Fast Ack/Nack Reporting

Fast Ack/Nack Reporting

Last updated: November 25, 2010

This section is only applicable to the EGPRS lab applications.

The Fast Ack/Nack reporting is part of the Reduced Latency (RL) procedures, it refers to the possibility to include, in a radio block for data transfer sent in one direction, piggy-backed Ack/Nack information relative to the data transfer, i.e. relative to the TBF, in the other direction. This is achieved by inserting a fixed-size Piggy-backed Ack/Nack (PAN) field in the RLC radio block. Therefore a Radio Block for data transfer consists of one RLC/MAC header, one or two RLC data block(s) and, optionally, one PAN field. The following table shows the radio block structure.

Radio Block
RLC/MAC header HCS RLC data BCS PAN and PCS (optional)

This mechanism provides the ability to increase the ratio of Packet Switched bandwidth used for data transfer and also reduce the latency between a given transmission and the reception of the corresponding acknowledgement.

Constrains on FANR Configuration

When setting the FANR configuration, the following overriding restrictions apply:

Configurable Parameters

The FANR related settings are as shown in the table below:


GPIB Command

FANR State CALL:(PDTCH|PDTChannel):FANReporting[:STATe]
Event-based FANR State CALL:(PDTCH|PDTChannel):FANReporting:EVENt[:STATe]

Deferred FANR State


Deferred Event-based FANR State


Deferred Time-based FANR TSH


Deferred PDTCH2 Time-based FANR reporting bitmap


Downlink PAN Encoding Type


Downlink PAN Payload Generator


Downlink PAN Custom Payload


Downlink PAN Custom Encoding Payload Pattern


Time-based PAN corruption type


Time-based PAN unused type


PDTCH Time-based FANR reporting bitmap


Time-based FANR TSH


CES/P (Ack/Nack)


Block Polling Interval (PAN)


Uplink Piggy-Back Ack/Nack Interval CALL:FUNCtion:DATA:PUPLink:INTerval:PAN

How to set the FANR mode?

The following procedure details how to access and configure the FANR state and Event-based FANR state.

  1. Press CALL SETUP .
  2. Press PDTCH Parameters softkey,then press the More key to display FANR Setup (3 of 3)
  3. Press FANR Setup ( F9 ) , Use the knob to select the parameter that you want to set.

The following procedure details how to access and set the Block Polling Interval and Uplink Piggy-Back Ack/Nack Interval.

  1. Press CALL SETUP .
  2. Press the More key on the lower left corner to display the Control menu (2 of 4).
  3. Press the Protocol Control softkey ( F4 ) to display a list of protocol layers .
  4. Press the RLC/MAC softkey ( F2 ).
  5. Press the Block Polling Parameters softkey ( F4 ), use the knob to highlight and set "Block Polling Interval".
  6. Press the TBT Control softkey ( F5 ), use the knob to highlight and set "Uplink Piggy-Back Ack/Nack Interval".

Operating Considerations

The FANR is applicable in both uplink and downlink in Active Cell (EGPRS) operating mode.

FANR is only supported in the downlink in EGPRS BCH+PDTCH and EGPRS BCH+PDTCH+TCH operating modes. More specifically, polling for uplink PAN fields is not supported in EGPRS BCH+PDTCH and EGPRS BCH+PDTCH+TCH operating modes.However, parameters associated with FANR can be changed in any other operating modes.

Two-Box handovers in Packet-Idle state shall behave the same regardless of FANR mode, however PS handovers performed during Packet-Transfer mode shall not be supported for FANR mode TBFs and shall results in unsuccessful TBF establishment in the destination cell

Related Topics

TTI Mode Configuration