Implemented Paging procedure on CCCH.

Added functions:
- gprs_bssgp_pcu_rx_paging_ps() for handling paging message from BSSGP;
- write_paging_request() for writing paging request message;
- gprs_rlcmac_paging_request() and pcu_l1if_tx_pch() for sending paging request message to BTS.

src/gprs_bssgp_pcu.cpp

@@ -56,6 +56,20 @@ int gprs_bssgp_pcu_rx_dl_ud(struct msgb *msg, struct tlv_parsed *tp)
 	tbf_dl_data_transfer(tbf, llc_pdu, llc_pdu_len);
 }
 
+int gprs_bssgp_pcu_rx_paging_ps(struct msgb *msg, struct tlv_parsed *tp)
+{
+	uint8_t *ptmsi = (uint8_t *) TLVP_VAL(tp, BSSGP_IE_TMSI);
+	uint16_t ptmsi_len = TLVP_LEN(tp, BSSGP_IE_TMSI);
+
+	LOGP(DBSSGP, LOGL_NOTICE, " P-TMSI = ");
+	for (int i = 0; i < ptmsi_len; i++)
+	{
+		LOGPC(DBSSGP, LOGL_NOTICE, "%02x", ptmsi[i]);
+	}
+	LOGPC(DBSSGP, LOGL_NOTICE, "\n");
+
+	gprs_rlcmac_paging_request(ptmsi, ptmsi_len);
+}
 
 /* Receive a BSSGP PDU from a BSS on a PTP BVCI */
 int gprs_bssgp_pcu_rx_ptp(struct msgb *msg, struct tlv_parsed *tp, struct bssgp_bvc_ctx *bctx)
@@ -123,7 +137,8 @@ int gprs_bssgp_pcu_rx_sign(struct msgb *msg, struct tlv_parsed *tp, struct bssgp
 			LOGP(DBSSGP, LOGL_NOTICE, "rx BSSGP_PDUT_BVC_RESET_ACK\n");
 			break;
 		case BSSGP_PDUT_PAGING_PS:
-			LOGP(DBSSGP, LOGL_NOTICE, "rx BSSGP_PDUT_PAGING_PS\n");
+			LOGP(DBSSGP, LOGL_NOTICE, "RX: [SGSN->PCU] BSSGP_PDUT_PAGING_PS\n");
+			gprs_bssgp_pcu_rx_paging_ps(msg, tp);
 			break;
 		case BSSGP_PDUT_PAGING_CS:
 			LOGP(DBSSGP, LOGL_NOTICE, "rx BSSGP_PDUT_PAGING_CS\n");

src/gprs_rlcmac.cpp

@@ -718,6 +718,35 @@ int write_immediate_assignment(bitvec * dest, uint8_t downlink, uint8_t ra, uint
 		return wp/8;
 }
 
+int write_paging_request(bitvec * dest, uint8_t *ptmsi, uint16_t ptmsi_len)
+{
+	unsigned wp = 0;
+
+	bitvec_write_field(dest, wp,0x0,4);  // Skip Indicator
+	bitvec_write_field(dest, wp,0x6,4);  // Protocol Discriminator
+	bitvec_write_field(dest, wp,0x21,8); // Paging Request Message Type
+
+	bitvec_write_field(dest, wp,0x0,4);  // Page Mode
+	bitvec_write_field(dest, wp,0x0,4);  // Channel Needed
+
+	// Mobile Identity
+	bitvec_write_field(dest, wp,ptmsi_len+1,8);  // Mobile Identity length
+	bitvec_write_field(dest, wp,0xf,4);          // unused
+	bitvec_write_field(dest, wp,0x4,4);          // PTMSI type
+	for (int i = 0; i < ptmsi_len; i++)
+	{
+		bitvec_write_field(dest, wp,ptmsi[i],8); // PTMSI
+	}
+	bitvec_write_field(dest, wp,0x0,1); // "L" NLN(PCH) = off
+	bitvec_write_field(dest, wp,0x0,1); // "L" Priority1 = off
+	bitvec_write_field(dest, wp,0x1,1); // "L" Priority2 = off
+	bitvec_write_field(dest, wp,0x0,1); // "L" Group Call information = off
+	bitvec_write_field(dest, wp,0x0,1); // "H" Packet Page Indication 1 = packet paging procedure
+	bitvec_write_field(dest, wp,0x1,1); // "H" Packet Page Indication 2 = packet paging procedure
+	bitvec_write_field(dest, wp,0x3,2); // spare padding
+	return wp/8;
+}
+
 void write_packet_uplink_ack(RlcMacDownlink_t * block, uint8_t tfi, uint32_t tlli, uint8_t fi, uint8_t bsn)
 {
 	// Packet Uplink Ack/Nack  TS 44.060 11.2.28
@@ -1158,3 +1187,12 @@ void gprs_rlcmac_packet_downlink_assignment(gprs_rlcmac_tbf *tbf)
 	bitvec_free(packet_downlink_assignment_vec);
 }
 
+void gprs_rlcmac_paging_request(uint8_t *ptmsi, uint16_t ptmsi_len)
+{
+	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] Paging Request (CCCH)\n");
+	bitvec *paging_request = bitvec_alloc(23);
+	bitvec_unhex(paging_request, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
+	int len = write_paging_request(paging_request, ptmsi, ptmsi_len);
+	pcu_l1if_tx_pch(paging_request, len);
+	bitvec_free(paging_request);
+}

src/gprs_rlcmac.h

@@ -154,4 +154,6 @@ void gprs_rlcmac_tx_ul_ud(gprs_rlcmac_tbf *tbf);
 void gprs_rlcmac_downlink_assignment(gprs_rlcmac_tbf *tbf);
 
 void gprs_rlcmac_packet_downlink_assignment(gprs_rlcmac_tbf *tbf);
+
+void gprs_rlcmac_paging_request(uint8_t *ptmsi, uint16_t ptmsi_len);
 #endif // GPRS_RLCMAC_H

src/pcu_l1_if.cpp

@@ -125,6 +125,17 @@ void pcu_l1if_tx_agch(bitvec * block, int len)
 	osmo_wqueue_enqueue(&l1fh->udp_wq, msg);
 }
 
+void pcu_l1if_tx_pch(bitvec * block, int len)
+{
+	struct msgb *msg = l1p_msgb_alloc();
+	GsmL1_Prim_t *prim = msgb_l1prim(msg);
+	prim->id = GsmL1_PrimId_PhDataReq;
+	prim->u.phDataReq.sapi = GsmL1_Sapi_Pch;
+	bitvec_pack(block, prim->u.phDataReq.msgUnitParam.u8Buffer);
+	prim->u.phDataReq.msgUnitParam.u8Size = len;
+	osmo_wqueue_enqueue(&l1fh->udp_wq, msg);
+}
+
 int pcu_l1if_rx_pdch(GsmL1_PhDataInd_t *data_ind)
 {
 	bitvec *block = bitvec_alloc(data_ind->msgUnitParam.u8Size);

src/pcu_l1_if.h

@@ -53,6 +53,7 @@ void pcu_l1if_tx_pdtch(msgb *msg, uint8_t trx, uint8_t ts, uint16_t arfcn,
 void pcu_l1if_tx_ptcch(msgb *msg, uint8_t trx, uint8_t ts, uint16_t arfcn, 
         uint32_t fn, uint8_t block_nr);
 void pcu_l1if_tx_agch(bitvec * block, int len);
+void pcu_l1if_tx_pch(bitvec * block, int len);
 
 int pcu_l1if_open(void);
 void pcu_l1if_close(void);