diff --git a/src/pcuif_proto.h b/src/pcuif_proto.h
new file mode 100644
index 0000000..3609f79
--- /dev/null
+++ b/src/pcuif_proto.h
@@ -0,0 +1,137 @@
+#ifndef _PCUIF_PROTO_H
+#define _PCUIF_PROTO_H
+
+/* msg_type */
+#define PCU_IF_MSG_DATA_REQ	0x00	/* send data to given channel */
+#define PCU_IF_MSG_DATA_IND	0x02	/* receive data from given channel */	
+#define PCU_IF_MSG_RTS_REQ	0x10	/* ready to send data to given chan. */
+#define PCU_IF_MSG_RACH_IND	0x22	/* receive rach */
+#define PCU_IF_MSG_INFO_IND	0x32	/* retrieve BTS info */
+#define PCU_IF_MSG_ACT_REQ	0x40	/* activate/deactivate PDCH */
+#define PCU_IF_MSG_TIME_IND	0x52	/* gsm time indication */
+
+/* sapi */
+#define PCU_IF_SAPI_RACH	0x01	/* channel request on CCCH */
+#define PCU_IF_SAPI_AGCH	0x02	/* assignment on CCCH */
+#define PCU_IF_SAPI_PCH		0x03	/* paging request on CCCH */
+#define PCU_IF_SAPI_BCCH	0x04	/* SI on BCCH */
+#define PCU_IF_SAPI_PDTCH	0x05	/* packet data/control/ccch block */
+#define PCU_IF_SAPI_PRACH	0x06	/* packet random access channel */
+#define PCU_IF_SAPI_PTCCH	0x07	/* packet TA control channel */
+
+/* flags */
+#define PCU_IF_FLAG_ACTIVE	(1 << 0)/* BTS is active */
+#define PCU_IF_FLAG_SYSMO	(1 << 1)/* access PDCH of sysmoBTS directly */
+#define PCU_IF_FLAG_CS1		(1 << 16)
+#define PCU_IF_FLAG_CS2		(1 << 17)
+#define PCU_IF_FLAG_CS3		(1 << 18)
+#define PCU_IF_FLAG_CS4		(1 << 19)
+#define PCU_IF_FLAG_MCS1	(1 << 20)
+#define PCU_IF_FLAG_MCS2	(1 << 21)
+#define PCU_IF_FLAG_MCS3	(1 << 22)
+#define PCU_IF_FLAG_MCS4	(1 << 23)
+#define PCU_IF_FLAG_MCS5	(1 << 24)
+#define PCU_IF_FLAG_MCS6	(1 << 25)
+#define PCU_IF_FLAG_MCS7	(1 << 26)
+#define PCU_IF_FLAG_MCS8	(1 << 27)
+#define PCU_IF_FLAG_MCS9	(1 << 28)
+
+struct gsm_pcu_if_data {
+	uint8_t		sapi;
+	uint8_t		len;
+	uint8_t		data[162];
+	uint32_t	fn;
+	uint16_t	arfcn;
+	uint8_t		trx_nr;
+	uint8_t		ts_nr;
+	uint8_t		block_nr;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_rts_req {
+	uint8_t		sapi;
+	uint8_t		spare[3];
+	uint32_t	fn;
+	uint16_t	arfcn;
+	uint8_t		trx_nr;
+	uint8_t		ts_nr;
+	uint8_t		block_nr;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_rach_ind {
+	uint8_t		sapi;
+	uint8_t		ra;
+	int16_t		qta;
+	uint32_t	fn;
+	uint16_t	arfcn;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_info_trx {
+	uint16_t	arfcn;
+	uint8_t		pdch_mask;		/* PDCH channels per TS */
+	uint8_t		spare;
+	uint8_t		tsc[8];			/* TSC per channel */
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_info_ind {
+	uint32_t	flags;
+	struct gsm_pcu_if_info_trx trx[8];	/* TRX infos per BTS */
+	/* RAI */
+	uint16_t	mcc, mnc, lac, rac;
+	/* NSE */
+	uint16_t	nsei;
+	uint8_t		nse_timer[7];
+	uint8_t		cell_timer[11];
+	/* cell  */
+	uint16_t	cell_id;
+	uint16_t	repeat_time;
+	uint8_t		repeat_count;
+	uint16_t	bvci;
+	uint8_t		t3142;
+	uint8_t		t3169;
+	uint8_t		t3191;
+	uint8_t		t3193_10ms;
+	uint8_t		t3195;
+	uint8_t		n3101;
+	uint8_t		n3103;
+	uint8_t		n3105;
+	uint8_t		cv_countdown;
+	uint16_t	dl_tbf_ext;
+	uint16_t	ul_tbf_ext;
+	uint8_t		initial_cs;
+	uint8_t		initial_mcs;
+	/* NSVC */
+	uint16_t	nsvci[2];
+	uint16_t	local_port[2];
+	uint16_t	remote_port[2];
+	uint32_t	remote_ip[2];
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_act_req {
+	uint8_t		activate;
+	uint8_t		trx_nr;
+	uint8_t		ts_nr;
+	uint8_t		spare;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_time_ind {
+	uint32_t	fn;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if {
+	/* context based information */
+	uint8_t		msg_type;	/* message type */
+	uint8_t		bts_nr;		/* bts number */
+	uint8_t		spare[2];
+
+	union {
+		struct gsm_pcu_if_data		data_req;
+		struct gsm_pcu_if_data		data_ind;
+		struct gsm_pcu_if_rts_req	rts_req;
+		struct gsm_pcu_if_rach_ind	rach_ind;
+		struct gsm_pcu_if_info_ind	info_ind;
+		struct gsm_pcu_if_act_req	act_req;
+		struct gsm_pcu_if_time_ind	time_ind;
+	} u;
+} __attribute__ ((packed));
+
+#endif /* _PCUIF_PROTO_H */