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:
-
For downlink case, when FANR state is enabled and transmission of a PAN field in the given block satisfies the current configuration of the Uplink Piggy-backed Ack/Nack Interval setting, both downlink and uplink TBF are currently present, then network will decide when to transmit PAN fields
-
For uplink case, the network requests that the DUT send PAN fields through the use of the CES/P RLC/MAC header bits, then the DUT may transmit a PAN field to the network in the specified response block period, TBF must be allocated in that direction for PAN fields to be transmitted
-
When FANR is enabled, the existing block polling parameters shall be used to determine the frequency with which an uplink transmission is requested from the DUT, where the uplink transmission type requested is specified by the CES/P Setting (Ack/Nack) setting. The new Block Polling Interval (PAN) setting shall specify the frequency at which an uplink transmission is requested from the DUT, where the uplink transmission type requested at these intervals is specified by the CES/P Setting (PAN) setting. If the existing polling interval and PAN polling interval settings are both configured on the same block, the polling type for that block shall be determined by the CES/P Setting (Ack/Nack) setting
Configurable Parameters
The FANR related settings are as shown in the table below:
How to set the FANR mode?
The following procedure details how to access and configure the FANR state and Event-based FANR state.
-
Press
CALL SETUP
.
-
Press PDTCH Parameters softkey,then press the
More
key to display FANR Setup (3 of 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.
-
Press
CALL SETUP
.
-
Press the
More
key on the lower left corner to display the Control menu (2 of 4).
-
Press the Protocol Control softkey ( F4 ) to display a list of protocol layers .
-
Press the RLC/MAC softkey ( F2 ).
-
Press the Block Polling Parameters softkey ( F4 ), use the knob to highlight and set "Block Polling Interval".
-
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