HSUPA Category Definitions & Data Rates

HSUPA has categories defined to enable the base station, Node B to accommodate the data rates & capabilities of the UE .

3H HSPA includes:
3G HSPA introduction HSDPA HSDPA channels HSDPA categories HSUPA HSUPA categories HSUPA channels Evolved HSPA (HSPA+) Dual carrier HSPA

In the same way that HSDPA has a series of categories defined, so too does HSUPA.

The HSUPA categories define the basic capabilities for the handset or UE and enable the base station or Node B to communicate effectively, knowing the limits of the performance.

Knowing its capabilities, the Node B can allocate sufficient resources to the UE and enable the optimum performance to be obtained.

HSUPA category definitions

The HSUPA categories are detailed in the table below. This shows the different HSUPA categories, and basic definitions including the respective data rates.

HSUPA category definitions
HSUPA category number	Maximum number E-DPDCHs	Minimum spreading factor	Support for 2 ms TTI*	Maximum transport block size (10 ms TTI)	Maximum transport block size (2 ms TTI)	Maximum data rate (Mbps)
1	1	SF4	-	7110	-	0.7 Mbps
2	2	SF4	Y	14484	2798	1.4 Mbps
3	2	SF4	-	14484	-	1.4 Mbps
4	2	SF2	Y	20000	5837	2 Mbps for 10 ms TTI 2.9 Mbps for 2 ms TTI
5	2	SF2	-	20000	-	2.00 Mbps
6	2 + 2**	SF2	Y	20000	11520	2 Mbps for 10 ms TTI 5.74 Mbps for 2 ms TTI

Notes:
*A 10 ms TTI is supported in all categories
** Two E-DPDCHs at SF2 and two at SF4

Support for the E-DCH TTI (Transmission Time Interval) of 10 ms is required for all HSUPA categories. It is only some HSUPA categories that support a 2 ms TTI. Also the highest data rate supported with a 10 ms TTi is 2 Mbps. The reason for this is to limit the amount of buffer memory required in the NodeB for soft combining because a larger block transport size means that a larger soft buffer is needed for retransmissions.

With HSUPA deployed as part of the overall HSPA upgrade, data speeds available to users rose considerably. The uplink was a key part of this, reducing latency and enabling much faster transmission in the uplink.