4G/LTE - BL/CE

MAX Throughput

Just in terms of theoretical throughput, M1 Downlink Max throughput is same as DL Category 0 which is 1 Mbps, but considering the repetivity scheduling, MPDCCH and PDSCH in separate subframes, Half Duplex operation, it will not be easy to achieve this throughput. The practical throughput may vary widely depending on DL / UL scheduling.

< 36.306 v13.4 - Table 4.1A-1: Downlink physical layer parameter values set by the field ue-CategoryDL >   

36.213-8.6.1 Modulation order and redundancy version determination  and 8.6.2 Transport block size determination states as follows :

• The modulation order is determined according to following table.  CEModeB UE is not expected to receive a DCI format 6-0B indicating I_MCS >= 10.
• For CEModeA, TBS of a user data PUSCH (except PUSCH scheduled by Random Access Response) is determined by following table. (For the details of TBS allocation, refer to MCS/TBS Determination page)

< 36.213-Table 8.6.1-2: Modulation and TBS index table for PUSCH >

As mentioned above, real max throughput for user data can vary greatly depending on how eNB schedule the DL / UL transmission. General factors to influence the max throughput for user data are as follows :

• Duplex Mode : Half Duplex or Full Duplex (it is highly likely that Half Duplex will be used for LTE-M1 deployment)
• SIB Transmission : When SIB is transmitted, User Data does not transmitted.
• schedulingInfoSIB1-BR-r13 in MIB : This determines the repetition number of SIB1. As a result, it will influence user data throughput.
• si-Periodicity,si-WindowLength-BR-r13,si-RepetitionPattern-r13 in SIB1-BR : These determines the transmission pattern of other SIBs. As a result, it will influence user data throughput        
• mpdcch-NumRepetition-r13 in RRC Connection Setup : This may or may not influence user traffic. In 2 + 4 RB allocation, it would not influence the throughput, but in 6 RB allocation this would influence user data throughput since PDSCH / PUSCH cannot transmitted when MPDCCH is transmitted.
• fdd-DownlinkOrTddSubframeBitmapBR-r13, fdd-UplinkSubframeBitmapBR-r13 in SIB1-BR :  These can activate or deactivate a certain subframe for transmission.

Following is one example of scheduling pattern for user data. If we assume that eNB assing max TBS (i.e, 1000) the throughput will be around 300 Kbps DL and 300 Kbps UL.

< Example of User Traffic scheduling in Half Duplex mode >

Reference :

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