilot and code-domain power measurement, and codograms, which quickly highlight code-power variations.

According to Newitts, carriers should ensure their T&M tools cover all of the technologies they offer.

“If you are a provider of GRPS service, do you need T&M equipment that's in compliance with CDMA standards? The answer is yes,” he said. “You're operating in an environment where there is spectrum being used for CDMA networks that could impinge upon your GPRS or EDGE network.”

Once they reach 1XRTT and/or cdma2000 capabilities, carriers' T&M equipment should comply with the standards and be modular to meet future needs.

“Make sure that your test device is more than just a fancy spectrum analyzer that can identify code domains,” Newitts said.