Front-end architecture of multiband radio

A multiband radio (108) is presented that includes front-end architecture that can produce a substantial size/weight/cost reduction on the necessary air cavity multiband receive filter design of existing multiband radio (108)s. In particular, the disclosure presents a multiband radio (108) configured to filter a set of sub-bands of a multiband uplink signal. In an aspect, the multiband radio (108) includes one or more wideband filters (206) configured to filter any group of two or more adjacent sub-bands in a frequency spectrum utilized by the multiband radio (108) for communication with one or more user equipment (UE). In addition, the multiband radio (108) includes a multiplexer (343, 542) configured to isolate each of the uplink sub-bands using separate filters (340, 540). Furthermore, the multiband radio (108) includes a plurality of single sub-band filters (410), each of the plurality of single sub-band filters (410) configured to filter a different isolated uplink sub-band in the frequency spectrum.

BACKGROUND

Existing 3G and 4G broadband wireless communication networks are widely deployed in the world. For new deployment or network upgrade, multiband base station radio gradually becomes wireless network operator's favorite choice. Moreover, there is a greater market demand for base station radios that utilize multiple inputs and multiple outputs (MIMO), such as 2T2R, 4T4R or 4T4R (where xTyR represents x transmitters and y receivers), than single-input and/or single-output radios (i.e., 1T1R, 1T2R devices). For the upcoming Fifth-Generation (5G) wireless network, substantially more complex MIMO configurations are proposed, such as 64T64R Active Antenna System (AAS) or 128T128R AAS.

Currently, the radios of wireless base stations (e.g., nodeBs, enhanced nodeBs (eNBs), etc.) transmit signals with a power that is much higher than the user equipment (UEs) they serve. As a result, the downlink (DL) and uplink (UL) front-end filters of these existing base stations must be designed by using high-Q and high-power-handling air cavity filter technology. These air cavity multiband transmit (TX) and receive (RX) filters are designed by using two band-combining circuits and individual single-band TX or RX filters. The air cavity multiband TX and RX filters are usually designed together and built in one unit, and normally the unit is referred to as an air cavity multiband duplexer.

Conventional radio frequency (RF) front-end filter architectures for the multiband RF radios utilizing these air cavity multiband duplexers find that these components hold a large share of the entire radio unit size, weight, and cost. For example, for a conventional dual-band radio, the size ratio of the air cavity dual-band duplexer to the entire radio is approximately 1:3. Exacerbating the feasibility problem for these components going forward is the fact that size of the radio is proportional to the number of sub-bands supported by a multiband radio

Therefore, an innovative design approach that enables a reduction of the size, weight, and cost of the necessary air cavity multiband duplexer is needed by those in the wireless network industry who deploy radio base station units.

SUMMARY

The present disclosure presents a wireless receiver having front-end multiband filter architecture that can produce a substantial size, weight, cost reduction on the necessary air cavity multiband receive filter design of multiband radios. Likewise, the disclosure describes example network nodes and radios that use the architecture, as well as methods performed by these devices.

For instance, described herein is an example multiband radio (and a network node as well as a wireless communication device containing the multiband radio) configured to filter a set of uplink sub-bands in a wireless communication system. In an aspect, the multiband radio includes one or more wideband filters, where each of the wideband filters are configured to filter any group of two or more adjacent sub-bands in a frequency spectrum utilized by the multiband radio for communication with a user equipment (UE). In addition, the multiband radio includes a multiplexer configured to isolate each of the adjacent uplink sub-bands bands using separate filters. Furthermore, the multiband radio includes a plurality of single sub-band filters, each of the plurality of single sub-band filters configured to filter a different isolated uplink sub-band in the frequency spectrum.

Moreover, the present disclosure contemplates an example method performed by a multiband radio for filtering a set of uplink sub-bands in a wireless communication system. The example method can include filtering, by a wideband filter, any group of two or more adjacent uplink sub-bands in a frequency spectrum utilized by the multiband radio for communication with a UE. Additionally, the example method can include isolating, by a multiplexer, each of the adjacent uplink sub-bands using separate filters. Furthermore, the example method can include filtering, by each of a plurality of single sub-band filters, a different isolated uplink sub-band in the frequency spectrum.

Further aspects of these example techniques, including related methods, devices, and computer programs, will be described further below and in reference to the following figures.

DETAILED DESCRIPTION

The present disclosure envisions a wireless receiver having front-end multiband filter architecture that uses one or more wideband uplink sub-band filters (i.e., a bandpass wideband filter that captures bandwidth that corresponds to two or more adjacent uplink sub-bands of a multiband signal) that can capture multiple adjacent receiver (RX) sub-bands in a system frequency spectrum. In addition, a small type multiplexor can be used to separate the individual uplink sub-bands, and one or more multiband notch filters can be used to suppress blocking signals that may occur between the adjacent uplink sub-bands to protect a following low noise amplifier (LNA). In this additional aspect of the filtering process, relatively small and inexpensive wideband filters can be used to filter multiple adjacent uplink sub-bands of the multiband signal in a single filtering process. The small type multiplexor and the multiband notch filters can be designed by using ceramics (i.e., ceramics-based) or Surface Acoustic Wave (SAW) filter, Bulk Acoustic Wave (BAW) filter, or Film Bulk Acoustic Resonator (FBAR) filter technologies, because they do not need to handle a high-power signal. Because ceramics filters are about 50 times smaller than air cavity filters, and the SAW, BAW, FBAR filters are about 10,000 times smaller, a significant volume, cost, and weight reduction can be obtained by utilizing the front-end architecture for the multiband radio described in the present disclosure.

The filtering approach described herein differs from those implemented by the legacy front-end receiver architectures described above, which use a much heavier and more expensive legacy air cavity filter for each captured sub-band. Thus, according to example embodiments, the filter architecture can split the uplink (also referred to herein as RX, as uplink is received from a network node perspective) signal filtering load into two parts: first filtering groups of adjacent RX sub-bands and any isolated RX sub-bands from the system frequency spectrum, and then, for any filtered sub-band groups, isolate individual sub-bands in the group using a small type multiplexor made of less expensive and lighter components that exhibit a smaller form-factor in radio implementations.

FIG. 1illustrates an example wireless communication system100that includes a UE102in communication with a network node106of an access network. In some instances, the UE102and the network node106can include multiple transmit and/or receive antennas and may be configured for MIMO communication. Accordingly, as shown in the figure, the network node106includes a multiband radio108that is configured to receive a multiband uplink signal116transmitted by one or more transmit antennas of UE102. The uplink signal116received by the network node106via the multiband radio108can include multiple sub-bands each defining a subset of the frequency across which the uplink signal116is carried. These sub-bands may or may not lie adjacent to one or more other uplink sub-bands in the frequency spectrum utilized for the communication between the UE102and the network node106. As the UE102and the network node106also communicate in the downlink direction via one or more downlink (or transmission, TX sub-bands from the perspective of the network node106) some isolated sub-bands detected by the multiband radio receiver circuit may be signals transmitted by another antenna of the multiband radio108contemporaneously with the received sub-bands. Thus, the multiband radio106can contain a multiband uplink signal filter assembly to filter the downlink (TX) sub-bands from the desired uplink sub-bands (RX). As introduced above and described in further detail below, embodiments of the multiband radio108and its receiver assembly can be configured to incorporate wideband RX filters206that filter any groups or sets of adjacent uplink sub-bands, as well as isolated RX sub-bands (i.e., single sub-bands whose adjacent sub-bands do not include another RX sub-band), from the system frequency spectrum. Once these isolated RX sub-bands and RX sub-band groups have been filtered, notch filters and a small type multiplexor, both of which can be manufactured using smaller and lighter materials compared to the air cavity filters described above, can further refine the resulting signal to eventually isolate the RX sub-bands inside of the multiband radio, for instance, of a network node106. In an aspect, as the network node106and UE102are configured to communicate wirelessly, these devices are also referred to generally as wireless communication devices.

FIG. 2illustrates a sub-band configuration where three uplink sub-bands RX1, RX2, and RXNare positioned at the center of the available channel spectrum, surrounded on one side of the spectrum by transmit sub-bands TX1to TXMand on the opposite side, transmit sub-bands TXM+1to TXN(i.e., all the TX sub-bands sandwich all the RX sub-bands). Given that the signal power of signals transmitted on the TX sub-bands is much greater than the received uplink sub-bands (RX) a wideband receiver filter206can be utilized to isolate all of the adjacent uplink sub-bands from the surrounding downlink TX sub-bands, all while only utilizing one air cavity RX filter instead of N that would be necessary in existing implementations.

In addition to the wideband RX filter206isolating the adjacent uplink sub-bands RX1, RX2, and up to RXN, the front-end multiband radio receiver can also include a small type multiplexor that is configured to isolate each of the component sub-bands that were included in the filtered multiband uplink signal obtained by wideband RX filter206. Accordingly, by utilizing the wideband RX filter206in conjunction with the small type multiplexor, the multiband radio can effectively isolate each individual sub-band of the particular multiband uplink signal ofFIG. 2in two stages: (a) isolating a wideband signal made up of adjacent uplink sub-bands and (b) further isolating the individual sub-bands within the wideband signal by using a small type multiplexor component set in series with the multiband RX filter206of the present disclosure.

These two stages can be seen in the multiband radio108circuit implementation shown inFIG. 3, along with other aspects of the front-end receiver architecture proposed herein. As shown inFIG. 3, in addition to the multiband receiver assembly proposed herein, the multiband radio circuit108contains a TX filter for obtaining sub-bands received at the antenna304that are attributed to downlink transmissions. The lower portion of the radio circuit includes multiple components that allow the multiband radio108to isolate each of the uplink (RX)356sub-bands received at the antenna304. In the first stage discussed above, the wideband RX filter206can filter two or more adjacent uplink sub-bands received in the multiband signal.

Once these sub-bands are obtained, the signal can move to the one or more notch filters208, which are optionally included in the filter circuit, for example, in instances where blocking signals216(seeFIG. 2) are present between RX sub-bands, which could compress the first low noise amplifier (LNA1)338. Thus, by suppressing these blocking signals216, the one or more notch filters208can help to protect the LNA1from experiencing these negative effects. After passing through a low-pass filter330, the signal is multiplexed using a small type multiplexor343, which includes several further filters to separate the combined sub-bands. In an aspect, like the optional notch filter(s)208, the small type multiplexer343can be designed by using the ceramics or SAW/BAW/FBAR filter technologies because they are already isolated from the high-power DL signals of the TX sub-bands (seeFIG. 2, 4). These filter types can be designed to perform sufficiently to ensure a workable degree of isolation between the RX sub-bands. Typically, signal loss in the small type multiplexer343will not be a significant contributor to the ultimate UL noise.

In any case, the wideband RX filter206is typically designed to use air cavity filter technology, because it will be required to handle high-power TX sub-band signals in sub-bands that are adjacent in its TX sub-bands. The wideband RX filter206of the front-end architecture shown inFIG. 3, though used to filter three RX sub-bands, will be in size as big as one of the individual single sub-band RX filters of the air cavity variety, which saves space, cost, and weight significantly. Furthermore, the wideband RX filter206could be smaller than any one of the individual single sub-band RX filters (such as single sub-band RX filter410shown inFIG. 4), because the UL front-end filtering requirements in the present disclosure are split into the two parts discussed above. As a result, the portion of the requirements assigned to the wideband RX filter206will be less rigorous than those imposed to any one of the individual single-sub-band RX filters. Therefore, the air cavity front-end RX filter used in the present front-end architecture can be on the order of approximately 1/n the size of conventional air cavity front end filters, where n is the number of the sub-bands.

In an additional improvement, the wideband RX filter206of the present disclosure can exhibit 0.2 to 0.6 dB less loss than the conventional multiband RX filter. This is because the conventional filter requires n band-combining circuits to combine the n individual single-band RX filters. Moreover, if the multiband notch filter208ofFIGS. 2 and 3is not needed, then the front-end architecture exhibits an improved UL noise figure, mainly due to a lower loss of the wideband RX filter206explained above.

FIG. 4illustrates an additional possible scenario where the multiband signal includes two or more adjacent RX sub-bands and at least one isolated RX sub-band having no adjacent RX sub-bands. As shown in the figure, if two or more adjacent RX sub-bands exist, then a wideband RX filter206can be designed to filter the group of adjacent RX sub-bands. In FIG.4, these adjacent uplink sub-bands are RX1and RX2. Like the example inFIG. 2, if there is a blocking signal216between these adjacent RX sub-bands, then a multiband notch filter408can be designed and placed after the wideband RX filter206(seeFIG. 5) to suppress these blocking signals.

In addition,FIG. 4shows a sub-band combination of a triple sub-band multiband radio that has TX2sub-band sandwiched by RX2and RX3, but RX1and RX2are adjacent. In this case, a wideband RX filter206can be designed to filter, together, RX1and RX2. Unlike the example presented inFIG. 2, where all of the RX sub-bands were grouped adjacently, the example presented inFIG. 4requires a further air cavity front-end RX filter, shown in the figure as single sub-band RX filter410. The wideband filter206and the single sub-band filter410can be designed together as a dual-band air cavity filter412. In other words, compared to the conventional architecture that will have three individual single sub-band RX filters410used to form the necessary front-end RX filter, the proposed architecture requires only two sub-band RX filters to form the front-end RX filter. Therefore, even in the relatively simple example shown inFIG. 4, utilizing aspects of the present disclosure will save an entire air cavity sub-band filter.

As described above in reference to other examples, should a blocking signal216exist between adjacent uplink sub-bands RX1and RX2, a notch filter408can be designed and implemented in the front-end of the multiband radio example shown inFIG. 5. Specifically, this notch filter408can be placed between (a) the parallel arrangement of the wideband RX filter206and the single sub-band RX filter410and (b) the LNA1528. Like the exemplary front-end architecture of the multiband radio108ofFIG. 3, the corresponding architecture inFIG. 5is arranged such that UL front-end filtering requirements are split mainly into two parts: (a) a first part where the air cavity dual-band RX filter206and air cavity single-sub-band RX filter410filter pass their respective RX sub-bands signal and (b) a second part where the filtered signal from the first part is input to a small type triplexer542that is placed between the LNA1528and one or multiple LNA2s544, as shown inFIG. 5. Furthermore, both the notch filter408and the components of the small type triplexer542(e.g., filters540) can be designed to use ceramics or the SAW/BAW/FBAR filter technologies.

FIG. 6presents an example method600performed by a multiband radio108for filtering a set of uplink sub-bands in a wireless communication system. The method can include, at block602, filtering, by one or more wideband filters of the multiband receiver, any group of two or more adjacent uplink sub-bands in a frequency spectrum utilized by the multiband radio for communication with one or more UEs102. In addition, at block604, the method600can include isolating, by a multiplexor of the multiband receiver, each of the adjacent uplink sub-bands using separate filters. Furthermore, the method600can further include filtering, by each of a plurality of single sub-band filters, different isolated uplink sub-bands in the frequency spectrum, as is shown in relation to the single sub-band RX filter410inFIGS. 4 and 5.

In addition, although not explicitly shown inFIG. 6, the following optional aspects may be included in one or more example embodiments of the present disclosure. For instance, some examples of method600can include utilizing multiband notch filters to mitigate blocking signals between adjacent uplink sub-bands. In addition, the method600can include amplifying any of the set of sub-bands using one or more low noise amplifiers.

With the above description in mind, let us turn toFIGS. 7A, 7B, 8A, and 8B, which present example aspects of a network node106and multiband radio108, respectively, that are configured to carry out the techniques and methods presented herein.

FIG. 7Aillustrates additional details of an example network node106of a wireless communication system100according to one or more embodiments. The network node106is configured, e.g., via functional means or units (also may be referred to as modules or components herein), to implement processing to perform certain aspects described above in reference to at least the aspects ofFIGS. 1-6. As shown inFIG. 7B, the network node106in some embodiments for example includes means, modules, components, or units730and740(among other possible means, modules, components, or units not shown explicitly inFIG. 7B) for performing aspects of these techniques. In some examples, these means, modules, components, or units can be realized in processing circuitry700. Specifically, the functional means or units of the network node106may include a filtering unit/module730configured to a filter any group of two or more adjacent uplink sub-bands in a frequency spectrum utilized by the multiband radio for communication with a user equipment, for example, as performed in block602ofFIG. 6, above. In addition, the network node106can include an isolating unit/module740configured to isolate each of the two of more adjacent uplink sub-bands using separate filters, for example, as performed in block604ofFIG. 6, above.

In at least some embodiments, the network node106comprises processing circuits700, which may include one or more processing circuits, configured to implement techniques described in reference to method600presented inFIG. 6and certain associated processing of the features described in relation toFIG. 6and/or other figures, such as by implementing functional means or units above (or those not explicitly shown). In one embodiment, for example, the processing circuit(s)700implements functional means or units as respective circuits. The circuits in this regard may comprise circuits dedicated to performing certain functional processing and/or one or more microprocessors in conjunction with memory720. In embodiments that employ memory720, which may comprise one or several types of memory such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc., the memory720stores program code that, when executed by the one or more for carrying out one or more microprocessors, carries out the techniques described herein.

In one or more embodiments, the network node106also comprises communication circuitry710. The communication circuitry710includes various components (e.g., antennas) for sending and receiving data and control signals. More particularly, the circuitry710includes a transmitter that is configured to use known signal processing techniques, typically according to one or more standards, and is configured to condition a signal for transmission (e.g., over the air via one or more antennas). Similarly, the communication circuitry710includes a receiver that is configured to convert signals received (e.g., via the antenna(s)) into digital samples for processing by the one or more processing circuits. In some examples, this communication circuitry710may include multiband radio108ofFIG. 1.

FIG. 8Aillustrates additional details of an example multiband radio108of a wireless communication system100according to one or more embodiments. The multiband radio108is configured, e.g., via functional means or units (also may be referred to as modules or components herein), to implement processing to perform certain aspects described above in reference to at least the aspects ofFIGS. 1-6. As shown inFIG. 8B, the multiband radio108in some embodiments for example includes means, modules, components, or units830and/or840(among other possible means, modules, components, or units not shown explicitly inFIG. 8B) for performing aspects of the techniques described above. In some examples, these means, modules, components, or units can be realized in processing circuitry800. Specifically, the functional means or units of the multiband radio108may include a filtering unit/module830configured to a filter any isolated sub-bands or any group of two or more adjacent uplink sub-bands in a frequency spectrum utilized by the multiband radio for communication with a user equipment, for example, as performed in blocks602and606ofFIG. 6, above. In addition, the multiband radio108can include an isolating unit/module840configured to isolate each of the two of more adjacent uplink sub-bands using separate filters, for example, as performed in block604ofFIG. 6, above.

In at least some embodiments, the multiband radio108comprises one or more processing circuitry/circuits800configured to implement processing of the method600presented inFIG. 6and certain associated processing of the features described in relation toFIG. 6and other figures, such as by implementing functional means or units above. In one embodiment, for example, the processing circuit(s)800implements functional means or units as respective circuits. The circuits in this regard may comprise circuits dedicated to performing certain functional processing and/or one or more microprocessors in conjunction with memory820. In embodiments that employ memory820, which may comprise one or several types of memory such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc., the memory820stores program code that, when executed by the one or more for carrying out one or more microprocessors, carries out the techniques described herein.

In one or more embodiments, the multiband radio108also comprises communication circuitry810. The communication circuitry810includes various components (e.g., antennas) for sending and receiving data and control signals. More particularly, the circuitry510includes a transmitter that is configured to use known signal processing techniques, typically according to one or more standards, and is configured to condition a signal for transmission (e.g., over the air via one or more antennas). Similarly, the communication circuitry includes a receiver that is configured to convert signals received (e.g., via the antenna(s)) into digital samples for processing by the one or more processing circuits.

In an aspect, the multiband radio108may correspond to any mobile (or even stationary) device that is configured to receive/consume user data from a network-side infrastructure, including laptops, phones, tablets, IoT devices, etc. Thus, multiband radio108is any type device capable of communicating with a network node106over radio signals, such as, but not limited to, a device capable of performing autonomous wireless communication with one or more other devices, including a machine-to-machine (M2M) device, a machine-type communications (MTC) device, a user equipment (UE) (however it should be noted that the UE does not necessarily have a “user” in the sense of an individual person owning and/or operating the device). An UE may also be referred to as a radio device, a radio communication device, a wireless terminal, or simply a terminal—unless the context indicates otherwise, the use of any of these terms is intended to include device-to-device UEs or devices, machine-type devices or devices capable of machine-to-machine communication, sensors equipped with a wireless device, wireless-enabled table computers, mobile terminals, smart phones, laptop-embedded equipped (LEE), laptop-mounted equipment (LME), USB dongles, wireless customer-premises equipment (CPE), etc. In the discussion herein, the terms machine-to-machine (M2M) device, machine-type communication (MTC) device, wireless sensor, and sensor may also be used. It should be understood that these devices may be UEs, but are generally configured to transmit and/or receive data without direct human interaction.

Those skilled in the art will also appreciate that embodiments herein further include corresponding computer programs. A computer program comprises instructions which, when executed on at least one processor of the network node106or multiband radio108, cause these devices to carry out any of the respective processing described above. Furthermore, the processing or functionality of network node106or multiband radio108may be considered as being performed by a single instance or device or may be divided across a plurality of instances of network node106or multiband radio108that may be present in a given system such that together the device instances perform all disclosed functionality. Embodiments further include a carrier containing such a computer program. This carrier may comprise one of an electronic signal, optical signal, radio signal, or computer readable storage medium. A computer program in this regard may comprise one or more code modules corresponding to the means or units described above.