Generation of radio frequency in microwave radio links
A microwave radio system and a method of generating an operational frequency in the microwave radio system. The microwave radio system includes at least one radio link. Each radio link has one or more radio unit(s). Each radio link has a common local oscillator (LO) which is configured to transmit a common LO frequency signal to each of the radio units of each radio link. Each radio link has a respective joint transmission line arranged to be coupled to each respective radio unit and configured to carry a plurality of signals comprising the common LO frequency signal to each of the respective radio units of each radio link. The common LO is arranged remotely from the one or more radio unit(s) and each radio unit is configured to receive and convert the transmitted common frequency signal of the common LO to an operational radio frequency of each radio unit.
1 . A microwave multiple-input, multiple-output (MIMO) radio system, comprising:
at least one radio link, the at least one radio link comprising:
one or more radio units, the one or more radio units comprising:
a transceiver unit configured to one or both transmit and receive a wireless signal, the transceiver unit comprising:
a receiving (RX) module, and
a transmitting (TX) module;
a signal processing unit operatively coupled to the transceiver unit to process the wireless signal from one or both of the RX module and the TX module of the transceiver unit; and
one or more antenna arrangements for one or both of transmitting and receiving the wireless signal, the one or more antenna arrangements coupled to an antenna port of the transceiver unit;
the at least one radio link further comprising:
a baseband unit comprising at least one filter unit;
a common local oscillator (LO) arranged in the baseband unit to generate a common LO frequency signal, the baseband unit to transmit the common LO frequency signal from the baseband unit to each of the one or more radio units of the at least one radio link; and
a respective joint transmission line arranged to couple the baseband unit with the common LO deployed therein to each respective radio unit and to carry from the baseband unit a plurality of signals comprising the common LO frequency signal of the common LO to each of the one or more respective radio units of the at least one radio link, the respective joint transmission line being further configured to carry a transmit intermediate frequency (IF) signal from the baseband unit towards the TX module and to carry a receive IF signal from the RX module towards the baseband unit,
the baseband unit with the common LO deployed therein being arranged remotely from the one or more radio units of the at least one radio link and the one or more radio units being configured to receive and convert the transmitted common LO frequency signal to an operational radio frequency of the one or more radio units.
2 . The microwave radio system according to claim 1 , wherein the signal processing unit further comprises at least one frequency mixer element configured to produce an output signal based on the operational radio frequency of each radio unit.
3 . The microwave radio system according to claim 1 , wherein the signal processing unit further comprises at least one multiplier element configured to multiply the common frequency signal of the common LO by a predetermined multiplication factor.
4 . The microwave radio system according to claim 3 , wherein each radio unit further comprises a first multiplier element, and a second multiplier element, wherein the first multiplier element is a receiver multiplier element, configured to operate on the first common LO frequency of the first common LO for the received signal and the second multiplier element is a transmitter multiplier element, configured to operate on the second common LO frequency of the second common LO for the transmitted signal, wherein the first common LO frequency is different from the second common LO frequency.
5 . The microwave radio system according to claim 1 , wherein the common frequency signal of the common LO comprises a sub-harmonic frequency of the LO frequency.
6 . The microwave radio system according to claim 1 , wherein the signal processing unit further comprises a modulation/demodulation unit, configured to one or both modulate and demodulate one of both transmitted and received signals in each radio unit.
7 . The microwave radio system according to claim 1 , wherein the respective joint transmission line, is further configured to carry one or both of a power signal and a control signal to each of the one or more radio units.
8 . The microwave radio system according to claim 1 , wherein the respective joint transmission line, is further configured to carry a data stream one or both of transmitted from the baseband unit towards each of the one or more radio units and received from each of the one or more radio unit(s) at the baseband unit, wherein the respective joint transmission line is an intermediate frequency (IF) cable.
9 . The microwave radio system according to claim 1 , wherein the at least one filter unit is configured to separate the common frequency signal of the common LO from the plurality of signals being carried by the joint transmission line.
10 . The microwave radio system according to claim 1 , wherein the baseband unit further comprises at least one receiver filter unit and at least one transmitter filter unit, wherein the receiver filter unit is configured to separate, from the plurality of signals carried by the joint transmission line, the data stream received from each of the one or more radio unit(s) at the baseband unit and wherein the transmitter filter unit is configured to separate, from the plurality of signals carried by the joint transmission line, the data stream transmitted from the baseband unit toward each of the one or more radio unit(s).
11 . The microwave radio system according to claim 1 , wherein the at least one filter unit corresponds to at least one filter unit of the baseband unit and configured to separate the common frequency signal of the common LO from the plurality of signals being carried by the joint transmission line.
12 . The microwave radio system according to claim 1 , wherein each radio unit further comprises at least one receiver filter unit and at least one transmitter filter unit corresponding to at least one receiver filter unit and at least one transmitter filter unit of the baseband unit, wherein a receiver filter unit of a radio unit is configured to separate, from the plurality of signals carried by the joint transmission line, the data stream transmitted from each of the one or more radio units toward the baseband unit, and wherein a transmitter filter unit of a radio unit is configured to separate, from the plurality of signals carried by the joint transmission line, the data stream received from the baseband unit at each of the one or more radio units.
13 . The microwave radio system according to claim 1 , wherein each radio link comprises a first common LO, and a second common LO, wherein the first common LO is a receiver common LO having a first common LO frequency for the received signal and the second common LO is a transmitter common LO having a second common LO frequency for the transmitted signal, wherein the first common LO frequency is different from the second common LO frequency.
14 . The microwave radio system according to claim 1 , wherein the microwave radio system is a line-of-sight (LOS) multi-stream multi-input multi-output, MIMO microwave backhaul communication system.
15 . A radio unit of a microwave Multiple-Input-Multiple-Output (MIMO) system, the radio unit comprising:
a transceiver unit configured to one or both transmit and receive a wireless signal, the transceiver unit comprising:
a receiving (RX) module,
a transmitting (TX) module, and
an antenna port;
a signal processing unit operatively coupled to the transceiver unit to process the wireless signal from one or both of the RX module and the TX module of the transceiver unit;
an antenna arrangement for one or both transmitting and receiving the wireless signal, the antenna arrangement coupled to the antenna port of the transceiver unit;
the radio unit of the microwave MIMO system being arranged remotely from a baseband unit, the baseband unit including at least one filter unit, and a common local oscillator (LO) deployed therein to generate a common LO frequency signal, and the radio unit being arranged to be coupled to a joint transmission line, and configured to receive the common LO frequency signal from the common LO of the baseband unit via said joint transmission line, the joint transmission line being further configured to carry a transmit intermediate frequency, IF, signal from the baseband unit to the TX module and carry a receive IF signal from the RX module to the baseband unit; and
the signal processing unit of the radio unit being configured to convert the received common LO frequency signal from the common LO of the baseband unit to an operational radio frequency of the radio unit.
16 . A method for generating an operational radio frequency in a microwave multiple-input, multiple-output (MIMO) radio system, the method comprising:
transmitting, over a respective joint transmission line coupled to respective radio units, a common local oscillator (LO) frequency signal generated by a common LO deployed in a baseband unit remotely located from the respective radio units of a MIMO radio link, the baseband unit comprising at least one filter unit, each of the respective radio units comprising:
a transceiver unit to one or both transmit and receive a wireless signal;
a signal processing unit operatively coupled to the transceiver unit to process the wireless signal from one or both of the RX module and the TX module; and
one or more antenna arrangements for one or more of transmitting and receiving the wireless signal, the one or more antenna arrangements coupled an antenna port of the transceiver unit, each respective joint transmission line being further configured to carry a transmit intermediate frequency, IF, signal from the baseband unit to a transmitting (TX) module of the transceiver unit, and to carry a receive IF signal from the receiving (RX) module of the transceiver unit to the baseband unit;
receiving, in each radio unit, the transmitted common LO frequency signal of the common LO of the baseband unit; and
converting, in each radio unit, the received common LO frequency signal of the common LO to the operational radio frequency of each radio unit.
17 . The method according to claim 16 , wherein the common frequency signal of the common LO comprises a sub-harmonic frequency of the LO frequency.
18 . The method according to claim 16 , wherein converting the received common frequency of the common LO to the operational frequency of each radio unit comprises:
multiplying the received common frequency signal of the common LO by a predetermined multiplication factor.
19 . The method according to claim 18 , wherein the predetermined multiplication factor is determined based on at least one of: radio link operation frequency, degree of phase noise correlation of the at least one radio link, the MIMO order, baud rate and phase noise strength of the microwave radio system.