diff --git a/src/osmo_gsm_tester/obj/gnuradio_zmq_broker.py b/src/osmo_gsm_tester/obj/gnuradio_zmq_broker.py
new file mode 100644
index 0000000..ba43794
--- /dev/null
+++ b/src/osmo_gsm_tester/obj/gnuradio_zmq_broker.py
@@ -0,0 +1,161 @@
+# osmo_gsm_tester: class defining a RF emulation object implemented using SRS ENB stdin interface
+#
+# Copyright (C) 2020 by sysmocom - s.f.m.c. GmbH
+#
+# Author: Pau Espin Pedrol <pespin@sysmocom.de>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU 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 General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import json
+import socket
+
+from ..core import log
+from ..core import util
+from ..core import process
+from ..core import remote
+from ..core.event_loop import MainLoop
+
+class GrBroker(log.Origin):
+
+    # static fields:
+    refcount = 0
+    instance = None
+
+    def __init__(self):
+        super().__init__(log.C_RUN, 'gr_zmq_broker')
+        self.process = None
+        self.ctrl_port = 5005
+        self.run_dir = None
+        self.rem_host = None
+        self.enb_li = []
+        self.addr = None
+        self.ctrl_sk = None
+        self.num_enb_started = 0
+
+    @staticmethod
+    def ref():
+        if GrBroker.refcount == 0:
+            GrBroker.instance = GrBroker()
+        GrBroker.refcount = GrBroker.refcount + 1
+        return GrBroker.instance
+
+    @staticmethod
+    def unref():
+        GrBroker.refcount = GrBroker.refcount - 1
+        if GrBroker.refcount == 0:
+            GrBroker.instance.cleanup()
+            GrBroker.instance = None
+
+
+    def cleanup(self):
+        if self.ctrl_sk is not None:
+            self.cmd_exit()
+            self.ctrl_sk.close()
+            self.ctrl_sk = None
+        self.enb_li = []
+        self.testenv = None
+
+    def register_enb(self, enb):
+        self.enb_li.append(enb)
+
+    def unregister_enb(self, enb):
+        self.enb_li.remove(enb)
+
+    def gen_json_enb(self, enb):
+        res = []
+        cell_list = enb.gen_conf['enb']['cell_list']
+        for cell in cell_list:
+            # TODO: probably add enb_id, cell_id to support several ENB
+            data = {'earfcn': int(cell['dl_earfcn']),
+                    'bind_port': int(cell['zmq_enb_peer_port']),
+                    'peer_addr': enb.addr(),
+                    'peer_port': int(cell['zmq_enb_bind_port']),
+                    'use_mimo': True if enb.num_ports() > 1 else False
+                    }
+            res.append(data)
+        return res
+
+    def gen_json_ue(self, enb):
+        res = {}
+        res = []
+        earfcns_done = []
+        cell_list = enb.gen_conf['enb']['cell_list']
+        for cell in cell_list:
+            data = {}
+            if int(cell['dl_earfcn']) in earfcns_done:
+                continue
+            earfcns_done.append(int(cell['dl_earfcn']))
+            data = {'earfcn': int(cell['dl_earfcn']),
+                    'bind_port': int(cell['zmq_ue_peer_port']),
+                    'peer_addr': enb.ue.addr(),
+                    'peer_port': int(cell['zmq_ue_bind_port']),
+                    'use_mimo': True if enb.num_ports() > 1 else False
+                    }
+            res.append(data)
+        return res
+
+    def gen_json(self):
+        res = {'enb': [self.gen_json_enb(enb) for enb in self.enb_li],
+               'ue': [self.gen_json_ue(self.enb_li[0])]}
+        return res
+
+    def configure(self):
+        self.addr = self.enb_li[0].addr()
+        self.testenv = self.enb_li[0].testenv
+        self.run_dir = util.Dir(self.testenv.test().get_run_dir().new_dir(self.name()))
+        if not self.enb_li[0]._run_node.is_local():
+            self.rem_host = remote.RemoteHost(self.run_dir, self.enb_li[0]._run_node.ssh_user(), self.enb_li[0]._run_node.ssh_addr())
+
+    def start(self):
+        self.num_enb_started += 1
+        self.dbg('start(%d/%d)' % (self.num_enb_started, len(self.enb_li)))
+        if self.num_enb_started == 1:
+            self.configure()
+            args = ('osmo-gsm-tester_zmq_broker.py',
+                    '-c', str(self.ctrl_port),
+                    '-b', self.addr)
+            if self.enb_li[0]._run_node.is_local():
+                self.process = process.Process(self.name(), self.run_dir, args)
+            else:
+                self.process = self.rem_host.RemoteProcessSafeExit('zmq_gr_broker', util.Dir('/tmp/ogt_%s' % self.name()), args, wait_time_sec=7)
+            self.testenv.remember_to_stop(self.process)
+            self.process.launch()
+        # Wait until all ENBs are configured/started:
+        if self.num_enb_started == len(self.enb_li):
+            self.dbg('waiting for gr script to be available...')
+            MainLoop.sleep(5)
+            self.ctrl_sk = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+            self.cmd_setup()
+
+    def send_cmd(self, str_buf):
+        self.dbg('sending cmd: "%s"' % str_buf)
+        self.ctrl_sk.sendto(str_buf.encode('utf-8'), (self.addr, self.ctrl_port))
+
+    def cmd_setup(self):
+        cfg = self.gen_json()
+        buf = json.dumps(cfg)
+        self.send_cmd(buf)
+
+    def cmd_set_relative_gain_on_local_port(self, port, rel_gain):
+        d = { 'action': 'set_relative_gain',
+              'port': port,
+              'rel_gain': rel_gain
+            }
+        buf = json.dumps(d)
+        self.send_cmd(buf)
+
+    def cmd_exit(self):
+        d = { 'action': 'exit' }
+        buf = json.dumps(d)
+        self.send_cmd(buf)