continue timestamp

SystemX-tutorial-design.md

+# OpenAirInterface for SystemX
+
+#Terminology
+
+****This document use the 5G terminology****
+
+**Central Unit (CU): **It is a logical node that includes the gNB
+functions like Transfer of user data, Mobility control, Radio access
+network sharing, Positioning, Session Management etc., except those
+functions allocated exclusively to the DU. CU controls the operation of
+DUs over front-haul (Fs) interface. A central unit (CU) may also be
+known as BBU/REC/RCC/C-RAN/V-RAN/VNF
+
+**Distributed Unit (DU):** This logical node includes a subset of the
+gNB functions, depending on the functional split option. Its operation
+is controlled by the CU. Distributed Unit (DU) also known with other
+names like RRH/RRU/RE/RU/PNF.
+
+In OpenAir code, the terminology is often RU and BBU.
+
+#Usage
+##EPC and general environment
+### OAI EPC
+
+Use the stable OAI EPC, that can run in one machine (VM or standalone)
+
+Draft description:
+<https://open-cells.com/index.php/2017/08/22/all-in-one-openairinterface-august-22nd/>
+
+##Standalone 4G
+
+EPC+eNB on one machine, the UE can be commercial or OAI UE.
+### USRP B210
+
+Main current issue: traffic is good only on coaxial link between UE and
+eNB (probably power management issue).
+
+### Simulated RF
+
+Running eNB+UE both OAI can be done over a virtual RF link.
+
+The UE current status is that threads synchronization is implicit in
+some cases. As the RF simulator is very quick, a “sleep()” is required
+in the UE main loop
+
+(line 1744, targets/RT/USER/lte-ue.c).
+
+Running also the UE in the same machine is possible with simulated RF.
+
+Running in same machine is simpler, offers about infinite speed for
+virtual RF samples transmission.
+
+A specific configuration is required because the EPC Sgi interface has
+the same IP tunnel end point as the UE.
+
+So, we have to create a network namespace for the UE and to route data
+in/out of the namespace.
+``` bash
+ip netns delete aNameSpace 2&gt; /dev/null
+
+ip link delete v-eth1 2&gt; /dev/null
+
+ip netns add aNameSpace
+
+ip link add v-eth1 type veth peer name v-peer1
+
+ip link set v-peer1 netns aNameSpace
+
+ip addr add 10.200.1.1/24 dev v-eth1
+
+ip link set v-eth1 up
+
+iptables -t nat -A POSTROUTING -s 10.200.1.0/255.255.255.0 -o enp0s31f6
+-j MASQUERADE
+
+iptables -A FORWARD -i enp0s31f6 -o v-eth1 -j ACCEPT
+
+iptables -A FORWARD -o enp0s31f6 -i v-eth1 -j ACCEPT
+
+ip netns exec aNameSpace ip link set dev lo up
+
+ip netns exec aNameSpace ip addr add 10.200.1.2/24 dev v-peer1
+
+ip netns exec aNameSpace ip link set v-peer1 up
+
+ip netns exec aNameSpace bash
+```
+
+After the last command, the Linux shell is in the new namespace, ready
+to run the UE.
+
+To make user plan traffic, the traffic generator has to run in the same
+namespace
+
+`ip netns exec aNameSpace bash
+`
+
+The traffic genenrator has to specify the interface:
+
+`route add default oaitun_ue1
+`
+
+or specify the outgoing route in the traffic generator (like option “-I”
+in ping command).
+
+## Split 6 DL 4G
+
+The contract describes to reuse the uplink existing if4p5 and to develop
+is this work the downlink “functional split 6”.
+
+The customer required after signature to develop also the uplink
+functional split 6. This is accepted, as long as the whole work is
+research with no delivery completeness warranty.
+### Simulation
+
+To be able to verify the new features and to help in all future
+developments, Open Cells added and improved the Rf board simulator
+during this contract.
+
+We added the channel modeling simulation, that offer to simulate various
+3GPP defined channels.
+### Main loop
+
+The main log is in RF simulator is in
+
+ targets/RT/USER/lte-ru.c and targets/RT/USER/lte-enb.c
+
+As this piece of SW is very complex and doesn’t meet our goals
+(functional split 6), a cleaned version replaces these 2 files in
+executables/ocp-main.c (openair1/SCHED/prach\_procedures.c is also
+replaced by this new file as it only launching the RACH actual work in a
+way not compatible with our FS6).
+
+The main loop cadences the I/Q samples reception, signal processing and
+I/Q samples sending.
+
+The main loop uses extensively function pointers to call the right
+processing function depending on the split case.
+
+This is enough for RF board dialog, but the FS6 is higher in SW layers,
+we need to cut higher functions inside downlink and uplink procedures.
+
+### DownLink
+
+The main procedure is phy\_procedures\_eNB\_TX
+
+This is building the common channels (beacon, multi-UE signaling).
+
+The FS6 split breaks this function into pieces:
+
+-   The multi-UE signals, built by common\_signal\_procedures(),
+    subframe2harq\_pid(), generate\_dci\_top(), subframe2harq\_pid()
+
+    -   These functions will be executed in the DU, nevertheless all
+        context has to be sent (it is also needed partially for
+        UL spitting)
+    -   IT should be in the DU also to meet the requirement of pushing
+        in DU the data encoded with large redundancy (&gt;3 redundancy)
+-   the per UE data: pdsch\_procedures() that needs further splitting:
+
+    -   dlsch\_encoding\_all() that makes the encoding: turbo code
+        and lte\_rate\_matching\_turbo() that will be in the DU (some
+        unlikely cases can reach redundancy up to x3, when MCS is very
+        low (negative SINR cases)).
+
+        -   dlsch\_encoding() output needs to be transmitted between the
+            DU and the CU for functional split 6.
+    -   dlsch\_scrambling() that will go in the DU
+    -   dlsch\_modulation() that will go in the DU
+
+### Uplink
+
+The uplink require configuration that is part of the DL transmission.
+
+It interprets the signalling to extract the RACH and the per UE data
+channels.
+
+Ocp-main.c:rxtx() calls directly the entry procedure
+phy\_procedures\_eNB\_uespec\_RX() calls:
+
+-   rx\_ulsch() that demodulate and extract soft bits per UE.
+
+    -   This function runs in the DU
+    -   the output data will be processes in the DU, so it needs to be
+        transmitted to the DU
+-   ulsch\_decoding() that do lte\_rate\_matching\_turbo\_rx()
+    sub\_block\_deinterleaving\_turbo() then turbo decode
+
+    -   it runs
+-   fill\_ulsch\_cqi\_indication()
+
+    -   TBD: either runs in DU or output needs to be transmitted to DU
+-   fill\_crc\_indication() , fill\_rx\_indication() results need also
+    to be transmitted or made in the DU
+
+### UDP transport layer
+
+A general UDP transport layer is in executables/transport\_split.c
+
+Linux offers a UDP socket builtin timeout, that we use.
+
+In and out buffers are memory zones that contains compacted
+(concatenated) UDP chunks.
+
+For output, sendSubFrame() sends each UDP chunk
+
+For input, receiveSubFrame() collects all UDP chunks for a group (a
+subframe in OAI LTE case). It returns in the following cases:
+
+-   all chunks are received
+-   a timeout expired
+-   a chunk from the next subframe already arrived
+
+### Functional split 6 usage
+
+The ocp cleaned main hale to be used: run ocp-softmodem instead of
+lte-softmodem.
+
+The functionality and parameters is the same, enhanced with FS6 mode.
+
+The environment variable “fs6” enables the fs6 mode and decided to be cu
+or du from the fs6 variable content.
+
+Example:
+
+`fs6=cu ./ocp-softmodem -O … (regular lte-softmodem paramters)
+`
+
+Run the CU init of the split 6 eNB.
+
+CU and DU IP address and port are configurable in the eNB configuration
+file (as X2, GTP, … interfaces).
+
+##5G and F1
+
+Today 5G achievement is limited to physical layer.
+
+The available modulation is 40MHz, that require one X310 or N300 for the
+gNB and a X310 or N300 for the nrUE.
+
+### Usage with X310
+
+Linux configuration:
+<https://files.ettus.com/manual/page_usrp_x3x0_config.html>
+
+We included most of this configuration included in OAI source code.
+
+Remain to set the NIC (network interface card) MTU to 9000 (jumbo
+frames).
+
+### Running 5G
+
+Usage with RFsimulator:
+
+gNB
+
+`sudo RFSIMULATOR=server ./nr-softmodem -O
+../../../targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.conf
+--parallel-config PARALLEL\_SINGLE\_THREAD`
+
+nrUE
+
+`sudo RFSIMULATOR=127.0.0.1 ./nr-uesoftmodem --numerology 1 -r 106 -C
+3510000000 -d`

cmake_targets/CMakeLists.txt

@@ -183,8 +183,8 @@ set(CMAKE_EXE_LINKER_FLAGS  "${CMAKE_EXE_LINKER_FLAGS} -Wl,-rpath -Wl,${CMAKE_CU
 #########################
 # set a flag for changes in the source code
 # these changes are related to hardcoded path to include .h files
-set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS} -g -DMALLOC_CHECK_=3")
-set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS} -g -DMALLOC_CHECK_=3 -O2")
+set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS} -g3  -DMALLOC_CHECK_=3")
+set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS} -g3 -DMALLOC_CHECK_=3 -O0")
 
 
 set(GIT_BRANCH        "UNKNOWN")

executables/main-fs6.c

@@ -653,6 +653,8 @@ void phy_procedures_eNB_TX_extract(uint8_t *bufferZone, PHY_VARS_eNB *eNB, L1_rx
     hDL(bufferZone)->amp=AMP;
   }
 
+  if (num_mdci) abort();
+
   if (do_meas==1) stop_meas(&eNB->dlsch_common_and_dci);
 
   if (do_meas==1) start_meas(&eNB->dlsch_ue_specific);
@@ -741,21 +743,21 @@ void phy_procedures_eNB_TX_extract(uint8_t *bufferZone, PHY_VARS_eNB *eNB, L1_rx
   return;
 }
 
-void DL_du_fs6(RU_t *ru, int frame, int subframe, uint64_t TS) {
+void DL_du_fs6(RU_t *ru) {
   RU_proc_t *ru_proc=&ru->proc;
 
   for (int i=0; i<ru->num_eNB; i++) {
     initBufferZone(bufferZone);
-    int nb_blocks=receiveSubFrame(&sockFS6, TS, bufferZone, sizeof(bufferZone) );
+    int nb_blocks=receiveSubFrame(&sockFS6, ru_proc->timestamp_tx, bufferZone, sizeof(bufferZone), CTsentCUv0 );
+
+    if (nb_blocks > 0) {
       L1_rxtx_proc_t *L1_proc = &ru->eNB_list[i]->proc.L1_proc_tx;
       L1_proc->timestamp_tx=hUDP(bufferZone)->timestamp;
       L1_proc->frame_tx=hDL(bufferZone)->frame;
       L1_proc->subframe_tx=hDL(bufferZone)->subframe;
-
-    if (nb_blocks>0)
       phy_procedures_eNB_TX_process( bufferZone, nb_blocks, ru->eNB_list[i], &ru->eNB_list[i]->proc.L1_proc, 1);
-    else
-      LOG_E(PHY,"DL not received for subframe: %d\n", subframe);
+    } else
+      LOG_E(PHY,"DL not received for subframe\n");
   }
 
   /* OAI data model is wrong: hardcode link ru to enb index 0*/
@@ -799,8 +801,14 @@ void UL_du_fs6(RU_t *ru, int frame, int subframe) {
     phy_procedures_eNB_uespec_RX_extract(bufferZone, FS6_BUF_SIZE, eNB, &proc->L1_proc );
   }
 
+  if (hUDP(bufferZone)->nbBlocks==0) {
+    hUDP(bufferZone)->nbBlocks=1; // We have to send the signaling, even is there is no user plan data (no UE)
+    hUDP(bufferZone)->blockID=0;
+    hUDP(bufferZone)->contentBytes=sizeof(fs6_ul_t);
+  }
+
   for (int i=0; i<ru->num_eNB; i++) {
-    sendSubFrame(&sockFS6,bufferZone, sizeof(fs6_ul_t));
+    sendSubFrame(&sockFS6, bufferZone, sizeof(fs6_ul_t), CTsentDUv0);
   }
 }
 
@@ -827,12 +835,12 @@ void DL_cu_fs6(RU_t *ru,int frame, int subframe) {
     hUDP(bufferZone)->contentBytes=sizeof(fs6_dl_t);
   }
 
-  sendSubFrame(&sockFS6, bufferZone, sizeof(fs6_dl_t) );
+  sendSubFrame(&sockFS6, bufferZone, sizeof(fs6_dl_t), CTsentCUv0 );
 }
 
 void UL_cu_fs6(RU_t *ru,int frame, int subframe, uint64_t TS) {
   initBufferZone(bufferZone);
-  int nb_blocks=receiveSubFrame(&sockFS6, TS, bufferZone, sizeof(bufferZone) );
+  int nb_blocks=receiveSubFrame(&sockFS6, TS, bufferZone, sizeof(bufferZone), CTsentDUv0 );
 
   if (nb_blocks ==0) {
     LOG_W(PHY, "CU lost a subframe\n");
@@ -878,7 +886,6 @@ void *cu_fs6(void *arg) {
 void *du_fs6(void *arg) {
   RU_t               *ru      = (RU_t *)arg;
   //RU_proc_t          *proc    = &ru->proc;
-  int64_t           AbsoluteSubframe=-1;
   fill_rf_config(ru,ru->rf_config_file);
   init_frame_parms(&ru->frame_parms,1);
   phy_init_RU(ru);
@@ -887,11 +894,9 @@ void *du_fs6(void *arg) {
   AssertFatal(createUDPsock(NULL, "7777", "127.0.0.1", "8888", &sockFS6),"");
 
   while(1) {
-    AbsoluteSubframe++;
-    int subframe=AbsoluteSubframe%10;
-    int frame=(AbsoluteSubframe/10)%1024;
-    UL_du_fs6(ru, frame,subframe);
-    DL_du_fs6(ru, frame,subframe, AbsoluteSubframe);
+    L1_rxtx_proc_t *proc = &ru->eNB_list[0]->proc;
+    UL_du_fs6(ru, proc->frame_rx,proc->subframe_rx);
+    DL_du_fs6(ru);
   }
 
   return NULL;

executables/main-ocp.c

@@ -582,13 +582,11 @@ static inline int rxtx(PHY_VARS_eNB *eNB,L1_rxtx_proc_t *proc, char *thread_name
   return(0);
 }
 
-void eNB_top(PHY_VARS_eNB *eNB, int frame_rx, int subframe_rx, char *string,RU_t *ru) {
+void eNB_top(PHY_VARS_eNB *eNB, int dummy1, int dummy2,  char *string,RU_t *ru) {
   L1_proc_t *proc           = &eNB->proc;
   L1_rxtx_proc_t *L1_proc = &proc->L1_proc;
   LTE_DL_FRAME_PARMS *fp = &ru->frame_parms;
   RU_proc_t *ru_proc=&ru->proc;
-  proc->frame_rx    = frame_rx;
-  proc->subframe_rx = subframe_rx;
 
   if (!oai_exit) {
     L1_proc->timestamp_tx = ru_proc->timestamp_rx + (sf_ahead*fp->samples_per_tti);
@@ -650,16 +648,6 @@ void rx_rf(RU_t *ru,int *frame,int *subframe) {
   proc->subframe_tx  = (proc->subframe_rx+sf_ahead)%10;
   proc->frame_tx     = (proc->subframe_rx>(9-sf_ahead)) ? (proc->frame_rx+1)&1023 : proc->frame_rx;
 
-  if (proc->first_rx == 0) {
-    AssertFatal( proc->subframe_rx == *subframe && proc->frame_rx == *frame,
-                 "Received Timestamp (%llu) doesn't correspond to the time we think it is (proc->subframe_rx %d, subframe %d) (proc->frame_rx %d frame %d)\n",
-                 (long long unsigned int)proc->timestamp_rx,proc->subframe_rx,*subframe, proc->frame_rx,*frame);
-  } else {
-    proc->first_rx = 0;
-    *frame = proc->frame_rx;
-    *subframe = proc->subframe_rx;
-  }
-
   if (rxs != fp->samples_per_tti) {
 #if defined(USRP_REC_PLAY)
     exit_fun("Exiting IQ record/playback");

executables/split_headers.h

@@ -18,6 +18,9 @@ typedef struct {
   int sockHandler;
 } UDPsock_t;
 
+#define CTsentCUv0 0xA500
+#define CTsentDUv0 0x5A00
+
 typedef struct commonUDP_s {
   uint64_t timestamp; // id of the group (subframe for LTE)
   uint16_t nbBlocks;       // total number of blocks for this timestamp
@@ -67,8 +70,8 @@ typedef struct {
 } fs6_dl_uespec_t;
 
 bool createUDPsock (char *sourceIP, char *sourcePort, char *destIP, char *destPort, UDPsock_t *result);
-int receiveSubFrame(UDPsock_t *sock, uint64_t expectedTS, void *bufferZone,  int bufferSize);
-int sendSubFrame(UDPsock_t *sock, void *bufferZone, ssize_t secondHeaderSize);
+int receiveSubFrame(UDPsock_t *sock, uint64_t expectedTS, void *bufferZone,  int bufferSize, uint16_t contentType);
+int sendSubFrame(UDPsock_t *sock, void *bufferZone, ssize_t secondHeaderSize, uint16_t contentType);
 
 #define initBufferZone(xBuf) \
   uint8_t xBuf[FS6_BUF_SIZE];\
@@ -77,12 +80,12 @@ int sendSubFrame(UDPsock_t *sock, void *bufferZone, ssize_t secondHeaderSize);
 #define hUDP(xBuf) ((commonUDP_t *)xBuf)
 #define hDL(xBuf)  (((fs6_dl_t*)((commonUDP_t *)xBuf)+1))
 
-inline size_t alignedSize(uint8_t *ptr) {
+static inline size_t alignedSize(uint8_t *ptr) {
   commonUDP_t *header=(commonUDP_t *) ptr;
   return ((header->contentBytes+sizeof(commonUDP_t)+blockAlign-1)/blockAlign)*blockAlign;
 }
 
-inline void *commonUDPdata(uint8_t *ptr) {
+static inline void *commonUDPdata(uint8_t *ptr) {
   return (void *) (((commonUDP_t *)ptr)+1);
 }
 

executables/transport_split.c

@@ -56,7 +56,8 @@ bool createUDPsock (char *sourceIP, char *sourcePort, char *destIP, char *destPo
 
   int enable=1;
   AssertFatal(setsockopt(result->sockHandler, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable))==0,"");
-  struct timeval tv= {0,UDP_TIMEOUT};
+  //struct timeval tv= {0,UDP_TIMEOUT};
+  struct timeval tv= {2,UDP_TIMEOUT}; //debug: wait 2 seconds for human understanding
   AssertFatal(setsockopt(result->sockHandler, SOL_SOCKET, SO_RCVTIMEO,&tv,sizeof(tv)) ==0,"");
   // Make a send/recv buffer larger than a a couple of subframe
   // so the kernel will store for us in and out paquets
@@ -69,9 +70,9 @@ bool createUDPsock (char *sourceIP, char *sourcePort, char *destIP, char *destPo
 // sock: udp socket
 // expectedTS: the expected timestamp, 0 if unknown
 // bufferZone: a reception area of bufferSize
-int receiveSubFrame(UDPsock_t *sock, uint64_t expectedTS, void *bufferZone,  int bufferSize) {
+int receiveSubFrame(UDPsock_t *sock, uint64_t expectedTS, void *bufferZone,  int bufferSize, uint16_t contentType) {
   int rcved=0;
-  commonUDP_t *tmp=NULL;
+  commonUDP_t *bufOrigin=(commonUDP_t *)bufferZone;
 
   do {
     //read all subframe data from the control unit
@@ -85,22 +86,37 @@ int receiveSubFrame(UDPsock_t *sock, uint64_t expectedTS, void *bufferZone,  int
         return -1;
       }
     } else {
-      tmp=(commonUDP_t *)bufferZone;
+      if (hUDP(bufferZone)->contentType != contentType)
+        abort();
 
-      if ( expectedTS && tmp->timestamp != expectedTS) {
-        LOG_W(HW,"Received a paquet in mixed subframes, dropping it\n");
+      if ( hUDP(bufferZone)->timestamp != expectedTS) {
+        if ( hUDP(bufferZone)->timestamp < expectedTS) {
+          LOG_W(HW,"Received a paquet from past subframes, dropping it\n");
+        } else {
+          LOG_W(HW,"Received a paquet in future subframes\n");
+
+          if ( rcved == 0 ) {
+            LOG_W(HW,"First paquet in the sub-frame, keeping it\n");
+            rcved++;
+            bufferZone+=ret;
+            expectedTS=hUDP(bufferZone)->timestamp;
+          }
+        }
       } else {
         rcved++;
         bufferZone+=ret;
       }
     }
-  } while ( !rcved || rcved < tmp->nbBlocks );
+  } while ( !rcved || rcved < hUDP(bufferZone)->nbBlocks );
 
+  LOG_D(HW,"Received: nb_blocks: %d, TS: %lu, frame: %d, subframe: %d\n",
+        rcved, bufOrigin->timestamp, *(((int *)bufOrigin)+1), *(((int *)bufOrigin)+2));
   return rcved;
 }
 
-int sendSubFrame(UDPsock_t *sock, void *bufferZone, ssize_t secondHeaderSize) {
+int sendSubFrame(UDPsock_t *sock, void *bufferZone, ssize_t secondHeaderSize, uint16_t contentType) {
   commonUDP_t *UDPheader=(commonUDP_t *)bufferZone ;
+  UDPheader->contentType=contentType;
   int nbBlocks=UDPheader->nbBlocks;
   int blockId=0;
 
@@ -131,5 +147,7 @@ int sendSubFrame(UDPsock_t *sock, void *bufferZone, ssize_t secondHeaderSize) {
     nbBlocks--;
   } while (nbBlocks);
 
+  LOG_D(HW,"Sent: TS: %lu, frame: %d, subframe: %d\n",
+        UDPheader->timestamp, *(((int *)UDPheader)+1), *(((int *)UDPheader)+2));
   return 0;
 }

openair1/SCHED/phy_procedures_lte_eNb.c

@@ -409,10 +409,10 @@ void phy_procedures_eNB_TX(PHY_VARS_eNB *eNB,
   ul_frame = pdcch_alloc2ul_frame (fp, frame, subframe);
 
   // clear previous allocation information for all UEs
-  for (i = 0; i < NUMBER_OF_UE_MAX; i++) {
+  //for (i = 0; i < NUMBER_OF_UE_MAX; i++) {
     //if (eNB->dlsch[i][0])
       //eNB->dlsch[i][0]->subframe_tx[subframe] = 0;
-  }
+  //}
 
   /* TODO: check the following test - in the meantime it is put back as it was before */
   //if ((ul_subframe < 10)&&