 is subject to the Terms of Use as given at the website. Radio and MS-PCUSN Interfaces Chapter 6 For an UL packet transfer, each mobile station knows when to transmit because of the bitmap transmission in the Packet Resource Assignment (or in the Immediate Assignment for short or one-phase access) if static alloca- tion is used, or from the USF transmitted on the successive DL blocks (MAC header) if dynamic allocation is used. For a DL packet transfer, the bitmap is never transmitted (it remains in the PCU). Therefore, the mobile stations sharing the same PDCH DL have to listen to all the DL blocks transmitted on this time slot, and they know which mobile station the block is destined to by decoding the Temporary Flow Identifier (TFI), transmitted in the RLC header of each RLC data block, and initially assigned to the mobile station in the Packet Resource Assignment (or Immediate Assignment). Static Uplink (UL) Allocation In UL static allocation, a mobile station that has requested packet resources for UL network access is allocated in the following ways: It is allocated from one to eight time slots (PDCH) on the same TDMA. Nortel Networks' implementation, for example, makes sure that the assigned time slots are always successive. The first mobile stations (GPRS Phase II) will be 3 + 1 terminal equipment (three time slots downlink plus one time slot uplink). It is allocated by a TBF STARTING TIME (optional) indicating the position of the first block to use as a TDMA number (for all the allocated time slots for this mobile station). This TDMA number is the Frame Number ([FN] on 22 bits) modulo three minutes. It is coded onto 2 bytes. The TBF STARTING TIME description is similar to the STARTING TIME description in some GSM messages. If the TBF STARTING TIME is not used, the mobile station applies the bitmap on the next received blocks of all the allocated time slots. It is allocated by a DL control time slot, indicating which of the assigned PDCHs on the downlink channel will the mobile station continuously monitor