diff --git a/src/Makefile.am b/src/Makefile.am
index e52a597..b4dcfed 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -19,6 +19,11 @@
 #
 
 AM_CPPFLAGS = $(STD_DEFINES_AND_INCLUDES) $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGB_CFLAGS) $(LIBOSMOGSM_CFLAGS)
+
+if ENABLE_SYSMODSP
+AM_CPPFLAGS += -DENABLE_SYSMODSP
+endif
+
 AM_CXXFLAGS = -Wall -ldl -pthread
 
 noinst_LTLIBRARIES = libgprs.la
@@ -50,6 +55,11 @@
 bin_PROGRAMS = \
 	osmo-pcu
 
+if ENABLE_SYSMODSP
+noinst_PROGRAMS += \
+	osmo-pcu-remote
+endif
+
 noinst_HEADERS = \
 	gprs_debug.h \
 	csn1.h \
@@ -60,7 +70,9 @@
 	pcu_l1_if.h \
 	gsm_timer.h \
 	bitvector.h \
-	pcu_vty.h
+	pcu_vty.h \
+	sysmo_l1_if.h \
+	femtobts.h
 
 RLCMACTest_SOURCES = RLCMACTest.cpp
 RLCMACTest_LDADD = \
@@ -69,6 +81,18 @@
 	$(COMMON_LA)
 
 osmo_pcu_SOURCES = pcu_main.cpp
+
+if ENABLE_SYSMODSP
+osmo_pcu_SOURCES += sysmo_l1_if.c \
+	sysmo_l1_hw.c \
+	femtobts.c
+
+osmo_pcu_remote_SOURCES = pcu_main.cpp \
+	sysmo_l1_if.c \
+	sysmo_l1_fwd.c \
+	femtobts.c
+endif
+
 osmo_pcu_LDADD = \
 	libgprs.la \
 	$(LIBOSMOGB_LIBS) \
@@ -76,4 +100,13 @@
 	$(LIBOSMOGSM_LIBS) \
 	$(COMMON_LA)
 
+if ENABLE_SYSMODSP
+osmo_pcu_remote_LDADD = \
+	libgprs.la \
+	$(LIBOSMOGB_LIBS) \
+	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOGSM_LIBS) \
+	$(COMMON_LA)
+endif
+
 #MOSTLYCLEANFILES += testSource testDestination
diff --git a/src/femtobts.c b/src/femtobts.c
new file mode 100644
index 0000000..69b33be
--- /dev/null
+++ b/src/femtobts.c
@@ -0,0 +1,288 @@
+/* sysmocom femtobts L1 API related definitions */
+
+/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <sysmocom/femtobts/superfemto.h>
+#include <sysmocom/femtobts/gsml1const.h>
+#include <sysmocom/femtobts/gsml1dbg.h>
+
+#include "femtobts.h"
+
+const enum l1prim_type femtobts_l1prim_type[GsmL1_PrimId_NUM] = {
+	[GsmL1_PrimId_MphInitReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphCloseReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphConnectReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphDisconnectReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphActivateReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphDeactivateReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphConfigReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphMeasureReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_MphInitCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphCloseCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphConnectCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphDisconnectCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphActivateCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphDeactivateCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphConfigCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphMeasureCnf]	= L1P_T_CONF,
+	[GsmL1_PrimId_MphTimeInd]	= L1P_T_IND,
+	[GsmL1_PrimId_MphSyncInd]	= L1P_T_IND,
+	[GsmL1_PrimId_PhEmptyFrameReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_PhDataReq]	= L1P_T_REQ,
+	[GsmL1_PrimId_PhConnectInd]	= L1P_T_IND,
+	[GsmL1_PrimId_PhReadyToSendInd]	= L1P_T_IND,
+	[GsmL1_PrimId_PhDataInd]	= L1P_T_IND,
+	[GsmL1_PrimId_PhRaInd]		= L1P_T_IND,
+};
+
+const struct value_string femtobts_l1prim_names[GsmL1_PrimId_NUM+1] = {
+	{ GsmL1_PrimId_MphInitReq,	"MPH-INIT.req" },
+	{ GsmL1_PrimId_MphCloseReq,	"MPH-CLOSE.req" },
+	{ GsmL1_PrimId_MphConnectReq,	"MPH-CONNECT.req" },
+	{ GsmL1_PrimId_MphDisconnectReq,"MPH-DISCONNECT.req" },
+	{ GsmL1_PrimId_MphActivateReq,	"MPH-ACTIVATE.req" },
+	{ GsmL1_PrimId_MphDeactivateReq,"MPH-DEACTIVATE.req" },
+	{ GsmL1_PrimId_MphConfigReq,	"MPH-CONFIG.req" },
+	{ GsmL1_PrimId_MphMeasureReq,	"MPH-MEASURE.req" },
+	{ GsmL1_PrimId_MphInitCnf,	"MPH-INIT.conf" },
+	{ GsmL1_PrimId_MphCloseCnf,	"MPH-CLOSE.conf" },
+	{ GsmL1_PrimId_MphConnectCnf,	"MPH-CONNECT.conf" },
+	{ GsmL1_PrimId_MphDisconnectCnf,"MPH-DISCONNECT.conf" },
+	{ GsmL1_PrimId_MphActivateCnf,	"MPH-ACTIVATE.conf" },
+	{ GsmL1_PrimId_MphDeactivateCnf,"MPH-DEACTIVATE.conf" },
+	{ GsmL1_PrimId_MphConfigCnf,	"MPH-CONFIG.conf" },
+	{ GsmL1_PrimId_MphMeasureCnf,	"MPH-MEASURE.conf" },
+	{ GsmL1_PrimId_MphTimeInd,	"MPH-TIME.ind" },
+	{ GsmL1_PrimId_MphSyncInd,	"MPH-SYNC.ind" },
+	{ GsmL1_PrimId_PhEmptyFrameReq,	"PH-EMPTY_FRAME.req" },
+	{ GsmL1_PrimId_PhDataReq,	"PH-DATA.req" },
+	{ GsmL1_PrimId_PhConnectInd,	"PH-CONNECT.ind" },
+	{ GsmL1_PrimId_PhReadyToSendInd,"PH-READY_TO_SEND.ind" },
+	{ GsmL1_PrimId_PhDataInd,	"PH-DATA.ind" },
+	{ GsmL1_PrimId_PhRaInd,		"PH-RA.ind" },
+	{ 0, NULL }
+};
+
+const GsmL1_PrimId_t femtobts_l1prim_req2conf[GsmL1_PrimId_NUM] = {
+	[GsmL1_PrimId_MphInitReq]	= GsmL1_PrimId_MphInitCnf,
+	[GsmL1_PrimId_MphCloseReq]	= GsmL1_PrimId_MphCloseCnf,
+	[GsmL1_PrimId_MphConnectReq]	= GsmL1_PrimId_MphConnectCnf,
+	[GsmL1_PrimId_MphDisconnectReq]	= GsmL1_PrimId_MphDisconnectCnf,
+	[GsmL1_PrimId_MphActivateReq]	= GsmL1_PrimId_MphActivateCnf,
+	[GsmL1_PrimId_MphDeactivateReq]	= GsmL1_PrimId_MphDeactivateCnf,
+	[GsmL1_PrimId_MphConfigReq]	= GsmL1_PrimId_MphConfigCnf,
+	[GsmL1_PrimId_MphMeasureReq]	= GsmL1_PrimId_MphMeasureCnf,
+};
+
+const enum l1prim_type femtobts_sysprim_type[SuperFemto_PrimId_NUM] = {
+	[SuperFemto_PrimId_SystemInfoReq]		= L1P_T_REQ,
+	[SuperFemto_PrimId_SystemInfoCnf]		= L1P_T_CONF,
+	[SuperFemto_PrimId_SystemFailureInd]	= L1P_T_IND,
+	[SuperFemto_PrimId_ActivateRfReq]		= L1P_T_REQ,
+	[SuperFemto_PrimId_ActivateRfCnf]		= L1P_T_CONF,
+	[SuperFemto_PrimId_DeactivateRfReq]	= L1P_T_REQ,
+	[SuperFemto_PrimId_DeactivateRfCnf]	= L1P_T_CONF,
+	[SuperFemto_PrimId_SetTraceFlagsReq]	= L1P_T_REQ,
+	[SuperFemto_PrimId_RfClockInfoReq]	= L1P_T_REQ,
+	[SuperFemto_PrimId_RfClockInfoCnf]	= L1P_T_CONF,
+	[SuperFemto_PrimId_RfClockSetupReq]	= L1P_T_REQ,
+	[SuperFemto_PrimId_RfClockSetupCnf]	= L1P_T_CONF,
+	[SuperFemto_PrimId_Layer1ResetReq]	= L1P_T_REQ,
+	[SuperFemto_PrimId_Layer1ResetCnf]	= L1P_T_CONF,
+};
+
+const struct value_string femtobts_sysprim_names[SuperFemto_PrimId_NUM+1] = {
+	{ SuperFemto_PrimId_SystemInfoReq,	"SYSTEM-INFO.req" },
+	{ SuperFemto_PrimId_SystemInfoCnf,	"SYSTEM-INFO.conf" },
+	{ SuperFemto_PrimId_SystemFailureInd,	"SYSTEM-FAILURE.ind" },
+	{ SuperFemto_PrimId_ActivateRfReq,	"ACTIVATE-RF.req" },
+	{ SuperFemto_PrimId_ActivateRfCnf,	"ACTIVATE-RF.conf" },
+	{ SuperFemto_PrimId_DeactivateRfReq,	"DEACTIVATE-RF.req" },
+	{ SuperFemto_PrimId_DeactivateRfCnf,	"DEACTIVATE-RF.conf" },
+	{ SuperFemto_PrimId_SetTraceFlagsReq,	"SET-TRACE-FLAGS.req" },
+	{ SuperFemto_PrimId_RfClockInfoReq,	"RF-CLOCK-INFO.req" },
+	{ SuperFemto_PrimId_RfClockInfoCnf,	"RF-CLOCK-INFO.conf" },
+	{ SuperFemto_PrimId_RfClockSetupReq,	"RF-CLOCK-SETUP.req" },
+	{ SuperFemto_PrimId_RfClockSetupCnf,	"RF-CLOCK-SETUP.conf" },
+	{ SuperFemto_PrimId_Layer1ResetReq,	"LAYER1-RESET.req" },
+	{ SuperFemto_PrimId_Layer1ResetCnf,	"LAYER1-RESET.conf" },
+	{ 0, NULL }
+};
+
+const SuperFemto_PrimId_t femtobts_sysprim_req2conf[SuperFemto_PrimId_NUM] = {
+	[SuperFemto_PrimId_SystemInfoReq]	= SuperFemto_PrimId_SystemInfoCnf,
+	[SuperFemto_PrimId_ActivateRfReq]	= SuperFemto_PrimId_ActivateRfCnf,
+	[SuperFemto_PrimId_DeactivateRfReq]	= SuperFemto_PrimId_DeactivateRfCnf,
+	[SuperFemto_PrimId_RfClockInfoReq]	= SuperFemto_PrimId_RfClockInfoCnf,
+	[SuperFemto_PrimId_RfClockSetupReq]	= SuperFemto_PrimId_RfClockSetupCnf,
+	[SuperFemto_PrimId_Layer1ResetReq] 	= SuperFemto_PrimId_Layer1ResetCnf,
+};
+
+const struct value_string femtobts_l1sapi_names[GsmL1_Sapi_NUM+1] = {
+	{ GsmL1_Sapi_Fcch,	"FCCH" },
+	{ GsmL1_Sapi_Sch,	"SCH" },
+	{ GsmL1_Sapi_Sacch,	"SACCH" },
+	{ GsmL1_Sapi_Sdcch,	"SDCCH" },
+	{ GsmL1_Sapi_Bcch,	"BCCH" },
+	{ GsmL1_Sapi_Pch,	"PCH" },
+	{ GsmL1_Sapi_Agch,	"AGCH" },
+	{ GsmL1_Sapi_Cbch,	"CBCH" },
+	{ GsmL1_Sapi_Rach,	"RACH" },
+	{ GsmL1_Sapi_TchF,	"TCH/F" },
+	{ GsmL1_Sapi_FacchF,	"FACCH/F" },
+	{ GsmL1_Sapi_TchH,	"TCH/H" },
+	{ GsmL1_Sapi_FacchH,	"FACCH/H" },
+	{ GsmL1_Sapi_Nch,	"NCH" },
+	{ GsmL1_Sapi_Pdtch,	"PDTCH" },
+	{ GsmL1_Sapi_Pacch,	"PACCH" },
+	{ GsmL1_Sapi_Pbcch,	"PBCCH" },
+	{ GsmL1_Sapi_Pagch,	"PAGCH" },
+	{ GsmL1_Sapi_Ppch,	"PPCH" },
+	{ GsmL1_Sapi_Pnch,	"PNCH" },
+	{ GsmL1_Sapi_Ptcch,	"PTCCH" },
+	{ GsmL1_Sapi_Prach,	"PRACH" },
+	{ 0, NULL }
+};
+
+const struct value_string femtobts_l1status_names[GSML1_STATUS_NUM+1] = {
+	{ GsmL1_Status_Success,		"Success" },
+	{ GsmL1_Status_Generic,		"Generic error" },
+	{ GsmL1_Status_NoMemory,	"Not enough memory" },
+	{ GsmL1_Status_Timeout,		"Timeout" },
+	{ GsmL1_Status_InvalidParam,	"Invalid parameter" },
+	{ GsmL1_Status_Busy,		"Resource busy" },
+	{ GsmL1_Status_NoRessource,	"No more resources" },
+	{ GsmL1_Status_Uninitialized,	"Trying to use uninitialized resource" },
+	{ GsmL1_Status_NullInterface,	"Trying to call a NULL interface" },
+	{ GsmL1_Status_NullFctnPtr,	"Trying to call a NULL function ptr" },
+	{ GsmL1_Status_BadCrc,		"Bad CRC" },
+	{ GsmL1_Status_BadUsf,		"Bad USF" },
+	{ GsmL1_Status_InvalidCPS,	"Invalid CPS field" },
+	{ GsmL1_Status_UnexpectedBurst,	"Unexpected burst" },
+	{ GsmL1_Status_UnavailCodec,	"AMR codec is unavailable" },
+	{ GsmL1_Status_CriticalError,	"Critical error" },
+	{ GsmL1_Status_OverheatError,	"Overheat error" },
+	{ GsmL1_Status_DeviceError,	"Device error" },
+	{ GsmL1_Status_FacchError,	"FACCH / TCH order error" },
+	{ GsmL1_Status_AlreadyDeactivated, "Lchan already deactivated" },
+	{ GsmL1_Status_TxBurstFifoOvrn,	"FIFO overrun" },
+	{ GsmL1_Status_TxBurstFifoUndr,	"FIFO underrun" },
+	{ GsmL1_Status_NotSynchronized,	"Not synchronized" },
+	{ GsmL1_Status_Unsupported,	"Unsupported feature" },
+	{ 0, NULL }
+};
+
+const struct value_string femtobts_tracef_names[29] = {
+	{ DBG_DEBUG,			"DEBUG" },
+	{ DBG_L1WARNING,		"L1_WARNING" },
+	{ DBG_ERROR,			"ERROR" },
+	{ DBG_L1RXMSG,			"L1_RX_MSG" },
+	{ DBG_L1RXMSGBYTE,		"L1_RX_MSG_BYTE" },
+	{ DBG_L1TXMSG,			"L1_TX_MSG" },
+	{ DBG_L1TXMSGBYTE,		"L1_TX_MSG_BYTE" },
+	{ DBG_MPHCNF,			"MPH_CNF" },
+	{ DBG_MPHIND,			"MPH_IND" },
+	{ DBG_MPHREQ,			"MPH_REQ" },
+	{ DBG_PHIND,			"PH_IND" },
+	{ DBG_PHREQ,			"PH_REQ" },
+	{ DBG_PHYRF,			"PHY_RF" },
+	{ DBG_PHYRFMSGBYTE,		"PHY_MSG_BYTE" },
+	{ DBG_MODE,			"MODE" },
+	{ DBG_TDMAINFO,			"TDMA_INFO" },
+	{ DBG_BADCRC,			"BAD_CRC" },
+	{ DBG_PHINDBYTE,		"PH_IND_BYTE" },
+	{ DBG_PHREQBYTE,		"PH_REQ_BYTE" },
+	{ DBG_DEVICEMSG,		"DEVICE_MSG" },
+	{ DBG_RACHINFO,			"RACH_INFO" },
+	{ DBG_LOGCHINFO,		"LOG_CH_INFO" },
+	{ DBG_MEMORY,			"MEMORY" },
+	{ DBG_PROFILING,		"PROFILING" },
+	{ DBG_TESTCOMMENT,		"TEST_COMMENT" },
+	{ DBG_TEST,			"TEST" },
+	{ DBG_STATUS,			"STATUS" },
+	{ 0, NULL }
+};
+
+const struct value_string femtobts_tch_pl_names[] = {
+	{ GsmL1_TchPlType_NA,			"N/A" },
+	{ GsmL1_TchPlType_Fr,			"FR" },
+	{ GsmL1_TchPlType_Hr,			"HR" },
+	{ GsmL1_TchPlType_Efr,			"EFR" },
+	{ GsmL1_TchPlType_Amr,			"AMR(IF2)" },
+	{ GsmL1_TchPlType_Amr_SidBad,		"AMR(SID BAD)" },
+	{ GsmL1_TchPlType_Amr_Onset,		"AMR(ONSET)" },
+	{ GsmL1_TchPlType_Amr_Ratscch,		"AMR(RATSCCH)" },
+	{ GsmL1_TchPlType_Amr_SidUpdateInH,	"AMR(SID_UPDATE INH)" },
+	{ GsmL1_TchPlType_Amr_SidFirstP1,	"AMR(SID_FIRST P1)" },
+	{ GsmL1_TchPlType_Amr_SidFirstP2,	"AMR(SID_FIRST P2)" },
+	{ GsmL1_TchPlType_Amr_SidFirstInH,	"AMR(SID_FIRST INH)" },
+	{ GsmL1_TchPlType_Amr_RatscchMarker,	"AMR(RATSCCH MARK)" },
+	{ GsmL1_TchPlType_Amr_RatscchData,	"AMR(RATSCCH DATA)" },
+	{ 0, NULL }
+};
+
+const struct value_string femtobts_clksrc_names[] = {
+	{ SuperFemto_ClkSrcId_None,	"None" },
+	{ SuperFemto_ClkSrcId_Ocxo,	"ocxo" },
+	{ SuperFemto_ClkSrcId_Tcxo,	"tcxo" },
+	{ SuperFemto_ClkSrcId_External,	"ext" },
+	{ SuperFemto_ClkSrcId_GpsPps,	"gps" },
+	{ SuperFemto_ClkSrcId_Trx,	"trx" },
+	{ SuperFemto_ClkSrcId_Rx,	"rx" },
+	{ SuperFemto_ClkSrcId_Edge,	"edge" },
+	{ SuperFemto_ClkSrcId_NetList,	"nwl" },
+	{ 0, NULL }
+};
+
+const struct value_string femtobts_dir_names[] = {
+	{ GsmL1_Dir_TxDownlink,	"TxDL" },
+	{ GsmL1_Dir_TxUplink,	"TxUL" },
+	{ GsmL1_Dir_RxUplink,	"RxUL" },
+	{ GsmL1_Dir_RxDownlink,	"RxDL" },
+	{ GsmL1_Dir_TxDownlink|GsmL1_Dir_RxUplink, "BOTH" },
+	{ 0, NULL }
+};
+
+const struct value_string femtobts_chcomb_names[] = {
+	{ GsmL1_LogChComb_0,	"dummy" },
+	{ GsmL1_LogChComb_I,	"tch_f" },
+	{ GsmL1_LogChComb_II,	"tch_h" },
+	{ GsmL1_LogChComb_IV,	"ccch" },
+	{ GsmL1_LogChComb_V,	"ccch_sdcch4" },
+	{ GsmL1_LogChComb_VII,	"sdcch8" },
+	{ GsmL1_LogChComb_XIII,	"pdtch" },
+	{ 0, NULL }
+};
+
+const uint8_t pdch_msu_size[_NUM_PDCH_CS] = {
+	[PDCH_CS_1]	= 23,
+	[PDCH_CS_2]	= 34,
+	[PDCH_CS_3]	= 40,
+	[PDCH_CS_4]	= 54,
+	[PDCH_MCS_1]	= 27,
+	[PDCH_MCS_2]	= 33,
+	[PDCH_MCS_3]	= 42,
+	[PDCH_MCS_4]	= 49,
+	[PDCH_MCS_5]	= 60,
+	[PDCH_MCS_6]	= 78,
+	[PDCH_MCS_7]	= 118,
+	[PDCH_MCS_8]	= 142,
+	[PDCH_MCS_9]	= 154
+};
diff --git a/src/femtobts.h b/src/femtobts.h
new file mode 100644
index 0000000..f2ac59d
--- /dev/null
+++ b/src/femtobts.h
@@ -0,0 +1,59 @@
+#ifndef FEMTOBTS_H
+#define FEMTOBTS_H
+
+#include <stdlib.h>
+#include <osmocom/core/utils.h>
+
+#include <sysmocom/femtobts/superfemto.h>
+#include <sysmocom/femtobts/gsml1const.h>
+
+#ifdef L1_HAS_RTP_MODE
+/* This is temporarily disabled, as AMR has some bugs in RTP mode */
+//#define USE_L1_RTP_MODE		/* Tell L1 to use RTP mode */
+#endif
+
+enum l1prim_type {
+	L1P_T_REQ,
+	L1P_T_CONF,
+	L1P_T_IND,
+};
+
+const enum l1prim_type femtobts_l1prim_type[GsmL1_PrimId_NUM];
+const struct value_string femtobts_l1prim_names[GsmL1_PrimId_NUM+1];
+const GsmL1_PrimId_t femtobts_l1prim_req2conf[GsmL1_PrimId_NUM];
+
+const enum l1prim_type femtobts_sysprim_type[SuperFemto_PrimId_NUM];
+const struct value_string femtobts_sysprim_names[SuperFemto_PrimId_NUM+1];
+const SuperFemto_PrimId_t femtobts_sysprim_req2conf[SuperFemto_PrimId_NUM];
+
+const struct value_string femtobts_l1sapi_names[GsmL1_Sapi_NUM+1];
+const struct value_string femtobts_l1status_names[GSML1_STATUS_NUM+1];
+
+const struct value_string femtobts_tracef_names[29];
+
+const struct value_string femtobts_tch_pl_names[15];
+
+const struct value_string femtobts_clksrc_names[8];
+
+const struct value_string femtobts_dir_names[6];
+
+enum pdch_cs {
+	PDCH_CS_1,
+	PDCH_CS_2,
+	PDCH_CS_3,
+	PDCH_CS_4,
+	PDCH_MCS_1,
+	PDCH_MCS_2,
+	PDCH_MCS_3,
+	PDCH_MCS_4,
+	PDCH_MCS_5,
+	PDCH_MCS_6,
+	PDCH_MCS_7,
+	PDCH_MCS_8,
+	PDCH_MCS_9,
+	_NUM_PDCH_CS
+};
+
+const uint8_t pdch_msu_size[_NUM_PDCH_CS];
+
+#endif /* FEMTOBTS_H */
diff --git a/src/gprs_debug.h b/src/gprs_debug.h
index 1a5f01a..abd5d95 100644
--- a/src/gprs_debug.h
+++ b/src/gprs_debug.h
@@ -21,10 +21,14 @@
 #define GPRS_DEBUG_H
 
 #include <stdio.h>
+#ifdef __cplusplus
 extern "C" {
+#endif
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/core/logging.h>
+#ifdef __cplusplus
 };
+#endif
 /* Debug Areas of the code */
 enum {
 	DCSN1,
diff --git a/src/gprs_rlcmac.h b/src/gprs_rlcmac.h
index 24a84e5..1d3fad9 100644
--- a/src/gprs_rlcmac.h
+++ b/src/gprs_rlcmac.h
@@ -58,6 +58,7 @@
 };
 
 struct gprs_rlcmac_trx {
+	void *fl1h;
 	uint16_t arfcn;
 	struct gprs_rlcmac_pdch pdch[8];
 	struct gprs_rlcmac_tbf *ul_tbf[32]; /* array of UL TBF, by UL TFI */
@@ -65,6 +66,7 @@
 };
 
 struct gprs_rlcmac_bts {
+	uint8_t bsic;
 	uint8_t fc_interval;
 	uint8_t cs1;
 	uint8_t cs2;
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 3ebe90b..a4ab1d4 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -37,6 +37,15 @@
 #include <gprs_bssgp_pcu.h>
 #include <pcuif_proto.h>
 
+// FIXME: move this, when changed from c++ to c.
+extern "C" {
+void *l1if_open_pdch(void *priv, uint32_t hlayer1);
+int l1if_close_pdch(void *obj);
+int l1if_connect_pdch(void *obj, uint8_t ts);
+int l1if_pdch_req(void *obj, uint8_t ts, int is_ptcch, uint32_t fn,
+        uint16_t arfcn, uint8_t block_nr, uint8_t *data, uint8_t len);
+}
+
 extern void *tall_pcu_ctx;
 
 // Variable for storage current FN.
@@ -126,16 +135,32 @@
 void pcu_l1if_tx_pdtch(msgb *msg, uint8_t trx, uint8_t ts, uint16_t arfcn,
 	uint32_t fn, uint8_t block_nr)
 {
-	pcu_tx_data_req(trx, ts, PCU_IF_SAPI_PDTCH, arfcn, fn, block_nr,
-		msg->data, msg->len);
+#ifdef ENABLE_SYSMODSP
+	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+
+	if (bts->trx[trx].fl1h)
+		l1if_pdch_req(bts->trx[trx].fl1h, ts, 0, fn, arfcn, block_nr,
+			msg->data, msg->len);
+	else
+#endif
+		pcu_tx_data_req(trx, ts, PCU_IF_SAPI_PDTCH, arfcn, fn, block_nr,
+			msg->data, msg->len);
 	msgb_free(msg);
 }
 
 void pcu_l1if_tx_ptcch(msgb *msg, uint8_t trx, uint8_t ts, uint16_t arfcn,
 	uint32_t fn, uint8_t block_nr)
 {
-	pcu_tx_data_req(trx, ts, PCU_IF_SAPI_PTCCH, arfcn, fn, block_nr,
-		msg->data, msg->len);
+#ifdef ENABLE_SYSMODSP
+	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+
+	if (bts->trx[trx].fl1h)
+		l1if_pdch_req(bts->trx[trx].fl1h, ts, 1, fn, arfcn, block_nr,
+			msg->data, msg->len);
+	else
+#endif
+		pcu_tx_data_req(trx, ts, PCU_IF_SAPI_PTCCH, arfcn, fn, block_nr,
+			msg->data, msg->len);
 	msgb_free(msg);
 }
 
@@ -166,11 +191,18 @@
 	pcu_tx_data_req(0, 0, PCU_IF_SAPI_PCH, 0, 0, 0, data, 23+3);
 }
 
+// FIXME: remove this, when changed from c++ to c.
 static void pcu_l1if_tx_bcch(uint8_t *data, int len)
 {
 	pcu_tx_data_req(0, 0, PCU_IF_SAPI_BCCH, 0, 0, 0, data, len);
 }
 
+extern "C" int pcu_rx_data_ind_pdtch(uint8_t trx, uint8_t ts, uint8_t *data,
+	uint8_t len, uint32_t fn)
+{
+	return gprs_rlcmac_rcv_block(trx, ts, data, len, fn);
+}
+
 static int pcu_rx_data_ind(struct gsm_pcu_if_data *data_ind)
 {
 	int rc = 0;
@@ -182,7 +214,7 @@
 
 	switch (data_ind->sapi) {
 	case PCU_IF_SAPI_PDTCH:
-		rc = gprs_rlcmac_rcv_block(data_ind->trx_nr, data_ind->ts_nr,
+		rc = pcu_rx_data_ind_pdtch(data_ind->trx_nr, data_ind->ts_nr,
 			data_ind->data, data_ind->len, data_ind->fn);
 		break;
 	default:
@@ -216,6 +248,13 @@
 	return rc;
 }
 
+// FIXME: remove this, when changed from c++ to c.
+extern "C" int pcu_rx_rts_req_pdtch(uint8_t trx, uint8_t ts, uint16_t arfcn,
+	uint32_t fn, uint8_t block_nr)
+{
+	return gprs_rlcmac_rcv_rts_block(trx, ts, arfcn, fn, block_nr);
+}
+
 static int pcu_rx_rts_req(struct gsm_pcu_if_rts_req *rts_req)
 {
 	int rc = 0;
@@ -226,7 +265,7 @@
 
 	switch (rts_req->sapi) {
 	case PCU_IF_SAPI_PDTCH:
-		gprs_rlcmac_rcv_rts_block(rts_req->trx_nr, rts_req->ts_nr,
+		pcu_rx_rts_req_pdtch(rts_req->trx_nr, rts_req->ts_nr,
 			rts_req->arfcn, rts_req->fn, rts_req->block_nr);
 		break;
 	case PCU_IF_SAPI_PTCCH:
@@ -337,6 +376,7 @@
 	LOGP(DL1IF, LOGL_DEBUG, " lac=%d\n", info_ind->lac);
 	LOGP(DL1IF, LOGL_DEBUG, " rac=%d\n", info_ind->rac);
 	LOGP(DL1IF, LOGL_DEBUG, " cell_id=%d\n", ntohs(info_ind->cell_id));
+	LOGP(DL1IF, LOGL_DEBUG, " bsic=%d\n", info_ind->bsic);
 	LOGP(DL1IF, LOGL_DEBUG, " nsei=%d\n", info_ind->nsei);
 	LOGP(DL1IF, LOGL_DEBUG, " nse_timer=%d %d %d %d %d %d %d\n",
 		info_ind->nse_timer[0], info_ind->nse_timer[1],
@@ -365,6 +405,7 @@
 	LOGP(DL1IF, LOGL_DEBUG, " cv_countdown=%d\n", info_ind->cv_countdown);
 	LOGP(DL1IF, LOGL_DEBUG, " dl_tbf_ext=%d\n", info_ind->dl_tbf_ext);
 	LOGP(DL1IF, LOGL_DEBUG, " ul_tbf_ext=%d\n", info_ind->ul_tbf_ext);
+	bts->bsic = info_ind->bsic;
 	for (i = 0; i < 4; i++) {
 		if ((info_ind->flags & (PCU_IF_FLAG_CS1 << i)))
 			LOGP(DL1IF, LOGL_DEBUG, " Use CS%d\n", i+1);
@@ -415,11 +456,40 @@
 
 	for (trx = 0; trx < 8; trx++) {
 		bts->trx[trx].arfcn = info_ind->trx[trx].arfcn;
+		if ((info_ind->flags & PCU_IF_FLAG_SYSMO)
+		 && info_ind->trx[trx].hlayer1) {
+#ifdef ENABLE_SYSMODSP
+			LOGP(DL1IF, LOGL_DEBUG, " TRX %d hlayer1=%x\n", trx,
+				info_ind->trx[trx].hlayer1);
+				if (!bts->trx[trx].fl1h)
+					bts->trx[trx].fl1h = l1if_open_pdch(
+						(void *)trx,
+						info_ind->trx[trx].hlayer1);
+			if (!bts->trx[trx].fl1h) {
+				LOGP(DL1IF, LOGL_FATAL, "Failed to open direct "
+					"DSP access for PDCH.\n");
+				exit(0);
+			}
+#else
+			LOGP(DL1IF, LOGL_FATAL, "Compiled without direct DSP "
+					"access for PDCH, but enabled at "
+					"BTS. Please deactivate it!\n");
+			exit(0);
+#endif
+#warning close TBD
+		}
+
 		for (ts = 0; ts < 8; ts++) {
 			pdch = &bts->trx[trx].pdch[ts];
 			if ((info_ind->trx[trx].pdch_mask & (1 << ts))) {
 				/* FIXME: activate dynamically at RLCMAC */
 				if (!pdch->enable) {
+#ifdef ENABLE_SYSMODSP
+					if ((info_ind->flags &
+							PCU_IF_FLAG_SYSMO))
+						l1if_connect_pdch(
+							bts->trx[trx].fl1h, ts);
+#endif
 					pcu_tx_act_req(trx, ts, 1);
 					INIT_LLIST_HEAD(&pdch->paging_list);
 					pdch->enable = 1;
@@ -449,9 +519,9 @@
 	/* omit frame numbers not starting at a MAC block */
 	if (fn13 != 0 && fn13 != 4 && fn13 != 8)
 		return 0;
-
-	LOGP(DL1IF, LOGL_DEBUG, "Time indication received: %d\n",
-		time_ind->fn % 52);
+#warning uncomment
+//	LOGP(DL1IF, LOGL_DEBUG, "Time indication received: %d\n",
+//		time_ind->fn % 52);
 
 	set_current_fn(time_ind->fn);
 
diff --git a/src/pcu_l1_if.h b/src/pcu_l1_if.h
index f3ac597..6b889e0 100644
--- a/src/pcu_l1_if.h
+++ b/src/pcu_l1_if.h
@@ -21,12 +21,15 @@
 #define PCU_L1_IF_H
 
 #include <stdint.h>
+#ifdef __cplusplus
 extern "C" {
+#endif
 #include <osmocom/core/write_queue.h>
 #include <osmocom/core/socket.h>
 #include <osmocom/core/timer.h>
 #include <osmocom/core/bitvec.h>
 #include <osmocom/gsm/gsm_utils.h>
+#ifdef __cplusplus
 }
 
 int get_current_fn();
@@ -44,4 +47,18 @@
 
 int pcu_rx(uint8_t msg_type, struct gsm_pcu_if *pcu_prim);
 int pcu_sock_send(struct msgb *msg);
+#endif
+
+#ifdef __cplusplus
+extern "C"
+#endif
+int pcu_rx_rts_req_pdtch(uint8_t trx, uint8_t ts, uint16_t arfcn,
+	uint32_t fn, uint8_t block_nr);
+
+#ifdef __cplusplus
+extern "C"
+#endif
+int pcu_rx_data_ind_pdtch(uint8_t trx, uint8_t ts, uint8_t *data,
+	uint8_t len, uint32_t fn);
+
 #endif // PCU_L1_IF_H
diff --git a/src/sysmo_l1_fwd.c b/src/sysmo_l1_fwd.c
new file mode 100644
index 0000000..535a7f0
--- /dev/null
+++ b/src/sysmo_l1_fwd.c
@@ -0,0 +1,145 @@
+/* Interface handler for Sysmocom L1 (forwarding) */
+
+/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/write_queue.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/gsm/gsm_utils.h>
+
+#include <sysmocom/femtobts/superfemto.h>
+#include <sysmocom/femtobts/gsml1prim.h>
+#include <sysmocom/femtobts/gsml1const.h>
+#include <sysmocom/femtobts/gsml1types.h>
+
+#include "gprs_debug.h"
+#include "sysmo_l1_if.h"
+
+
+#define L1FWD_L1_PORT   9999
+#define L1FWD_SYS_PORT  9998
+#define L1FWD_TCH_PORT  9997
+#define L1FWD_PDTCH_PORT 9996
+
+static const uint16_t fwd_udp_ports[] = {
+	[MQ_SYS_WRITE]	= L1FWD_SYS_PORT,
+	[MQ_L1_WRITE]	= L1FWD_L1_PORT,
+	[MQ_TCH_WRITE]	= L1FWD_TCH_PORT,
+	[MQ_PDTCH_WRITE]= L1FWD_PDTCH_PORT,
+};
+
+static int fwd_read_cb(struct osmo_fd *ofd)
+{
+	struct msgb *msg = msgb_alloc_headroom(sizeof(SuperFemto_Prim_t) + 128,
+		128, "udp_rx");
+	struct femtol1_hdl *fl1h = ofd->data;
+	int rc;
+
+	if (!msg)
+		return -ENOMEM;
+
+	msg->l1h = msg->data;
+	rc = read(ofd->fd, msg->l1h, msgb_tailroom(msg));
+	if (rc < 0) {
+		LOGP(DL1IF, LOGL_ERROR, "Short read from UDP\n");
+		msgb_free(msg);
+		return rc;
+	} else if (rc == 0) {
+		LOGP(DL1IF, LOGL_ERROR, "Len=0 from UDP\n");
+		msgb_free(msg);
+		return rc;
+	}
+	msgb_put(msg, rc);
+
+	if (ofd->priv_nr == MQ_SYS_WRITE)
+		rc = l1if_handle_sysprim(fl1h, msg);
+	else
+		rc = l1if_handle_l1prim(ofd->priv_nr, fl1h, msg);
+
+	return rc;
+}
+
+static int prim_write_cb(struct osmo_fd *ofd, struct msgb *msg)
+{
+	/* write to the fd */
+	return write(ofd->fd, msg->head, msg->len);
+}
+
+int l1if_transport_open(int q, struct femtol1_hdl *fl1h)
+{
+	int rc;
+	char *bts_host = getenv("L1FWD_BTS_HOST");
+
+	printf("sizeof(GsmL1_Prim_t) = %zu\n", sizeof(GsmL1_Prim_t));
+	printf("sizeof(SuperFemto_Prim_t) = %zu\n", sizeof(SuperFemto_Prim_t));
+
+	if (!bts_host) {
+		fprintf(stderr, "You have to set the L1FWD_BTS_HOST environment variable\n");
+		exit(2);
+	}
+
+	struct osmo_wqueue *wq = &fl1h->write_q[q];
+	struct osmo_fd *ofd = &wq->bfd;
+
+	osmo_wqueue_init(wq, 10);
+	wq->write_cb = prim_write_cb;
+	wq->read_cb = fwd_read_cb;
+
+	ofd->data = fl1h;
+	ofd->priv_nr = q;
+	ofd->when |= BSC_FD_READ;
+
+	rc = osmo_sock_init_ofd(ofd, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP,
+				bts_host, fwd_udp_ports[q],
+				OSMO_SOCK_F_CONNECT);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+int l1if_transport_close(int q, struct femtol1_hdl *fl1h)
+{
+	struct osmo_wqueue *wq = &fl1h->write_q[q];
+	struct osmo_fd *ofd = &wq->bfd;
+
+	osmo_wqueue_clear(wq);
+	osmo_fd_unregister(ofd);
+	close(ofd->fd);
+	
+	return 0;
+}
diff --git a/src/sysmo_l1_hw.c b/src/sysmo_l1_hw.c
new file mode 100644
index 0000000..87c2c55
--- /dev/null
+++ b/src/sysmo_l1_hw.c
@@ -0,0 +1,215 @@
+/* Interface handler for Sysmocom L1 (real hardware) */
+
+/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <assert.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/write_queue.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/gsm/gsm_utils.h>
+
+#include <sysmocom/femtobts/superfemto.h>
+#include <sysmocom/femtobts/gsml1prim.h>
+#include <sysmocom/femtobts/gsml1const.h>
+#include <sysmocom/femtobts/gsml1types.h>
+
+#include "gprs_debug.h"
+#include "femtobts.h"
+#include "sysmo_l1_if.h"
+
+
+#ifdef HW_SYSMOBTS_V1
+#define DEV_SYS_DSP2ARM_NAME	"/dev/msgq/femtobts_dsp2arm"
+#define DEV_SYS_ARM2DSP_NAME	"/dev/msgq/femtobts_arm2dsp"
+#define DEV_L1_DSP2ARM_NAME	"/dev/msgq/gsml1_dsp2arm"
+#define DEV_L1_ARM2DSP_NAME	"/dev/msgq/gsml1_arm2dsp"
+#else
+#define DEV_SYS_DSP2ARM_NAME	"/dev/msgq/superfemto_dsp2arm"
+#define DEV_SYS_ARM2DSP_NAME	"/dev/msgq/superfemto_arm2dsp"
+#define DEV_L1_DSP2ARM_NAME	"/dev/msgq/gsml1_sig_dsp2arm"
+#define DEV_L1_ARM2DSP_NAME	"/dev/msgq/gsml1_sig_arm2dsp"
+
+#define DEV_TCH_DSP2ARM_NAME	"/dev/msgq/gsml1_tch_dsp2arm"
+#define DEV_TCH_ARM2DSP_NAME	"/dev/msgq/gsml1_tch_arm2dsp"
+#define DEV_PDTCH_DSP2ARM_NAME	"/dev/msgq/gsml1_pdtch_dsp2arm"
+#define DEV_PDTCH_ARM2DSP_NAME	"/dev/msgq/gsml1_pdtch_arm2dsp"
+#endif
+
+static const char *rd_devnames[] = {
+	[MQ_SYS_READ]	= DEV_SYS_DSP2ARM_NAME,
+	[MQ_L1_READ]	= DEV_L1_DSP2ARM_NAME,
+#ifndef HW_SYSMOBTS_V1
+	[MQ_TCH_READ]	= DEV_TCH_DSP2ARM_NAME,
+	[MQ_PDTCH_READ]	= DEV_PDTCH_DSP2ARM_NAME,
+#endif
+};
+
+static const char *wr_devnames[] = {
+	[MQ_SYS_WRITE]	= DEV_SYS_ARM2DSP_NAME,
+	[MQ_L1_WRITE]	= DEV_L1_ARM2DSP_NAME,
+#ifndef HW_SYSMOBTS_V1
+	[MQ_TCH_WRITE]	= DEV_TCH_ARM2DSP_NAME,
+	[MQ_PDTCH_WRITE]= DEV_PDTCH_ARM2DSP_NAME,
+#endif
+};
+
+/* callback when there's something to read from the l1 msg_queue */
+static int l1if_fd_cb(struct osmo_fd *ofd, unsigned int what)
+{
+	//struct msgb *msg = l1p_msgb_alloc();
+	struct msgb *msg = msgb_alloc_headroom(sizeof(SuperFemto_Prim_t) + 128,
+		128, "1l_fd");
+	struct femtol1_hdl *fl1h = ofd->data;
+	int rc;
+
+	msg->l1h = msg->data;
+	rc = read(ofd->fd, msg->l1h, msgb_tailroom(msg));
+	if (rc < 0) {
+		if (rc != -1) 
+			LOGP(DL1IF, LOGL_ERROR, "error reading from L1 msg_queue: %s\n",
+				strerror(errno));
+		msgb_free(msg);
+		return rc;
+	}
+	msgb_put(msg, rc);
+
+	switch (ofd->priv_nr) {
+	case MQ_SYS_WRITE:
+		if (rc != sizeof(SuperFemto_Prim_t))
+			LOGP(DL1IF, LOGL_NOTICE, "%u != "
+			     "sizeof(SuperFemto_Prim_t)\n", rc);
+		return l1if_handle_sysprim(fl1h, msg);
+	case MQ_L1_WRITE:
+#ifndef HW_SYSMOBTS_V1
+	case MQ_TCH_WRITE:
+	case MQ_PDTCH_WRITE:
+#endif
+		if (rc != sizeof(GsmL1_Prim_t))
+			LOGP(DL1IF, LOGL_NOTICE, "%u != "
+			     "sizeof(GsmL1_Prim_t)\n", rc);
+		return l1if_handle_l1prim(ofd->priv_nr, fl1h, msg);
+	default:
+		/* The compiler can't know that priv_nr is an enum. Assist. */
+		LOGP(DL1IF, LOGL_FATAL, "writing on a wrong queue: %d\n",
+			ofd->priv_nr);
+		exit(0);
+		break;
+	}
+};
+
+/* callback when we can write to one of the l1 msg_queue devices */
+static int l1fd_write_cb(struct osmo_fd *ofd, struct msgb *msg)
+{
+	int rc;
+
+	rc = write(ofd->fd, msg->l1h, msgb_l1len(msg));
+	if (rc < 0) {
+		LOGP(DL1IF, LOGL_ERROR, "error writing to L1 msg_queue: %s\n",
+			strerror(errno));
+		return rc;
+	} else if (rc < msg->len) {
+		LOGP(DL1IF, LOGL_ERROR, "short write to L1 msg_queue: "
+			"%u < %u\n", rc, msg->len);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+int l1if_transport_open(int q, struct femtol1_hdl *hdl)
+{
+	int rc;
+
+	/* Step 1: Open all msg_queue file descriptors */
+	struct osmo_fd *read_ofd = &hdl->read_ofd[q];
+	struct osmo_wqueue *wq = &hdl->write_q[q];
+	struct osmo_fd *write_ofd = &hdl->write_q[q].bfd;
+
+	rc = open(rd_devnames[q], O_RDONLY);
+	if (rc < 0) {
+		LOGP(DL1IF, LOGL_FATAL, "unable to open msg_queue: %s\n",
+			strerror(errno));
+		return rc;
+	}
+	read_ofd->fd = rc;
+	read_ofd->priv_nr = q;
+	read_ofd->data = hdl;
+	read_ofd->cb = l1if_fd_cb;
+	read_ofd->when = BSC_FD_READ;
+	rc = osmo_fd_register(read_ofd);
+	if (rc < 0) {
+		close(read_ofd->fd);
+		read_ofd->fd = -1;
+		return rc;
+	}
+
+	rc = open(wr_devnames[q], O_WRONLY);
+	if (rc < 0) {
+		LOGP(DL1IF, LOGL_FATAL, "unable to open msg_queue: %s\n",
+			strerror(errno));
+		goto out_read;
+	}
+	osmo_wqueue_init(wq, 10);
+	wq->write_cb = l1fd_write_cb;
+	write_ofd->fd = rc;
+	write_ofd->priv_nr = q;
+	write_ofd->data = hdl;
+	write_ofd->when = BSC_FD_WRITE;
+	rc = osmo_fd_register(write_ofd);
+	if (rc < 0) {
+		close(write_ofd->fd);
+		write_ofd->fd = -1;
+		goto out_read;
+	}
+
+	return 0;
+
+out_read:
+	close(hdl->read_ofd[q].fd);
+	osmo_fd_unregister(&hdl->read_ofd[q]);
+
+	return rc;
+}
+
+int l1if_transport_close(int q, struct femtol1_hdl *hdl)
+{
+	struct osmo_fd *read_ofd = &hdl->read_ofd[q];
+	struct osmo_fd *write_ofd = &hdl->write_q[q].bfd;
+
+	osmo_fd_unregister(read_ofd);
+	close(read_ofd->fd);
+	read_ofd->fd = -1;
+
+	osmo_fd_unregister(write_ofd);
+	close(write_ofd->fd);
+	write_ofd->fd = -1;
+
+	return 0;
+}
diff --git a/src/sysmo_l1_if.c b/src/sysmo_l1_if.c
new file mode 100644
index 0000000..7cb1d17
--- /dev/null
+++ b/src/sysmo_l1_if.c
@@ -0,0 +1,353 @@
+
+#include <string.h>
+#include <errno.h>
+
+#include <sysmocom/femtobts/superfemto.h>
+#include <sysmocom/femtobts/gsml1prim.h>
+#include <sysmocom/femtobts/gsml1const.h>
+#include <sysmocom/femtobts/gsml1types.h>
+
+#include <osmocom/core/gsmtap.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/timer.h>
+#include <sysmo_l1_if.h>
+#include <gprs_debug.h>
+#include <pcu_l1_if.h>
+
+uint32_t l1if_ts_to_hLayer2(uint8_t trx, uint8_t ts)
+{
+	return (ts << 16) | (trx << 24);
+}
+
+/* allocate a msgb containing a GsmL1_Prim_t */
+struct msgb *l1p_msgb_alloc(void)
+{
+	struct msgb *msg = msgb_alloc(sizeof(GsmL1_Prim_t), "l1_prim");
+
+	if (msg)
+		msg->l1h = msgb_put(msg, sizeof(GsmL1_Prim_t));
+
+	return msg;
+}
+
+static int l1if_req_pdch(struct femtol1_hdl *fl1h, struct msgb *msg)
+{
+	struct osmo_wqueue *wqueue = &fl1h->write_q[MQ_PDTCH_WRITE];
+
+	osmo_wqueue_enqueue(wqueue, msg);
+
+	return 0;
+}
+
+static void *prim_init(GsmL1_Prim_t *prim, GsmL1_PrimId_t id, struct femtol1_hdl *gl1)
+{
+	prim->id = id;
+
+	/* for some reason the hLayer1 field is not always at the same position
+	 * in the GsmL1_Prim_t, so we have to have this ugly case statement here... */
+	switch (id) {
+	case GsmL1_PrimId_MphInitReq:
+		//prim->u.mphInitReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphCloseReq:
+		prim->u.mphCloseReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphConnectReq:
+		prim->u.mphConnectReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphDisconnectReq:
+		prim->u.mphDisconnectReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphActivateReq:
+		prim->u.mphActivateReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphDeactivateReq:
+		prim->u.mphDeactivateReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphConfigReq:
+		prim->u.mphConfigReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphMeasureReq:
+		prim->u.mphMeasureReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_MphInitCnf:
+	case GsmL1_PrimId_MphCloseCnf:
+	case GsmL1_PrimId_MphConnectCnf:
+	case GsmL1_PrimId_MphDisconnectCnf:
+	case GsmL1_PrimId_MphActivateCnf:
+	case GsmL1_PrimId_MphDeactivateCnf:
+	case GsmL1_PrimId_MphConfigCnf:
+	case GsmL1_PrimId_MphMeasureCnf:
+		break;
+	case GsmL1_PrimId_MphTimeInd:
+		break;
+	case GsmL1_PrimId_MphSyncInd:
+		break;
+	case GsmL1_PrimId_PhEmptyFrameReq:
+		prim->u.phEmptyFrameReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_PhDataReq:
+		prim->u.phDataReq.hLayer1 = gl1->hLayer1;
+		break;
+	case GsmL1_PrimId_PhConnectInd:
+		break;
+	case GsmL1_PrimId_PhReadyToSendInd:
+		break;
+	case GsmL1_PrimId_PhDataInd:
+		break;
+	case GsmL1_PrimId_PhRaInd:
+		break;
+	default:
+		LOGP(DL1IF, LOGL_ERROR, "unknown L1 primitive %u\n", id);
+		break;
+	}
+	return &prim->u;
+}
+
+struct sapi_dir {
+	GsmL1_Sapi_t sapi;
+	GsmL1_Dir_t dir;
+};
+
+static const struct sapi_dir pdtch_sapis[] = {
+	{ GsmL1_Sapi_Pdtch,	GsmL1_Dir_TxDownlink },
+	{ GsmL1_Sapi_Pdtch,	GsmL1_Dir_RxUplink },
+	{ GsmL1_Sapi_Ptcch,	GsmL1_Dir_TxDownlink },
+	{ GsmL1_Sapi_Prach,	GsmL1_Dir_RxUplink },
+#if 0
+	{ GsmL1_Sapi_Ptcch,	GsmL1_Dir_RxUplink },
+	{ GsmL1_Sapi_Pacch,	GsmL1_Dir_TxDownlink },
+#endif
+};
+
+
+/* connect PDTCH */
+int l1if_connect_pdch(void *obj, uint8_t ts)
+{
+	struct femtol1_hdl *fl1h = obj;
+	struct msgb *msg = l1p_msgb_alloc();
+	GsmL1_MphConnectReq_t *cr;
+
+	cr = prim_init(msgb_l1prim(msg), GsmL1_PrimId_MphConnectReq, fl1h);
+	cr->u8Tn = ts;
+	cr->logChComb = GsmL1_LogChComb_XIII;
+	
+	return l1if_req_pdch(fl1h, msg);
+}
+
+static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1h,
+				     GsmL1_PhReadyToSendInd_t *rts_ind)
+{
+	struct gsm_time g_time;
+	int rc = 0;
+
+	gsm_fn2gsmtime(&g_time, rts_ind->u32Fn);
+
+	DEBUGP(DL1IF, "Rx PH-RTS.ind %02u/%02u/%02u SAPI=%s\n",
+		g_time.t1, g_time.t2, g_time.t3,
+		get_value_string(femtobts_l1sapi_names, rts_ind->sapi));
+
+	switch (rts_ind->sapi) {
+	case GsmL1_Sapi_Pdtch:
+	case GsmL1_Sapi_Pacch:
+		rc = pcu_rx_rts_req_pdtch((long)fl1h->priv, rts_ind->u8Tn,
+			rts_ind->u16Arfcn, rts_ind->u32Fn, rts_ind->u8BlockNbr);
+	case GsmL1_Sapi_Ptcch:
+		// FIXME
+	default:
+		break;
+	}
+
+	return rc;
+}
+
+static int handle_ph_data_ind(struct femtol1_hdl *fl1h,
+	GsmL1_PhDataInd_t *data_ind, struct msgb *l1p_msg)
+{
+	int rc = 0;
+
+	gsmtap_send(fl1h->gsmtap, data_ind->u16Arfcn | GSMTAP_ARFCN_F_UPLINK,
+			data_ind->u8Tn, GSMTAP_CHANNEL_PACCH, 0,
+			data_ind->u32Fn, 0, 0, data_ind->msgUnitParam.u8Buffer,
+			data_ind->msgUnitParam.u8Size);
+
+	DEBUGP(DL1IF, "Rx PH-DATA.ind %s (hL2 %08x): %s",
+		get_value_string(femtobts_l1sapi_names, data_ind->sapi),
+		data_ind->hLayer2,
+		osmo_hexdump(data_ind->msgUnitParam.u8Buffer,
+			     data_ind->msgUnitParam.u8Size));
+
+	switch (data_ind->sapi) {
+	case GsmL1_Sapi_Pdtch:
+	case GsmL1_Sapi_Pacch:
+		/* drop incomplete UL block */
+		if (data_ind->msgUnitParam.u8Buffer[0]
+			!= GsmL1_PdtchPlType_Full)
+			break;
+		/* PDTCH / PACCH frame handling */
+		pcu_rx_data_ind_pdtch((long)fl1h->priv, data_ind->u8Tn,
+			data_ind->msgUnitParam.u8Buffer + 1,
+			data_ind->msgUnitParam.u8Size - 1,
+			data_ind->u32Fn);
+		break;
+	case GsmL1_Sapi_Ptcch:
+		// FIXME
+		break;
+	default:
+		LOGP(DL1IF, LOGL_NOTICE, "Rx PH-DATA.ind for unknown L1 SAPI %s\n",
+			get_value_string(femtobts_l1sapi_names, data_ind->sapi));
+		break;
+	}
+
+	return rc;
+}
+
+#define MIN_QUAL_RACH	5.0f
+
+static int handle_ph_ra_ind(struct femtol1_hdl *fl1h, GsmL1_PhRaInd_t *ra_ind)
+{
+	uint8_t acc_delay;
+
+	if (ra_ind->measParam.fLinkQuality < MIN_QUAL_RACH)
+		return 0;
+
+	DEBUGP(DL1IF, "Rx PH-RA.ind");
+
+	/* check for under/overflow / sign */
+	if (ra_ind->measParam.i16BurstTiming < 0)
+		acc_delay = 0;
+	else
+		acc_delay = ra_ind->measParam.i16BurstTiming >> 2;
+#if 0
+	if (acc_delay > bts->max_ta) {
+		LOGP(DL1C, LOGL_INFO, "ignoring RACH request %u > max_ta(%u)\n",
+		     acc_delay, btsb->max_ta);
+		return 0;
+	}
+#endif
+
+	return 0;
+}
+
+
+/* handle any random indication from the L1 */
+int l1if_handle_l1prim(int wq, struct femtol1_hdl *fl1h, struct msgb *msg)
+{
+	GsmL1_Prim_t *l1p = msgb_l1prim(msg);
+	int rc = 0;
+
+	LOGP(DL1IF, LOGL_DEBUG, "Rx L1 prim %s on queue %d\n",
+		get_value_string(femtobts_l1prim_names, l1p->id), wq);
+
+	switch (l1p->id) {
+#if 0
+	case GsmL1_PrimId_MphTimeInd:
+		rc = handle_mph_time_ind(fl1h, &l1p->u.mphTimeInd);
+		break;
+	case GsmL1_PrimId_MphSyncInd:
+		break;
+	case GsmL1_PrimId_PhConnectInd:
+		break;
+#endif
+	case GsmL1_PrimId_PhReadyToSendInd:
+		rc = handle_ph_readytosend_ind(fl1h, &l1p->u.phReadyToSendInd);
+		break;
+	case GsmL1_PrimId_PhDataInd:
+		rc = handle_ph_data_ind(fl1h, &l1p->u.phDataInd, msg);
+		break;
+	case GsmL1_PrimId_PhRaInd:
+		rc = handle_ph_ra_ind(fl1h, &l1p->u.phRaInd);
+		break;
+	default:
+		break;
+	}
+
+	msgb_free(msg);
+
+	return rc;
+}
+
+int l1if_handle_sysprim(struct femtol1_hdl *fl1h, struct msgb *msg)
+{
+	return -ENOTSUP;
+}
+
+/* send packet data request to L1 */
+int l1if_pdch_req(void *obj, uint8_t ts, int is_ptcch, uint32_t fn,
+	uint16_t arfcn, uint8_t block_nr, uint8_t *data, uint8_t len)
+{
+	struct femtol1_hdl *fl1h = obj;
+	struct msgb *msg;
+	GsmL1_Prim_t *l1p;
+	GsmL1_PhDataReq_t *data_req;
+	GsmL1_MsgUnitParam_t *msu_param;
+	struct gsm_time g_time;
+
+	gsm_fn2gsmtime(&g_time, fn);
+
+	DEBUGP(DL1IF, "TX packet data %02u/%02u/%02u is_ptcch=%d ts=%d "
+		"block_nr=%d, arfcn=%d, len=%d\n", g_time.t1, g_time.t2,
+		g_time.t3, is_ptcch, ts, block_nr, arfcn, len);
+
+	msg = l1p_msgb_alloc();
+	l1p = msgb_l1prim(msg);
+	l1p->id = GsmL1_PrimId_PhDataReq;
+	data_req = &l1p->u.phDataReq;
+	data_req->hLayer1 = fl1h->hLayer1;
+	data_req->sapi = (is_ptcch) ? GsmL1_Sapi_Ptcch : GsmL1_Sapi_Pdtch;
+	data_req->subCh = GsmL1_SubCh_NA;
+	data_req->u8BlockNbr = block_nr;
+	data_req->u8Tn = ts;
+	data_req->u32Fn = fn;
+	msu_param = &data_req->msgUnitParam;
+	msu_param->u8Size = len;
+	memcpy(msu_param->u8Buffer, data, len);
+
+	gsmtap_send(fl1h->gsmtap, arfcn, data_req->u8Tn, GSMTAP_CHANNEL_PACCH,
+			0, data_req->u32Fn, 0, 0,
+			data_req->msgUnitParam.u8Buffer,
+			data_req->msgUnitParam.u8Size);
+
+
+	/* transmit */
+	osmo_wqueue_enqueue(&fl1h->write_q[MQ_PDTCH_WRITE], msg);
+
+	return 0;
+}
+
+void *l1if_open_pdch(void *priv, uint32_t hlayer1)
+{
+	struct femtol1_hdl *fl1h;
+	int rc;
+
+	fl1h = talloc_zero(priv, struct femtol1_hdl);
+	if (!fl1h)
+		return NULL;
+
+	fl1h->hLayer1 = hlayer1;
+	fl1h->priv = priv;
+	fl1h->clk_cal = 0;
+	/* default clock source: OCXO */
+	fl1h->clk_src = SuperFemto_ClkSrcId_Ocxo;
+
+	rc = l1if_transport_open(MQ_PDTCH_WRITE, fl1h);
+	if (rc < 0) {
+		talloc_free(fl1h);
+		return NULL;
+	}
+
+	fl1h->gsmtap = gsmtap_source_init("localhost", GSMTAP_UDP_PORT, 1);
+	if (fl1h->gsmtap)
+		gsmtap_source_add_sink(fl1h->gsmtap);
+
+	return fl1h;
+}
+
+static int l1if_close_pdch(void *obj)
+{
+	struct femtol1_hdl *fl1h = obj;
+	if (fl1h)
+		l1if_transport_close(MQ_PDTCH_WRITE, fl1h);
+	return 0;
+}
+
diff --git a/src/sysmo_l1_if.h b/src/sysmo_l1_if.h
new file mode 100644
index 0000000..49bbb62
--- /dev/null
+++ b/src/sysmo_l1_if.h
@@ -0,0 +1,81 @@
+#ifndef _SYSMO_L1_IF_H
+#define _SYSMO_L1_IF_H
+
+#include <osmocom/core/select.h>
+#include <osmocom/core/write_queue.h>
+#include <osmocom/core/gsmtap_util.h>
+#include <osmocom/gsm/gsm_utils.h>
+#include "femtobts.h"
+
+enum {
+	MQ_SYS_READ,
+	MQ_L1_READ,
+#ifndef HW_SYSMOBTS_V1
+	MQ_TCH_READ,
+	MQ_PDTCH_READ,
+#endif
+	_NUM_MQ_READ
+};
+
+enum {
+	MQ_SYS_WRITE,
+	MQ_L1_WRITE,
+#ifndef HW_SYSMOBTS_V1
+	MQ_TCH_WRITE,
+	MQ_PDTCH_WRITE,
+#endif
+	_NUM_MQ_WRITE
+};
+
+struct femtol1_hdl {
+	struct gsm_time gsm_time;
+	uint32_t hLayer1;			/* handle to the L1 instance in the DSP */
+	uint32_t dsp_trace_f;
+	int clk_cal;
+	uint8_t clk_src;
+	struct llist_head wlc_list;
+
+	struct gsmtap_inst *gsmtap;
+	uint32_t gsmtap_sapi_mask;
+
+	void *priv;			/* user reference */
+
+	struct osmo_timer_list alive_timer;
+	unsigned int alive_prim_cnt;
+
+	struct osmo_fd read_ofd[_NUM_MQ_READ];	/* osmo file descriptors */
+	struct osmo_wqueue write_q[_NUM_MQ_WRITE];
+
+	struct {
+		uint8_t dsp_version[3];
+		uint8_t fpga_version[3];
+		uint32_t band_support;	/* bitmask of GSM_BAND_* */
+	} hw_info;
+};
+
+#define msgb_l1prim(msg)	((GsmL1_Prim_t *)(msg)->l1h)
+#define msgb_sysprim(msg)	((SuperFemto_Prim_t *)(msg)->l1h)
+
+typedef int l1if_compl_cb(struct msgb *l1_msg, void *data);
+
+/* send a request primitive to the L1 and schedule completion call-back */
+int l1if_req_compl(struct femtol1_hdl *fl1h, struct msgb *msg,
+		   int is_system_prim, l1if_compl_cb *cb, void *data);
+
+int l1if_reset(struct femtol1_hdl *hdl);
+int l1if_activate_rf(struct femtol1_hdl *hdl, int on);
+int l1if_set_trace_flags(struct femtol1_hdl *hdl, uint32_t flags);
+int l1if_set_txpower(struct femtol1_hdl *fl1h, float tx_power);
+
+struct msgb *l1p_msgb_alloc(void);
+struct msgb *sysp_msgb_alloc(void);
+
+uint32_t l1if_lchan_to_hLayer2(struct gsm_lchan *lchan);
+struct gsm_lchan *l1if_hLayer2_to_lchan(struct gsm_bts_trx *trx, uint32_t hLayer2);
+
+/* tch.c */
+int l1if_tch_rx(struct gsm_lchan *lchan, struct msgb *l1p_msg);
+int l1if_tch_fill(struct gsm_lchan *lchan, uint8_t *l1_buffer);
+struct msgb *gen_empty_tch_msg(struct gsm_lchan *lchan);
+
+#endif /* _SYSMO_L1_IF_H */