Patent Application
20240283470
Embodiments presented herein relate to a filter unit for wideband multicarrier time-division duplexing operation and to a radio transceiver device comprising such a filter unit.
In general terms, in a multicarrier communication system several input carrier signals can be combined into one multicarrier signal output. Commonly this combining is performed at the transmitting side of a communication system. Devices that are configured to perform this combining are commonly called Radio Frequency (RF) combiners or Output Multiplexers (OMUX). On the receiving side of the communication system, the reverse operations are performed. One multicarrier signal is split into several single carrier signals. This is commonly referred to as channelization. Devices that perform this channelization are commonly called RF channelizers or Input Multiplexers (IMUX) or demultiplexers. A common term for entities configured for both the combining and the channelization is a multiplexer (MUX).
For small power (mW) applications there are several technologies already available for multiplexing (such as surface-acoustic-wave (SAW) processing, Low Temperature Co-Fired Ceramic (LTCC) filters, printed circuit boards (PCB)). For higher power applications where the output power from the power amplifier (PA) that is input to the multiplexer is on order of 1 W to ca 20 W, the multiplexer has to have the possibility to handle these power levels and in addition needs to have low losses to account for, thermal effect, to be compact and to have Passive Intermodulation (PIM) stability.
Multiplexers can be designed to handle contiguous multicarrier signals (typically in satellite communication) or noncontiguous multicarrier signals (typically in mobile communication systems).
There are different ways to realize, or implement, multiplexers, with each approach suitable for certain application areas.
Whilst
A multiband radio communication system is described in U.S. Pat. No. 10,027,006 B2. Both FDD and TDD systems can be transmitted simultaneously. Band of operation is selected by switches.
Existing multiplexers and multiplexing networks are usually limited to several separated frequency bands combined to one output. During the design phase, the network response is controlled and optimized to the frequency bands of use. Parameters such as return loss (RL) and insertion loss (IL) are optimized for selected passbands. The bandwidth of the multiplexers is usually limited by the bandwidths of components used. For hybrid multiplexers, the bandwidth of hybrids determines the multiplexer bandwidth. Similarly, for the circulator, multiplexers concept, the bandwidth of the circulators limits the multiplexer bandwidth. Existing multiplexers, due to limited bandwidths of the single components, are therefore not possible to use in ultrawideband systems. For high power levels, for example as used in mobile base stations such as in transmission and reception points (TRPs), the realizations are lossy and therefore multiplexing is not possible to use. For chain type multiplexers, the loss increases for channels that are at the end of a chain (e.g. hybrid, circulator, or directional filter).
Further, the performance of the multiplexer outside the passbands is not optimized and depends on the type of realization used. Reflective filters have full reflection for frequencies outside of the band. Due to RLs and insertion losses (ILs) this parameter is below zero in practical realizations. Star-type multiplexers have low insertion losses (ILs) but are more difficult to design and realize since all the filters need to be tuned together. In addition, connecting several filters to one point can be challenging when the number of channels increases.
For ultrawideband systems where the wideband PA together with a digital pre-distorter (DPD) and/or feed forward are used, the performance of the filter network for the whole ultrawideband frequency of operation is important, especially the RL within and outside the frequency bands of operation. The high level of returned power can degrade radio performance and in the worst case destroy ultrawideband PA. At the same time the passbands transmission losses of a multiplexing network shall be kept to as low as possible.
One solution to the above is to provide an ultrawideband low-loss isolator in the signal path after the PA. Unfortunately, such isolators are currently not yet available.
Hence, there is still a need for an improved multiplexer for wideband multicarrier TDD operation.
An object of embodiments herein is to provide a filter unit for wideband multicarrier TDD operation that addresses the above issues.
According to a first aspect there is presented a filter unit for wideband multicarrier TDD operation. The filter unit comprises a transmission multiplexer (MXT), at least one circulator, and a filter bank. The MXT and the filter bank are connected via the at least one circulator. The MXT is configured to receive a transmission (TX) wideband multicarrier signal as provided by at least one PA, and to provide a first bandpass (BP) filtered TX wideband multicarrier signal to the at least one circulator. The MXT comprises at least one first BP filter structure for first BP filtering of the TX wideband multicarrier signal. The at least one circulator is configured to receive the first BP filtered TX wideband multicarrier signal from the MXT and provide the first BP filtered TX wideband multicarrier signal to the filter bank. The filter bank is configured to receive the first BP filtered TX wideband multicarrier signal from the at least one circulator, and to provide a second BP filtered TX wideband multicarrier signal towards an antenna port. The filter bank comprises at least as many second BP filter structures as there are first BP filter structures for second BP filtering of the first BP filtered TX wideband multicarrier signal to provide the second BP filtered TX wideband multicarrier signal.
According to a second aspect there is presented a radio transceiver device. The radio transceiver device comprises a filter unit according to the first aspect.
Advantageously, the filter unit and the radio transceiver device do not suffer from the above issues.
Advantageously, the filter unit and the radio transceiver device enable the use of wideband PAs for multicarrier ultrawideband systems.
Advantageously, the filter unit and the radio transceiver device result in low RL across the whole ultrawideband frequency band (within and in-between the passbands).
Advantageously, the filter unit and the radio transceiver device result in low IL for the multiplexer.
Advantageously, standard existing isolators (as well as customized) can be used in the filter unit and the radio transceiver device.
Advantageously, the filter unit and the radio transceiver device do not require filters that are in different multiplexer channels to be tuned/designed or/and manufactured together.
Advantageously, the filter unit and the radio transceiver device can be used in high-power applications.
Advantageously, all frequency dependent elements such as filters, multiplexers, circulators/isolators, LNA can be grouped into one independent filter unit.
Advantageously, the radio transceiver device only need to exchange, or update, the filter unit when changing operating frequency band combination.
Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, module, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:
The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.
As noted above there is still a need for an improved multiplexer for wideband multicarrier TDD operation.
The embodiments disclosed herein therefore relate to a filter unit for wideband multicarrier TDD operation and a radio transceiver device comprising such a filter unit 300.
Reference is now made to
The MXT 310 is configured to receive a TX wideband multicarrier signal as provided by at least one PA 400. The MXT 310 is configured to provide a first BP filtered TX wideband multicarrier signal to the at least one circulator 320. The MXT 310 comprises at least one first BP filter structure 311 for first BP filtering of the TX wideband multicarrier signal.
The at least one circulator 320 is configured to receive the first BP filtered TX wideband multicarrier signal from the MXT 310. The at least one circulator 320 is configured to provide the first BP filtered TX wideband multicarrier signal to the filter bank 330.
The filter bank 330 is configured to receive the first BP filtered TX wideband multicarrier signal from the at least one circulator 320. The filter bank 330 is configured to provide a second BP filtered TX wideband multicarrier signal towards an antenna port 380. The filter bank 330 comprises at least as many second BP filter structures 331 as there are first BP filter structures 311 for second BP filtering of the first BP filtered TX wideband multicarrier signal to provide the second BP filtered TX wideband multicarrier signal.
The TX wideband signal is thus divided at the MXT input into selected multiplexer channels. Each channel can have one or more carriers that are close to each other. A multiplexer channel can cover one or more LTE (3GPP) bands. After each MTX channel the TX wideband signal is passed to a corresponding circulator 320 that will have at least the same bandwidth as each MTX channel. The isolator performance is optimized for the multiplexer channel bandwidth, and not for a single frequency band.
Embodiments relating to further details of the filter unit 300 will now be disclosed.
As noted above, the filter bank 330 comprises at least as many second BP filter structures 331 as there are first BP filter structures 311 for second BP filtering of the first BP filtered TX wideband multicarrier signal to provide the second BP filtered TX wideband multicarrier signal. In some embodiments, the filter bank 330 comprises one more second BP filter structures 331 than there are first BP filter structures 311.
Aspects of the first BP filter structure 311 in the MXT 310 will now be disclosed. In some embodiments, the filter unit 300 further comprises an input port 370. Each of the at least one first BP filter structure 311 defines a respective first multiplexer channel. Each of the at least one first BP filter structure 311 is configured to, via the input port 370, receive the TX wideband multicarrier signal from the at least one PA 400. Each of the at least one first BP filter structure 311 is configured to BP filter the TX wideband multicarrier signal so as to provide the first BP filtered TX wideband multicarrier signal to the at least one circulator 320.
Aspects of the at least one circulator 320 will now be disclosed. In some embodiments, there are as many circulators 320 as there are first BP filter structures 311. Each circulator 320 has a bandwidth being at least same as a bandwidth of the first multiplexer channel of the BP filter from which it receives the first BP filtered TX wideband multicarrier signal.
Aspects of the second BP filter structure 331 in the filter bank 330 will now be disclosed. In some embodiments, each second BP filter structure 331 defines a respective second multiplexer channel. Each second BP filter structure 331 is configured to receive the first BP filtered TX wideband multicarrier signal from the circulator 320 to which it is connected. Each second BP filter structure 331 is configured for second BP filtering of the first BP filtered TX wideband multicarrier signal so as to provide the second BP filtered TX wideband multicarrier signal towards the antenna port 380.
Until now the filter unit 300 has been described in the context of transmission of a TX wideband multicarrier signal. Next will be disclosed details of how the filter unit 300 can be adapted for reception of an RX wideband multicarrier signal.
In some embodiments, the filter unit 300 further comprises an output port 390. The filter bank 330 is configured to receive an RX wideband multicarrier signal from the antenna port 380. The filter bank 330 is configured to provide a second BP filtered RX wideband multicarrier signal to the at least one circulator 320. The second BP filter structure 331 is configured for second BP filtering of the RX wideband multicarrier signal. The at least one circulator 320 is configured to receive the second BP filtered RX wideband multicarrier signal from the filter bank 330. The at least one circulator 320 is configured to provide the second BP filtered RX wideband multicarrier signal towards the output port 390.
As will be further disclosed next, the RX wideband multicarrier signal might be passed through a low noise amplifier (LNA) 360 and a reception multiplexer (MXR) 350 before reaching the output port 390.
In some aspects there is one or more LNAs 360 between the at least one circulator 320 and the output port 390. Particularly, in some embodiments, the filter unit 300 further comprises at least as many LNAs 360 as there are circulators 320, wherein there is at least one LNA 360 connected between each of the at least one circulator 320 and the output port 390.
Aspects of the MXR 350 will now be disclosed. In some embodiments, the filter unit 300 further comprises an MXR 350. The MXR 350 is configured to receive the second BP filtered RX wideband multicarrier signal from the at least one circulator 320. The MXR 350 is configured to provide a third BP filtered RX wideband multicarrier signal to the output port 390. The MXR 350 comprises at least one third BP filter structure 351 for third BP filtering of the second BP filtered RX wideband multicarrier signal. Output of the MXR 350 is passed to the output port 390.
Aspects of the third BP filter structure 351 in the MXR 350 will now be disclosed. In some embodiments, each of the at least one third BP filter structure 351 defines a respective third multiplexer channel. Each of the at least one third BP filter structure 351 is configured to receive the second BP filtered RX wideband multicarrier signal from the at least one circulator 320. Each of the at least one third BP filter structure 351 is configured for third BP filtering of the second BP filtered RX wideband multicarrier signal so as to provide the third BP filtered RX wideband multicarrier signal to the output port 390.
In some aspects, the filter unit 300 further comprises switches 321 between the circulators 320 and the output port 390. In particular, in some embodiments, the filter unit 300 further comprises as many switches 321 as there are circulators 320. There is one switch 321 connected between each of the at least one circulator 320 and the output port 390 for selectively switching operation of the filter unit 300 between transmission of the TX wideband multicarrier signal and reception of the RX wideband multicarrier signal. When the switch 321 is in the position for transmission of the TX wideband multicarrier, the leg of the circulator 320 that otherwise is connected to the MXR 250 (via one or more LNAs 360) is terminated with a 50 Ohm match 322.
In some embodiments, such as illustrated in
In some embodiments, the filter unit 300 further comprises an antenna multiplexer (MXA) 340. The MXA 340 is connected between the filter bank 330 and the antenna port 380.
Aspects of the MXA 340 in the context of transmission of a TX wideband multicarrier signal will now be disclosed. In some embodiments, the MXA 340 is configured to obtain the second BP filtered TX wideband multicarrier signal. The MXA 340 is configured to provide a third BP filtered TX wideband multicarrier signal to the antenna port 380. The MXA 340 comprises as many fourth BP filter structures 341 as there are first BP filter structures 311 for third BP filtering of the second BP filtered TX wideband multicarrier signal to provide the third BP filtered TX wideband multicarrier signal. Thus, from the circulators 320 the TX wideband multicarrier signal can be transferred to single or multiband standard duplex filters. All outputs of the duplex filters feed the MXA 340 that combines all signals to one antenna port 380.
Aspects of the MXA 340 in the context of reception of an RX wideband multicarrier signal will now be disclosed. In some embodiments, the MXA 340 is configured to receive the RX wideband multicarrier signal from the antenna port 380. The MXA 340 is configured to provide a first BP filtered RX wideband multicarrier signal to the filter bank 330. The fourth BP filter structure 341 is configured for first BP filtering of the RX wideband multicarrier signal. For RX wideband multicarrier signals the input from the output port 390 is thus distributed to bandpass filters using the MXA 340. The RX wideband multicarrier signals are next passed to LNAs 360 and combined in the MXR 350.
Aspects of the fourth BP filter structure 341 in the MXA 340 will now be disclosed. In some embodiments, each fourth BP filter structure 341 has a passband matched to a passband of a respective one of the at least one first BP filter structures 311. In general terms, the passband of the fourth BP filter structure 341 can be wider or narrower than the passband of the first BP filter structure 311.
In some embodiments, each of the fourth BP filter structure 341 defines a respective fourth multiplexer channel.
One example realization of the thus far described filter unit 300 are illustrated in
The MXT 310 comprises two first BP filter structures 311-1, 311-2, each composed of a single BP filter, each configured to receive a TX wideband multicarrier signal from the input port 370, and each configured to provide first BP filtered TX wideband multicarrier signals, one to each of the two circulators 320-1, 320-2. The MXT 310 thus provides two channels; a high band channel and a low band channel. Each channel is connected to corresponding circulator 320-1, 320-2.
The filter bank 330 comprises two second BP filter structure 331-1, 331-2. For transmission, each of the two second BP filter structures 331-1, 331-2 is configured to receive a signal from a respective one of the two circulators 320 and to provide two second BP filtered TX wideband multicarrier signals to the MXA 340. For reception, each of the two second BP filter structures 331-1, 331-2 is configured to receive a signal from the MXA 340 and to provide a respective second BP filtered RX wideband multicarrier signals to a respective one of the two circulators 320-1, 320-2. One of the two second BP filter structures 331-1 is composed of two BP filters, whereas the other of the two second BP filter structures 331-2 is composed of a single BP filter. For the high band channel, the filter bank 330 thus applies BP filtering in terms of a double band filter, whereas for the low band channel, the filter bank 330 thus applies BP filtering in terms of a single band filter.
The MXA 340 comprises two third BP filter structures 341-1, 341-2. For transmission, each of the two BP filter structures 341-1, 341-2 is configured to receive a signal from a respective one of the two second BP filter structures 331-1, 331-2 and to provide two third BP filtered TX wideband multicarrier signals to the antenna port 380. For reception, each of the two third BP filter structures 341-1, 341-2 is configured to receive a signal from the antenna port 380 and to provide a respective second BP filtered RX wideband multicarrier signals to respective one of the two second BP filter structures 331-1, 331-2. Signals from both the high band channel and the low band channel are thus combined in the MXA 340 and then provided to a wideband antenna via the antenna port 380.
The MXR 350 comprises two fourth BP filter structures 351-1, 351-2, each composed of a single BP filter; one for the high band channel and another for the low band channel. Each of the fourth BP filter structures 351-1, 351-2 is configured to receive a second BP filtered TX wideband multicarrier signal from one of the circulators 320 via a respective LNA 360. Each of the two BP filter structures 351-1, 351-2 is configured to provide a third BP filtered RX wideband multicarrier signal to the output port 390. RX signals from the antenna are thus pass through the MXA 340, the filter bank 330, via the circulators 320-2, 320-2 and the switches 321-1, 321-2 to the corresponding LNA 360 before reaching the MXR 350. The output from both LNAs 360 are combined in the MRX 350 and provided to the output port 390.
Aspects common for the BP filter structures 311, 331, 341, 351 will now be disclosed. It is however noted that these aspects might apply to a single one of the BP filter structures 311, 331, 341, 351, to two of the BP filter structures 311, 331, 341, 351, to three of the BP filter structures 311, 331, 341, 351, or to all of the BP filter structures 311, 331, 341, 351.
In some aspects, the BP structure for one channel is defined by one BP filter in combination with one LP filter and one HP filter for termination. In particular, in some embodiments, at least one of the BP filter structures 311, 331, 341, 351 is composed of a single BP filter, a terminating LP filter, and a terminating HP filter.
In some aspects, the BP structure for one channel is defined by one BP filter in combination with one LP filter and one HP filter for termination. In particular, in some embodiments, at least one of the BP filter structures 311, 331, 341, 351 is composed of a single BP filter, a non-terminating LP filter, a non-terminating HP filter, a terminating LP filter, and a terminating HP filter. In an example of this embodiment the MXT 310 is realized as a two-layer structure. Outputs from a first LP filter and a first HP filter are terminated with a 50 Ohm match whereas the output of the BP is split to be connected to a second LP filter and a second HP filter. The outputs from the second LP filter and the second HP filter forms two multiplexer channels. Frequencies outside the multiplexer channels are thereby terminated in a low RL load such that the MXT 310 fulfils wideband low RL requirements.
In some aspects, the BP structure for one or two channels is defined by a combination of HP filters and LP filters. In particular, in some embodiments, at least one of the BP filter structures 311, 331, 341, 351 is composed of a non-terminating LP filter, a non-terminating HP filter, a terminating LP filter, and a terminating HP filter.
In general terms, with respect to the examples in
Further aspects of the BP filter structures 311, 331, 341, 351 and their relation to LTE frequency bands will now be disclosed. It is here noted that the BP filter structures 311, 331, 341, 351 might alternatively be designed to cover also other frequency bands than those listed below.
In some examples, there are at least three first BP filter structures 311 defining as many first multiplexer channels, each covering its own one or more LTE frequency band. In some examples, there are three first multiplexer channels covering LTE frequency bands B41H, B43C and B79B, respectively.
In some examples, there are at least three second BP filter structures 331 defining as many second multiplexer channels, each covering its own one or more LTE frequency band. In some examples, there are three second multiplexer channels covering LTE frequency bands B41H, B43C and B79B, respectively.
In some examples, there are at least three third BP filter structures 351 defining as many third multiplexer channels, each covering its own one or more LTE frequency band. In some examples, there are three third multiplexer channels covering LTE frequency bands B41H, B43C, B79B, respectively.
In some examples, there are at least three fourth BP filter structures 341 defining as many fourth multiplexer channels, each covering its own one or more LTE frequency band. In some examples, there are three third multiplexer channels covering LTE frequency bands B41H, B43C, B79B, respectively.
In some aspects the filter unit 300 is provided as a standalone device, or entity. In other aspects the filter unit 300 is provided in, collocated with, or functionally and/or physically integrated with another unit, device, or entity. In particular, in some embodiments, the filter unit 300 is part of a radio transceiver device. Such a radio transceiver device might comprise at least one filter unit 300 as herein disclosed, at least one PA 400 and the antenna port 380.
Particularly, the processing circuitry 610 is configured to cause the radio transceiver device 600 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 630 may store the set of operations, and the processing circuitry 61o may be configured to retrieve the set of operations from the storage medium 630 to cause the radio transceiver device 600 to perform the set of operations. The set of operations may be provided as a set of executable instructions.
Thus the processing circuitry 61o is thereby arranged to execute methods as herein disclosed. The storage medium 630 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The radio transceiver device 600 may further comprise a communications interface 620 at least configured for communications with other entities, functions, nodes, and devices. As such the communications interface 620 may comprise one or more transmitters and receivers, comprising analogue and digital components. Particularly, the communications interface 620 might comprise at least one filer unit 300 as herein disclosed.
The processing circuitry 61o controls the general operation of the radio transceiver device 600 e.g. by sending data and control signals to the communications interface 620 and the storage medium 630, by receiving data and reports from the communications interface 620, and by retrieving data and instructions from the storage medium 630. Other components, as well as the related functionality, of the radio transceiver device 600 are omitted in order not to obscure the concepts presented herein.
The radio transceiver device 600 might be provided in, collocated with, or functionally and/or physically integrated with another unit, device, or entity, such as any of a (radio) access network node, radio base station, base transceiver station, Node B (NB), evolved Node B (eNB), gNBs, access point, access node, and integrated access and backhaul node, or even a user equipment.
In the example of
The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2021/050573 | 6/14/2021 | WO |
