Evolved HSPA gains ground

A growing number of 3G operators are looking to milk as much capacity out of the current 3G standard before 4G’s anticipated rise next decade. 3 Scandinavia today became the latest operator to embrace evolved high-speed packet access (E-HSPA), announcing today a contract with Ericsson to upgrade its current UMTS networks in Sweden and Denmark to the ultra-fast mobile broadband technology.

The northern European all-3G operator will upgrade its networks in stages throughout 2009, making it the first European operator to deploy E-HSPA—also known as HSPA+ or HSPA Evolution. Meanwhile, Australia’s Telstra has already deployed, announcing the start of trials over Ericsson E-HSPA gear that enhances peak network speeds from 14 Mb/s to 21 MB/s. PCCW in Asia also has been testing E-HSPA, and on Monday it announced the completion of trials of the technology in Hong Kong using commercially ready gear from Huawei Technologies. In the US, AT&T has said it would deploy E-HSPA before building its LTE networks but it gave no specific timeline.

E-HSPA is actually an amalgamation of several technical improvements in the UMTS network, building upon the high-speed downlink and uplink packet access (HSDPA and HSUPA) enhancements. Both Telstra and 3 Scandinavia are deploying a radio interface that introduces much more efficient modulation techniques (in technical terms E-HSPA uses 64 Quadrature Amplitude Modulation versus 16 Qam) which ultimately boost the number of bits that can be stuffed into a hertz of spectrum. That higher-order modulation expands downlink capacity over 5 MHz channel to 21 Mb/s. Later stages of E-HSPA call for antenna diversity technologies, which create multiple paths for radio traffic and theoretically doubling capacity on the 3G network to 42 Mb/s. Finally, E-HSPA also supports a flat IP network architecture, which eliminates the number of hops over legacy operator equipment that data traffic must take before reaching the Internet. While the flat IP core doesn’t add any additional radio capacity, it makes for a much simpler and more efficient architecture, which improves network latency and performance.

So far operators have only been deploying specific elements of E-HSPA. While Telstra and 3 focus on the radio interface, they haven’t yet explored using smart antenna technologies, probably because of limitations on the device. Like other 3G evolutionary steps, upgrades aren’t just needed on the infrastructure side but also on the device side to take advantage of boosted capacity. Both Qualcomm and Ericsson have developed E-HSPA chips and radio modules for the devices, but they have yet to make their way into commercial devices though Sierra Wireless has developed an E-HSPA modem that will support Telstra’s trials. The same design problems go for smart antenna technologies: Multiple input-multiple output (MIMO) antennas have to be added at both the cell site and the on the device. And due to the spacing requirements of those antennas and the limited real estate on most handsets, the market for full E-HSPA may be limited to laptops and other types of mobile computers.