HSPA is the name used for UMTS (Universal Mobile Telecommunications System) networks that provide both HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access). A presentation from 3G Americas included market statistics showing 169 UMTS operators in 71 countries and 117 HSDPA operators in 59 countries. Clearly, HSDPA is seeing a global surge of deployment, and for good reason. With user rates frequently above 1 Mbps and sub-100 msec latency, most networking applications work extremely well. As explained in a presentation from Ericsson, HSDPA was specified in 3GPP (Third Generation Partnership Project) Release 5 specifications. Release 6 includes HSUPA, and you’ll start seeing HSUPA this year from UMTS operators such as AT&T. HSUPA will bring uplink speeds in line with downlink speeds, though as with EV-DO Rev A and WiMAX, uplink spectral efficiency is typically only half of downlink spectral efficiency, so peak rates normally will be lower than the downlink rate. Nevertheless, uplink speeds will be impressive. Ericsson showed live operator data for one network with median bit rates of 1.0 Mbps. HSUPA also enables lower latencies, as low as 50 msec when measured from the mobile device to the edge of the network. HSDPA itself will get faster, with devices supporting peak rates of 7.2 Mbps, enabling real-world throughputs of 2 Mbps to 3 Mbps, assuming the operator has the bandwidth in its backhaul to support these rates.
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