Release 99 Uplink Packet Data

?There are two different techniques defined in the Release 99 specification to enable Uplink packet data. Most commonly, data transmission is supported using either the Dedicated Channel (DCH) or the Random Access Channel (RACH).

?The DCH is the primary means of supporting packet data services. Each UE uses an Orthogonal Variable Spreading Factor (OVSF) code, dependent on the required data rate. Fast closed loop Power Control is employed to ensure that a target Signal-to-Interference Ratio (SIR) is maintained in order to control the block error rate (BLER). Macro Diversity is supported using soft handover.

?Data transfer can also be supported on the RACH. This common channel employs an OVSF code, with a spreading factor between 32 and 256, as negotiated with UTRAN during the Access procedure. Because it needs to be shared among all UEs, higher data rates are generally not supported. Macro Diversity is also not supported and the channel operates with a fixed (or slow changing) power allocation.

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