Hello,
I have to implement 300Mbps data rate in LTE Downlink for 20MHz BW using evm (6616).So,It would require the support of 4x4 MIMO in DSP Aif2.
In aif2 user guide, it's been very well explained the programming for 20 MHz LTE CPRI 4x,DL, 2 AxC With Two Control Channels . But,I have few queries before making it adapt to 4 AxCs in order to support 4x4 MIMO-
1) Firstly,I would like to confirm that i would require to use link rate = 8x in order to support 4 Antenna Carriers? I have even read that we can use either 2 links having 4x link rate each or 1 link having 8x link rate to support 4 antennas for egress,so, what's the better approach to follow?
2) In aif2 user guide, at section 9.1.4, 20 MHz LTE CPRI 4x, DL, 2 AxC With One Control Channel , I have 2 questions-
a)for 20 MHz LTE with 4x Link rate , following cpri frame structure would be there- (Here S denotes Sample) -- AxC0 S0,AxC0 S1,AxC0 S2,AxC0 S3,AxC0 S4,AxC0 S5,AxC0 S6,AxC0 S7,AxC1 S0,AxC1 S1,AxC1 S2,AxC1 S3,AxC1 S4,AxC1 S5,AxC1 S6,AxC1 S7 + 1 Control Word , Right?
b)So, DbmX = 1 ; // X-1 = 2-1 = 1, Where X = no. of AxCs = 2
Now, As we know , (available link bandwidth)/(antenna stream bandwidth) is used to check whether bubble is required for rate matching or not .
In the above scenario, at section 9.1.4, why DbmXBubble = 1;//2 bubbles of 1 AxC sample? (Since, i have read,for 20 MHz BW, available link bandwidth(= value?) is multiple of the bandwidth for an individual antenna carrier(=value?),that is ,no bubble is required in this case)
3) If i select for 1 AxC, egress DB buffer depth = CSL_AIF2_DB_FIFO_DEPTH_QW64 = 3, then actual FIFO size assigned = 128* 8 = 1024 bytes,Correct?
I need to clear my above queries in aif2 in order to realize my approach for 4x4 MIMO in LTE DL. Hope to see a reply from you as soon as possible.
Thanks and Regards, Jeanne
