documentation, bug in UDP timeout, merge develop
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laurent
+70
-23
@@ -18,7 +18,7 @@ names like RRH/RRU/RE/RU/PNF.
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In OpenAir code, the terminology is often RU and BBU.
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#Usage
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# OpenAirUsage
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##EPC and general environment
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### OAI EPC
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@@ -137,36 +137,60 @@ I/Q samples sending.
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The main loop uses extensively function pointers to call the right
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processing function depending on the split case.
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A lot of OAI reduntant global variables contains the same semantic data: time,frame, subframe.
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The reworked main loop take care of a uniq variable that comes directly from harware: RF board sampling number.
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To use OAI, we need to set all OAI variables that derivates from this timestamp value. The function setAllfromTS() implements this.
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### Splitted main level
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When FS6 is actived, a main loop for DU (du_fs6()) a main loop for CU case replaces the uniq eNB main loop.
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Each of these main loops calls initialization of OAI LTE data and the FS6 transport layer initialization.
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Then, it runs a infinite loop on: set time, call UL and DL. The time comes from the RF board, so the DU sends the time to the CU.
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This is enough for RF board dialog, but the FS6 is higher in SW layers,
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we need to cut higher functions inside downlink and uplink procedures.
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As much as possible, the FS6 code is in the directory OPENAIR_DIR/executables. When a given OAI piece of code is small or need complex changes, it is reworked in the file fs6-main.c. The functions naming keeps the OAI function name, adding suffix _fromsplit() or _tosplit().
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When this organization would lead to large code copy, it is better to insert modifications in OAI code. This is done in two files:
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- openair1/SCHED/phy_procedures_lte_eNb.c: to send signaling channels computation results
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- the function sendFs6Ulharq() centralizes all signaling channels forwarding to CU
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- openair1/PHY/LTE_TRANSPORT/ulsch_decoding.c: to deal with FS6 user plane split
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- sendFs6Ul() is used once to forward user plane to CU
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### DownLink
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The main procedure is phy\_procedures\_eNB\_TX
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The main procedure is phy\_procedures\_eNB\_TX()
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This is building the common channels (beacon, multi-UE signaling).
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The FS6 split breaks this function into pieces:
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- The multi-UE signals, built by common\_signal\_procedures(),
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* The multi-UE signals, built by common\_signal\_procedures(),
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subframe2harq\_pid(), generate\_dci\_top(), subframe2harq\_pid()
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- These functions will be executed in the DU, nevertheless all
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context has to be sent (it is also needed partially for
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UL spitting)
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- IT should be in the DU also to meet the requirement of pushing
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* These functions run in the DU, nevertheless all context has to be sent
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(it is also needed partially for UL spitting)
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* Run in the DU also to meet the requirement of pushing
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in DU the data encoded with large redundancy (>3 redundancy)
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- the per UE data: pdsch\_procedures() that needs further splitting:
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* the per UE data: pdsch\_procedures() needs further splitting:
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- dlsch\_encoding\_all() that makes the encoding: turbo code
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* dlsch\_encoding\_all() that makes the encoding: turbo code
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and lte\_rate\_matching\_turbo() that will be in the DU (some
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unlikely cases can reach redundancy up to x3, when MCS is very
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low (negative SINR cases)).
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- dlsch\_encoding() output needs to be transmitted between the
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* dlsch\_encoding() output needs to be transmitted between the
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DU and the CU for functional split 6.
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- dlsch\_scrambling() that will go in the DU
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- dlsch\_modulation() that will go in the DU
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* dlsch\_scrambling() that will go in the DU
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* dlsch\_modulation() that will go in the DU
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The du user plane data is made of expanded bit in OAI at FS6 split level. 1 pair of functions compact back these bits into 8bits/byte before sending data and expand it again in the DU data reception (functions: fs6Dl(un)pack()).
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### Uplink
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@@ -178,20 +202,36 @@ channels.
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Ocp-main.c:rxtx() calls directly the entry procedure
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phy\_procedures\_eNB\_uespec\_RX() calls:
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- rx\_ulsch() that demodulate and extract soft bits per UE.
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* rx\_ulsch() that demodulate and extract soft bits per UE.
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- This function runs in the DU
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- the output data will be processes in the DU, so it needs to be
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* This function runs in the DU
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* the output data will be processes in the DU, so it needs to be
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transmitted to the DU
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- ulsch\_decoding() that do lte\_rate\_matching\_turbo\_rx()
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sub\_block\_deinterleaving\_turbo() then turbo decode
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* ulsch\_decoding() that do lte\_rate\_matching\_turbo\_rx()
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sub\_block\_deinterleaving\_turbo()
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then turbo decode that is in the CU
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* fill\_ulsch\_cqi\_indication() fill\_crc\_indication() , fill\_rx\_indication()
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* DU performs the signal processing of each channel data, prepare and sent to the CU the computed result
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- it runs
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- fill\_ulsch\_cqi\_indication()
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* Random access channel detection runs in the DU
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* the DU reports to the CU only the detected temprary identifier for RACH response
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- TBD: either runs in DU or output needs to be transmitted to DU
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- fill\_crc\_indication() , fill\_rx\_indication() results need also
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to be transmitted or made in the DU
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### signaling data in each direction (UL and DL)
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* each LTE channel needs to be propagated between CU and DU
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* the simplest are the almost static data such as PSS/SSS, that need only static eNB parameters and primary information (frame numbering)
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* all the other channels require data transmission CU to DU and DU to CU
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* the general design push all the low level processing for these channels in the DU
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* the CU interface transports only signal processing results (UL) or configuration to create the RF signal (DL case)
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* HARQ is detected in the DU, then only the ACK or NACK is reported to CU
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* the CU have to control the power and MCS (modulation and coding scheme)
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* the DU performs the signal processing and report only the decoded data like the CQI
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* as the DU performas the modulation, scrambling and puncturing, each data packet is associated with the LTE parameters required for these features
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* in DL, the CU associates the control parameters and the user plane data
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* in UL, the CU sends upfront the scheduled UL data to the DU. So, the DU have the required knowledge to decode the next subframes in time.
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### UDP transport layer
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@@ -233,6 +273,10 @@ Run the CU init of the split 6 eNB.
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`fs6=du ./ocp-softmodem -O $OPENAIR_DIR/enb.fs6.example.conf --rfsim --log_config.phy_log_level debug
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`
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If the CU and the DU are not on the same machine, the remote address of each side need to be specified as per this example
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`fs6=du FS6_REMOTE_IP=192.168.2.211 ./ocp-softmodem -O $OPENAIR_DIR/enb.fs6.example.conf --rfsim --log_config.phy_log_level debug
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`
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runs the functional split 6 DU
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@@ -244,6 +288,9 @@ Runs the UE (to have the UE signal scope, compile it with make uescope)
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CU and DU IP address and port are configurable in the eNB configuration
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file (as X2, GTP, … interfaces).
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CU+DU+UE can run with option --noS1 to avoid to use a EPC.
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##5G and F1
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Today 5G achievement is limited to physical layer.
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