Cellular service providers are deploying an advanced version of the high-speed, mobile 3G data services already offered on many of their networks in an attempt to accelerate the adoption of broadband-enabled wireless computing. By doing so, they’re hoping to fight off a growing challenge from alternative Wi-Max networks, which deliver data (and increasingly voice calls) over long distances – potentially threatening the core business model of these companies.
Already, 18 cellular networks worldwide have launched or upgraded a version of the High-Speed Downlink Packet Access (HSDPA) network in 14 countries, with another 29 nations expected to be upgraded by the end of this year, according to the Global Mobile Suppliers Association. The networks promise respectable speeds of 1.4-3.6 Mbps – the limit of today’s mobile phones and PC cards – although the HSDPA technology can actually support up to 14 Mbps.
Philippe Keryer, president for mobile radio activities for Paris-based network equipment vendor Alcatel, says that speed is critical because mobile providers don’t want to leave customers disappointed (as many were with 3G networks). “People are inevitably going to compare this to their DSL line,” says Keryer, so operators “need to have service that can compare.”
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While it’s taken the cellular companies some time to commit to HSDPA networks – equipment makers have been eager to sell them on it since 2004 – the changeover, once initiated, is a quick process. That’s because HSDPA is primarily a software upgrade on the network end.
Bill Krenik, manager of wireless advanced architectures for Texas Instruments, which is a major wireless semiconductor supplier, says the fundamental difference between HSDPA and current 3G technology is that the equipment operating the antennas that communicate with the mobile devices adapts on the fly. Rather than broadcasting one form of signal, they tailor their signals to each user based on the quality of the link. “The base station is going to assess the quality of the channel and use the coding and signal that’s most suitable,” says Krenik.
When the connection is good, for example, an HSDPA base station will transmit a more efficient signal, called 16-QAM, where each “symbol” transmitted and received corresponds to 16 bits of information – four times more per symbol than a 3G transmission. Over a strong connection, the base station will also transmit less error-correcting information, the coding that enables the phone to check whether it got a clean feed; a tighter code means faster transmission of the data packets the user wants.
And when a phone does detect a problem and asks the base station to resend garbled or lost data, HSDPA responds much faster than 3G. In 3G networks, such “retransmission requests” initiate a long, slow hunt for packets at various layers in the network. In HSDPA, the outgoing data is buffered in memory added to the base stations, which can thus respond immediately to the retransmission requests. Krenik says this feature, by reducing network traffic, can double data throughput on a cellular network.
Still, the best-laid plans of the cellular networks could be cast aside by the emerging Wi-Max technology – a wireless standard designed to send and deliver large amounts of data, including voice, across long distances (see “Why WiMax?”). Kirkland, WA-based Clearwire, for example, has installed Wi-Max in 27 metro markets in 12 states, as well as Ireland, Belgium, Denmark, and Mexico. If operators like Clearwire build out their networks to provide broad coverage, they could steal customers from both the traditional and cellular phone companies.
Wi-Max has one key advantage over HSDPA-boosted cellular service: users can upload data as rapidly as they download it. Whereas Wi-Max starts at uploads of 2Mbps and tops out at 10Mbps, HSDPA starts at just 200 kbps and tops out at 1 Mbps. That could limit the quality of upload-intensive applications like two-way video-conferencing.
The cellular networks, however, have a critical advantage over Wi-Max: reliability. It’s not yet clear if Wi-Max networks will, for example, be able to hand off a connection from one base station to another, for instance, as one video conferences in the taxi to the airport.
Keryer says the trial to watch is in Korea, where telecommunications firm KT has teamed with Intel to deploy Wi-Max as a next-generation mobile system. But, in his view, Wi-Max is not yet a competitor: “I would not put them in the same camp.”
Of course, creating the network is one thing, and deploying the equipment is another. The challenge for HSDPA is that faster transmission speeds demand a lot more mobile handsets, which require more sophisticated data processing and memory and, in some cases, multiple antennas. Krenik says hurdle this is why HSDPA hasn’t arrived until now. Until recently, the semiconductor technology required for an HSDPA handset consumed too much power and cost too much. “The handset is where the rubber meets road, especially since operators tend to subsidize the handsets,” Krenik says.
While Samsung and several other phone manufacturers are selling HSDPA phones, many cellular network operators offering HSDPA say they won’t be offering phones until later this summer at the earliest, as they wait for more competition among handset makers to bring down prices. In the meantime, HSDPA access is by PC card only, which means users must access their mobile data through a portable computer.
Until the consumer handsets are ready, though, cellular providers are working with corporations whose employees increasingly need access to voice and data services while on the road. Orange, the wireless service of France Telecom, became the latest European operator to announce its plans, saying it would begin offering HSDPA to corporate clients in the fall. Cellular giant Vodafone, meanwhile, is already running HSDPA in seven European countries and South Africa. In the United States, Cingular jumped first, deploying HSDPA in 16 cities.
Whatever technology wins the mobile broadband market, one thing is clear: there’s plenty of untapped demand. Last week, for instance, Orange presented the results of its six-month beta trial with HSDPA, stating that its 240 corporate testers responded to the service’s two- and threefold speed increase by more than tripling their use of the network. And its 100 noncorporate testers responded with an impressive 60 percent increase in usage. Build a fast mobile network, it seems, and the consumers will come.
