Modulation Coding Scheme

Downlink EGPRS Level

The Downlink EGPRS Level is used to group certain subsets of downlink Modulation Coding Scheme Choices together. The available downlink MCS selections in EGPRS Active Cell operating mode are determined by the selected Downlink EGPRS Level.

The Downlink EGPRS Level can be set to one of the following values:

• EGPRS: The available downlink modulation coding schemes are MCS-1 to MCS-9.
• EGPRS2-A: The available downlink modulation coding schemes are MCS-1 to MCS-4, MCS-6 (only for retransmissions of blocks originally transmitted using EGPRS), MCS-7, MCS-8 and DAS-5 to DAS-12.

MCS-1 through MCS-4 use GMSK modulation, MCS-5 through MCS-9 use 8PSK modulation, DAS-5 through DAS-9 use 16QAM modulation, while

DAS-10 through DAS-12 use 32QAM modulation.

The change of EGPRS Level may cause the change of MCS settings. If the MCS setting is no longer available with a new EGPRS Level, it will be forced to MCS-4.

The GPIB command to set the Downlink EGPRS Level is CALL:(PDTCH|PDTChannel):EGPRS:LEVel:DOWNlink .

Note, "As Uplink" is also an available selection for downlink MCS setting when the uplink MCS setting is within the MCS group determined by the selected Downlink EGPRS Level. Otherwise, the downlink MCS will be forced to the default value.

Uplink EGPRS Level

The Uplink EGPRS Level is used to group certain subsets of downlink Modulation Coding Scheme Choices together. The available uplink MCS selections in EGPRS Active Cell operating mode are determined by the selected Downlink EGPRS Level.

The uplink EGPRS Level can be set to one of the following values:

• EGPRS: The available uplink modulation coding schemes are MCS-1 to MCS-9.
• EGPRS2-A: The available uplink modulation coding schemes are MCS-1 to MCS-6, and UAS-7 to DAS-11.

MCS-1 through MCS-4 use GMSK modulation, MCS-5 through MCS-9 use 8PSK modulation, UAS-7 through UAS-11 use 16QAM modulation.

The change of EGPRS Level may cause the change of MCS settings. If the MCS setting is no longer available with a new EGPRS Level, it will be forced to MCS-4.

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Operating Considerations

The following restrictions apply when the 16QAM or 32QAM MCS is selected:

1. It is only possible to configure downlink blocks using GMSK modulation and no more than one non-GMSK modulation format (8PSK, 16QAM or 32QAM) on a PDCH-carrier basis.
2. Due to the restriction in 1, the MCS used for retransmission in an link adaptation process is always GMSK or the same non-GMSK modulation used by the previous blocks.
3. Fading can not be supported with the EGPRS2A Modulation Coding Schemes simultaneously.

When an ETSI Type B connection is to be established, the test set shall apply the same MCS on the downlink data blocks as the commanded MCS on the uplink. An attempt to establish an ETSI Type B connection with asymmetric MCS capability shall fail.

Asymmetric Switched Radio Block Loopback Mode (ASRB) is allowable when the modulation types in downlink and uplink are different. If the downlink modulation type is 8PSK and the uplink modulation type is GMSK, a radio block sent by the test set on a downlink timeslot using 8PSK modulation should be followed by two radio blocks on the same timeslot where the test set transmits GSM dummy bursts.

However, ASRB with 16QAM or 32QAM modulation in either direction is not supported.

GPRS Bit Error Ratio (GBER) or GPRS Block Error Ration (BLER) with loopback mode and EGPRS SRB Bit Error Measurement is not supported when the 16QAM or 32QAM is used. However, the BLER measurement with polling mode is supported.

Related Topics

EGPRS Data Rate Configurations

Incremental Redundancy