Patent Application
20220102857
Telecommunication service providers may own and operate more than one frequency band at a time within a given geographic region. To support their operations, base station nodes are typically required to deploy multiple frequency bands at any given time. Base station nodes typically include three sectors to service a service area that extends radially from the base station node. In order to deploy one frequency band, the base station node requires three remote radio units (RRU)—one for each of the three sectors. Accordingly, if the base station node is to deploy multiple frequency bands, the number of RRUs increases by the corollary multiple of three.
Current 5G-New Radio (5G-NR) millimeter wave (mmW) frequency bands use separate dedicated RRUs for each band. Most 5G-NR-enabled client devices are capable of operating on most, if not all 5G-NR mmW frequency bands, either singularly or via carrier aggregation. However, as the number of 5G-NR mmW frequency bands increase, so too does the number of RRUs required at each base station node.
The corollary of an increase in RRUs is physical space congestion on a base station tower. Each RRU requires a physical hardware installation on a base station site/tower. As the number of RRUs increase, the physical space available on the base station tower is proportionally reduced. In addition, the operating expenditures (OPEX) and capital expenditures (CAPEX) associated with additional RRUs also increase. In the event that a base station site/tower does not have enough physical space for additional RRUs, then the frequency bands that correspond to the additional RRUs cannot be deployed, which prevents a service provider from deploying additional spectrum assets. In turn, this leads to a reduction in spectral efficiency and may negatively impact user experience, which sometimes may be very significantly.
The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items or features.
This disclosure describes techniques that enable individual antenna arrays of a base station node to transmit digital information via one or more frequency bands. More specifically, a remote radio unit (RRU) is described that may include a plurality of antenna arrays that service multiple frequency bands. The RRU may be configured to service multiple frequency bands across antenna arrays, within antenna array, or a combination of both.
The ability to service multiple frequency bands within a single RRU is intended to ease physical congestion on a base station tower. As the number of 5G-NR mmW frequency bands increase, so too does the number of RRUs required at each base station node. Since each RRU requires a physical hardware installation on a base station tower, as the number of RRUs increase, the physical space available on the base station tower is proportionally reduced. In addition, the operating expenditures (OPEX) and capital expenditures (CAPEX) associated with additional RRUs also increase. Therefore, this disclosure describes techniques that are intended to ease the physical space burden on base station towers, by reducing the number of RRU hardware installations required to service a growing number of 5G-NR mmW frequency bands.
In one example, an RRU may include a plurality of antenna arrays. Each antenna array may be configured to service a single frequency band, and each antenna array may service different frequency bands relative to one another. Therefore, an aggregate of antenna arrays that each service different frequency bands may effectively create a multi-band RRU.
In another example, the RRU may include at least one antenna array that comprises antenna elements that service different frequency bands. Each antenna element may be configured to service a single frequency band. However, an aggregate of antenna elements within an antenna array that service different frequency bands may effectively create a multi-band RRU.
More specifically, this disclosure describes an RRU of a base station node that comprises at least a first set of antenna arrays and a second set of antenna arrays. The first set of antenna arrays may be configured for use with a first frequency band, and the second set of antenna arrays may be configured for use with a second frequency band that is different from the first frequency band. In this way, the RRU, through the simultaneous use of the first and second sets of antenna arrays, may be configured to service the first frequency band and the second frequency band either one band at a time or both at the same time. In some examples, the first and second frequency bands may correspond to different mmW bands associated with a 5G-NR air-interface technology. In other examples, the first and/or second frequency bands may correspond to frequency bands associated with a 2G, 3G, LTE air-interface technology.
Moreover, the RRU may include an antenna array that comprises antenna elements that are configured for use with multiple frequency bands. In other words, rather than being configured to service a single frequency band, the antenna array may service different frequency bands based on the frequency bands serviced by the in situ antenna elements.
An antenna array with multiple sets of antenna elements that service different frequency bands may have one set of antenna elements interspersed within the spacing of another set of antenna elements. The spacing between antenna elements is inversely proportional to the frequency band in which the antenna elements serve. For example, the optimum antenna element spacing for a 48 GHz frequency is 50% of the spacing for a 24 GHz frequency band. Therefore, if an antenna array is to comprise of multiple sets of antenna elements, the geometric arrangement of antenna elements is based on the relative frequencies that each set of antenna elements serve. For example, a first set of antenna elements associated with a first frequency may be interspersed within the spacing of a second set of antenna elements associated with second frequency, provided the first frequency (i.e. 48 GHz) is relatively higher than the second frequency (i.e. 24 GHz). If the first frequency (i.e. 48 GHz) is relatively higher than the second frequency (i.e. 24 GHz), then the corresponding first set of antenna elements requires less relative spacing between antenna elements and thus can be interspersed between the relatively larger spacing that is required of the second set of antenna elements that serves the second frequency (i.e. 24 GHz).
Moreover, rather than interspersing a first set of antenna elements within the spacing of a second set of antenna elements, the first set may be stacked above the second set, such that the first set overlays the second set in a third geometric dimension. In this example, the first and second sets of antenna elements remain coplanar with one another. Further, the first set of antenna elements that overlay above the second set of antenna elements may incorporate RF transparency holes that permit the frequency band associated with the underlying second set of antenna elements to pass through the first set of antenna elements. In this way, despite one set of antenna elements overlaying another, the incorporation of RF transparency holes ensures that both sets of antenna elements can service their respective frequency bands.
In some examples, an RRU may include antenna arrays that serve three or more frequency bands. For example, consider an antenna array that services three different frequency bands. Here, the antenna array may include three sets of antenna elements, with each set corresponding to one of the three different frequency bands. One set of antenna elements may be outlaid within the array in a grid pattern. The spacing between the antenna elements may be a function of the frequency band served. Further, a second set of antenna elements associated with a relatively higher, second frequency band may be interspersed within the spacing between the antenna elements of the first set of antenna elements. Moreover, the third set of antenna elements associated with the third frequency band may overlay the first or second sets of antenna elements. The third set of antenna elements may include RF transparency holes within each antenna element to ensure the underlying antenna element can service their respective frequency bands.
It is noteworthy that the terms “frequency bands” and “spectrum” are used interchangeably throughout this disclosure.
It is noteworthy that each RRU 110 may share hardware and software elements across all serviced frequency bands. Shared resources may include enclosures, power supplies, cable interfaces, baseband and digital processing, interface elements, and so forth, across multiple frequency bands. The degree of resource sharing may relate to the average or maximum total bandwidth or throughput associated with the RRU 110. In turn, by sharing resources, operational and capital expenditure associated with a RRU 110 is reduced, along with a reduction in cabling that extends from the base to the top of the tower 108.
The RRU 110 is configured to receive digital information and control signals from the baseband unit 106 and further modulate the digital information into a radio frequency (RF) signal. The RRU 110 may also receive RF signals, demodulate the RF signals, and supply the demodulated signals to the baseband unit 106.
Moreover, the RRU 110 may be configured in one of two ways to support multiple frequency bands. Firstly, the RRU 110 may include multiple single-band antenna arrays that each service a different frequency band. Alternatively, or additionally, the RRU 110 may include at least one antenna array that comprises single band antenna elements that each service different frequency bands.
In the illustrated example, the RRU 110 may be located at the top of the tower 108 to reduce signal loss between the RRU 110 and antenna arrays that transmit the RF signals. In this disclosure, the antenna arrays are depicted as part of the RRU 110, however, in other embodiments, the antenna arrays and the RRU 110 may be physically distinct. The RRU 110 is communicatively coupled to the baseband unit 106 via a cable 112 that extends from the baseband unit 106, up the tower 108, and to the RRU 110. The cable 112 may be a hybrid connector system (HCS) cable that combines fiber communications (i.e. fiber optic cable connected to the baseband unit 106).
The RRU 110 may be configured to receive digital information and control signals from the baseband unit 106 via cable 112, and further modulate the digital information into a radio frequency (RF) signal that is transferred through to one of the antenna array(s) 202(1)-202(4). The RRU 110 may also receive RF signals from one of the antenna array(s) 202(1)-202(4), demodulate the RF signals, and supply the demodulated signals to the baseband unit 106.
The RRU 110 may include an interface unit 204, antenna array(s) 202(1)-202(4), and transceiver(s) 206(1)-206(4). The interface unit 204 is communicatively coupled to the baseband unit 106 via the cable 112 and to the transceiver(s) 206(1)-206(4) of the RRU 110. Accordingly, the interface unit 204 may be configured to receive the digital information and control signals from the baseband unit 106. In doing so, the interface unit 204 may route the digital information to one of the transceiver(s) 206(1)-206(4) based on the corresponding control information.
The transceiver(s) 206(1)-206(4) may be communicatively coupled to the interface unit 204 and the antenna array(s) 202(1)-202(4). Each of the transceiver(s) 206(1)-206(4) is tasked with modulating digital information received from the interface unit 204 into RF signals and demodulating RF signals received from the antenna array(s) 202(1)-202(4) into digital information. The digital information is then transmitted to the interface unit 204 for further transmission to baseband unit 106. At each of the transceiver(s) 206(1)-206(4), the modulation and demodulation of RF signals is based on the frequency bands supported by the counterpart antenna array(s) 202(1)-202(4) to which the transceiver(s) 206(1)-206(4) are coupled. For example, transceiver 206(1) may be configured to modulate and demodulate RF signals associated with antenna array 202(1) and so forth.
The antenna array(s) 202(1)-202(4) are communicatively coupled to counterpart transceiver(s) 206(1)-206(4). For example, antenna array 202(1) is communicatively coupled to transceiver 206(1) and so forth. As discussed above, each of the antenna array(s) 202(1)-202(4) are configured to receive modulated RF signals from their counterpart transceiver(s) 206(1)-206(4) and transmit RF signals to their counterpart transceiver(s) 206(1)-206(4) for demodulation.
Each of the antenna array(s) 202(1)-202(4) may comprise a set of multiple connected antenna element(s) 208(1)-208(4) which work together as a single antenna, to transmit or receive RF signals. Each antenna element radiates an RF signal that is combined and superposed and added together to enhance the power radiated in desired directions. The shape of each antenna array 202(1)-202(4) may be square, rectangular, triangular, or any other geometric shape that is conducive to the transmission and receipt of RF signals.
The antenna element(s) 208(1)-208(4), as discussed above, are the components of the antenna array(s) 202(1)-202(4), which in combination, transmit or receive RF signals in a desired direction. The number of antenna elements is typically inversely proportional to the size of the antenna elements, themselves. Further, the element size is typically greater than a wavelength. Also, the spacing between antenna elements is inversely proportional to the frequency. For example, the ideal antenna element spacing for a 48 GHz frequency band is 50% of the spacing for a 24 GHz frequency band. Further, it follows that the area of antenna elements for a 48 GHz frequency band is 25% of the area for a 24 GHz frequency band.
Even though
In the illustrated example, the antenna array 202(1) comprises antenna element(s) 208(1), which are configured to service “Frequency A.” Each of the antenna element(s) 208(1) are single band antenna elements, meaning that the antenna elements are configured to service one frequency band, namely “Frequency A.” The corollary of antenna array 202(1) comprising antenna element(s) 208(1) is that antenna array 202(1) is a single band antenna array that is configured to service “Frequency A.”
Similarly, antenna array 202(2) comprises antenna element(s) 208(2), which are configured to service “Frequency A.” Therefore, antenna array 202(2) is a single band antenna array that is configured to service “Frequency B.”
In contrast, the antenna array 202(3) comprises antenna element(s) 208(3), which are configured to service “Frequency B.” Each of the antenna element(s) 208(3) are single band antenna elements, meaning that the antenna elements are configured to service one frequency band, namely “Frequency B.” The corollary of antenna array 202(3) comprising antenna element(s) 208(3) is that antenna array 202(3) is a single band antenna array that is configured to service “Frequency B.”
Similarly, antenna array 202(4) comprises antenna element(s) 208(4), which are configured to service “Frequency B.” Therefore, antenna array 202(4) is a single band antenna array that is configured to service “Frequency B.”
While the RRU 110 comprises single-band antenna arrays that service one of “Frequency A” or “Frequency B”, namely antenna array(s) 202(1)-202(4), the aggregate of the four antenna array(s) 202(1)-202(4) effectively creates a multi-band RRU 110 that services “Frequency A” and “Frequency B.”
Moreover,
In the illustrated example, the RRU 110 is configured to service “Frequency A,” “Frequency B,” “Frequency C,” and “Frequency D.” Each of the four enumerated frequency bands is different from one another and may correspond to the 2G spectrum, 3G spectrum, LTE spectrum, or 5G-NR spectrum (i.e. 5G-NR mmW spectrum).
In the illustrated example, the RRU 110 includes an antenna array 302(1), which is configured to service “Frequency C.” Similar to the embodiment depicted in
Moreover,
In the illustrated example, a subset of antenna element(s) 304(2) that service “Frequency B” may be interspersed between another subset than service “Frequency A.” Depending on the required spacing between antenna elements, the antenna elements of each frequency band subset may be positioned within the antenna array 302(2) in alternating order, or variation thereof.
For example, the order of the antenna element(s) 304(2) within the antenna array 302(2) may be “Frequency A” antenna element, “Frequency B” antenna element, “Frequency A” antenna element, and so forth. However, any alternating order may be possible, based at least in part on the magnitude of the served frequencies. For example, the spacing between antenna elements is inversely proportional to the frequency band in which the antenna elements serve. Consider the antenna element spacing for two subsets of antenna elements that serve a 48 GHz frequency band and a 24 GHzGHz frequency band. In this example, the antenna element spacing for a 48 GHz frequency is 50% of the spacing required for a 24 GHz frequency band. Therefore, it is conceivable for a positional order of antenna elements within an antenna array to include one 24 GHz antenna element, followed by two 48 GHz antenna elements, and a next 24 GHz antenna element.
Further,
In the illustrated example, a subset of the antenna element(s) 304(3) that service “Frequency C” may overlay another subset of the antenna element(s) 304(3) that service “Frequency A.” In this example, the subsets of the antenna element(s) 304(3) remain coplanar with one another. While
Moreover, and as described in more detail with reference to
Additionally,
In the illustrated example, a first subset of the antenna element(s) 304(4) that service “Frequency B” may be interspersed between a second subset that service “Frequency A.” While
Antenna array 202(4) further includes a third subset of the antenna element(s) 304(4) that service “Frequency C.” In this example, the third subset is shown to overlay the first and second subsets that service “Frequency B” and “Frequency A,” respectively. Moreover, unlike antenna array 202(3), the positioning of the third subset of antenna element(s) 304(4) is staggered to overlay the spacing between the underlying antenna elements, namely the first and second subsets. In this way, the third subset of the antenna element(s) 304(4) may avoid the inclusion of RF transparency holes, since the underlying antenna elements may have an exposed path to transmit/receive RF signals via the spacing between the overlaid antenna element(s) (i.e. serving “Frequency C”).
Moreover, the first antenna element 404 (i.e. serving the first frequency band) may include one or more RF transparency hole(s) 408 that permit RF signals associated with the underlying, second antenna element 406 (i.e. serving the second frequency band) to pass through the first antenna element 404. Alternatively, rather than including RF transparency hole(s) 408 in the first antenna element 404, the overlay position of the first antenna element 404 may be staggered relative to the underlying, second antenna element 406, such that the second antenna element 406 may have an exposed path to transmit/receive RF signals via the space created by the staggered and overlaid, first antenna element 404.
Although the subject matter has been described in language specific to features and methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described herein. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claims.
