High Speed Packet Access

The following table is derived from table 5.1a of the release 11 of 3GPP TS 25.306[4] and shows maximum data rates of different device classes and by what combination of features they are achieved. The per-cell per-stream data rate is limited by the "maximum number of bits of an HS-DSCH transport block received within an HS-DSCH TTI" and the "minimum inter-TTI interval". The TTI is 2 ms. So, for example, Cat 10 can decode 27,952 bits/2 ms = 13.976 Mbit/s (and not 14.4 Mbit/s as often claimed incorrectly). Categories 1-4 and 11 have inter-TTI intervals of 2 or 3, which reduces the maximum data rate by that factor. Dual-Cell and MIMO 2x2 each multiply the maximum data rate by 2, because multiple independent transport blocks are transmitted over different carriers or spatial streams, respectively. The data rates given in the table are rounded to one decimal point.

Further UE categories were defined from 3GGP Release 7 onwards as Evolved HSPA (HSPA+) and are listed in Evolved HSDPA UE Categories.

GPRS-speed in a HSDPA plan

As of 28 August 2009, 250 HSDPA networks have commercially launched mobile broadband services in 109 countries. 169 HSDPA networks support 3.6 Mbit/s peak downlink data throughput. A growing number are delivering 21 Mbit/s peak data downlink.

CDMA2000-EVDO networks had the early lead on performance, and Japanese providers were highly successful benchmarks for it. But lately this seems to be changing in favour of HSDPA as an increasing number of providers worldwide are adopting it.

During 2007, an increasing number of telcos worldwide began selling HSDPA USB modems to provide mobile broadband connections. In addition, the popularity of HSDPA landline replacement boxes grew—providing HSDPA for data via Ethernet and WiFi, and ports for connecting traditional landline telephones. Some are marketed with connection speeds of "up to 7.2 Mbit/s",[5] which is only attained under ideal conditions. As a result, these services can be slower than expected, when in fringe coverage indoors.

Enhanced Uplink adds a new transport channel to WCDMA, called the Enhanced Dedicated Channel (E-DCH). It also features several improvements similar to those of HSDPA, including multi-code transmission, shorter transmission time interval enabling faster link adaptation, fast scheduling, and fast Hybrid Automatic Repeat Request (HARQ) with incremental redundancy making retransmissions more effective. Similarly to HSDPA, HSUPA uses a "packet scheduler", but it operates on a "request-grant" principle where the user equipment (UE) requests permission to send data and the scheduler decides when and how many UEs will be allowed to do so. A request for transmission contains data about the state of the transmission buffer and the queue at the UE and its available power margin. However, unlike HSDPA, uplink transmissions are not orthogonal to each other.

In addition to this "scheduled" mode of transmission, the standards allows a self-initiated transmission mode from the UEs, denoted "non-scheduled". The non-scheduled mode can, for example, be used for VoIP services for which even the reduced TTI and the Node B based scheduler will be unable to provide the very short delay time and constant bandwidth required.

Each MAC-d flow (i.e., QoS flow) is configured to use either scheduled or non-scheduled modes. The UE adjusts the data rate for scheduled and non-scheduled flows independently. The maximum data rate of each non-scheduled flow is configured at call setup, and typically not changed frequently. The power used by the scheduled flows is controlled dynamically by the Node B through absolute grant (consisting of an actual value) and relative grant (consisting of a single up/down bit) messages.

At the physical layer, HSUPA introduces new channels E-AGCH (Absolute Grant Channel), E-RGCH (Relative Grant Channel), F-DPCH (Fractional-DPCH), E-HICH (E-DCH Hybrid ARQ Indicator Channel), E-DPCCH (E-DCH Dedicated Physical Control Channel), and E-DPDCH (E-DCH Dedicated Physical Data Channel).

E-DPDCH is used to carry the E-DCH Transport Channel; and E-DPCCH is used to carry the control information associated with the E-DCH.

The following table shows uplink speeds for the different categories of HSUPA.

Further UE categories were defined from 3GGP Release 7 onwards as Evolved HSPA (HSPA+) and are listed in Evolved HSUPA UE Categories.