The described embodiments relate generally to wireless communications. More particularly, the described embodiments relate to systems, methods and apparatuses for a TDD (time division duplex) radio configuration for reduction in transmit and receive path resources.
Current TDD remote radio unit (RRU) and mMIMO (massive multi-input, multi-output) base stations have one dedicated LPTX (low power Transmit) path and corresponding one dedicated RX (receiver) path for each antenna. Only one path (Tx or RX) can be used at a time in TDD (time division duplex) systems.
It is desirable to have methods, apparatuses, and systems for a TDD (time division duplex) radio configuration for reduction in transmit and receive path resources.
An embodiment includes a transceiver system. The transceiver system includes an RF system on a chip (RFSOC) comprising baseband communication circuitry and frequency upconverters for transmit wireless signals and frequency downconverters for received wireless signals. The system further includes a transmit switch receiving a plurality of transmit signals from the RFSOC through single transmit line, and operative to connect each of the plurality of transmit signals to a one of a plurality of antennas, one at a time, continuously over time, and a receive switch receiving a plurality of received signals from the plurality of antennas, and operative to connect each of the plurality of received signals to the RFSOC on a single receive line, one at a time, continuously over time, wherein each antenna of the plurality of antennas is either transmitting or receiving.
Another embodiment includes a method. The method includes frequency upconverting and frequency down-converting, by an RF system on a chip (RFSOC), transmit and received wireless signals, receiving, by a transmit switch, a plurality of transmit signals from the RFSOC through single transmit line, connecting each of the plurality of transmit signals to a one of a plurality of antennas, one at a time, continuously over time, and receiving, by a receive switch, a plurality of received signals from the plurality of antennas, and connecting each of the plurality of received signals to the RFSOC on a single receive line, one at a time, continuously over time, wherein each antenna of the plurality of antennas is either transmitting or receiving.
Other aspects and advantages of the described embodiments will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the described embodiments.
The embodiments described include methods, apparatuses, and systems for a TDD (time division duplex) radio that provides for reduction in transmit and receive path resources. The described embodiments include an architecture where the TRX (transmit and receive) resources are reduced, and available resources are more efficiently used. Further, the TDD radio is operated without any loss of throughput. This reduction in resources is substantially beneficial in terms of BOM (bill of materials) cost and the space needed. Deployment of 5G wireless technologies is driving demand for mMIMO technology, and the described embodiments can be utilized to save money while reducing complexity of RRUs (remote radio units) utilized in the deployments. The described embodiments not only save BOM costs for LPTX and RX paths within RRUs, the described embodiments also reduce the memory and processing resources (for example, FPGA (field programmable gate arrays) within the RRUs. By utilizing the describes embodiments, the overall DC power consumption of an RRU is improve due to the lesser number of active paths and the reduced silicon resources. This additionally reduces the overall operational cost for the network operators and is better for the environment.
For the described embodiments, time division duplex (TDD) refers to duplex communication links where uplink (RRU wirelessly receive communications from a user) is separated from downlink (RRU wirelessly transmits communications to a user) by the allocation of different time slots in the same frequency band. Current TDD remote radio unit (RRU) base stations have one dedicated LPTX (low power transmit) path and a corresponding one dedicated RX (receiver) path for each antenna. For example, a typical 4T4R (Four transmit and four receive) macro base station has four dedicated LPTX paths and corresponding four RX paths. Similarly, an 8T8R macro base station has eight dedicated LPTX paths and corresponding eight RX paths, and for a 64T64R mMIMO (massive multi-input, multi-output) base station, there are 64LPTX path and corresponding 64 RX paths.
In a traditional TDD system, for a given Tx-RX chain pair, only one of the paths is used at a time. That is, when a radio is transmitting the corresponding receiving path is idle, and similarly, when the radio is receiving, the corresponding transmit path is idle. Initially, these TDD systems had equal uplink and downlink time slots. This way, the LPTX and the corresponding Rx paths were only used 50% of the time.
However, at least some of the described embodiments provide for use the LPTX path and RX path all the time except for when the paths are switching. This allows for a reduction of the LPTX, RX and corresponding FPGA resources by half, while still maintaining the same amount of data throughput. The described embodiments include connecting one LPTX and a corresponding RX path to two antenna modules (that include PAs (power amplifiers, and LNAs (low-noise amplifiers) through a SPDT (single pole, double throw) switch which can switch between the two antenna modules depending on which antenna of a plurality of antennas is transmitting or receiving.
Since in this case the uplink and downlink are utilized 50% of the time each, the LPTX/RX and FPGA resources can be reduced by half without any reduction in system throughput. At least some embodiments include an asymmetric flow for uplink and downlink data transmission. That is, for example, the downlink (RRU transmitting) may have more data transmission needs or requirements than the uplink (RRU receiving). For an embodiment, downlink and uplink transmission of users are allocated time slots for uplink and downlink transmission as needed. Using the described embodiments, for a TDD system with the 20% Uplink and 80% downlink, the uplink resources can be reduced by one fifth (⅕) and downlink resources can be reduced by four fifth (⅘) as compared to traditional TDD systems.
Traditional cellular, or Radio Access Networks (RAN), consist of many stand-alone base stations (BTS). For 3G (third generation of wireless mobile telecommunications technology), a distributed base station architecture was introduced by leading telecom equipment vendors. In this architecture the radio function unit, also known as the remote radio unit (RRU), is separated from the digital function unit, or baseband unit (BBU) by fiber. Digital baseband signals are carried over fiber, using the Open Base Station Architecture Initiative (OBSAI) or Common Public Radio Interface (CPRI) standard. The RRU can be installed on the top of tower close to the antenna, reducing the loss compared to the traditional base station where the RF signal has to travel through a long cable from the base station cabinet to the antenna at the top of the tower. The fiber link between RRH and BBU also allows more flexibility in network planning and deployment as they can be placed a few hundreds of meters or a few kilometers away. Most modern base stations now use this decoupled architecture.
A C-RAN (Cloud Radio Access Network) is made of a baseband unit (BBU), a remote radio unit (RRU), and a transport network that is also called a fronthaul. The BBU is a pool of centralized resources that function as a cloud or data center. The Remote Radio Unit (RRU) transmits RF signals and is connected to the Baseband Unit (BBU) through optical fibers. With advanced RF and antenna technologies, the RRU enables high-rate and low-latency data processing and significantly enhances eNodeB (3GPP's term for an LTE femtocell or Small Cell) capacity.
For an embodiment, the RRU 200 further includes a first antenna module 240 and a second antenna module 242. The first antenna module 240 and the second antenna module 242 operate as interfaces between the plurality of antennas A1, A2 and the transmit switch 221 and the receive switch 224.
For an embodiment, the first antenna module 240 includes a circulator 252 configured to couple a first transmit signal of the transmit switch 221 to a first antenna A1 of the plurality of antennas A1, A2, and couple a first received signal of the first antenna A1 of the plurality of antennas A1, A2 to a first module switch 251. For an embodiment, the first module switch 251 is configured to connect an input to the first module switch 251 to a matched impedance (shown as 50Ω) during a first period of time (t1 in
For an embodiment, the second antenna module includes a second circulator 254 configured to couple a second transmit signal of the transmit switch 221 to a second antenna A2 of the plurality of antennas A1, A2, and couple a second received signal of the second antenna A2 of the plurality of antennas A1, A2 to a second module switch 253. For an embodiment, the second module switch 253 is configured to connect an input to the second module switch 253 to a matched impedance (shown as 50Ω) during the second period of time (t2 in
As shown in
As shown in
For an embodiment, the first transmit switch 425 of the plurality of transmit switches 425, 426 operates (or is configured to) to connect a first band (B1(Tx)) of the multiple transmission frequency bands (B1(Tx), B2(Tx)) to a first transmitter chain (which feeds or is connected to antenna A1B1) of the plurality of transmitter chains or connect the first band (B1(Tx)) of the multiple transmission frequency bands (B1(Tx), B2(Tx)) to a third transmitter chain (which feeds or is connected to antenna A3B1) of the plurality of transmitter chains.
For an embodiment, the second transmit switch 426 of the plurality of transmit switches 425, 426 operates (or is configured to) to connect a second band (B2(Tx)) of the multiple transmission frequency bands (B1(Tx), B2(Tx)) to a second transmitter chain (which feeds or is connected to antenna A2B2) of the plurality of transmitter chains or connect the second band (B2(Tx)) of the multiple transmission frequency bands (B1(Tx), B2(Tx)) to a fourth transmitter chain (which feeds or is connected to antenna A4B2) of the plurality of transmitter chains.
Again, while only two transmit frequency bands (B1(Tx), B2(Tx)) are shown in
The embodiment of
For an embodiment, the first receiver switch 427 of the plurality of receiver switches 427, 428 operates to connect a first band (B1(Rx) of the multiple receiver frequency bands (B1(Rx, B2(Rx)) from a first receive chain (which fed by or is connected to antenna A1B1) of the plurality of receiver chains associated (that is, corresponds with) with the first transmitter chain or connects the first band (B1(Rx) of the multiple transmission frequency bands (B1(Rx, B2(Rx)) from a third receiver chain (which fed by or is connected to antenna A3B1) of the plurality of receiver chains associated with the third transmitter chain to the receive multiplexer 422.
For an embodiment, the second receiver switch 428 of the plurality of receiver switches 427, 428 operates to connect a second band (B2(Rx) of the multiple receiver frequency bands (B1(Rx, B2(Rx)) from a second receiver chain (which fed by or is connected to antenna A2B2) of the plurality of receiver chains associated with the second transmitter chain or connect the second band (B2(Rx) of the multiple receive frequency bands (B1(Rx, B2(Rx)) from a fourth receiver chain (which fed by or is connected to antenna A4B2) of the plurality of receiver chains associated with the fourth transmitter chain to the receive multiplexer 422.
Again, while only two receive frequency bands (B1(Rx), B2(Rx)) are shown in
For an embodiment, a first antenna module 490 includes a first circulator 492 configured to couple a first transmit signal B1Tx(t1) of the first transmit switch 425 to the first antenna A1B1 of the plurality of antennas, and couple a first receive signal B1Rx(t2) of the first antenna A1B1 of the plurality of antennas to the first receive switch 427 through a first module switch 455. Further, for at least some embodiments, the first module switch 455 is configured to connect an input (an output of the circulator 492) to the first module switch 455 to a matched impedance (designated as 50Ω) during a first period of time (designated as t1 in
For an embodiment, a second antenna module 491 includes a second circulator 493 configured to couple a second transmit signal B1Tx(t2) of the first transmit switch 425 to a second antenna (A3B1) of the plurality of antennas, and couple a second receive signal B1Rx(t1) of the second antenna A3B1 of the plurality of antennas to the first receive switch 427 through a second module switch 457. Further, for at least some embodiments, the second module switch 457 is configured to connect an input to the second module switch to a matched impedance (designated as 50Ω) during the second period of time (designated as t2 in
The second transmit switch 426 and the second receive switch 428 operate in a similar fashion as described for the first transmit switch 425 and the first receive switch 427. The second transmit switch 426 and the second receive switch 428 are controllably operated with antenna modules associated with the antennas A2B2, A4B2, wherein the antenna modules associated with antennas A2B2, A4B2 include circulators 494, 495 and module switches 456, 458.
As shown, the first and second transmit switches 425, 427, and first and second receive switches 426, 428 are controlled by C1, C2, C3, C4. Further, module switches 455, 456, 457, 458 are controlled by C5, C6, C7, C8. Timing of the controls C1, C2, C3, C4, C5, C6, C7, C8 are shown in
For the receive diplexer 422, only individual band signals (B1, B2 (Rx)) are input at the respective band ports (Port2 & Port3) and the combined multi-band signal is obtained at the common port (Port1)
For at least some embodiments, the N-plexers are (N+1) port device that have a common port (Port1) and multiple different frequency ports (Port2, Port3 . . . Port(N+1)). The multiplexer is bi-directional device and can be used in both transmission and reception of wireless signals.
For the transmit N-plexers, a combined multiple band signal (B1, B2, . . . BN) in the frequency domain is input at the common port (Port1) and only the respective/individual band signals (B1, B2, . . . BN) are obtained separately at the output of the multiplexer (Port2, Port3 . . . Port(N+1)). The amount of rejection and fidelity between the bands depends on the design quality of the diplexer and the requirements. At the common port, since the desired signal is multi-band, the input return loss of this port must be good over the combined range of the multi-band signal (B1, B2, . . . BN). Similarly, at the individual ports the return loss must be good over the respective frequency bands.
For the receive N-plexers, only individual band signals (B1, B2, . . . BN) are input at the respective band ports (Port2, Port3 . . . Port(N+1)) and the combined multi-band signal (B1, B2, . . . BN) is obtained at the common port (Port1).
As shown and as will be described, the embodiment of
For at least some embodiments, the first transmit switch 425 is controlled by C1 to connect the first transmit signal (B1(Tx) at t1) to the first antenna A1B1 through the first antenna module 490 during the first period (t1), and configured to connect the second transmit signal (B1(T(x) at time t2) to the second antenna A3B1 through the second antenna module 491 during the second period (t2). That is, during the first time periods (t1) the first transmit switch is controlled by C1 to connect B1(Tx) to antenna A1B1, and during the second time periods (t2) the first transmit switch 425 is controlled by C1 to connect B1(Tx) to antenna A3B1.
Further, for at least some embodiments, the first receive switch 427 is controlled by C3 to connect the first receive signal (B1(Rx at t1) of the second module 491 to the RFSOC 430 to during the first period (t1), and configured to connect the second received signal (B1(Rx) at t2) of the first antenna module 490 to the RFSOC 430 during the second period (t2).
Further, for at least some embodiments, the second transmit switch 426 is controlled by C2 to connect a third transmit signal (B2(Tx) at t1) to a third antenna A2B3 through a third antenna module (not shown) during the first period (t1), and configured to connect a fourth transmit signal (B2(T(x) at time t2) to a fourth antenna A4B2 through a fourth antenna module (not shown) during the second period (t2). That is, during the first time periods (t1) the second transmit switch 426 is controlled by C2 to connect B2(Tx) to antenna A2B2, and during the second time periods (t2) the second transmit switch 426 is controlled by C2 to connect B2(Tx) to antenna A4B2.
Further, for at least some embodiments, the second receive switch 428 is controlled by C4 to connect a third receive signal (B2(Rx at t1) of the third module to the RFSOC 430 to during the first period (t1), and configured to connect a fourth received signal (B2(Rx) at t2) of the third antenna module to the RFSOC 430 during the second period (t2).
As shown, the module switches 455, 456, 457, 458 are controlled by C5, C6, C7, C8, wherein the control is synchronized with the control of the transmit switches 425, 426 and the receive switches 427, 428. For an embodiment, the module switch 455 of the first antenna module 490 is controlled by C5 to connect the output of the module switch 455 to a matched impedance (shown as 50Ω) during the first period t1. That is, the transmit switch 425 is controlled by C1 to connect the first transmit signal (B1(Tx) at t1) to the first antenna A1B1 through the first antenna module 490 during the first period (t1). Accordingly, the first antenna A1B1 is transmitting the first transmit signal (B1(Tx) at t1), and the output of the circulator 492 is connected to the matched impedance. For an embodiment, the module switch 455 of the first antenna module 490 is controlled by C1 to connect the output of the module switch 455 to the receive switch 427 during the second periods of time. That is, the first receive switch 427 is controlled by C3 to connect the second received signal (B1(Rx) at t2) of the first antenna module 490 to the RFSOC 430 during the second periods (t2). Accordingly, the first antenna A1B1 is receiving the second received signal (B1(Rx) at t2), and the output of the circulator 492 should be connected to the receive switch 427.
For an embodiment, the module switch 457 of the second antenna module 491 is controlled to connect the output of the module switch 457 to the receive switch 427 during the first periods of time. That is, the first receive switch 427 is controlled by C3 to connect the received signal (B1(Rx) at t1) of the third antenna module 491 to the RFSOC 430 during the first periods (t1). Accordingly, the first antenna A3B1 is receiving the received signal (B1(Rx) at t1), and the output of the circulator 493 should be connected to the receive switch 427. For an embodiment, the module switch 457 of the second antenna module 490 is controlled by C7 to connect the output of the module switch 457 to a matched impedance (shown as 50Ω) during the second periods t2. That is, the transmit switch 427 is controlled by C3 to connect the second transmit signal (B1(Tx) at t2) to the second antenna A3B1 through the second antenna module 491 during the second period (t2). Accordingly, the second antenna A3B2 is transmitting the second transmit signal (B1(Tx) at t2), and the output of the circulator 493 should be connected to the matched impedance.
For this embodiment, the transmit switch 825 controls the 75% timing distribution of the output of the RFSOC 830 to antenna A1, and the 25% timing distribution to antenna A3 through secondary transmit switch 828. The transmit switch 826 controls the 75% timing distribution of the output of the RFSOC 830 to antenna A2, and the 25% timing distribution to antenna A3 through the secondary transmit switch 828. The transmit switch 827 controls the 75% timing distribution of the output of the RFSOC 830 to antenna A4, and the 25% timing distribution to antenna A3 through the secondary transmit switch 828.
The receive switch 829 receives the received signals from the antennas A1, A2, A3, A4 at a time duration of 25% each. The antennas A1, A2, A3, A4 are operative to transmit 75% of the time, and receive wireless signals that are each coupled to the receive switch 829 25% of the time. The antennas A1, A2, A3, A4 are operative to transmit 75% of the time, and receive wireless signals that are each coupled to the receive switch 829 25% of the time. The outputs of the receive switch 829 is connected to the RFSOC 830 over a single line.
The control C4 controls the output of receive switch 829 being connected to receive from the antenna A1 for 1 out of four time periods, receive from the antenna A2 for 1 out of four time periods, receive from the antenna A3 for 1 out of four time periods, or receive from the antenna A4 for one out of four time periods.
The controls C5, C6, C7, C8 are controlled to connect the outputs of the module switches 855, 856, 857, 858 to the matched impedance (50Ω) while the antenna associated with each module switch is transmitting, connect the outputs of the module switches 855, 856, 857, 858 to the receive switch 829 while the antenna associated with each module switch is receiving.
The control C9 controls the secondary transmit switch 828 to connect a one of the transmit switches 825, 826, 827 to the antenna A3 a needed to maintain continuous transmission through the transmit switches 825, 826, 827.
The block diagram of
As shown, a second transmit multiplexer 1022 receives through a single line a band 1 (B1) signal with 75% of the time dedicated to antenna A2B1 and 25% of the time dedicated antenna A3B1, and a band 2 (B2) signal with 75% of the time dedicated to antenna A2B2 and 25% of the time dedicated antenna A3B2. The transmit diplexer 1021 generates the B1 signal for antennas A2B1 and A3B1, and generates the B2 signal for antenna A2B2 and A3B2.
As shown, a third transmit multiplexer 1023 receives through a single line a band 1 (B1) signal with 75% of the time dedicated to antenna A4B1 and 25% of the time dedicated antenna A3B1, and a band 2 (B2) signal with 75% of the time dedicated to antenna A4B2 and 25% of the time dedicated antenna A3B2. The transmit diplexer 1021 generates the B1 signal for antennas A4B1 and A3B1, and generates the B2 signal for antenna A4B2 and A3B2.
The block diagram of
The transmit switch 1025B receives the Band 2 (B2) output of the first transmit diplexer 1021, and controls the 75% timing distribution of the output of the Band 2 (B2) output of the first transmit diplexer 1021 to antenna A1B2 through the antenna module 1095B, and the 25% timing distribution to antenna A3B2 through secondary transmit switch 1028B and through the antenna module 1097B. The transmit switch 1026B receives the Band 2 (B2) output of the second transmit diplexer 1022, and controls the 75% timing distribution of the output of the Band 2 (B2) output of the second transmit diplexer 1022 to antenna A2B2 through the antenna module 1096B, and the 25% timing distribution to antenna A3B2 through the secondary transmit switch 1028B and through the antenna module 1097B. The transmit switch 1027B receives the Band 2 (B2) output of the third transmit diplexer 1023, and controls the 75% timing distribution of the output of the Band 2 (B2) output of the third transmit diplexer 1023 to antenna A4B2 through the antenna module 1098B, and the 25% timing distribution to antenna A3B2 through the secondary transmit switch 1028B and through the antenna module 1097B.
The block diagram of
The outputs of the receive switches 1029A, 1029B are connected to the receive multiplexer 1024 which provides the signals received over the two bands (B1, B2) to the RFSOC 1030 over a single line.
While the RRU of
An embodiment further includes coupling, by a circulator of a first antenna module, a first transmit signal of the transmit switch to a first antenna of the plurality of antennas, and coupling, by the circulator, a first received signal of the first antenna of the plurality of antennas to a first module switch. Further the first module switch connects an input to the first module switch to a matched impedance during a first period of time, and connecting, by the first module switch, the first received signal of the first antenna of the plurality of antennas to the receive switch during a second period of time.
An embodiment further includes coupling, by a second circulator of a second antenna module, a second transmit signal of the transmit switch to a second antenna of the plurality of antennas, and coupling, by the second circulator, a second received signal of the second antenna of the plurality of antennas to a receive switch. Further, the second module switch connects an input to the second module switch to a matched impedance during the second period of time, and connecting, by the second module switch, the second received signal of the second antenna of the plurality of antennas to the receive switch during the first period of time.
For at least some embodiments, the transmit switch is configured to connect the first transmit signal to the first antenna through the first antenna module during the first period, and configured to connect the second transmit signal to the second antenna through the second antenna module during the second period. For at least some embodiments, the receive switch is configured to connect the first received signal of the second module to the RFSOC to during the first period, and configured to connect the second received signal of the first antenna module to the RFSOC during the second period.
For an embodiment, a plurality of transmit switches include the transmit switch, and a plurality of receive switches include the receive switch. Further the method includes receiving, by each of one or more transmit multiplexers, transmit signals from the RFSOC through a single transmit line, and generating by each of the one or more transmit multiplexers, transmit signals for a sub-plurality of the transmitter switches through multiple transmit lines, wherein the transmit signals include multiple transmission frequency band, and receiving, by each of one or more receive multiplexers, received signals from a sub-plurality of the receiver switches through multiple receive lines, and providing, by each of one or more receive multiplexers, the received signals to the RFSOC through a single receive line, wherein the receive signals include multiple receive frequency bands.
As previously described, for an embodiment, the system includes more transmit multiplexers than receive multiplexers when the system is configured to transmit wireless communication a majority of time, and wherein the system includes more receive multiplexers than transmit multiplexers when the system is configured to receive wireless communication a majority of time.
As previously described, for an embodiment, the RFSOC is operable at a high enough frequency to process the transmit signals having the multiple frequency bands and the receive signals having the multiple frequency bands. As previously described, for an embodiment, a one of the transmitter switches operates to transmit a wireless signal through one of the multiple transmission frequency band simultaneous with a one of the receiver switches operating to receive a wireless signal through one of the multiple receive frequency bands.
Although specific embodiments have been described and illustrated, the embodiments are not to be limited to the specific forms or arrangements of parts so described and illustrated. The described embodiments are to only be limited by the claims.