The idea was to conduct an apples-with-apples trial of the newly launched EV-DO (Evolution Data Optimized) Rev A service from Telecom, and compare it to Vodafone's UMTS (Universal Mobile Telecommunications Service) HSDPA (High Speed Downlink Data Packet Access).
Before the trial, Vodafone pointed out that its network is a production one that is lightly loaded compared with Telecom's Rev A grid. However, Rev A runs over the same physical network as the existing Rev O one, sharing backhaul with it, and according to Telecom, it's a production network too.
Telecom's Rev A has very limited coverage at the moment ' just Auckland central business district. On the suggestion of both operators, Computerworld New Zealand tested their services in the downtown Britomart, lower Queen Street area. In those spots, both services registered very good signal strength ' five bars on the respective software clients, with the Sierra showing -47dBm, or twice as good as what Telecom's techies say is 'exceptional."
The real-life results were surprising. Although testing at Telecom's Auckland headquarters pushed 2.6Mbit/s down and 500kbit/s up, this time around the Rev A data card managed only around half that performance: just over 1Mbit/s down, and 200kbit/s up.
Low latency is the strong point of Rev A though: 50-70ms is very good indeed, making time-sensitive applications nice and smooth to use.
Vodafone's HSDPA wasn't overshadowed by the EV-DO contender however. In fact, it put in very similar performance figures to Rev A, although the download speed was somewhat lower.
HSDPA's weak point is its latency, generally twice as high as Rev A at 130ms or more.
The theoretical maximum performance for Rev A is 3.1Mbit/s down, and 1.8Mbit/s up. For HSDPA, it's 3.6Mbit/s currently, with 384kbit/s uploads. As evidenced by our testing, neither service comes close to its theoretical maximum performance, something that, to give them their due, both operators admit in their average speed promises which are around third of the top speed.
Interestingly, the new Sierra card performed much better in Telecom's EV-DO Rev O coverage than the older 580 model: upload speeds stayed the same at 130kbit/s or so, but downloads in areas with low signal strength almost doubled. You may wish to upgrade to the newer card if you're a Telecom customer.
The verdict: both 3G services offer high performance ' remember, we're talking cellular broadband here ' with Telecom currently having a slight edge. It's not much though and the situation should change next year when Vodafone upgrades its network to 7.2Mbit/s, and adds HSUPA (High Speed Uplink Packet Access) for faster uploads.
Vodafone's Achilles heel is the step-down to GPRS (General Packet Radio Services ) when out of 3G coverage, and first-generation UMTS when HSDPA isn't available. GPRS is dog-slow with high latency compared with CDMA (Code Division Multiple Access) 2000 1xRTT for Telecom, which itself isn't fast either.