IT202100030107A1 - REDUCTION OF INTERFERENCE, IN A RECEPTION SIGNAL, CAUSED BY A SIMULTANEOUS TRANSMISSION SIGNAL IN THE SAME FREQUENCY BAND AS THE RECEPTION SIGNAL - Google Patents

Description

DESCRIPTION of the patent for industrial utility model: ?REDUCING INTERFERENCE, IN A RECEPTION SIGNAL, CAUSED BY A SIMULTANEOUS TRANSMISSION SIGNAL IN THE SAME FREQUENCY BAND AS THE RECEPTION SIGNAL?

DESCRIPTION

SUMMARY

[0001] Figure 1 ? a block diagram of a distributed antenna system (DAS) 10, which is? configured for pairing with one or more? 12 base stations, and which includes one or more? unit? of remote antenna 14. Typically, each base station 12 corresponds to, and ? controlled by, a particular cellular operator such as T-Mobile?, Verizon? or ATT?, and ? configured to receive uplink signals, and to transmit downlink signals, via one or more? of the units? of remote antenna 14. For example, each base station 12 can? be configured to receive uplink signals and to transmit downlink signals through all units? of remote antenna 14 so that each cellular operator is granted the complete signal coverage area served by the specially configured DAS 10.

[0002] When operated according to a standard, such as the 5G New Radio (5GNR) standard, which requires the DAS 10 to operate in a Radio Access Network (RAN), where uplink-downlink schemes of the multiple signals change dynamically and may not be synchronized with each other, an antenna 16 of a unit? of remote antenna 14 can? receive an uplink signal at the same time as the antenna, or another antenna on the same or different unit? of remote antenna, is it transmitting a downlink signal in the same frequency band, or even at one or more? carrier frequencies, of the uplink signal. In one mode? Traditional TDD, the DAS 10 can? switch between Tx and Rx. That is, the uplink-downlink patterns of all TDD signals in the band are static and synchronized such that the DAS 10 can operate in one mode. Traditional TDD, switching between Tx/Rx in sync with the predictable pattern of synchronized TDD signals that the DAS 10 is carrying. On the contrary, in more standard as recent as 5GNR, TDD signals within a band change dynamically and are not necessarily synchronized with each other; therefore, in this case, it would be, at best, difficult for the DAS 10 to operate in a Why traditional TDD? aren't you? any predictable Tx/Rx pattern to follow that will apply? to all channels.

[0003] Unfortunately, if an antenna 16 of a unit? of remote antenna 14 is receiving an uplink signal at the same time as the antenna, or another antenna on the same or a different unit? of remote antenna, transmits a downlink signal, then the reception signal that the antenna generates in response to the uplink signal can? include interference (for example, nonlinear distortion such as adjacent channel noise and amplification noise) arising from the transmit signal driving the antenna, or from one or more? downlink signals transmitted by one or more? other nearby antennas.

[0004] Since? the transmission signal that excites the receiving antenna 16, and the one or more? downlink signals transmitted via one or more different antennas, they are decidedly more? powerful at the receiving antenna compared to the uplink signal, the transmission interference in the receiving signal usually ?overwhelms? the uplink component of the receive signal.

[0005] To obtain, for example, a noise figure of 5 dB for the receive signal at the receiver coupled to a receiving antenna 16 over a 5 MHz uplink channel bandwidth while a 100 milliwatt signal (mW) with a channel leakage ratio (ACLR) of -45 dB is simultaneously transmitted on an adjacent channel, it is expected that the unit? of remote antenna 14 should be configured to reduce the effective transmit interference power in the uplink channel by approximately 77 dB.

[0006] Consequently, ? the need emerged? of isolation circuitry and interference cancellation circuitry configured to reduce, to an acceptable level, interference in a receive signal generated by a device of remote antenna 14 of a DAS 10 operating in a radio access network; and ? a need for a unit also emerged remote antenna incorporating such circuitry.

[0007] In one embodiment, a unit? of remote antenna that can? satisfying the characteristics described above includes a transmitter or a portion thereof, a receiver or a portion thereof, an antenna array, and first and second interference circuits. The transmitter, or portion of it, is configured to generate at least one transmit signal, and the receiver, or portion thereof, is configured to process at least one receive signal. For example, as used herein, "transmitter" and "receiver" are intended to mean at least a portion of the transmission or reception chain that can? be split between a host location (for example, a base station 12 or master drive 18) and a drive remote antenna 14. For example, generation (modulation) and processing (demodulation) can again take place at a base station 12, not at a unit? of remote antenna 14. In an example, the unit? of remote antenna 14 includes the end circuitry? frontal RF, what can? include, for example, a digital-to-analog converter (DAC), an upconverter, and a power amplifier on the downlink path, and which can include a low-noise amplifier, a downconverter, and an analog-to-digital converter (ADC) on the uplink path. Does the antenna array include one or more? antennas, each of at least one of one or more antennas coupled to the transmitter and configured to radiate a respective downlink signal in response to a respective one of the at least one transmit signal, and each of the at least one or more? antennas coupled to the receiver and configured to generate a respective of the at least one receive signal in response to an uplink signal. And the first and second interference circuits are each coupled to the transmitter and the receiver and are each configured to reduce, in each of the at least one receiving signal, interference caused by one or more of the at least one transmission signal, the at least one downlink signal emanating from one of the one or more? antennas on the same unit? of remote antenna, and the at least one interfering downlink signal emanating from one or more? other antennas on one or more? other units? of the remote antenna.

[0008] For example, this unit? of remote antenna can? include multiple different interference reduction circuits that together provide a suitable level of interference reduction in the received signal.

[0009] As a further example, one of the interference reduction circuits can be an isolation circuit configured to isolate the transmitter from the receiver so as to reduce the interference that a transmit signal to an antenna causes to a receive signal from the same antenna, where the transmit signal and the receive signal overlap at least partially in time, and also when the interference includes passive intermodulation (PIM).

[0010] In yet a further example, one of the interference reduction circuits can be an analog interference cancellation circuit configured to provide first-order linear correction by canceling, from a receive signal, a transmit signal to the same antenna or a downlinked signal from an adjacent antenna on the same, or on a different unit? of remote antenna, in which the transmission signal or downlink signal overlaps at least partially with the reception signal over time.

[0011] As yet another example, one of the interference cancellation circuits can be a digital interference cancellation circuit configured to provide first-order linear correction, and nonlinear correction, to a receive signal. The digital interference cancellation circuit can provide a first-order linear correction to a receive signal in the same way as the analog interference cancellation circuit as described above, and can provide a non-linear correction, for example, by canceling, from the received signal, the out-of-band distortion (also called frequency sidebands and frequency ?flanking?) that can still be sufficiently close to the frequency of the receiving signal such that it is difficult to reduce this distortion to an acceptable level with traditional filtering.

[0012] As yet another example, each of one or more? of interference reduction circuits can? include one or more? control cycles, and two or more? Interference reduction circuits may form, or be part of, a control loop. For example, a digital interference cancellation circuit can use negative feedback to control the parameters of an isolation circuit to further reduce a level of transmit interference in a receive signal.

DRAWINGS

[0013] Figure 1? a diagram of a distributed antenna system (DAS), base stations coupled to the DAS, and user equipment configured to communicate with the DAS and with base stations via the DAS.

[0014] Figure 2? a diagram of a portion of a unit? of remote antenna of Figure 1, wherein the portion includes circuitry configured to reduce, in a receive signal from an antenna, interference caused by a simultaneous transmission signal to the same antenna, according to one embodiment.

[0015] Figure 3? a diagram of a portion of a unit? of remote antenna of Figure 1, wherein the portion includes circuitry configured to reduce, in a receive signal from an antenna, interference caused by a simultaneous transmission signal to the same antenna, according to one embodiment.

[0016] Figure 4? a diagram of a portion of a unit? 1, wherein the portion includes circuitry configured to reduce, in a receive signal from an antenna, interference caused by a simultaneous transmission signal to the same antenna, and interference caused by one or more? downlink signals coming from one or more? different antennas on the same unit? of remote antenna, according to one embodiment.

[0017] Figure 5? a diagram of a portion of a unit? 1, wherein the portion includes circuitry configured to reduce, in a receive signal from an antenna, interference caused by a simultaneous transmission signal to the same antenna, and caused by one or more ? downlink signals coming from one or more? different antennas on one or more? different units? of remote antennas, according to one embodiment.

[0018] Figure 6? a diagram of a portion of a unit? 1, wherein the portion includes circuitry configured to reduce, in a receive signal from an antenna, interference caused by a simultaneous transmission signal to the same antenna, and caused by one or more ? downlink signals coming from one or more? different antennas on the same one, or on one or more? unit? of different remote antennas, according to one embodiment.

[0019] Figure 7? a diagram of the transmitter-receiver isolation circuit of figures 2 ? 6, according to one embodiment.

[0020] Figure 8? a diagram of the transmitter-receiver isolation circuit of figures 2 ? 6, according to one embodiment.

[0021] Figure 9? a plot of transmission insertion loss versus frequency of the transmitter-receiver isolation circuit of Figure 8, according to one embodiment.

[0022] Figure 10 ? a plot of receive insertion loss versus frequency of the transmitter-receiver isolation circuit of Figure 8, according to one embodiment.

[0023] Figure 11 ? a plot, versus frequency, of the isolation provided by the transmitter-receiver isolation circuit of Figure 8 between the transmitter and receiver of Figures 2 - 6, according to one embodiment.

[0024] Figure 12 ? a graph comparing the transmitter-to-antenna insertion loss and transmitter-receiver isolation provided by the Figure 8 transmitter-receiver isolation circuit to the transmitter-to-antenna insertion loss and transmitter-receiver isolation that would be provided by one of the circulators of figure 8, according to one embodiment.

[0025] Figure 13 ? a diagram of the transmitter-receiver isolation circuit of figures 2 ? 6, according to one embodiment.

[0026] Figure 14 ? a plot of transmitter-to-antenna insertion loss, antenna-to-receiver insertion loss, and transmitter-receiver isolation provided by the transmitter-receiver isolation circuit of Figure 13, according to one embodiment.

[0027] Figure 15 ? a graph comparing the transmitter-to-antenna insertion loss and transmitter-receiver isolation provided by the transmitter-receiver isolation circuit of Figure 13 to the transmitter-to-antenna insertion loss and transmitter-receiver isolation that would be provided by one of the circulators of figure 13, according to one embodiment.

[0028] Figure 16 ? a diagram of the transmitter-receiver isolation circuit of figures 2 ? 6, according to one embodiment.

[0029] Figure 17 ? a diagram of a portion of a unit? of remote antenna of Figure 1, wherein the portion includes circuitry configured to reduce, in a receive signal from an antenna, interference caused by a simultaneous transmission signal to the same antenna, according to one embodiment.

[0030] Figure 18 ? a diagram of a portion of a unit? of remote antenna of figure 1, in which the unit? remote antenna includes separate transmit and receive antennas, according to one embodiment.

[0031] Figure 19 ? a diagram of a portion of a unit? of remote antenna of figure 1, in which the unit? of remote antenna includes, for each of one or more? operators, a respective transmit and receive antenna coupled to a transmitter and a receiver with a switch, according to one embodiment.

DETAILED DESCRIPTION

[0032] ?Approximately?, ?substantially? and similar words, as used herein, indicate that a given quantity? b can? be within an interval b ?10% of b, or b ?1 if |10% of b| < 1. ?Approximately?, ?substantially? and similar words, as used herein, also indicate that an interval b ? can you? be between b ? 0.10(c ?b) and c 0.10(cb). What about flatness? of a surface or other region, "approximately", "substantially", and similar words, as used herein, mean that a difference in thickness between a point more high and a point more? bottom of the surface/region does not exceed 0.20 millimeters (mm).

[0033] As described above, figure 1? a diagram of a DAS 10, which is? coupled with one or more? 12 base stations and which includes one or more? unit? of remote antenna 14.

[0034] In one embodiment, one or more? of the units? remote 14 can? be configured to reduce, in one or more? receiving signals, interference caused by one or more? respective transmission signals towards the same antenna and caused by one or more? downlink signals coming from the antennas on the same unit? of remote antenna or on one or more? unit? of different remote antennas.

[0035] The units? Remote antenna arrays 14 of the (DAS) 10 are typically deployed within a facility (e.g., an office building, a warehouse, a shopping mall, a sports complex) or in or around an outdoor area (e.g. , a stadium, a city center, an outdoor event venue, a park, a beach) to provide wireless communication coverage, so? that people can use their wireless devices (e.g., smartphones, tablets, laptops), while inside the facility or in the outdoor area. Examples of the types of wireless coverage a DAS can? provide include Wi-Fi?, cellular service, and data service on one of several Long Term Evolution (LTE) frequency bands (for example, B1, B3, B7, B25, and B66). And the frequency range on which ? It is possible to configure the DAS 10?, for example, approximately 600 MHz - 71 GHz. For example, the DAS 10 can? be configured to operate in the 5GNR frequency band of approximately 3.4 GHz? 3.8GHz.

[0036] In addition to the units? of remote antenna 14, the DAS 10? coupled to, or includes, one or more? unit? master 18, one or which are communicatively coupled to the units? of remote antennas. Furthermore, in one embodiment, the DAS 10 includes a digital DAS, wherein the DAS traffic is distributed between one or more? unit? master 18 and the units? of 14 remote antennas in digital form. In other embodiments, the DAS 10 is implemented, at least in part, as an analog DAS, where the DAS traffic is ? distributed at least partly between one or more unit? master 18 and the units? of remote antenna 14 in analogue form.

[0037] Each unit? master 18? coupled in a communicative way also with one or more? base stations 12. One or more? of 12 base stations can be placed together with the respective unit? master 18 to which they are coupled (for example, where the base station 12 is dedicated to providing basic capacity to the DAS 10). Furthermore, one or more? of the 12 base stations can be located remotely from the respective unit? master 18 to which? coupled (for example, where base station 12 is a macro base station that provides base station capacity to a macro cell in addition to providing capacity to the DAS 10). In the latter case, a unit? master 18 can? be coupled to a donor antenna (not shown in figure 1) in order to communicate in wirelessly with the base station 12 located remotely. Furthermore, one or more? of one or more 12 base stations can each be paired to the unit? master 18 using a respective network of attenuators, combiners, separators, amplifiers, filters, units? of cross connection, etc., which respective network? named as a respective Point of Interface (POI) circuit 20. Ci? is carried out in such a way that, in the downward flow, the desired set of RF carriers emitted by one or more 12 base stations can be extracted, combined, and routed to the unit? master 18 is appropriate, and in such a way that, in the upward flow, the desired set of carriers emitted by the unit? master 18 can be extracted, combined, and forwarded to the appropriate interface of each base station.

[0038] One or more 12 base stations can each be implemented as respective traditional monolithic base stations. Furthermore, one or more 12 base stations can each be implemented using a distributed base station architecture in which one unit Base Band Unit (BBU) (not shown in Figure 1) ? coupled with one or more? unit? remote radio heads (RRH) (not shown in Figure 1), where the fronthaul between the BBU and the RRH uses digital IQ sample streams. Examples of this approach are described in the CPRI (Common Public Radio Interface) and OBSAI (Open Base Station Architecture Initiative) families of specifications, which are incorporated by reference herein.

[0039] One or more unit? master 18 can each be configured to use broadband interfaces or narrowband interfaces to one or more base stations 12. Furthermore, one or more? unit? master 18 can each be configured to interface with one or more? base stations 12 using analog radio frequency (RF) interfaces or digital interfaces (for example, using CPRI or OBSAI digital IQ interfaces).

[0040] Traditionally, each unit? master 18 interfaces with each base station 12 using analog radio frequency signals that each base station communicates to or from the user equipment (for example, smartphone, tablet, laptop) 22 using a suitable air interface standard. The DAS 10 serves as a distributed repeater for such radio frequency signals. The RF signals transmitted by each base station 12 (also referred to herein as "downlink RF signals") are received at one or more unit? master 18. Each unit? master 18 uses the downlink RF signals to generate a downlink transport signal that is distributed to one or more? of the units? of remote antenna 14. Each of these units? of remote antenna 14 receives the downlink transport signal and reconstructs a version of the downlink RF signals based on the downlink transport signal and does s? that the reconstructed downlink RF signals emanate from at least one antenna array 16 included in, or otherwise coupled to, that unit? of remote antenna.

[0041] A similar process is performed in the uplink direction. The RF signals transmitted by the user equipment 22 (also referred to herein as "uplink RF signals") are received at one or more unit? of remote antenna 14. Each unit? remote 14 uses uplink RF signals to generate an uplink transport signal that is transmitted from the unit? remote 14 to a unit? master 18. Each unit? master 18 receives uplink transport signals transmitted by one or more unit? remote 14 paired to it. The unit? master 18 combines data or signals transmitted via the uplink transport signals received at the unit? master and reconstructs a version of the uplink RF signals received at the units? remote 14. The unit? master 18 communicates the reconstructed uplink RF signals to one or more base stations 12. In this way, ? It is possible to expand the signal and communication coverage of one or more? 12 base stations using the DAS 10.

[0042] One or more? unit? intermediate units 24 (some of which are here called ?expansion units?) can be placed between one or more? unit? master 18 and one or more? unit? remote 14. There? can? be carried out, for example, to increase the number of units? remote 14 that a single unit? master 18 can? food, to increase the distance between units? master and unit? remote, and/or to reduce the quantity? of wiring necessary to couple a unit? master to their units? associated remotes.

[0043] As indicated above, the DAS 10 can? be implemented as a ?digital? DAS. In a "digital" DAS, the signals received from and delivered to one or more base stations 12 and user equipment 22 are used to produce digital in-phase (I) and quadrature (Q) samples, which are transmitted between one or more unit? master 18 and the units? remote 14. Note that this digital IQ representation of the original signals received from the base stations 12 and user equipment 22 still maintains the original modulation (i.e., the change in the amplitude, phase, or frequency of a carrier) used to convey telephony or data information according to the cellular air interface protocol used to communicate in cellular mode? wireless between one or more? base stations and user equipment. Examples of such cellular air interface protocols include, for example, 5GNR, Global System Mobile (GSM), Universal Mobile Telecommunications System (UMTS), and Long Term air interface protocols. Evolution (LTE). Additionally, each digital IQ sample stream represents or includes a portion of the wireless spectrum. For example, digital IQ samples may represent a single radio access network carrier (for example, a 5 MHz UMTS or LTE carrier) over which voice and data information has been modulated using the UMTS or LTE air interface. However, it must be understood that each of these flows can also represent multiple carriers (for example, in a frequency spectrum band or sub-band of a given frequency spectrum band).

[0044] Furthermore, one or more? of the units? master 18 can be configured to interface with one or more? base stations 12 using an analog RF interface (for example, a traditional monolithic base station 12 or via the analog RF interface of an RRH). As described above, one or more 12 base stations can be paired to the units? master 18 using a network of attenuators, combiners, separators, amplifiers, filters, units? cross connection, etc. (sometimes collectively referred to as ?interface point? or ?POI? 20). There? is carried out in such a way that, in the downward flow, the desired set of RF carriers emitted by one or more base stations 12 can be extracted, combined, and forwarded to the unit? master 18 is appropriate, and in such a way that, in the ascending flow, it is possible to extract, combine and route the desired set of units? of carriers emitted by the unit? master to the appropriate interface of each base station.

[0045] Each unit? master 18 can? produce digital IQ samples from a received analog wireless radio frequency (RF) signal by underconverting the received signal to an intermediate frequency (IF) or baseband, digitizing the underconverted signal to produce true digital samples, and digitally underconverting the true digital samples into to produce digital in-phase (I) and quadrature (Q) samples. These digital IQ samples can also be filtered, amplified, attenuated, and/or re-sampled or decimated at a faster rate. of lower sampling. Digital samples can be produced in other ways. Each digital IQ sample stream represents a portion of wireless radio frequency spectrum emitted by one or more? base stations 12. Each portion of the wireless radio frequency spectrum can? include, for example, a wireless spectrum band, a sub-band of a given wireless spectrum band, or a single wireless carrier.

[0046] Similarly, in the upward flow, each unit? master 18 can? produce an upstream analog wireless signal from one or more digital IQ sample streams received from one or more unit? of remote antennas 14 by digitally combining digital IQ sample streams representing the same carriers or frequency bands or sub-bands (e.g., digitally summing such digital IQ samples), digitally overconverting the combined digital IQ samples to produce actual digital samples , performing a digital-to-analog process on actual samples to produce an analog IF or baseband signal, and overconverting the analog IF or baseband signal to the desired RF frequency. Digital IQ samples can also be filtered, amplified, attenuated, and/or re-sampled or interpolated at a faster rate. of superior sampling, before and/or after being combined. Can the analog signal? be produced in other ways (for example, where digital IQ samples are fed to a quadrature digital-to-analog converter which directly produces the analog IF or baseband signal).

[0047] One or more? of the units? master 18 can? be configured to interface with one or more? base stations 12 using a digital interface (in addition to, or instead of) interfacing with one or more? base stations via an analog RF interface. For example, the unit? master 18 can? be configured to interact directly with one or more? BBU using the digital IQ interface which is used to communicate between the BBUs and an RRH (for example, using the CPRI serial digital IQ interface).

[0048] In the downward flow, each unit? master 18 ends one or more? descending streams of digital IQ samples supplied to it by one or more? BBU and, if necessary, converts them (by resampling, synchronization, combining, separation, gain adjustment, etc.) into descending streams of digital IQ samples compatible with the units? remote 14 used in DAS 10. In the upward flow, each unit? master 18 receives ascending streams of digital IQ samples from one or more unit? remote 14, digitally combining streams of digital IQ samples representing the same carriers or frequency bands or sub-bands (for example, digitally summing such digital IQ samples), and, if necessary, converting them (by resampling, synchronization, combining , separation, gain adjustment, etc.) in ascending streams of digital IQ samples compatible with one or more? BBUs that are coupled to that unit? master's degree.

[0049] Each unit? master 18 can? also be implemented in other ways.

[0050] In the downward flow, each unit? of remote antenna 14 receives streams of digital IQ samples coming from one or more? unit? master 18, wherein each digital IQ sample stream represents a portion of wireless radio frequency spectrum emitted by one or more? base stations 12.

[0051] Each unit? remote 14 ? coupled in a communicative way to one or more? unit? master 18 using, for example, one or more? optical fibers or cables, one or more? ETHERNET 26 compatible cables (for example, one or more CAT-6A cables), or any other suitable coupling means. For example, in this embodiment, each unit? remote 14 can? be connected directly to a unit? master 18 via a single ETHERNET 26 cable or indirectly via multiple ETHERNET 26 compatible cables as where a first ETHERNET cable connects the unit? remote to a patch panel or drive? expansion/intermediate cable 24 and a second fiber optic cable 28 connects the patch panel or the unit? of expansion/intermediate to the unit? master's degree. Each unit? remote 14 can? be paired with one or more? unit? master 18 in other ways. And the unit? master 18 or one or more? unit? expansion/intermediate 24 may include one or more? Power Supply Equipment (PSE) instances that are configured to provide power to the units? remote 14.

[0052] Figure 2? a diagram of a portion of a unit? of remote antenna 14 of figure 1, according to an embodiment in which the portion of the unit? of remote antenna includes one or more? interference reduction circuits. The word ?reduce? as used herein includes reducing interference to a non-zero value, as well as reduce the interference to approximately a value of zero, where the latter can? also be called ?elimination? of interference.

[0053] The unit? of remote antenna 14 includes one or more? transmitter circuits 40, an antenna array 42, a transmitter-receiver isolation circuit 44, an analog interference canceling circuit 46, a control circuit 48, a digital interference canceling circuit 50, and one or more receiver circuits 52. While the circuit diagram of FIG. 2 includes a single transmitter circuit 40 and a corresponding single receiver circuit 52, it is understood that the schematic circuit may be repeated for each additional interference-related pair of a corresponding transmitter circuit and receiver, except that, regardless of the number of transmitter circuits and receiver circuits 52, the unit? remote antenna array 14 may include a single antenna array 42 and a single control circuit 48. Additionally, the antenna array 42 includes a number of antennas 60. For a non-multiple-input, multiple-output configuration (non-MIMO, Multiple-Input-Multiple Output), each antenna 60 is operated, at any time, to transmit, to receive, or to both transmit and receive, a single downlink signal or a single uplink signal, and each antenna can include one or more? antenna elements configured to transmit or receive the same signal, but possibly with respective phase shifts or respective amplitude attenuations (for example, where the antenna is an in-phase array antenna). In a MIMO configuration, each group of multiple 60 antennas in the 42 antenna array? configured to transmit or receive a downlink signal or an uplink signal; during at least one transmission period in a MIMO configuration, each antenna in the multiple antenna group ? configured to transmit a respective separate component of the MIMO downlink signal. Furthermore, each transmitter circuit 40 can also be referred to as a downlink circuit, a downlink path, a transmission path, a partial transmitter, or the like; similarly, each receiving circuit 52 can? also be referred to as an uplink circuit, uplink path, receive path, partial receiver, or the like.

[0054] Each transmitter circuit 40 positioned on the unit? The remote antenna 14 includes a digital-to-analog converter (DAC) 54, frequency boosting circuitry 56, and a power amplifier 58. The DAC 54 is configured to receive a digital baseband information signal that a signal processing circuit (not shown in Figure 2) is integrated on the unit? of remote antenna 14 generates to include data (or other information) coming from a base station 12 (figure 1), and ? configured to convert the digital baseband information signal to an analog baseband information signal. The frequency boosting circuitry 56 ? configured to modulate a carrier signal with the analog signal, wherein the carrier signal has a carrier frequency that is within the frequency band (e.g., 3.4 GHz? 3.8 GHz) at which the DAS 10 (figure 1) operates according to its configuration. For example, the portion of each transmitter circuit 40 on the unit? of remote antenna 14 can? shift the respective DAC output signal up using a different carrier frequency within the same frequency band. And the 58 power amplifier? configured to amplify the modulated carrier signal to generate a transmit signal, and to operate one or more? antennas of the 42 antenna array with the broadcast signal. Note that the digital baseband information signal can include or modulate one or more? carrier signals; therefore, the carrier signal that the frequency boosting circuitry 56 can? use to shift up the DAC output signal (hereinafter called upshifted carrier signal) would be in addition to that other or more? carrier signals. Furthermore, the circuitry for transmitting a downlink signal can? be entirely included on the unit? of remote antenna 14 as transmitter circuit 40, or can? be included both on the unit? remote antenna either on the base station 12 or on the unit? master 18 (figure 1). Therefore, the transmitter circuit 40 can include the entire transmission circuitry, or can it? include only a portion of the transmission circuitry. In a related embodiment, transmitter circuit 40 implements a Digital Up-Conversion (DUC) DAC. In this embodiment, a digital upconverter (not shown in Figure 2) is located on the input side of the DAC 54, it receives a baseband IQ stream, digitally upconverts (upshifts) the IQ stream to a higher frequency band, and delivers the upshifted IQ stream to the DAC 54, which converts the upshifted IQ stream from a digital signal to an analog signal.

[0055] The antenna array 42 includes one or more 60 antennas, each of which ? configured to operate as both a transmit and receive antenna (other embodiments, such as one or more embodiments described below, may include one or more transmit antennas configured to transmit only, and one or more antennas configured to receive only). For example, the 42 antenna array can? be a multiple-input, multiple-output (MIMO) antenna array that includes two or more 60 antennas. Alternatively, the 42 antenna array can? include only a single antenna 60. Operating during a mode? of transmission, each antenna 60 of the array 42? configured to convert a transmission signal coming from a respective transmitter 40 into a respective downlink signal; that is, in response to being excited by a broadcast signal, each antenna emanates a respective downlink signal to, for example, the user equipment 22 of FIG. 1. Where the antenna array 42 is a MIMO array, the combination of signals emanating from the array's 60 antennas can? be considered a single downlink signal although, as described below, each MIMO component transmit signal is considered separately for interference cancellation purposes. During the mode? reception, each antenna 60 of the array 42 receives an uplink signal, for example from a user equipment 22 of figure 1, and converts the uplink signal into a respective reception signal. Where the 42 antenna array? a MIMO array, the combination of the signal components received from the antennas 60 of the array can? be considered a single uplink signal although, as described below, each MIMO component receive signal is processed by its own receiver circuit and is considered separately for interference cancellation purposes.

[0056] The transmitter-receiver isolation circuit 44 ? configured to reduce, in a reception signal coming from an antenna 60 of the antenna array 42, the interference caused by a transmission signal coming from the transmitter 40, in particular where the transmission signal and the reception signal are simultaneous, or otherwise overlap in time. Since? the transmission signal path along which the transmission signal propagates from the transmitter 40 to the antenna array 42 can? overlap, at least partially, with the receive signal path along which the receive signal propagates from the antenna array to the corresponding receiver 52, a portion, or component, of the transmit signal may ?disperse? in the receiving signal. And why? the transmission signal? usually considerably more? powerful reception signal, even with a small amount? of this dispersion the transmission signal can? ?submerge? the reception signal at the receiver 52. To limit this dispersion to a level that is acceptable for the application, the transmit-receive isolation circuit 44 is configured to electrically isolate the receiver circuit 52 from the transmitter circuit 42. For example, the transmit-receive isolation circuit 44 can provide, for example, approximately 10 dB? 20 dB more isolation than a conventional isolation circuit (for example, a circulator). Furthermore, one or more? parameters of the transmit-receive isolation circuit 44 may be adjustable by the digital interference canceling circuit 50, particularly when the transmit-receive isolation circuit and the digital interference canceling circuit are part of a control loop of closed feedback which works to reduce, to a minimum achievable level, the interference of the transmitter in the received signal. Additional embodiments of the transmit-receive isolation circuit 44 are described in detail below with Figures 7? 16.

[0057] The analog interference cancellation circuit 46 ? configured to further reduce, in a corresponding reception signal to the receiver circuit 52, the interference from a transmission signal coupled to the same antenna 60 which is configured to generate the receive signal. That is, the transmit-receive isolation circuit 44 and the analog interference canceling circuit 46 together can reduce the transmit interference in the receive signal to a level that is ? lower than the level of interference reduction that one of the two circuits 44 and 46 can? provide it yourself.

[0058] The analog interference cancellation circuit 46 can? be configured to provide a first order correction to the receive signal by removing, or otherwise canceling, from the receive signal a component of the transmit signal that the transmitter-receiver isolation circuit 44 allows to be dispersed in the receive signal. The analog interference canceling circuit 46 can carry out this first-order correction by generating, as an analog correction signal, an estimated first-order representation of the dispersed component of the transmission signal as it appears at the corresponding receiver circuit 52, and providing the analog correction signal to the receiver circuit, which is configured to reduce transmit interference by combining the correction signal with the receive signal. For example, the receiver circuit 52 can be configured to subtract the analog correction signal from the receive signal to remove, or otherwise cancel out, some or all of the stray transmit signal component from the received signal. Alternatively, the analog interference canceling circuit 46 can be configured to correct for anything other than the dispersion of the transmit signal into the receive signal. For example, if the impedance of the corresponding antenna 60 of the antenna array 42 is not ? well matched with the actual output impedance of the transmit-receiver isolation circuit 44, then this impedance mismatch can do s? that the antenna redirects a portion of the transmission signal, and, therefore, superimposes the redirected portion of the transmission signal on the reception signal. Furthermore, a portion of the downlink signal emanating from the antenna 60 of the array 42 in response to the transmit signal can be reflected by objects external to the unit? of remote antenna 14 back to the antenna. The analog interference canceling circuit 46, therefore, can be configured to generate the first-order analog correction signal also to take into account the redirected portion of the transmission signal and the redirected portion of the downlink signal superimposed on the reception signal at the antenna 60. Furthermore, the analog interference 46 can? include, or can? be part of, one or more? control loops configured to reduce transmit interference in the receive signal to a minimum achievable value. The analog interference canceling circuit 46 is further described below in connection with FIGS. 3? 6 and 17-19.

[0059] The control circuit 48 ? configured to control the operation of the analog and digital interference cancellation circuits 46 and 50, and can? also be configured to control the operation of one or more? different circuits integrated into the unit? of remote antenna 14. For example, the control circuit 48 can? be, or can? include, one or more? microprocessors or microcontrollers. Furthermore, the control circuit 48 can implement part or all? of one or both of the analog and digital interference canceling circuits 46 and 50. For example, the control circuit 48 can? include, or can? be placed on, or implemented by, a digital signal processor (DSP) or field programmable logic gate array (FPGA) that is configured to implement digital interference cancellation circuit 50.

[0060] The digital interference cancellation circuit 50? configured to further reduce, in a corresponding reception signal to the receiver circuit 52, the interference coming from a transmission signal coupled to the antenna which is configured to generate the receive signal. That is to say, the transmit-receive isolation circuit 44, the analog interference cancellation circuit 46, and the digital interference cancellation circuit 50 together can reduce the level of transmission interference in the receiving signal more? than one of the three circuits 44, 46, and 50 can alone.

[0061] The digital interference cancellation circuit 50 can? be configured to provide a first-order linear correction, and a nonlinear correction, to the receive signal by removing, or otherwise canceling, from the receive signal a component of the transmit signal that the transmitter-receiver isolation circuit 44 allows for disperse in the receiving signal.

[0062] The digital interference cancellation circuit 50 can? be configured to perform such first-order linear correction by generating, as a digital correction signal, an estimated first-order linear representation of the dispersed component of the transmission signal as the component occurs at the corresponding receiver circuit 52, and providing the digital correction signal to the receiver circuit, which is configured to reduce transmit interference by combining the correction signal with the receive signal. For example, the receiver circuit 52 can be configured to subtract the digital correction signal from the analog and digitized corrected receive signal to remove, from the receive signal, some or all of the stray component of the transmit signal that ?passes through? the isolation circuit 44 and which ?passes? for the analog interference canceling circuit 46. Alternatively, the digital interference canceling circuit 50 can? be configured to correct for anything other than the dispersion of the transmit signal into the receive signal. For example, the digital interference cancellation circuit 50 can be configured to generate the first order digital correction signal also to take into account the redirected portion of the transmission signal, and the redirected portion of the downlink signal, superimposed on the reception signal at the antenna 60 as described above in relation to the analog interference cancellation circuit 46.

[0063] The digital interference cancellation circuit 50 can? also be configured to perform a nonlinear correction by generating, as part of the digital correction signal, an estimated representation of the nonlinear dispersed components of the transmission signal as they occur at the corresponding receiver circuit 52. For example, one or more? between the DAC 54, the frequency boosting circuitry 56 and the power amplifier 58 of the transmitter 40 can introduce non-linear components, such as harmonic distortion, to the transmission signal. Such nonlinear components often give rise to a ?flanking? signal. manifesting as frequency sidebands that ?flank? the transmit signal and the corresponding downlink signal.

[0064] And the digital interference cancellation circuit 50 can? be configured to perform a nonlinear correction by generating, as part of the digital correction signal, an estimated representation of nonlinear components that the receiver 52 can introduce into the reception signal. For example, one or more? between the low-noise amplifier, frequency-stepping circuitry, and analog-to-digital converter (ADC), the receiver 52 can? introduce non-linear components, such as harmonic distortion, to the received signal. Such nonlinear components can combine with the nonlinear components of the transmission signal to form, at the output of the ADC receiver, the flanking signal described above.

[0065] Each receiver circuit 52 located on the unit? of remote antenna 14 ? configured to condition a receive signal from a respective antenna 60 of the antenna array 42, and provide the conditioned receive signal to the signal processing circuitry on the unit. of remote antenna 14, which signal processing circuitry? configured to provide the processed receive signal to a base station 12 (FIG. 1) of the DAS 10. The receiver circuit 52 includes a first signal combining circuit, for example, an adder, 62, a low noise amplifier (LNA, Low -Noise Amplifier) 64, a frequency step down circuitry 66, an ADC 68 and a second signal combining circuit, for example, an adder 70. The signal combining 62 is configured to combine the analog correction signal coming from the analog interference cancellation circuit 46 with the receiving signal coming from the respective antenna 60 of the antenna array 42; for example, the combinator 62 ? an adder configured to subtract the analog cancel signal from the receive signal. The LNA 64? configured to amplify the receive signal with single correction, and the frequency lowering circuitry 66 ? configured to downshift the single-corrected receive signal to a baseband frequency range. The ADC 68? configured to convert the analog baseband receive signal to a digital baseband receive signal, and the combiner 70? configured to combine the digital correction signal from the digital interference canceling circuit 50 with the single correction digital receive signal; for example, the combiner 70 ? an adder that? configured to subtract the digital correction signal from the single correction digital receive signal to generate a double correction digital receive signal. And the signal processing circuitry built into the unit? of remote antenna 14 or elsewhere (for example, in the master unit 18, in a base station 12 of figure 1)? configured to convert the double-corrected digital receive signal into a number of modulated subcarriers from which the signal processing circuitry ? configured to recover the data carried by the received signal. The signal processing circuitry can include error correction circuitry and other circuitry to perform data recovery. Furthermore, the circuitry for receiving an uplink signal can? be entirely included on the unit? of remote antenna 14 as receiver circuit 52 or can? be included both on the unit? remote antenna either on the base station 12 or on the unit? master 18 (figure 1). Therefore, the receiver circuit 52 can include the receiving circuitry in its entirety or can? include only a portion of the receiving circuitry.

[0066] Referring again to figure 2, the operation of the unit is described. of remote antenna 14 according to an embodiment in which the unit? remote antenna transmits a downlink signal with a 60 antenna at the same time as the unit? remote antenna receives an uplink signal with the same antenna.

[0067] A base station 12 (figure 1) sends a signal to the signal processing circuitry (not shown in figures 1-2) integrated into the unit? master 18 or in the unit? of remote antenna 14, and the signal processing circuitry modulates one or more? baseband carrier frequencies with data in the digital domain, and generates, from one or more? modulated carrier frequencies, a digital time domain signal. For example, signal processing circuitry can use sixteen or sixty-four quadrature amplitude modulation (16-QAM, 64-QAM) to modulate the baseband carriers. Alternatively, base station 12 performs this modulation.

[0068] Next, the DAC 54 converts the digital time domain signal from the signal processing circuitry into an analog time domain signal.

[0069] Next, the frequency boost circuitry 56 shifts the analog time domain signal up in frequency to the broadcast frequency band (e.g., 3.4 GHz? 3.8 GHz) for which ? configured the unit? of remote antenna 14. The frequency boosting circuitry 56 can? perform this frequency raising in any suitable way, for example by modulating a carrier signal with the analog time domain signal.

[0070] Next, power amplifier 58 amplifies the frequency-shifted analog time domain signal (e.g., amplifies the modulated carrier signal) to generate the transmit signal.

[0071] Next, the transmit-receiver isolation circuit 44 matches the transmit signal to the antenna 60 while reducing the magnitude of a component of the transmit signal that ?leaks out? in the receiver circuit 52.

[0072] Next, in response to being excited by the broadcast signal, the antenna 60 emanates a downlink signal which includes the data in the broadcast signal.

[0073] Although the antenna 60 is emanating the downlink signal, the control circuit 48 controls the analog and digital interference cancellation circuits 46 and 50 to generate, respectively, an analog correction signal and a digital correction signal. The analog interference cancellation circuit 46 generates the analog correction signal from, or in any case in response to, the transmission signal, and the digital interference cancellation circuit 50 generates the digital correction signal from, or in any case in response to, the signal of digital time domain from the signal processing circuitry. Furthermore, the control circuit 48 can control the digital interference cancellation circuit 50 to generate a regulation signal that makes s? that the transmitter-receiver isolation circuit 44 reduces the dispersion of the transmission signal towards the receiver 52 to a minimum achievable level. For example, the digital interference cancellation circuit 50 can be coupled to the receiver 52 in a control loop configuration, it can monitor a level of the transmit dispersion component in the receive signal or in a signal derived from it, can? dither the adjustment signal to determine the minimum achievable level of transmit signal leakage into the receive signal or a signal derived from it, and then can? set an adjustment signal value to keep the transmit signal leakage level at or close to the determined minimum achievable level.

[0074] The antenna 60 also receives an uplink signal while emanating the downlink signal and converts the uplink signal into a receive signal.

[0075] Signal combiner 62 combines the analog correction signal with the receive signal to generate a single correction receive signal. For example, if the signal combiner 62 ? an adder, then the adder subtracts the analog correction signal from the receive signal to generate the double-corrected receive signal.

The low-noise amplifier 64 amplifies the single-corrected receive signal, and the frequency step-down circuitry 66 frequency-shifts (e.g., demodulates) the single-corrected receive signal to a domain receive signal of analog time.

[0077] The ADC 68 converts the analog time domain receive signal to a digital time domain receive signal.

[0078] The signal combiner 70 combines the digital correction signal with the digital time domain receive signal to generate a double corrected digital time domain receive signal. For example, adder 70 subtracts the digital correction signal from the digital time domain receive signal to generate a double corrected digital time domain receive signal.

[0079] The signal processing circuitry (not shown in FIG. 2) decomposes the double-corrected digital time domain receive signal into its data-modulated frequency components, and recovers, from the data-modulated frequency components, the data carried by the uplink signal.

[0080] The reduction of first-order linear transmit interference and nonlinear transmit interference in data-modulated frequency components, as offered by the transmitter-receiver isolation circuit 44 and the analog and digital interference cancellation circuits 46 and 50, typically allows signal processing circuitry (not shown in FIG. 2) to recover data more efficiently. accurate than the signal processing circuitry would do if the isolation circuitry and interference cancellation circuitry were omitted from the unit? of remote antenna 14.

[0081] Referring again to figure 2, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, one or two of the transmitter-receiver isolation circuit 44, the analog interference canceling circuit 46 and the digital interference canceling circuit 50 can be omitted from the unit. of remote antenna 14. Furthermore, the control circuit 48 can? including, or otherwise implementing, the digital interference canceling circuit 50; for example, the control circuit can? be a microprocessor, a microcontroller, an FPGA, or a combination or subcombination of a microprocessor, microcontroller, and FPGA, configured to implement the function and operation of the digital interference canceling circuit. Additionally, analog and digital interference canceling circuits 46 and 50 may incorporate circuitry, or implement techniques, described in one or more? of the following references, which are incorporated herein by reference: US Patent Publication 2017/0170903 to Jain et al., US Patent 9,698,861 to Braithwaite, US Patent 10,020,837 to Braithwaite, Full Duplex Radios, Bharadia et al. (2013), and IEEE 802,11-18/0191r0. In addition, each of the analog and digital interference canceling circuits 46 and 50 can incorporate circuitry that ? a modified version of the circuitry described in one or more? of the aforementioned references, and can? implement one or more? techniques that are each a modified version of a technique described in one or more? of the aforementioned references. Furthermore, the portion of the transmitter circuit 40 located on the unit? of remote antenna 14 can? be modified from what is described. For example, the frequency boosting circuitry 56 can be omitted, and the unit? of base 12, the unit? master 18, or the transmitter circuit 40 can carry out all the frequency raising before the DAC 54, which is configured to generate, and provide to power amplifier 58, the frequency-shifted analog time domain signal. Or, the DAC 54 can? be configured to perform some or all of the frequency boosting of the analog time domain signal. For example, the DAC 54 and the frequency boosting circuitry 56 may be combined into a DAC frequency boosting circuit. Furthermore, the portion of the receiver circuit 42 located on the unit? of remote antenna 14 can? be modified from what is described. For example, the frequency step-down circuitry 66 can be omitted, and the ADC 68, the unit? of base 12, the unit? master 18, or a combination or subcombination thereof, can perform all the frequency lowering of the signal coming from the low noise amplifier 64 to generate a downwardly shifted digital receive signal. For example, the ADC 68 and the frequency droop circuitry 66 may be combined into an ADC frequency droop circuit. In addition, the topologies (e.g., the order of series-coupled components) of the portions of the transmitter circuit 40 and the receiver circuit 52 located on the unit? of remote antenna 14 can be arranged in any suitable configuration. Furthermore, in the receiver circuit 52, the LNA 64 can be placed between the transmitter-receiver isolation circuit 44 and the adder 62 instead of? be placed between the adder and the frequency droop circuitry 66, there may be multiple series-coupled LNAs, and other circuit topologies are contemplated. Furthermore, although described as operating in open loop, the analog interference cancellation circuit 46 can? operate in mode? closed cycle, or in mode? both open cycle and closed cycle, also having one or more? open loops and closed loops operating simultaneously. Similarly, although described as operating in open-loop and closed-loop, the 50 digital interference cancellation circuit can? operate only in one or more? mode? closed cycle or only in one or more? mode? open cycle. In addition, the embodiments described above in relation to Figure 1 or below in relation to Figures 3? 19 may be applicable to the unit? of remote antenna 14 of figure 2.

[0082] Figure 3? a diagram of the unit? of remote antenna 14 of Figure 1, and of the analog and digital interference cancellation circuits 46 and 50, according to one embodiment. In figure 3, do the same numbers refer to elements common to figures 1? 3.

[0083] The analog interference cancellation circuit 46 includes a finite-impulse-response (FIR) filter 80, which includes one or more filter paths 821 ? 82n and a signal combiner 84, for example, an adder.

[0084] Each filter path 82 includes a respective delay circuit 86, a respective phase shift circuit 88, and a respective gain circuit 90. The respective delay gives each delay circuit 86 ? configured to apply to the transmit signal pu? be determined and set in advance in response to any suitable calculation algorithm or during a calibration procedure that takes place while the unit? of remote antenna 14 is not used to transmit or receive downlink and uplink signals. Alternatively, the respective delay d pu? be adjusted dynamically by one or more? control cycles integrated into the unit? of remote antenna 14. Similarly, the respective phase shift ps and the respective gain at which each phase shift circuit 88 and amplifier circuit 90 ? respectively configured to impart to the delayed transmit signal, may be determined and set in advance in response to any respective suitable calculation algorithm or during a respective calibration procedure that takes place while the unit is of remote antenna 14 is not used to transmit or receive downlink and uplink signals. Alternatively, each of the phase shifts ps and respective gains a can be dynamically adjusted by one or more control cycles integrated into the unit? of remote antenna 14. Furthermore, the respective gain a of each amplifier 90 can? be less than, equal to, or greater than one.

[0085] The combinational circuit 84 ? configured to generate the analog correction signal in response to the output signals from the 821 paths? 82n. For example, when the combinator 84 ? an adder, the combinator? configured to generate the analog correction signal equal to the sum of the output signals from the paths 821 ? 82n.

[0086] Referring again to Figure 3, the digital interference cancellation circuit 50 includes a linear distortion estimation circuit 92, a nonlinear distortion estimation circuit 94, a signal combining circuit 96, and a circuit controller of isolation 98.

[0087] The linear distortion estimation circuit 92 ? configured to generate a first-order linear correction signal in response to the digital time domain signal from the signal processing circuitry, and the nonlinear distortion estimation circuit 94? configured to generate a nonlinear correction signal in response to the same digital time domain signal.

[0088] The signal combining circuit 96 ? configured to generate the digital correction signal in response to first-order linear and nonlinear correction signals; for example, where the signal combiner 96 ? an adder, the signal combiner? configured to generate the digital correction signal equal to the sum of the first-order linear and nonlinear correction signals.

[0089] And the isolation circuit controller 98? configured to generate, in response to first-order linear and nonlinear correction signals, a control signal to adjust one or more isolation characteristics or parameters of the transmitter-receiver isolation circuit 44.

[0090] Referring again to figure 3, the operation of the unit is described. of remote antenna 14 according to an embodiment in which the unit? remote antenna transmits a downlink signal with a 60 antenna at the same time as the unit? remote antenna receives an uplink signal with the same antenna.

[0091] The unit? of remote antenna 14 operates as described above in relation to figure 2 and performs the following operations in addition to the operations described above in relation to figure 2, or in place of one or more? of the operations described above in relation to figure 2.

[0092] The analog interference canceling circuit 46 operates as follows.

[0093] Each delay circuit 86 imparts a respective delay d to the transmission signal coming from the transmitter 40.

[0094] Each phase shift circuit 88 imparts a respective phase shift ps to the delayed transmit signal from the respective delay circuit 86 in the same path 82.

[0095] Each amplifier circuit 90 amplifies or attenuates, by a respective gain a, the phase-shifted and delayed transmission signal from the respective phase-shift circuit 88.

[0096] The signal combiner 96 generates the digital correction signal in response to the amplified or attenuated, phase-shifted and delayed versions of the transmit signal output by the amplifiers 901 ? 90n. For example, where the signal combiner 96 ? an adder, then the signal combiner generates the digital correction signal equal to the sum of the amplified or attenuated, phase-shifted, and delayed versions of the transmit signal output by the amplifiers 901 ? 90n.

[0097] And the digital interference canceling circuit 50 operates as follows.

[0098] The unit? The linear distortion estimator 92 generates a linear correction signal in response to the digital time domain signal from the signal processing circuitry, which is not ? illustrated in figure 3 but ? integrated into the unit or not? antenna remote 14.

[0099] The unit? The nonlinear distortion estimator 94 generates a nonlinear correction signal in response to the digital time domain signal.

[00100] The signal combiner circuit 96 generates the digital correction signal in response to the linear and non-linear correction signals coming from the units respectively. of estimates 92 and 94. For example, if the signal combiner 96 is an adder, then the signal combiner generates the digital correction signal equal to the sum of the linear and nonlinear correction signals.

[00101] Furthermore, the isolation loop controller 98 generates, in response to the first-order linear and nonlinear correction signals, a control signal to adjust one or more isolation characteristics or parameters of the transmitter-receiver isolation circuit 44. For example, the controller 98 can? dither the control signal to determine, and maintain, the transmitter-receiver isolation circuit 44 operational, at a point at which the transmitter-receiver isolation circuit 44 achieves the maximum level of isolation between the transmitter circuit 40 and the receiver circuit 52, and therefore achieves the highest level? low dispersion of the transmission signal in the reception signal.

[00102] Referring again to figure 3, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, each of one or more? of the paths 82 of the analog interference cancellation circuit 46 can? do not present a?unit? of phase shift 88. Furthermore, the digital interference cancellation circuit 50 can? do not present the isolation circuit controller 98. Furthermore, the analog interference cancellation circuit 46 can? include circuitry as described in Full Duplex Radio, Bharadia et al., which is incorporated herein by reference, or may include the described circuitry modified for inclusion in a unit? of remote antenna 14 configured to operate in one mode? TDD. Similarly, the digital interference canceling circuit 50 can include circuitry described in Full Duplex Radio, Bharadia et al., or can? include the described circuitry modified for inclusion in a unit? of remote antenna 14 configured to operate in one mode? TDD. Additionally, the circuitry on the unit? of remote antenna 14 can? notify one or more? base stations 12 (figure 1) that the transmitter circuit 40 is generating a transmission signal while the antenna 60 is receiving an uplink signal so that one or more base stations can coordinate the transmitter circuit's generation of the transmitter signal so that it does not coincide with the reception of an uplink signal by the antenna 60. Furthermore, embodiments described above in relation to Figures 1? 2 or below in relation to figures 4? 19 may be applicable to the unit? of remote antenna 14 of figure 3.

[00103] Figure 4? a diagram of the unit? of remote antenna 14 of figure 1, according to an embodiment in which the unit? of remote antenna? configured to reduce, in a reception signal generated by an antenna 601 of the antenna array 42, transmission interference coming from one or more other 602 antennas? 60n of the same antenna array. In figure 4, do the same numbers refer to elements common to figures 1? 4.

[00104] In addition to the transmitter circuit 401, which is similar to the transmitter circuit 40 of figures 2? 3, the unit? of remote antenna 14 includes one or more? other 402 transmitter circuits ? 40n, which are each coupled to a respective 602 antenna? 60n of the antenna array 42, but which are otherwise similar to the transmitter circuit 401.

[00105] In addition to the transmitter-receiver isolation circuit 441, which is similar to the transmitter-receiver isolation circuit 44 of Figures 2? 3, the unit? of remote antenna 14 includes one or more? other transmitter-receiver isolation circuits 442 ? 44n, which are each coupled between a respective one of the transmitter circuits 402? 40n and a respective of the 602 antennas? 60n, but which are otherwise similar to the 441 transmitter-receiver isolation circuit.

[00106] And in addition to the receiver circuit 521, which is similar to the receiver circuit 52 of Figures 2? 3, the unit? of remote antenna 14 includes one or more? other 522 receiver circuits ? 52n (not shown in FIG. 4), which are each coupled to a respective of the other antennas 602 ? 60n of the antenna array 42, but which are otherwise similar to the receiver circuit 521.

[00107] If the antenna 601 is receiving an uplink signal at the same time as one or more of the other 602 antennas? 60n is emitting respective signals in downlink, since? a downlink signal? usually much more? powerful signal in the uplink, one or more? downlink signals ?overwhelm? the uplink signal, so that the reception signal generated by the 601 antenna will include? a transmission interference that is? much more? powerful of the receiving signal component corresponding to the received uplink signal.

[00108] Therefore, the analog interference cancellation circuit 46 is not ? only configured to reduce, in the reception signal coming from the antenna 601, the transmission interference coming from the transmission signal generated by the transmitter circuit 401, but? also configured to reduce transmission interference from downlink signals transmitted by one or more other 602 antennas? 60n. The analog interference cancellation circuit 46 therefore includes a respective drive circuit. of analog cancellation 1021 ? 102n for each transmitter circuit 401 ? 40n for example, each unit circuit? of analog cancellation can? be equal to the FIR filter 80 of figure 3. Each unit circuit? of analog cancellation 1021 ? 102n ? configured to generate a respective component of the analog correction signal, and a signal combiner circuit 104 ? configured to generate the analog correction signal in response to the components. For example, if the signal combiner 104 ? an adder, then the signal combiner generates the analog correction signal equal to the sum of the component signals coming from the unit circuits? of analog cancellation 1021 ? 102n.

[00109] Similarly, the digital interference cancellation circuit 50 is not ? only configured to reduce, in the reception signal coming from the antenna 601, the transmission interference coming from the transmission signal generated by the transmitter circuit 401, but? also configured to reduce transmission interference from downlink signals transmitted by one or more other 602 antennas? 60n in the same antenna array 42 to which the antenna 601 belongs. The digital interference canceling circuit 50, therefore, includes a respective circuit of of digital cancellation 1061 ? 106n for each transmitter circuit 401 ? 40n for example, each unit circuit? of digital cancellation can? include a respective unit? of linear distortion estimate 92, a respective unit? of nonlinear distortion estimation 94 and a respective signal combiner 96 arranged as illustrated in figure 3. Each unit circuit? of digital cancellation 106 ? configured to generate a respective component of the digital correction signal, and a signal combiner circuit 108 ? configured to generate the digital correction signal in response to the components. For example, if the signal combiner 108 ? an adder, then the signal combiner generates the digital correction signal equal to the sum of the component signals coming from the unit circuits? of digital cancellation 1061 ? 106n. Furthermore, the isolation circuit controller 98 generates the control signal for the transmitter-receiver isolation circuit 441 in response to the component signals from the drive circuits. of digital cancellation 1061 ? 106n, or by the signals emitted by the respective units? of linear and nonlinear distortion estimation 92 and 94 of each of the unit circuits? of digital cancellation.

[00110] Referring again to figure 4, the operation of the unit? of remote antenna 14 while each or more? of the 401 transmitter circuits ? 40n generates a respective transmit signal at the same time as the antenna 601 receives an uplink signal, ? similar to the operation described above in relation to figure 2, and can? also be similar to the operation described above in relation to figure 3, with the addition of the following operations, or with one or more? of the following operations in replacement of one or more? operations described above in relation to figures 2? 3.

[00111] The analog interference canceling circuit 46 generates the analog correction signal in response to each of the one or more? transmission signals generated by a respective of the transmitter circuits 401 ? 40n.

[00112] The digital interference cancellation circuit 50 generates the digital correction signal and the isolation control signal, in response to the one or more digital time domain signals generated respectively by the signal processing circuitry.

[00113] Although not illustrated, the analog interference canceling circuit 46 includes a respective set of units cancellation circuits 102 for each of the other receiver circuits 522 ? 52n, in which each set of units? of analogue cancellations? similar in terms of topology and operation to the set of units? of analogue cancellations 1021? 102n.

[00114] Similarly, although not illustrated, the digital interference canceling circuit 50 includes a respective set of units cancellation circuits 106 for each of the other receiver circuits 522 ? 52n, in which each set of units? of digital cancellations? similar in terms of topology and operation to the set of units? of digital cancellations 1061 ? 106n. And, although not illustrated, the digital interference canceling circuit 50 includes a respective isolation circuit controller 98 for each of the other transmitter-receiver isolation circuits 442 ? 44n, where each isolation loop controller is ? Similar in topology and operation to the 98 Isolation Loop Controller.

[00115] Referring again to Figure 4, in an alternative embodiment, instead of, or in addition to, the reduction of transmission interference in the receive signal, the unit? of remote antenna 14 includes circuitry that is configured to detect that each of one or more? of the 401 transmitter circuits ? 40n is generating a respective transmit signal while each of one or more? receiver circuits 52 is receiving a receive signal, and ? configured to take a corresponding action in response to such detection. In other words, the unit? of remote antenna 14 includes circuitry that is configured to detect that each of one or more? of the 601 antennas? 60n is transmitting a respective downlink signal while at least one of the antennas is also receiving an uplink signal. For example, the unit? of remote antenna 14 can? be configured to send an alert to one or more? of the base stations 12 (figure 1) relating to the fact that the unit? remote antenna is undergoing simultaneous downlink transmission and uplink reception; in response to the notice, one or more? base stations can coordinate downlink signal transmissions from the unit? remote antenna with reception of uplink signals from the unit? remote antenna to reduce, or eliminate, simultaneous transmission and reception by the unit? remote antenna. Or, the unit? of remote antenna 14 can? do s? that each of one or more? of transmitter-receiver isolation circuits 441 ? 44n decouples the respective transmission signal from the respective antenna 601 ? 60n while each of one or more? of the antennas is receiving an uplink signal. Since? this last action can? cause data loss, the drive? of remote antenna 14 ? also configured to warn one or more? base stations 12 of one or more? decoupled transmission signals so that one or more? base stations can resend blocked, or otherwise lost, data for retransmission.

[00116] Referring again to figure 4, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, the embodiments described above in relation to Figures 1 ? 3 or below in relation to figures 5? 19 may be applicable to the unit? of remote antenna 14 of figure 4.

[00117] Figure 5? a diagram of the unit? of remote antenna 14 of figure 1, according to an embodiment in which the unit? of remote antenna? configured to reduce, in a reception signal generated by the antenna 601 of the antenna array 42, a transmission interference coming from one or more other antennas on one or more? other units? of remote antenna. In figure 5, do the same numbers refer to elements common to figures 1? 5.

[00118] In addition to the transmitter circuit 401 and the antenna 601, the unit? of remote antenna 14 includes one or more? 1201 "sniffer" antennas? 120m and one or more? corresponding "sniffer" receiver circuits 1221 ? 122m. As described above in relation to figure 4, the unit? of remote antenna 14 can? also include one or more? other 402 transmitter circuits ? 40n, one or more? other transmitter-receiver isolation circuits 442 ? 44n, one or more? other 522 receiver circuits ? 52one or more? other 602 antennas? 60n (these other transmitter circuits, other transmitter-receiver isolation circuits, other receiver circuits, and other antennas are omitted from Figure 5 for clarity).

[00119] If, while the antenna 601 is receiving an uplink signal, each of one or more? antennas on one or more? other units? of remote antenna 14 (the other remote antenna units not shown in figure 5) is transmitting a respective signal in downlink, since? a downlink signal (also coming from another nearby remote antenna unit) is usually much more? powerful signal in the uplink, one or more? downlink signals will ?overwhelm? the uplink signal so that the reception signal generated by the 601 antenna will include? a transmission interference that is? much more? powerful of the receiving signal component corresponding to the received uplink signal.

[00120] Since? the antennas 60 on the unit? of remote antenna 14 (not shown in FIG. 5) are typically directional at frequencies used in cellular wireless communications, each sniffer antenna 1201 ? 120m can? have a respective orientation that increases the effective gain of the sniffer antenna compared to a respective antenna 60 on another unit? of remote antenna. For example, a DAS 10 installer (figure 1) can orient each of the 1201 sniffer antennas? 120m in response to the position of a respective unit? of nearby remote antenna such that a main beam of the sniffer antenna is directed towards one or more? antennas on the other unit? of the remote antenna.

[00121] Each sniffer antenna 1201 ? 120m? configured to receive, from a respective other unit? of remote antenna 14 (the other remote antenna units not shown in figure 5), one or more? respective downlink signals that are interfering with the uplink signal received by the 601e antenna, to generate, in response to the one or more? received downlink signals, a respective sniffer read signal.

[00122] Each sniffer receiver 1221 ? 122m ? configured to convert the respective sniffer readout signal into a corresponding amplified sniffer readout signal suitable for input to the analog interference canceling circuit 46, and into a digital time domain sniffer signal suitable for input to the digital interference cancellation circuit 50. Each 1221 sniffer receiver ? 122m includes a respective LNA 124, a respective frequency droop circuit 126, and a respective ADC 128, which may be respectively similar to the LNA 641, the frequency droop circuit 661, and the ADC 681 of the receiver 521; Combining the LNA 641 and 124, the frequency-stepping circuits 661 and 126, and the ADCs 681 and 128 can increase the level of transmission interference reduction that the digital interference-cancelling circuit 50 can. supply. For example, this combination can be achieved by placing the LNA 641 and 124, the frequency droop circuits 661 and 126, and the ADCs 681 and 128 on the same integrated matrix.

[00123] Therefore, the analog interference cancellation circuit 46 is not ? only configured to reduce, in the reception signal coming from the antenna 601, a transmission interference coming from the transmission signal generated by the transmitter circuit 401, but ? also configured to reduce transmission interference from one or more downlink signals transmitted by one or more? other antennas 60 on one or more? other units? of remote antenna 14 (other remote antenna 14 units not shown in Figure 5). The analog interference cancellation circuit 46 therefore includes a respective drive circuit. of analog cancellation 1301 ? 130m for each 1221 sniffer receiver circuit? 122m, as well as including a circuit of units? of analog cancellation 130m+1 for the transmitter circuit 401. For example, each unit circuit? of analog cancellation 1301 ? 130m+1 can? be equal to the FIR filter 80 of figure 3. Each unit circuit? of analog cancellation 1301 ? 130m+1 ? configured to generate a respective component of the analog correction signal, and the signal combiner circuit 104 is configured to generate the analog correction signal in response to these components. For example, if the signal combiner 104 ? an adder, then the signal combiner? configured to generate the analog correction signal equal to the sum of the component signals from the unit circuits? of analogue cancellations 1301 ? 130m+1.

[00124] Similarly, the digital interference canceling circuit 50 is not ? only configured to reduce, in the reception signal coming from the antenna 601, a transmission interference coming from the transmission signal generated by the transmitter circuit 401, but ? also configured to reduce transmission interference from downlink signals transmitted by one or more other antennas 60 on one or more? other units? remote antenna unit 14 (other remote antenna units not shown in Figure 5). The digital interference cancellation circuit 50 therefore includes a respective drive circuit. of digital cancellation 1321 ? 132m for each sniffer receiver circuit 1221 ? 122m, and a circuit of units? digital cancellation 132m+1 for the 401 transmitter circuit; for example, each unit circuit? of digital cancellation can? include a respective unit? of linear distortion estimate 92, a respective unit? of nonlinear distortion estimation 94, and a respective signal combiner 96 arranged as illustrated in Figure 3. Each unit circuit? of digital cancellation 1321 ? 132m+1 ? configured to generate a respective component of the digital correction signal, and the signal combiner circuit 108 is configured to generate the digital correction signal in response to these components. For example, if the signal combiner 108 ? an adder, then the signal combiner? configured to generate the digital correction signal equal to the sum of the component signals coming from the unit circuits? of digital cancellation 1321 ? 132m+1. Furthermore, the isolation circuit controller 98 ? configured to generate the control signal for the transmitter-receiver isolation circuit 441 in response to component signals from the drive circuits. of digital cancellations 1321 ? 132m+1, or from the signals emitted by the respective units? of linear and nonlinear distortion estimation 92 and 94 of each of the unit circuits? of digital cancellation.

[00125] Referring again to figure 5, the operation of the unit? of remote antenna 14 while each of one or more? antennas 60 on one or more? other units? of nearby remote antenna units (the other remote antenna units not shown in Figure 5) is emanating a respective downlink signal at the same time that the antenna 601 is receiving an uplink signal, ? similar to the operation described above in relation to figure 2, and can? also be similar to the operation described above in relation to figures 3-4, but with the following operations in addition to the operations described above, or instead of one or more? of the operations described above.

[00126] The analog interference canceling circuit 46 generates the analog correction signal in response to the transmit signal generated by the transmitter circuit 401 and in response to each of the one or more? amplified sniffer reception signals generated by a respective LNA 124 of each of one or more? of the 1221 sniffer receiver circuits? 122m.

[00127] The digital interference canceling circuit 50 generates the digital correction signal and the isolation control signal in response to the digital time domain signal from the signal processing circuitry to the transmitter circuit 401 and in response to each of one or more? digital time domain signals generated by a respective ADC 128 of each of one or more? of the 1221 sniffer receiver circuits? 122m.

[00128] Although not illustrated, the analog interference canceling circuit 46 includes a respective set of units cancellation circuits 130 for each of the other receiver circuits 522 ? 52n (not shown in figure 5), where each set of units? of analogue cancellations can? be similar in terms of topology and operation to the set of units? of analogue cancellations 1301 ? 130m+1.

[00129] Similarly, although not illustrated, the digital interference canceling circuit 50 includes a respective set of units cancellation circuits 132 for each of the other receiver circuits 522 ? 52n (not shown in figure 5) where each set of units? of digital cancellations can? be similar in terms of topology and operation to the set of units? of digital cancellations 1321 ? 132m+1. And, although not illustrated, the digital interference canceling circuit 50 includes a respective isolation circuit controller 98 for each of the other transmitter-receiver isolation circuits 442 ? 44n (not shown in Figure 5), where each isolation loop controller is ? similar in topology and operation to the isolation loop controller 98 illustrated, and described above in connection with FIG. 3.

[00130] Referring again to Figure 5, in an alternative embodiment, instead of, or in addition to, reducing transmission interference in the receive signal from antenna 601, the unit of remote antenna 14 includes circuitry that is configured to detect that each of one or more? of the 1221 sniffer circuits? 122m is receiving a readout signal from a respective of the 1201 sniffer antennas? 120m while each of one or more? of the receiver circuits 521 ? 52n is receiving a receive signal, and takes action in response to that detection. In other words, the unit? of remote antenna 14 includes circuitry that is configured to detect that each of one or more? of the antennas 60 on one or more? other units? of nearby remote antennas (the other remote antenna units not shown in Figure 5) are transmitting a respective downlink signal while at least one of the 601 antennas is 60n integrated into the unit? of remote antenna 14 is receiving an uplink signal, and to take action in response to such detection. For example, the unit? of remote antenna 14 can? be configured to alert one or more? of the 12 base stations (figure 1) that the unit? remote antenna is undergoing simultaneous downlink transmission and uplink reception; in response to the notice, one or more? base stations can coordinate the transmissions of downlink signals by other units? of remote antennas with reception of uplink signals by the unit? remote antenna to reduce, or eliminate, simultaneous transmission and reception by multiple units? of remote antennas in the same general location or in the ?neighborhood?. Or, the unit? of remote antenna 14 can? do s? that each of one or more? of transmitter-receiver isolation circuits 441 ? 44n decouples the respective receiving circuits 521 ? 52n from the respective 601 antennas? 60n while each of one or more? some antennas are receiving an uplink signal. Since? this last action can? cause the loss of uplink data coming from one or more? of the user equipment 22 (figure 1), the unit? of remote antenna 14 can? also be configured to alert one or more? of user equipment 22 of one or more? decoupled uplink signals so that one or more? user equipment can send the blocked data back to the drive? remote antenna unit (or to another remote antenna unit).

[00131] Referring again to figure 5, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, the embodiments described above in relation to Figures 1 ? 4 or below in relation to figures 6? 19 may be applicable to the unit? of remote antenna 14 of figure 5.

[00132] Figure 6? a diagram of the unit? of remote antenna 14 of figure 1, according to an embodiment in which the unit? of remote antenna? configured to reduce, in a reception signal generated by the antenna 601 of the antenna array 42, a transmission interference coming from one or more other 602 antennas? 60n of the antenna array, and transmission interference coming from one or more? other antennas on one or more? other units? antenna units (other remote antenna units not shown in figure 6). Therefore, in practice, the unit? of remote antenna 14 of figure 6? a combination of the units? of remote antenna 14 of figures 4 and 5. In figure 6, equal numbers refer to elements common to figures 1? 6.

[00133] In addition to the transmitter circuit 401, the unit? of remote antenna 14 includes one or more? other 402 transmitter circuits ? 40n (only transmitter circuits 401 and 40n illustrated in FIG. 6), which are each coupled to a respective antenna 602? 60n (only the antennas 601 and 60n illustrated in FIG. 6) of the antenna array 42, but which are otherwise similar to the transmitter circuit 401.

[00134] Furthermore, in addition to the transmitter-receiver isolation circuit 441, the unit? of remote antenna 14 includes one or more? other transmitter-receiver isolation circuits 442 ? 44n (only the transmitter-receiver isolation circuits 441 and 44n shown in FIG. 6), which are each coupled between a respective one of the transmitters 402? 40n and a respective of the 602 antennas? 60n, but which are otherwise similar to the 441 transmitter-receiver isolation circuit.

[00135] Furthermore, the unit? of remote antenna 14 includes one or more? 1201 "sniffer" antennas? 120m and one or more? "sniffer" receiver circuits 1221 ? 122m corresponding (only the sniffer antenna 1201 and a sniffer receiver circuit 1221 shown in Figure 6).

[00136] And in addition to the receiver circuit 521, the unit? of remote antenna 14 includes one or more? other 522 receiver circuits ? 52n (not shown in FIG. 6), which are each coupled to a respective antenna 602 ? 60n of the antenna array 42, but which are otherwise similar to the receiver circuit 521.

[00137] The analog interference cancellation circuit 46 is not ? only configured to reduce, in the reception signal coming from the antenna 601, a transmission interference coming from the transmission signal generated by the transmitter circuit 401, but ? also configured to reduce transmission interference from downlink signals transmitted simultaneously by one or more other 602 antennas? 60n.

[00138] Furthermore, the analog interference cancellation circuit 46? configured to reduce transmission interference from one or more downlink signals transmitted by one or more? other antennas 60 on one or more? other units? 14 remote antenna units (other remote antenna units not shown in Figure 6).

[00139] The analog interference cancellation circuit, therefore, includes a respective drive circuit. of analog cancellation 1401 ? 140n+m for each transmitter circuit 401 ? 40n and for each sniffer receiver circuit 1221 ? 122m. For example, each unit circuit? of analog cancellation 1401 ? 140n+m can? be equal to the FIR filter 80 of figure 3. Each unit circuit? of analog cancellation 1401 ? 140n+m ? configured to generate a respective component of the analog correction signal, and the signal combining circuit 104 is configured to generate the analog correction signal in response to the components. For example, if the signal combiner 104 ? an adder, then the signal combiner? configured to generate the analog correction signal equal to the sum of the component signals output by the unit circuits? of analogue cancellations 1401 ? 140m+n.

[00140] Similarly, the digital interference cancellation circuit 50 is not ? only configured to reduce, in the reception signal coming from the antenna 601, a transmission interference coming from the transmission signal generated by the transmitter circuit 401, but ? also configured to reduce transmission interference from one or more downlink signals transmitted simultaneously by one or more? other 602 antennas? 60n.

[00141] The digital interference cancellation circuit 50? also configured to reduce transmission interference from one or more downlink signals transmitted by one or more? other antennas 60 on one or more? other units? of nearby remote antenna units 14 (other remote antenna units not shown in Figure 6).

[00142] The digital interference cancellation circuit 50 therefore includes a respective drive circuit. of digital cancellation 1421 ? 142n+m for each transmitter circuit 401 ? 40n and for each sniffer receiver circuit 1221 ? 122m; for example, each unit circuit? of digital cancellation can? include a respective unit circuit? of linear distortion estimation 92, a respective circuit of units? of nonlinear distortion estimation 94 and a signal combining circuit 96 arranged as illustrated in FIG. 3. Each unit circuit? of digital cancellation 142 ? configured to generate a respective component of the digital correction signal, and the signal combining circuit 108 is configured to generate the digital correction signal in response to the components. For example, if the signal combiner 108 ? an adder, then the signal combiner? configured to generate the digital correction signal equal to the sum of the component signals coming from the unit circuits? of digital cancellation 1421 ? 142n+m. Furthermore, the isolation circuit controller 98 ? configured to generate the control signal for the transmitter-receiver isolation circuit 441 in response to component signals from the drive circuits. of digital cancellation 1421 ? 142n+m, or from the respective units? of linear and nonlinear distortion estimation 92 and 94 from each of the unit circuits? of digital cancellation.

[00143] Referring again to figure 6, the operation of the unit? of remote antenna 14 while each of one or more? of the 401 transmitter circuits ? 40n generates a transmission signal, and while each of one or more? of the antennas 60 on one or more? other units? of remote antenna emits a respective downlink signal, at the same time that the antenna 601 is receiving an uplink signal, ? similar to the operation described above in relation to figures 2? 5, and further as described below.

[00144] The analog interference canceling circuit 46 generates the analog correction signal in response to each of the one or more transmission signals generated by a respective transmitter circuit 401 ? 40n and in response to each of the one or more? sniffer receive signals generated by one of the 1221 sniffer receiver circuits ? 122m respective.

[00145] The digital interference cancellation circuit 50 generates the digital correction signal and the isolation control signal, in response to each of the one or more digital time domain signals that the signal processing circuitry generates for one of the transmitter circuits 401 ? 40n respective and in response to each of one or more? digital time domain signals generated by one or more? of the ADC 1281? 128m of 1221 sniffer receiver circuits ? 122m.

[00146] Although not illustrated, the analog interference canceling circuit 46 includes a respective set of units cancellation circuits 140 for each of the other receiver circuits 522 ? 52n (not shown in figure 6) where each set of units? of analogue cancellations can? be similar in terms of topology and operation to the set of units? of analogue cancellations 1401 ? 140n+m.

[00147] Similarly, although not illustrated, the digital interference canceling circuit 50 includes a respective set of units cancellation circuits 142 for each of the other receiver circuits 522 ? 52n (not shown in figure 6) where each set of units? of digital cancellations can? be similar in terms of topology and operation to the set of units? of digital cancellations 1421 ? 142n+m. And, although not illustrated, the digital interference canceling circuit 50 includes a respective isolation circuit controller 98 for each of the other transmitter-receiver isolation circuits 442 ? 44n, where each isolation loop controller is ? similar in topology and operation to the isolation loop controller 98 illustrated, and described in connection with FIG. 3.

[00148] Referring again to Figure 6, in an alternative embodiment, instead of, or in addition to, reducing transmission interference in the receive signal from antenna 601, the unit of remote antenna 14 includes circuitry that is configured to detect that each of one or more? of the 401 transmitter circuits ? 40n is generating a respective broadcast signal, and that each of one or more? of the 1221 sniffer circuits? 122m is receiving a readout signal from one of the 1201 sniffer antennas? 120m, while each of one or more? of the receiver circuits 52 is receiving a receive signal, and ? configured to take action in response to detection; said another way, the unit? remote antenna includes circuitry that is configured to detect that each of one or more? of the 601 antennas? 60n is transmitting a respective downlink signal, and that each of one or more? of the antennas 60 on one or more? other units? of remote antenna units (the other remote antenna units not shown in figure 6) is transmitting a respective downlink signal, while at least one of the 601 antennas is 60n integrated into the unit? of remote antenna 14 is receiving an uplink signal. For example, the unit? of remote antenna 14 can? be configured to send an alert to one or more? of the base stations 12 (figure 1) relating to the fact that the unit? of remote antenna is undergoing simultaneous downlink transmission and uplink reception; in response to the notice, one or more? base stations can coordinate the unit's downlink signal transmissions? remote antenna with reception of uplink signals by the unit? of remote antenna, and can coordinate the transmissions of downlink signals by the other units? of remote antennas with reception of uplink signals by the unit? remote antenna, to reduce, or eliminate, simultaneous transmission and reception by the unit? of remote antenna and by multiple units? of remote antennas in the ?neighborhood?. Or, the unit? of remote antenna 14 can? do s? that each of one or more? of transmitter-receiver isolation circuits 441 ? 44n decouples the respective transmission signal from one of the respective antennas 601 ? 60n, or can? do s? that each of one or more? of the transmitter-receiver isolation circuits decouples the respective receiving circuits 521 ? 52n from one of the respective 601 antennas? 60n, while each of one or more? of the antennas is receiving an uplink signal. Since? these last actions could cause data loss, the unit? of remote antenna 14 ? also configured to warn one or more? base stations 12 of one or more? decoupled transmission signals so that one or more? base stations can resend blocked, or otherwise lost, data for retransmission, and alert one or more of user equipment 22 of one or more? decoupled uplink signals so that one or more? user equipment can send the blocked data back to the drive? remote antenna unit (or to another remote antenna unit).

[00149] Referring again to figure 6, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, each antenna 60 can? be configured for use by a respective carrier or service provider (e.g., Verizon?, T-Mobile?, Sprint?, ATT?), which can? coordinate the transmission of downlink signals with the reception of uplink signals to prevent simultaneous transmission and reception with the same antenna. Such coordination of transmission and reception can? further increase the isolation between a transmitter circuit 40 and a receiver circuit 52 which share the same antenna 60, and therefore can allow the omission of one or more? of the transmitter-receiver isolation circuits 44 (and the omission of the one or more isolation circuit controllers 98). Furthermore, the isolation between transmitter circuits 40 and receiver circuits 52 can be increased further by configuring all 60 antennas on one unit? of remote antenna 14 for use by a single operator or service provider, which can? coordinate the transmissions of downlink signals and the reception of uplink signals such that no antenna transmits a downlink signal while the same or another antenna on the unit? remote antenna is receiving an uplink signal. Furthermore, embodiments described above in relation to Figures 1? 5 or below in relation to figures 7 to 19 may be applicable to the unit? of remote antenna 14 of figure 6.

[00150] Figure 7? a diagram of the transmitter-receiver isolation circuit 441 of Figures 2? 6, according to one embodiment. It is understood that each of one or more? of the other transmitter-receiver isolation circuits 442 ? 44n (figure 4) can? be similar to the 441 isolation circuit.

[00151] The transmitter receiver isolation circuit 441 includes a single pole, double contact electronic switch 150.

[00152] In the coupled state shown in solid line, the switch 150? configured to couple a respective transmitter circuit 40 to a corresponding antenna 60, and to decouple the antenna from a corresponding receiver circuit 52.

[00153] And in the coupled state shown with the dotted line, the switch 150 ? configured to couple a respective antenna 60 to a corresponding receiver circuit 52, and to decouple the antenna from a corresponding transmitter circuit 40.

[00154] In any of the described coupling states, the switch 150? configured to reduce transmission interference in the receive signal that the antenna 60 generates and supplies to the readout circuit 52.

[00155] During operation, the circuitry integrated into the unit? of remote antenna 14 (figures 1 - 6) controls the coupling state of the switch 150. For example, as described above in relation to figures 3 - 6, in response to a command from one or more? base stations 12 (figure 1), the circuitry does s? that the switch decouples a corresponding transmitter circuit 40 from the antenna 60, and couples the antenna to a corresponding receiver circuit 52, while the antenna is receiving an uplink signal and converting the uplink signal into a receive signal for the circuit receiver. Or, in response to a command from one or more? base stations 12 (figure 1), the circuitry does s? that the switch decouples the receiver circuit 52 from the antenna 60 while the antenna, or another antenna on the same one, or on a different unit? of remote antenna 14, is emitting a downlink signal. Alternatively, the isolation circuit 98 (Figures 3 - 6) monitors the state of the switch 150 in response to one or more signals generated by the digital interference cancellation circuit 50 (figures 2 - 6).

[00156] Referring again to figure 7, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, embodiments described above in relation to Figures 1 ? 6 or below in relation to figures 8? 19 may be applicable to the transmitter-receiver isolation circuit 44 of Figure 7.

[00157] Figure 8? a diagram of the transmitter-receiver isolation circuit 441 of Figures 2? 6, according to one embodiment. It is understood that each of one or more? of the other transmitter-receiver isolation circuits 442 ? 44n (figure 4) can? be similar to the 441 isolation circuit.

[00158] The transmitter-receiver isolation circuit 441 ? configured to couple, to the antenna 601 (figures 2 - 6), a transmission signal coming from the transmitter circuit 401 (figures 2 - 6) and simultaneously couple, to the receiver circuit 521 (figures 2 - 6), a reception signal coming from from the same antenna 601, electrically isolating at the same time the receiver circuit from the transmitter circuit. That is, the transmitter-receiver isolation circuit 441 allows the antenna 601 to emanate a downlink signal and receive an uplink signal at the same time, while reducing, to a suitable level, the interference in the receiving signal caused from the transmission signal. Put another way, the transmitter-receiver isolation circuit 441 ? configured to electrically isolate the receiver circuit 521 from the corresponding transmitter circuit 401 while the transmitter circuit is providing a transmit signal to the antenna 601 and the receiver circuit is simultaneously receiving a receive signal from the antenna 601. For example, the level of such insulation that the transmitter-receiver isolation circuit 441 ? configured to provide can? be a range of up to 20 dB and even more.

[00159] As described below, the transmitter-receiver isolation circuit 401 ? configured to provide such electrical isolation by splitting a broadcast signal into multiple components, and doing so? that the components interfere constructively at the 601e antenna making s? that any leakage component of the transmit signal destructively interferes at the receiver circuit 521 such that, ideally, no transmit signal power is coupled to the receiver circuit.

[00160] The transmitter-receiver isolation circuit 441 includes a transmitter port 160, an antenna port 162, a receiver port 164, a first phase shift coupler 166, a transmitter termination load 168, a first circulator 170, a second circulator 172, a second phase shift coupler 174, an antenna termination impedance or load 176, a third phase shift coupler 178, and a receiver termination impedance or load 180.

[00161] The transmitter port 160 ? configured to couple to the transmitter circuit 401 (Figures 2 - 6), the antenna port 162 - configured to couple to the antenna 601 (Figures 2 - 6), and the receiver port 164? configured to couple to the 521 receiver circuit (figures 2 - 6).

[00162] The first phase shift coupler 166 includes a first path 182 configured to shift a phase of a first component of the transmit signal input to the transmitter port 160 by a first amount. such as -90?, a second path 184 configured to shift the phase of a second component of the transmit signal by a second amount? like 0?, and a termination port 186 ? configured to couple to the transmitter termination load 168, which can? be any suitable resistive, reactive or complex impedance circuit or device. Furthermore, the first and second paths 182 and 184 respectively generate the first and second components of the transmission signal each having approximately the same power level.

[00163] The first circulator 170 can? be a conventional passive circulator, and has a first circulator port 188 coupled to the first path 182 of the first coupler 166, a second circulator port 190, and a third circulator port 192.

[00164] The second circulator 172 can? be a conventional passive circulator or otherwise can? be similar to the first circulator 170 and has a first circulator port 194 coupled to the second path 184 of the first coupler 166, a second circulator port 196, and a third circulator port 198.

[00165] For the purposes of describing the structure and operation of the first and second circulators 170 and 172, it is assumed that the first and second circulators impart similar attenuation and similar phase shifts to the signals such that in the operational description below, the attenuations and phase shifts learned by the first and second circulator are ignored. A way to realize, at least approximately, this assumption? to electrically combine the first and second circulators 170 and 172, for example, forming the circulators on the same integrated circuit matrix.

[00166] The second phase shift coupler 174 includes a first path 200 configured to shift the phase of a first subcomponent of the first component of the transmit signal received from the circulator port 190 by a first amount. such as -90?, a second path 202 configured to shift the phase of a second subcomponent of the first component of the transmit signal by a second amount? as 0?, and a termination port 204 configured to couple the first path 200 to the antenna termination load 176, which can? be any resistive, reactive, or complex impedance circuit or device. For example, the first and second paths 200 and 202 are configured to generate the first and second subcomponents of the first component of the transmit signal such that the first subcomponent at load 176 has little, if any, power, and the second subcomponent to antenna port 162 exhibits most, if not all, of the power of the first component of the transmit signal.

[00167] The second phase shift coupler 174 further includes a third path 206 coupled to the second circulator port 196 of the second circulator 172 and configured to shift the phase of a first subcomponent of the second component of the transmit signal by a first amount. as 0?, and a fourth path 208 configured to shift the phase of a second subcomponent of the transmit signal component by a second amount? like -90?. For example, the third and fourth paths 206 and 208 are configured to generate the first and second subcomponents of the second component of the transmit signal such that the first subcomponent at load 176 has little, if any, power, and the second subcomponent to antenna port 162 has most, if not all, of the power of the second component of the transmit signal.

[00168] Furthermore, the second path 202 of the second phase shift coupler 174? also configured to shift a phase of a first component of the reception signal coming from the antenna port 162 of the second quantity? as 0?, and the fourth path 208 ? configured to phase shift a second component of the receive signal coming from the fourth quantity antenna port? like -90?. Furthermore, the second and fourth paths 202 and 208 are configured to each generate the first and second components of the receive signal having approximately the same power level.

[00169] The third phase shift coupler 178 includes a first path 210 coupled to the third circulator port 192 of the first circulator 170 and configured to shift the phase of a first subcomponent of the first receive signal component by a first amount. such as -90?, a second path 212 configured to shift the phase of a second subcomponent of the first component of the receive signal by a second amount? as 0?, and a termination port 214 configured to couple the second path 212 to the receive termination load 180, which can? be any suitable resistive, reactive or complex impedance circuit or device. Furthermore, the first and second paths 210 and 212 are configured to generate the first and second subcomponents of the first component of the receive signal such that the first subcomponent at load 178 has little, if any, power, and the second subcomponent to antenna port 164 has most, if not all, of the power of the first component of the receive signal.

[00170] The third phase shift coupler 178 further includes a third path 216 coupled to the third circulator port 198 of the second circulator 172 and configured to shift the phase of a first subcomponent of the second component of the receive signal by a third amount. as 0?, and a fourth path 218 configured to shift the phase of a second subcomponent of the second component of the receive signal by a fourth amount? like -90?. Furthermore, the third and fourth paths 216 and 218 are configured to generate the first and second subcomponents of the second component of the receive signal such that the first subcomponent at load 180 has little, if any, power, and the second subcomponent to the receiver port 164 presents most, if not all, of the power of the second component of the receive signal.

[00171] Ideally, there can't be? be any leakage of the first component of the transmission signal from the third circulator port 192 of the first circulator 170, and there is no no leakage of the second component of the transmission signal from the third circulator port 198 of the second circulator 172.

[00172] However, in reality? can? such dispersion exists.

[00173] Accordingly, the first path 210 of the third phase shift coupler 178 ? configured to shift the phase of a dispersion subcomponent of the first component of the transmit signal of the first quantity? as -90?, and the third path 216 ? configured to shift the phase of a dispersion subcomponent of the second component of the third quantity transmit signal? like 0?.

[00174] Referring again to figure 8, the operation of the transmitter-receiver isolation circuit 401 is described according to an embodiment in which any dispersion subcomponent of the transmit signal destructively interferes at the receiver port 164 to reduce, in the receive signal, interference caused by a simultaneous transmit signal to the antenna 601 Furthermore, in the following description, any loss imparted by the first, second, and third couplers 166, 174, and 178, and by the first and second circulators 170 and 172, is ignored, any energy that the first, second, and third couplers couple at the termination loads 168, 176 and 180 respectively is ignored, any phase shift imparted by the circulators to the signals propagating within the circulators is ignored, it is assumed that the couplers impart to the signals only the phase shifts for which they are configured, it is assumed that the paths within the couplers split the signals input to multiple of the paths into signal components of equal power, and that any receive signal energy propagating from the antenna port 162 to the transmitter port 160 is ignored.

[00175] A power transmission signal T from the transmitter 401 (Figures 2 - 6) propagates into the transmitter port 160 and to the first coupler 166.

[00176] A first component of the transmission signal having power T/2 propagates along the first path 182 of the first coupler 166, which path shifts the phase of the first component by an amount as -90?, and a second component of the transmission signal having power T/2 propagates along the second path 184, which shifts the phase of the second component by an amount like 0?.

[00177] The first component of the transmission signal propagates from the first path 182 of the first coupler 166 to the first circulator port 188 of the first circulator 170, propagates from the first circulator port to the second circulator port 190 of the first circulator, and propagates from the second circulator port to the second path 202 of the second coupler 174.

[00178] The second component of the transmission signal propagates from the second path 184 of the first coupler 166 to the first circulator port 194 of the second circulator 172, propagates from the first circulator port to the second port 196 of the second circulator, and propagates from second circulator port to the third path 206 of the second coupler 174.

[00179] The second path 202 of the second coupler 174 couples a first subcomponent of the first component of the transmission signal to the antenna port 162 with a phase shift such as 0?, and the fourth path 208 of the second coupler couples a second subcomponent of the second component of the transmit signal to the antenna port with a phase shift such as -90?. The first subcomponent of the first transmit signal component and the second subcomponent of the second transmit signal component each have a signal strength of approximately T/2 because the first path 200 and third path 206 of the second coupler 174 each couple approximately zero energy to the termination load 176.

[00180] Since? both of the first subcomponent of the first transmission signal component and the second subcomponent of the second transmission signal component have approximately the same phase (e.g., -90?) at the antenna port 162, these first and second subcomponents are constructively add to ?reconstruct?, at the antenna port, a transmit signal having approximately a full transmit signal strength T.

[00181] In the manner described above, the first coupler 166, the first and second circulators 170 and 172, and the second coupler 174 effectively provide, to the antenna 601 (Figures 2 - 6), a reconstructed transmission signal having approximately the same power T as the transmit signal at the input port 160. That is, the transmitter-receiver isolation circuit 441 couples the transmit signal from the transmitter port 160 to the antenna port 162 with relatively low signal loss .

[00182] Ideally, the first circulator 170 does not couple any portion of the first component of the transmission signal from the first circulator port 188 to the third circulator port 192.

[00183] However, during actual operation, the first circulator 170 can coupling a dispersion subcomponent of the first transmission signal component from the first circulator port 188 to the third circulator port 192.

[00184] The first path 210 of the third coupler 178 couples the dispersion subcomponent of the first transmit signal component to the receiver port 164 with a total phase shift such as -180? (for example, -90? from the first coupler 166 and another -90? from the third coupler).

[00185] Furthermore, ideally, the second circulator 172 does not couple any portion of the second component of the transmission signal from the first circulator port 194 to the third circulator port 198.

[00186] However, during actual operation, the second circulator 172 can coupling a dispersion subcomponent of the second component of the transmission signal from the first circulator port 194 to the third circulator port 198.

[00187] The third path 216 of the third coupler 178 couples the dispersion subcomponent of the second component of the transmit signal to the receiver port 164 with a total phase shift such as 0? (for example, 0? from the first coupler 166 and another 0? from the third coupler).

[00188] Consequently, since? the dispersion subcomponents of the first and second components of the transmit signal have approximately opposite phases (e.g., 0? and 180?) at the receiver port 164, the dispersion components destructively interfere with each other such that At least ideally, no leakage energy from the transmit signal is coupled to the receiver circuit 521 (Figures 2 - 6) via the receiver port 164.

[00189] Furthermore, in operation of the transmitter-receiver isolation circuit 441, ideally, the second coupler 174 receives, from the antenna 601 (figures 2 - 6) at the reception port 162, an input reception signal having a power of R.

[00190] The second path 202 of the second coupler 174 shifts a phase of a first component of the receive signal having a power of R/2 by an amount which is 0?, and the fourth path 208 of the second coupler shifts a phase of a second component of the receive signal having a power of approximately R/2 by an amount which -90?.

[00191] The first component of the receive signal propagates from the second path 202 of the second coupler 174 to the second circulator port 190 of the first circulator 170, and the second component of the receive signal propagates from the fourth path 208 of the second coupler to the second circulator door 196 of the second circulator 172.

[00192] The first component of the reception signal propagates from the second circulator port 190 to the third circulator port 192 of the first circulator 170, and from the third circulator port to the first path 210 of the third coupler 178; the first path of the third coupler imparts, to the first component of the reception signal, a phase shift of an amount which -90? such that at the receiver port 164, the first component of the receive signal has a total phase shift such as -90? (for example, 0? from the second coupler 174 and -90? from the third coupler).

[00193] The second component of the receive signal propagates from the second circulator port 196 to the third circulator port 198 of the second circulator 172, and from the third circulator port to the third path 216 of the third coupler 178; the third path imparts, to the second component of the reception signal, a phase shift of an amount which -90? such that at the receiver port 164, the second component of the receive signal has a total phase shift of approximately -90? (for example, -90? from the second coupler 174 and 0? from the third coupler).

[00194] Consequently, since? both the first and second components of the receive input signal have approximately the same phase (e.g., -90?) at the receiver port 164, they constructively interfere and, therefore, effectively reconstruct the receive signal reception having approximately the total power of R, at the receiver port.

[00195] In summary, the transmitter isolation circuit 441 effectively divides the transmission signal at the transmission port 160 into multiple components that constructively interfere at the antenna port 162 such that the antenna 601 emanates a reconstructed transmit signal, of approximately full strength, and destructively interfering at the receiver port 164 to reduce interference in the receive signal caused by a simultaneous transmit signal to the same antenna 601.

[00196] Referring again to figure 8, alternative embodiments of the transmitter-receiver isolation circuit 441 are contemplated. For example, although in reality? the isolation circuit 441 can? not be ideal, ? however capable of coupling the transmission signal coming from the transmitter 401 (figures 2 - 6) to the antenna 601 with a suitable level of different attenuation and distortion, and of reducing, to a suitable level, interference in the direct reception signal to the receiver circuit 521 caused by the transmission signal. Furthermore, embodiments described above in relation to Figures 1? 7 or below in relation to figures 9? 19 may be applicable to the transmitter-receiver isolation circuit 441 of FIG. 8.

[00197] Figure 9? a graph 230 of a frequency response 232 of each circulator 170 and 172 of Figure 8 from the first circulator port (188, 194) to the second circulator port (190, 196) according to one embodiment. For frequency response 232, the transmit insertion loss that a signal exhibits in the frequency band between 3.4 GHz and 3.8 GHz as the signal propagates from the first circulator port (188, 194) to the second circulator port (190, 196) ? less than 1 dB.

[00198] Figure 10 ? a graph 240 of a frequency response 242 of each circulator 170 and 172 of Figure 8 from the second circulator port (190, 196) to the third circulator port (192, 198) according to one embodiment. For frequency response 232, the receive insertion loss that a signal exhibits in the frequency band between 3.4 GHz and 3.8 GHz as the signal propagates from the second circulator port (190, 196) to the third circulator port (192, 198) ? less than 1 dB.

[00199] Figure 11 ? a graph 250 of a frequency response 252 of each circulator 170 and 172 of Figure 8 from the first circulator port (188, 194) to the third circulator port (192, 198) according to one embodiment. For frequency response 252, in the frequency band between 3.4 GHz and 3.8 GHz, the isolation from the first circulator port (188, 194) to the third circulator port (192, 198) is from more to of 30 dB more? of 50 dB.

[00200] Figure 12 ? a plot 260 of a frequency response 262 of each circulator 170 and 172 of FIG. 8 from the first circulator port (188, 194) to the second circulator port (190, 196) versus a frequency response 264 of the transmitter isolation circuit -receiver 441 of FIG. 8 from the transmitter port 160 to the antenna port 162, and a frequency response 266 of each circulator from the first circulator port to the third circulator port (192, 198) relative to a frequency response 268 of the transmitter-receiver isolation circuit from the transmitter port to the receiver port 164, according to one embodiment. Based on the frequency responses 262, 264, 266, and 268, in the frequency band between 3.4 GHz and 3.8 GHz, the transmitter-receiver isolation circuit 441 has approximately the same transmit insertion loss (less than 1 dB) between transmit port 160 and antenna port 162 than a circulator 170, 172 would have, but provides a significantly higher level of isolation (greater than 30 dB) than a circulator would provide (25 dB or less) between the transmitter port and the receiver port 164.

[00201] Figure 13 ? a diagram of the transmitter-receiver isolation circuit 441 of Figures 2? 6, according to another embodiment. It is understood that each of one or more? of the other transmitter-receiver isolation circuits 442 ? 44n (figure 4) can? be similar to the isolation circuit 441 of FIG. 13. Furthermore, the elements common to FIGS. 8 and 13 are designated with the same reference numerals.

[00202] The transmitter-receiver isolation circuit 441 of Figure 13 ? similar to the transmitter-receiver isolation circuit of FIG. 8, but with the addition of two adjustable phase coupler circuits 280 and 282, which effectively allow pre-operation, in-operation, or dynamic adjustments of the phase shifts imparted by the first, second , and third couplers 166, 174, and 178. Such phase adjustments can increase the level of electrical isolation that the transmitter-receiver isolation circuit 441 provides between the transmitter circuit 401 (Figures 2 - 6) and the receiver circuit 521 (Figures 2 ? 6).

[00203] The adjustable phase coupler 280 includes a phase coupler 284, which can be analogous to phase couplers 166, 174, and 178, a phase regulator 286, which includes two electronically adjustable capacitors, such as varactors, 288 and 290, and at least one control line 292. Phase coupler 284 includes a first, second, third, and fourth phase shift signal paths 294, 296, 298, and 300, an input node 302, and an output node 304. Additionally, the adjustable phase coupler 280 can include a single control line 292, which capacitors 288 and 290 share, can? include two control lines 292, one control line for each capacitor, or can? include more? of two control lines, with one or more? control lines for each capacitor. Furthermore, the at least one control line can? be coupled to a respective isolation circuit controller 98 (figures 2 - 6), to the controller circuit 48 (figures 2 - 6), or to any other circuit on the unit? of remote antenna 14 (figures 2 - 6).

[00204] The operation of the adjustable phase coupler circuit 280? described, according to an embodiment in which the capacitances of the capacitors 288 and 290, and, therefore, the one or more? phase shifts imparted by the coupler circuit are controlled by one or more? signals coming from the corresponding isolation circuit controller 98 (figures 2 - 6). Furthermore, for the purposes of the description below, it is assumed that the adjustable phase coupler 280 splits a signal at the input node 302 into two signal components of approximately equal power that propagate along the first and the second path 294 and 296, and any loss introduced by the adjustable phase coupler is ignored.

[00205] An input signal enters input node 302, and a first component of the input signal having a power of P/2 propagates along path 294, which imparts a phase shift such as -90? to the first component.

[00206] Capacitor 288 imparts a second phase shift to the first single phase shift component of the input signal, where the magnitude of the second phase shift is ? controlled by a signal coming from the isolation circuit controller 98 (figures 2 - 6). For example, the second phase shift can? be in the approximate range of a fraction of a degree to 10?.

[00207] Capacitor 288 effectively redirects the first double phase shift component of the input signal to the third path 298, which imparts a third phase shift such as 0? to the first component such that the first triple phase-shifted component of the input signal is located at the output node 304.

[00208] Similarly, a second component of the input signal having a power of approximately P/2 propagates along the second path 296, which imparts a phase shift such as 0? to the second component of the input signal.

[00209] Capacitor 290 imparts a second phase shift to the second single phase shift component of the input signal, where the magnitude of the second phase shift is ? controlled by a signal coming from the isolation circuit controller 98 (figures 2 - 6). For example, the second phase shift can? be in the approximate range between a fraction of a degree and 10?.

[00210] Capacitor 290 effectively redirects the second double phase shift component of the input signal to the fourth path 300, which imparts a third phase shift such as -90? to the second component such that the second triple phase-shifted component of the input signal is located at the output node 304.

[00211] Assuming a coupled operation in which the total of the phase shifts that the first path 294, the first capacitor 288 and the third path 298 impart to the first component of the input signal ? equal to the total of the phase shifts of the second path 296, the second capacitor 290 and the third path 300 impart to the second component of the input signal, at the output node 304 the first and second components of the input signal interfere in a manner constructive to generate a phase-shifted version of the input signal having approximately the power P.

[00212] The phase shift that the capacitor 288 imparts to the first component of the input signal can? be, but not necessarily, equal to the phase shift that capacitor 290 imparts to the second component of the input signal. For example, in an unmatched operation where the total of the phase shifts that the first and third paths 294 and 298 impart to the first component of the input signal is ? -92?, and the total of the phase shifts that the second and fourth paths 296 and 300 impart to the second component of the input signal ? -89?, then the capacitor 288 can? be controlled to impart a phase shift that ? offset by 3? with respect to the phase shift that the capacitor 290 ? controlled to impart such that at the output node 304, the first and second components of the input signal have the same phase.

[00213] The adjustable phase coupler 282 can? have a structure, configuration, and operation similar to the structure, configuration, and operation of the phase shift coupler 280.

[00214] Referring again to figure 13, the operation of the transmitter-receiver isolation circuit 441 is described according to an embodiment in which any dispersion subcomponent of the transmit signal destructively interferes at the receiver port 164 to reduce, in the receive signal, interference caused by a simultaneous transmit signal. Furthermore, in the following description, any loss imparted by the couplers 166, 174, 178, 280, and 282, and the circulators 170 and 172, is ignored, any phase shift imparted to the signals propagating within the circulators is ignored, any signal energy that the couplers 166, 174, and 178 respectively couple to the termination loads 168, 176, and 180 is ignored, it is assumed that the paths within the couplers divide the signals fed into multiple of the paths into signal components having equal power, and any signal energy propagating from antenna port 162 to transmitter port 160 is ignored.

[00215] A power transmission signal T from the transmitter 401 (Figures 2 - 6) propagates into the transmitter port 160 of the first coupler 166.

[00216] A first component of the transmission signal having power T/2 propagates along the first path 182, which shifts the phase of the first component by an amount which -90?, and a second component of the transmission signal having power T/2 propagates along the second path 184, which shifts the phase of the second component by an amount which 0?.

[00217] The first component of the transmission signal propagates from the first path 182 of the first coupler 166 to the first circulator port 188 of the first circulator 170, propagates from the first circulator port to the second circulator port 190 of the first circulator, and propagates from the second circulator port to the second path 202 of the second coupler 174.

[00218] The second component of the transmission signal propagates from the second path 184 of the first coupler 166 to the first circulator port 194 of the second circulator 172, propagates from the first circulator port to the second circulator port 196 of the second circulator, and propagates from the second circulator port of the second circulator to the third path 206 of the second coupler 174.

[00219] The second path 202 of the second coupler 174 couples a first subcomponent of the first component of the transmission signal to the antenna port 162 with a phase shift such as 0?, and the fourth path 208 of the second coupler couples a second subcomponent of the second component of the transmit signal to the antenna port with a phase shift such as -90?. The first subcomponent of the first transmission signal component and the second subcomponent of the second transmission signal component each have a signal strength of approximately T/2 because the first path 200 and third path 206 of the second coupler 174 couple approximately zero energy to the termination load 176.

[00220] Since? both of the first subcomponent of the first transmission signal component and the second subcomponent of the second transmission signal component have approximately the same phase (e.g., -90?) at the antenna port 162, these first and second subcomponents are constructively add to ?reconstruct?, at the antenna port, the transmission signal having approximately a full transmission signal strength T.

[00221] In the manner described above, the first coupler 166, the first and second circulators 170 and 172, and the second coupler 174 effectively provide, to the antenna 601 (Figures 2 - 6), a reconstructed transmission signal having approximately the same power T as the transmit signal at the input port 160. That is, the transmitter-receive isolation circuit 441 effectively couples the transmit signal from the transmitter port 160 to the antenna port 162 with relatively low insertion loss low.

[00222] Ideally, the first circulator 170 does not couple any portion of the first component of the transmission signal from the first circulator port 188 to the third circulator port 192.

[00223] However, during actual operation, the first circulator 170 can coupling a dispersion subcomponent of the first transmission signal component from the first circulator port 188 to the third circulator port 192.

[00224] The adjustable phase coupler 280, operating as described above, shifts the phase of the dispersion subcomponent of the first transmission signal component from the circulator port 192 of the first circulator 170 by an amount which -90? ?cap1, which ? the phase shift that one or more? control signals on one or more? control lines 292 do s? that the capacitors 288 and 290 impart to the dispersion subcomponent of the first component of the transmission signal (?cap1 can be positive or negative). For example, the isolation circuit controller 98 (Figures 2 - 6) can generate one or more? control signals as part of a feedback control loop that acts to dynamically reduce, in the receive signal output at port 164, the amount of of interference caused by the transmission signal input to port 160.

[00225] The first path 210 of the third coupler 178 couples the single-shift dispersion subcomponent of the first transmit signal component to the receiver port 164 with a total phase shift such as -270? ?cap1 (-90? from the first coupler 166, -90? ?cap1 from the adjustable phase shift coupler 280, and -90? from the third coupler).

[00226] Furthermore, ideally, the second circulator 172 does not couple any portion of the second component of the transmission signal from the first circulator port 194 to the third circulator port 198.

[00227] However, during actual operation, the second circulator 172 can coupling a dispersion subcomponent of the second component of the transmission signal from the first circulator port 194 to the third circulator port 198.

[00228] Adjustable phase coupler 282, operating as described above for coupler 280, shifts the phase of the dispersion subcomponent of the second component of the transmit signal from the third circulator port 198 of the second circulator 172 by an amount which -90? ?ch2, what? the phase shift that one or more? control signals on one or more? control lines 310 do s? that the capacitors 312 and 314 impart to the dispersion subcomponent of the first component of the transmission signal (?cap2 can be positive or negative). For example, the isolation circuit controller 98 (Figures 2 - 6) can generate one or more? control signals as part of a feedback control loop that acts to reduce, in the receive signal output from port 164, the amount of of interference caused by the transmission signal input to port 160.

[00229] The third path 216 of the third coupler 178 couples the single phase shift dispersion subcomponent of the second transmit signal component to the receiver port 164 with a total phase shift such as -90? ?cap2 (0? from the first coupler 166, -90?+ ?cap2 from the adjustable phase coupler 282, and to another 0? from the third coupler).

[00230] Consequently, where ?cap1 = ?cap2, or where ?cap1 ? different from ?cap2 to compensate for phase differences in the paths along which the dispersion subcomponents propagate, since? the dispersion subcomponents of the first and second components of the transmit signal have approximately opposite phases (e.g., -90? and -270?) at the receiver port 164, the dispersion components destructively interfere with each other in a manner such that, at least ideally, no leakage energy from the transmit signal is coupled to the receiver circuit 521 (Figures 2 - 6) via the receiver port 164. Furthermore, the control loop described above acts dynamically ?cap1 and ? cap2 to maintain the transmission signal leakage energy at the receiver port 164 at a minimum achievable level.

[00231] Furthermore, during the operation of the transmitter-receiver isolation circuit 441, ideally, the second coupler 174 receives, from the antenna 601 (figures 2 - 6) at the reception port 162, an input reception signal having a power R.

[00232] The second path 202 of the second coupler 174 shifts a phase of a first component of the reception signal having power R/2 by an amount which is 0?, and the fourth path 208 of the second coupler shifts a phase of a second component of the receive signal having a power of approximately R/2 by an amount which -90?.

[00233] The first component of the receive signal propagates from the second path 202 of the second coupler 174 to the second circulator port 190 of the first circulator 170, and the second component of the receive signal propagates from the fourth path 208 of the second coupler to the second circulator door 196 of the second circulator 172.

[00234] The first component of the receive signal propagates from the second circulator port 190 to the third circulator port 192 of the first circulator 170, and from the third circulator port to the adjustable phase coupler 280.

[00235] Adjustable phase coupler 280, operating as described above, shifts the phase of the first component of the receive signal by an amount like -90? ?cap1, which ? the phase shift that one or more? control signals on one or more? control lines 292 do s? that the capacitors 288 and 290 impart to the first component of the reception signal (?cap1 can be positive or negative).

[00236] The first path 210 of the third coupler 178 imparts, to the first component with double phase shift, of the reception signal, a phase shift of an amount like -90? such that at the receiver port 164 the first component of the receive signal has a total phase shift such as -180? ?cap1 (0? from the second coupler 174, -90? ?cap1 from the adjustable phase coupler 280, and -90? from the third coupler).

[00237] The second component of the receive signal propagates from the second circulator port 196 to the third circulator port 198 of the second circulator 172, and from the third circulator port to the adjustable phase coupler 282.

[00238] Adjustable phase coupler 282, operating as described above, shifts the phase of the second component of the receive signal by an amount like -90? ?ch2, what? the phase shift that one or more? control signals on one or more? control lines 310 do s? that the capacitors 312 and 314 impart to the second component of the reception signal (?cap2 can be positive or negative).

[00239] The third path 216 of the third coupler 178 imparts, to the second component with double phase shift, of the reception signal, a phase shift of an amount like -90? such that at the receiver port 164 the second component of the receive signal has a total phase shift equal to approximately -180? ?cap2 (-90? from the second coupler 174, -90? ?cap2 from the adjustable phase shift coupler 282, and 0? from the third coupler).

[00240] Consequently, since? both the first and second components of the receive input signal have approximately the same phase (e.g., -180?) at the receiver port 164, they interfere constructively and, therefore, effectively reconstruct, at the port of receiver, the reception signal having approximately a full power R. Ci? assumes that ?cap1 = ?cap2, or ?cap1and ?cap2 are such that they equalize the total phase shifts undergone by the first and second components of the reception signal.

[00241] In summary, the transmitter isolation circuit 441 effectively divides the transmission signal at the transmission port 160 into multiple components that constructively interfere at the antenna port 162 such that the antenna 601 emanates a reconstructed transmission signal, approximately complete, and which interferes destructively at the receiver port 164 to reduce, in the reception signal from the antenna 601, the interference caused by a simultaneous transmission signal towards the same antenna 601.

[00242] Referring again to figure 13, alternative embodiments of the transmitter-receiver isolation circuit 441 are contemplated. For example, given that the components of the transmission and reception signals follow different paths, the values of ?cap1 and ?cap2 which are best for canceling transmission interference may not be best for reconstructing the reception signal at port 164, and vice versa. Therefore, the isolation circuit controller 98 (Figures 2 - 6), and one or more Control loops that include the isolation loop controller can be weighted to favor cancellation of transmission interference over reconstruction of the receive signal, or vice versa. Furthermore, instead of be controlled by the isolation loop controller 98, the phase shifts of the adjustable phase couplers 280 and 282 may be set to fixed values during manufacturing or assembly of the unit. of remote antenna 14 (figures 2 - 6), or set to calibrated values during a calibration procedure that is carried out once or periodically. Furthermore, embodiments described above in relation to Figures 1? 12 or below in relation to figures 14? 19 may be applicable to the transmitter-receiver isolation circuit 441 of Figure 13.

[00243] Figure 14 ? a plot 330 of a frequency response 332 between the transmit port 160 and the antenna port 162 of the transmitter-receiver isolation circuit 441 of FIG. 13, a frequency response 334 between the antenna port and the receiver port 164, and a frequency response 336 between the transmitter port and the receiver port, according to one embodiment. Based on the frequency responses 332, 334, and 336, in the frequency band 3.4 GHz to 3.8 GHz, the transmitter-receiver isolation circuit 441 has a relatively low level (e.g., approximately 0.5 dB ? 1.0 dB) of transmit insertion loss between transmitter and antenna ports 160 and 162 and relatively low insertion loss between antenna and receiver ports 162 and 164, but provides a relatively high level ( for example, approximately 38 dB or more) of electrical isolation between the transmitter and receiver ports.

[00244] Figure 15 ? a plot 340 of a frequency response 342 of each circulator 170 and 172 of FIG. 13 from the first circulator port (188, 194) to the second circulator port (190, 196) versus a frequency response 344 of the transmitter isolation circuit -receiver 441 of FIG. 13 from the transmitter port 160 to the antenna port 162, and a frequency response 346 of each circulator from the first circulator port to the third circulator port (192, 198) relative to a frequency response 348 of the transmitter-receiver isolation circuit from the transmitter port to the receiver port 164, according to one embodiment. Based on the frequency responses 342, 344, 346, and 348, in the 3.4 GHz to 3.8 GHz frequency band, the transmitter-receiver isolation circuit 441 of FIG. 13 has approximately the same insertion loss as transmission (e.g., less than 1 dB) as the circulator 170, 172 would have, but provides a significantly higher level of isolation (e.g., greater than 38 dB) than a circulator would (e.g., 25 dB or minus) between the transmitter port and the receiver port 164.

[00245] Figure 16 ? a diagram of the transmitter-receiver isolation circuit 441 of Figures 2? 6, according to yet another embodiment. It is understood that one or more? of the other transmitter-receiver isolation circuits 442 ? 44n may be similar to the 441 transmitter-receiver isolation circuit.

[00246] Isolation circuit 441 includes a transmitter port 360, an antenna port 362, a receiver port 364, a circulator 366, a balun 368, a filter circuit 370, a signal combiner circuit 372, and a intensity indicator circuit? of reception signal (RSSI, Receive Signal Strength Indicator) 374.

[00247] The transmitter port 360 ? configured for coupling to the transmitter circuit 401 (Figures 2 - 6), the antenna port 362 - configured for coupling to the antenna 601 (figures 2 - 6), and the receiver port 364? configured for coupling to the 521 receiver circuit (figures 2 - 6).

[00248] The circulator 366 can? be similar to the circulators 170 and 172 of figures 8 and 13.

[00249] The 368 balun can? be a conventional balun and ? configured to generate a reference signal in response to a transmit signal at transmit port 360; for example, the reference signal can? be a lower power replica of the broadcast signal.

[00250] The filter circuit 370 is, for example, an FIR filter, of which one or more coefficients are controllable by the RSSI circuit 374. The filter circuit 370 can? be an analog or digital filter circuit (if the latter, then the filter circuit may include an ADC to convert the reference signal from the analog to the digital domain, and may include a DAC to convert the filtered reference signal from the digital domain to the analog domain).

[00251] The combiner circuit 372 ? configured to combine the filtered reference signal with a receive signal from the antenna 601 (FIGS. 2 - 6) via the circulator 366 to generate a receive signal with canceled transmission interference at the receiver port 364. For example, the combiner circuit 372 can? be a summing circuit.

[00252] And the RSSI circuit 374? configured to determine an?intensity? of the receiving signal with transmission interference canceled and to control, in response to the intensity? determined, the parameters of the filtering algorithm with which the circuit 370 filters the reference signal. For example, as described above, the RSSI circuit 374 ? configured to control one or more? coefficients of an FIR filter implemented using circuit 370.

[00253] Referring again to figure 16, the operation of the transmitter-receiver isolation circuit 441 is described, according to one embodiment.

[00254] The transmitter 401 (figures 2 - 6) generates, at the transmitter port 360, a transmission signal which propagates through the balun 368, to a circulator port 376 of the circulator 366, through the circulator to a another circulator port 378, and to the antenna 601 (figures 2 - 6), which emanates a downlink signal in response to the transmission signal.

[00255] The balun 368 generates the reference signal in response to the transmit signal, and the filter circuit 370 filters the reference signal with an algorithm having one or more coefficients, or one or more? different parameters, set by a feedback signal coming from the RSSI 374 circuit.

[00256] During the emanation of the downlink signal, the antenna 601 (figures 2 - 6) receives an uplink signal, and generates, in response to the uplink signal, a reception signal at the circulator port 378 of the circulator 366.

[00257] The receive signal propagates from circulator port 378 to a circulator port 380 of circulator 366.

[00258] Since? the 366 circulator? not ideal, a component of the transmit signal is lost, for example, interferes with the receive signal.

[00259] Therefore, at the circulator port 380, the receive signal includes interference from the transmit signal, which distorts the receive signal.

[00260] The distorted receive signal propagates from the circulator port 380 to the signal combiner circuit 372, which combines the filtered reference signal with the distorted receive signal to produce an undistorted (e.g., interference canceled) receive signal ), at the receiver port 364. Although the undistorted receive signal may still include some transmission interference, the transmitter-receiver isolation circuit 441 reduces the transmission interference in the receive signal to a level below level of transmission interference in the receive signal at the circulator port 380.

[00261] The transmitter-receiver isolation circuit 441 operates on a principle of conditioning the distorted receive signal so that it has the minimum achievable intensity, or power, at the receiver port 364 provides the most interference cancellation. achievable high level of transmission interference from the receiving signal.

[00262] Accordingly, the feedback loop including filter 370, combiner circuit 372, and RSSI circuit 374 acts to maintain, at a minimum achievable level, the power of the receive signal emitted by the combiner circuit.

[00263] If the transmission circuit 401 (figures 2 - 6) does not generate a transmission signal, then the reference signal is ? approximately equal to zero such that the receive signal is substantially unchanged as it propagates through combiner circuit 372.

[00264] Referring again to Figure 16, alternative embodiments of the transmitter-receiver isolation circuit 441 are contemplated. For example, the filter circuit 370 can be, or can? implement, a suitable filter other than an FIR filter. Furthermore, ? You can replace the 368 balun with another suitable circuit, such as a high-frequency buffer or current mirror. Furthermore, embodiments described above in relation to Figures 1? 15 or below in relation to figures 17? 19 may be applicable to the transmitter-receiver isolation circuit 441 of Figure 16.

[00265] Figure 17 ? a diagram of a unit? of remote antenna 14 of figure 1, the unit? of remote antenna being similar in structure and operation to the unit? remote antenna of FIG. 2 but to include, in place of the analog interference canceling circuit 46 of FIG. 2, an optical analog interference canceling circuit 390 according to one embodiment. Furthermore, do the same numbers refer to elements common to Figures 2? 6 and 17? 19.

[00266] The analog interference canceling circuit 390 can? include electrical and optical circuitry analogous to the electrical and optical circuitry illustrated in U.S. Patent 2017/0170903 of which? incorporated by reference. For example, the analog interference canceling circuit 390 includes an electro-optical converter 392 configured to convert the transmission signal from the transmitter 401 from the electrical domain to the optical domain, and includes an optical-electrical converter 394 configured to convert the analog canceling signal from the optical domain to the electrical domain.

[00267] Referring again to Figure 17, alternative embodiments of the transmitter-receiver isolation circuit 441 are contemplated. For example, the analog interference cancellation circuit 390 can integrate, rather than replace, the analog interference canceling circuit 46 of FIG. 2. Furthermore, the analog interference canceling circuit 390 can? integrate or replace the analog interference cancellation circuit 46 of any one or more? of figures 3? 6. Additionally, embodiments described above in relation to Figures 1 ? 16 and below in relation to figures 18-19 may be applicable to the transmitter-receiver isolation circuit 441 of figure 17.

[00268] Figure 18 ? a diagram of the unit? of remote antenna 14 of figure 1, according to an embodiment in which the unit? of remote antenna? analogous to the unit? remote antenna 14 of Figure 6 but with separate (e.g., not shared) transmit and receive antennas 60, according to one embodiment. That is to say that each antenna 60 ? dedicated to transmit a downlink signal or one of its components, or to receive an uplink signal. Being configured with separate transmit and receive antennas 60 increases the total isolation between the transmit and receive antennas and, therefore, allows the transmitter-receiver isolation circuits 44 to be omitted from the unit. of remote antenna 14. And omitting the transmitter-receiver isolation circuits 44, allows you to omit the one or more? isolation circuit controllers 98 from the digital interference canceling circuit 50. In FIG. 18, like numbers refer to elements common to FIGS. 1? 6 and 17-18.

[00269] Except for changes in operation due to the lack of the transmitter-receiver isolation circuits 44 and the one or more isolation circuit controllers 98, the circuitry of the unit? of remote antenna 14 can? operate in a similar way to that described above in relation to figure 6.

[00270] Referring again to figure 18, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, the embodiments described above in relation to Figures 1 ? 17 and below in relation to figure 19 can be applicable to the unit? of remote antenna 14 of figure 18.

[00271] Figure 19 ? a diagram of the unit? of remote antenna 14 of figure 1, according to an embodiment in which the unit? of remote antenna? analogous to the unit? remote antenna 14 of figure 6 but with a respective shared transmission and reception antenna 60, and with a respective transmitter circuit 40 and a respective receiver circuit 52, for each operator, according to one embodiment. That is to say that each antenna 60 ? dedicated to a respective operator, and ? configured both to transmit a downlink signal or one of its components, and receive an uplink signal, in a coordinated and synchronized manner with respect to the operator. That is to say, the operator synchronizes the transmission of downlink signals and the reception of uplink signals on the respective antenna 60 in such a way that such transmission and reception do not overlap in time. A 400 switch, which can? be analogous to the switch 150 of figure 7, ? configured to provide isolation between the respective receiver circuit 52 and the respective antenna 60 while the unit of remote antenna 14 is transmitting a downlink signal, and ? configured to provide isolation between the respective transmitter circuit 40 and the respective antenna while the unit? remote antenna is receiving an uplink signal. In figure 19, do the same numbers refer to elements common to figures 1? 6 and 17-19.

[00272] Referring again to figure 19, are alternative embodiments of the unit contemplated? of remote antenna 14. For example, embodiments described above in relation to Figures 1 ? 18 may be applicable to the unit? of remote antenna 14 of figure 19.

[00273] ? It is possible to implement the methods and techniques described herein in analog electronic circuitry, in digital electronic circuitry, or with a programmable processor (e.g., a special purpose processor, a general purpose processor such as a computer, a microprocessor, or a microcontroller) or other circuit (for example, FPGA), firmware, software, or combinations thereof. Devices incorporating these techniques may include appropriate input and output devices, a programmable processor, and a storage medium that tangibly embodies program instructions for execution by the programmable processor. A process that incorporates these techniques can be executed by a programmable processor that executes a program of instructions to perform the desired functions by operating on the input data and generating an appropriate output. The techniques can be advantageously implemented in one or more? programs that are executable on a programmable system that includes at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Generally, a processor will receive? instructions and data from read-only memory and/or random access memory. Storage devices suitable for embodying computer program data and instructions include all forms of non-volatile memory, including, but not limited to, semiconductor memory devices, such as EPROMs, EEPROMs, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-resistive disks; and DVD discs. Any of the above can? be integrated by, or incorporated into, application-specific integrated circuits (ASICs).

EXAMPLES OF EMBODIMENTS

[00274] Does Example 1 include a unit? of remote antenna, comprising: a first transmitter configured to generate at least a first transmission signal; a first receiver configured to process at least one reception signal; a first array of antennas that includes one or more? first antennas each coupled to at least one of the first transmitter and the receiver, each of at least one of the first antennas configured to emanate a respective downlink signal in response to a respective of the at least one first transmission signal, and each of the at least one of the first antennas configured to generate a respective of the at least one receive signal in response to an uplink signal; and first and second interference circuits each coupled to the first transmitter and the receiver and each configured to reduce, in each of the at least one receiving signal, interference caused by one or more of the at least one first transmission signal, at least one downlink signal emanating from one of the one or more first antennas, and at least one interfering downlink signal emanating from one or more? different antennas.

[00275] Example 2 includes the unit? remote antenna of example 1, further comprising: a second transmitter; a second receiver; and wherein the antenna array includes a multiple-input, multiple-output antenna array having at least two antennas respectively coupled to the first and second transmitters and to the first and second receivers.

[00276] Example 3 includes the unit? remote antenna of any of Examples 1-2 where the antenna array includes a single antenna.

[00277] Example 4 includes the unit? remote antenna of any of Examples 1-3 wherein one of the first and second interference circuits includes an isolation circuit configured to electrically isolate the receiver from the transmitter.

[00278] Example 5 includes the unit? remote antenna of any of Examples 1-4 wherein: one of the first and second interference circuits includes an analog interference cancellation circuit configured to generate, for each receive signal, a corresponding correction signal; and the receiver? configured to generate, for each receive signal, a respective receive signal with canceled interference in response to the receive signal and the corresponding correction signal.

[00279] Example 6 includes the unit? remote antenna of any of Examples 1-5 wherein: one of the first and second interference circuits includes an analog interference cancellation circuit configured to generate, for each receive signal, a corresponding correction signal; and the receiver includes, for each receive signal, a respective signal combiner configured to generate an interference-cancelled receive signal in response to the receive signal and the corresponding correction signal.

[00280] Example 7 includes the unit? remote antenna of any of Examples 5-6 where the analog interference canceling circuit includes a finite pulse response filter.

[00281] Example 8 includes the unit? remote antenna of any of Examples 5-7 wherein the analog interference canceling circuit includes: an electro-optical converter configured to generate an optical transmit signal in response to the transmit signal; an optical filter configured to generate, in response to the optical transmit signal for each receive signal, a corresponding optical correction signal; and an octo-electric converter configured to generate each corresponding correction signal in response to a corresponding optical correction signal.

[00282] Example 9 includes the unit? remote antenna of any of Examples 1-8 wherein: one of the first and second interference circuits includes a digital interference cancellation circuit configured to generate, for each receive signal, a corresponding correction signal; and the receiver includes, for each receive signal, an analog-to-digital converter configured to generate a respective digital receive signal in response to the receive signal; and the receiver? configured, for each receive signal, to generate a respective interference-cancelled receive signal in response to the respective digital receive signal and the corresponding correction signal.

[00283] Example 10 includes the unit? remote antenna of any of Examples 1-9 wherein: one of the first and second interference circuits includes a digital interference cancellation circuit configured to generate, for each receive signal, a corresponding correction signal; and the receiver includes, for each receive signal, an analog-to-digital converter configured to generate a respective digital receive signal in response to the receive signal, and a respective signal combiner configured to generate an interference-cancelled receive signal in response to the respective digital reception signal and the corresponding correction signal.

[00284] Example 11 includes the unit? remote antenna of any of Examples 1-10, further comprising: an interference receiver configured to process at least one interference receive signal; an array of interference antennas that includes one or more? interfering antennas each coupled to the interfering receiver and each configured to generate a respective of the at least one interfering receiving signal in response to one or more of the at least one interfering downlink signal, and wherein each of at least one of the first and second interfering circuits ? coupled to the interference receiver and ? configured to reduce, in each of the at least one receiving signal, the interference caused by one or more? of the at least one interfering downlink signal.

[00285] Example 12 includes the unit? remote antenna of any of Examples 1-11, further comprising: a second transmitter configured to generate at least a second transmit signal; a second array of antennas including one or more? second antennas each coupled to the second transmitter and configured to emanate a respective second downlink signal in response to a respective one of the at least one second transmission signal; and in which each of at least one of the first and second interference circuits ? coupled to the second transmitter and ? configured to reduce, in each of the at least one receiving signal, interference caused by one or more second downlink signals.

[00286] Example 13 includes the unit? remote antenna of any of the examples 1-12 where the at least one transmit signal and the at least one receive signal are in the same frequency band.

[00287] Example 14 includes the unit? remote antenna of any of Examples 1-13 wherein the at least one transmit signal and the at least one receive signal include at least one same frequency.

[00288] Example 15 includes the unit? remote antenna of any of Examples 1-14 where each respective downlink signal and the uplink signal are in the same frequency band.

[00289] Example 16 includes the unit? remote antenna of any of Examples 1-15 where each respective downlink signal and the uplink signal include at least one same frequency.

[00290] Example 17 includes the unit? remote antenna of any of the examples 1-16 where the downlink signal emanates from one or more? different antennas and the uplink signal are in the same frequency band.

[00291] Example 18 includes a distributed antenna system, comprising: a unit master's degree; and at least one?unit? of remote antenna coupled to the unit? master, each of at least one unit? of remote antenna including a respective transmitter configured to generate at least one transmission signal; a respective receiver configured to process at least one reception signal; a respective array of antennas including one or more? antennas each coupled to at least one of the transmitter and receiver, each of the at least one of the antennas configured to emanate a respective downlink signal in response to a respective of the at least one transmit signal, and each of at least one of the antennas configured to generate a respective of the at least one receive signal in response to an uplink signal; and first and second interference circuits each coupled to the transmitter and receiver and each configured to reduce, in each of the at least one receiving signal, interference caused by one or more of the at least one transmission signal, at least one downlink signal emanating from one of the one or more antennas, and at least one interfering downlink signal emanating from one or more? different antennas.

[00292] Example 19 includes the distributed antenna system of Example 18, further comprising: at least one base station coupled to the unit master and each configured to generate one or more? respective downlink data signals, and to receive one or more? respective uplink data signals; in which each transmitter ? configured to generate the respective at least one transmit signal in response to a respective of the one or more? downlink data signals; and in which each receiver ? configured to generate one respective of one or more? signals given in uplink in response to the respective at least one received signal.

[00293] Example 20 includes the distributed antenna system of Example 19 wherein at least one of the at least one base station ? configured to do s? that each transmitter of at least one of the at least one?unit? remote antenna generates a transmission signal only while the receiver of the same unit? remote antenna is not processing a receive signal.

[00294] Example 21 includes the distributed antenna system of any of Examples 18-20 where one of the at least one unit? of remote antenna includes: an interference receiver configured to process at least one interference reception signal; an array of interference antennas that includes one or more? interfering antennas each coupled to the interfering receiver and each configured to generate a respective of the at least one interfering receiving signal in response to one or more of at least one interfering downlink signal coming from one of the units? remote antenna; and in which each of at least one of the first and second interference circuits ? coupled to the interference receiver and ? configured to reduce, in each of the at least one reception signal, the interference caused by one or more? of at least one interfering downlink signal coming from at least one of the units? of remote antennas.

[00295] Example 22 includes a method, comprising: reducing, with a first interference circuit, an interference in a receive signal caused by at least one of a transmit signal generated by a unit of remote antenna and a downlink signal emanating from a unit? remote antenna; and further reduce, with a second interference circuit, an interference in the reception signal caused by at least one of the transmission signal and the downlink signal.

[00296] Example 23 includes the method of Example 22, further comprising: generating the receive signal with an antenna in response to an uplink signal; and couple the transmit signal to the antenna while generating the receive signal with the antenna.

[00297] Example 24 includes the method of any of Examples 22-23, further comprising: generating the receive signal with an antenna; and emanate the signal downlink with another antenna while generating the receive signal with the antenna.

[00298] Example 25 includes the method of any of Examples 22-24 wherein reducing, with the first interference circuit, the interference in the receive signal includes electrically isolating the receive signal from the transmit signal with the first interference circuit.

[00299] Example 26 includes the method according to any of Examples 22-25, further comprising: generating the downlink signal in response to another transmit signal; and wherein reducing the interference in the receiving signal includes generating a canceling signal in response to the other transmitting signal, and generating a corrected receiving signal in response to the receiving signal and the canceling signal.

[00300] Example 27 includes the method according to any of Examples 22-26, wherein reducing interference in the receive signal includes: generating a cancellation signal in response to the downlink signal, and generating a receive signal corrected in response to the receive signal and the cancel signal.

[00301] Example 28 includes the method according to any of Examples 22-27, further comprising: generating the downlink signal in response to another transmit signal; and wherein further reducing the interference in the receiving signal includes generating a canceling signal in response to the other transmitting signal, and generating a corrected receiving signal in response to the receiving signal and the canceling signal.

[00302] Example 29 includes the method according to any of Examples 22-28, wherein further reducing the interference in the receive signal includes: generating a canceling signal in response to the downlink signal, and generating a receive signal corrected in response to the receive signal and the cancel signal.

[00303] Example 30 includes a transmitter-receiver isolation circuit comprising: a transmitter port configured to receive a transmit signal; an antenna port configured for coupling to an antenna; a receiver port configured to receive a receive signal; a first signal path between the transmitter port and the antenna port is configured to impart a first phase shift to a first transmission portion of the transmission signal; a second signal path between the transmitter port and the antenna port is configured to approximately impart the first phase shift to a second transmission portion of the transmit signal; a leakage path between the transmitter port and the receiver port is configured to impart a second phase shift to a first leakage portion of the transmit signal; and a second leakage path between the transmitter port and the receiver port is configured to impart to a second leakage portion of the transmit signal a third phase shift which is approximately opposite to the second phase shift.

[00304] Example 31 includes the transmitter-receiver isolation circuit of Example 30 wherein: the first signal path includes a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator coupled between the first and second units? phase shift; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? of phase shift configured to impart approximately the first phase shift to the second transmission portion of the transmission signal; and a second circulator coupled between the third and fourth unit? of phase shift.

[00305] Example 32 includes the transmitter-receiver isolation circuit of Example 31, further comprising: a first coupling circuit including the first unit of phase shift and the third unit? phase shift; and a second coupling circuit that includes the second unit? of phase shift and the fourth unit? of phase shift.

[00306] Example 33 includes the transmitter-receiver isolation circuit of any of Examples 31-32 where the former, the latter. The third and fourth units? of phase shift are configured to make s? that the first and second transmission portions of the transmission signal have approximately the same signal strength at the antenna port.

[00307] Example 34 includes the transmitter-receiver isolation circuit of any of Examples 31-33, further comprising: a first coupling circuit including the first unit of phase shift and the third unit? phase shift; a second coupling circuit that includes the second unit? of phase shift and the fourth unit? phase shift; and wherein the first and second coupling circuits are configured to cause s? that the first and second transmission portions of the transmission signal have approximately the same signal strength at the antenna port.

[00308] Example 35 includes the transmitter-receiver isolation circuit of any of Examples 30-34 where: the first signal path includes a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second door coupled to the second unit? phase shift, and a third port coupled to the receiver port; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? of phase shift configured to impart approximately the first phase shift to the second transmission portion of the transmission signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second gate coupled to the fourth unit? of phase shift and a third port coupled to the receiver port.

[00309] Example 36 includes the transmitter-receiver isolation circuit of any of Examples 30-35 where: the first leakage path includes a first unit? phase shift configured to impart a first portion of the second phase shift to the first dispersion portion of the transmit signal; a second unit? of phase shift configured to impart to a second portion of the second phase shift to the first portion of transmission signal dispersion; and a first circulator coupled between the first and second units? phase shift; and does the second dispersal path include a third unit? phase shift configured to impart a first portion of the third phase shift to the second dispersion portion of the transmit signal; a fourth unit? phase shift configured to impart a second portion of the third phase shift to the second dispersion portion of the transmit signal; and a second circulator coupled between the third and fourth units? of phase shift.

[00310] Example 37 includes the transmitter-receiver isolation circuit of Example 36, further comprising: a first coupling circuit including the first unit of phase shift and the third unit? phase shift; and a second coupling circuit that includes the second unit? of phase shift and the fourth unit? of phase shift.

[00311] Example 38 includes the transmitter-receiver isolation circuit of any of Examples 36-37 where the first, third, and fourth units? of phase shift are configured to make s? that the first and second dispersion portions of the transmit signal have approximately the same signal strength at the receiver port.

[00312] Example 39 includes the transmitter-receiver isolation circuit of any of Examples 36-38, further comprising: a first coupling circuit including the first unit of phase shift and the third unit? phase shift; a second coupling circuit that includes the second unit? of phase shift and the fourth unit? phase shift; and wherein the first and second coupling circuits are configured to cause s? that the first and second dispersion portions of the transmit signal have approximately the same signal strength at the receiver port.

[00313] Example 40 includes the transmitter-receiver isolation circuit according to any of Examples 30-39 where: the first leakage path includes a first unit? of phase shift configured to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; a second unit? of phase shift configured to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second port coupled to the antenna port and a third port coupled to the second unit? phase shift; and does the second dispersal path include a third unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; a fourth unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second port coupled to the antenna port and a third port coupled to the fourth unit? of phase shift.

[00314] Example 41 includes the transmitter-receiver isolation circuit of any of Examples 30-40 where: the first signal path includes a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second door coupled to the second unit? phase shift gate and a third gate; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? phase shift configured to impart approximately the first phase shift to the second drive portion of the drive signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second gate coupled to the fourth unit? phase shift gate and a third gate; does the first dispersal path include the first unit? phase shift configured to impart the first phase shift to the first dispersion portion of the transmit signal; a fifth unit? phase shift coupled to the third port of the first circulator and configured to impart approximately the first phase shift to the first dispersion portion of the transmit signal; and does the second dispersion path include the third unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; and a sixth unit? phase shift coupled to the third port of the second circulator and configured to impart approximately zero phase shift to the second leakage portion of the transmit signal.

[00315] Example 42 includes the transmitter-receiver isolation circuit of any of Examples 30-41 where: the first leakage path includes a first unit? phase shift configured to impart a first portion of the second phase shift to the first dispersion portion of the transmit signal; a second unit? of phase shift configured to impart to a second portion of the second phase shift to the first portion of transmission signal dispersion; a third unit? phase shift configured to impart a third portion of the second phase shift to the first dispersion portion of the transmit signal; and a first circulator coupled between the first and second units? phase shift; and the second dispersion path includes a fourth unit? phase shift configured to impart a first portion of the third phase shift to the second dispersion portion of the transmit signal; a fifth unit? phase shift configured to impart a second portion of the third phase shift to the second dispersion portion of the transmit signal; a sixth unit? phase shift configured to impart a third portion of the third phase shift to the second dispersion portion of the transmit signal; and a second circulator coupled between the fourth and fifth units? of phase shift.

[00316] Example 43 includes the transmitter-receiver isolation circuit of Example 42 in which: the second unit? of phase shift? configured to alter the second portion of the second phase shift in response to a first control signal; and the fifth unit? of phase shift? configured to alter the second portion of the third phase shift in response to a second control signal.

[00317] Example 44 includes the transmitter-receiver isolation circuit of any of Examples 42-43 where the first, second, third, fourth, fifth and sixth units? of phase shift are configured to make s? that the first and second dispersion portions of the transmission signal have approximately the same signal strength at the receiver port.

[00318] Example 45 includes the transmitter-receiver isolation circuit of any of Examples 30-44 where: the first leakage path includes a first unit? of phase shift configured to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; a second unit? of electronically adjustable phase shift configured to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; a third unit? of phase shift configurable to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second port coupled to the antenna port, and a third port coupled to the second unit? phase shift; and the second dispersion path includes a fourth unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; a fifth unit? of electronically adjustable phase shift configured to impart approximately 90? of phase shift to the second dispersion portion of the transmission signal; a sixth unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; and a second circulator having a first door coupled to the fourth unit? of phase shift, a second port coupled to the antenna port and a third port coupled to the fifth unit? of phase shift.

[00319] Example 46 includes the transmitter-receiver isolation circuit of any of Examples 30-45 where: the first signal path includes a first unit? phase shift configured to impart a first phase shift to the first transmission portion of the transmission signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second door coupled to the second unit? phase shift gate and a third gate; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? phase shift configured to impart approximately the first phase shift to the second drive portion of the drive signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second gate coupled to the fourth unit? phase shift gate and a third gate; does the first dispersal path include the first unit? phase shift configured to impart the first phase shift to the first dispersion portion of the transmit signal; a fifth unit? an electronically adjustable phase shift device coupled to the third port of the first circulator and configured to impart approximately the first phase shift to the first dispersion portion of the transmit signal; and a sixth unit? of phase shift configurable to impart approximately the first phase shift to the first distortion portion of the transmit signal; and does the second dispersion path include the third unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; a seventh unit? electronically adjustable phase shift coupled to the third port of the second circulator and configured to impart approximately the first phase shift to the second dispersion portion of the transmit signal; and an eighth unit? phase shift configured to impart approximately zero phase shift to the second portion of the transmit signal.

[00320] Example 47 includes a unit? remote antenna, comprising: a transmitter configured to generate a broadcast signal; a receiver configured to process a receive signal; an array of antennas that includes one or more? antennas each coupled to the transmitter and receiver and each configured to emanate a respective downlink signal in response to a respective of the at least one transmit signal, and to generate a respective of the at least one receive signal in response to an uplink signal ; and a transmitter-receiver isolation circuit coupled to one or more antennas, the transmitter and the receiver, the transmitter-receiver isolation circuit including a first signal path between the transmitter and the antenna and configured to impart a first phase shift to a first transmission portion of the transmit signal; a second signal path between the transmitter and the antenna is configured to approximately impart the first phase shift to a second transmission portion of the transmission signal; a first leakage path between the transmitter and the receiver is configured to impart a second phase shift to a first leakage portion of the transmission signal; and a second leakage path between the transmitter and the receiver is configured to impart to a second leakage portion of the leakage signal a third phase shift that is ? approximately opposite to the second phase shift.

[00321] Example 48 includes a distributed antenna system, comprising: a unit master's degree; and at least one unit? of remote antenna coupled to the unit? master, each of at least one unit? of remote antenna including a respective transmitter configured to generate a transmission signal; a respective receiver configured to process a receiving signal; a respective array of antennas including one or more? antennas each coupled to the transmitter and receiver and each configured to emanate a respective downlink signal in response to a respective of the at least one transmit signal; and to generate a respective of the at least one receive signal in response to an uplink signal; and a respective transmitter-receiver isolation circuit coupled to one or more? antennas, to the transmitter and the receiver, the transmitter-receiver isolation circuit including a first signal path between the transmitter and the antenna and configured to impart a first phase shift to a first transmission portion of the transmit signal; a second signal path between the transmitter and the antenna is configured to approximately impart the first phase shift to a second transmission portion of the transmission signal; a first leakage path between the transmitter and the receiver is configured to impart a second phase shift to a first leakage portion of the transmission signal; and a second leakage path between the transmitter and the receiver is configured to impart to a second leakage portion of the transmit signal a third phase shift that is ? approximately opposite to the second phase shift.

[00322] Example 49 includes the distributed antenna system of Example 48, further comprising: at least one base station coupled to the unit master and each configured to generate one or more? respective downlink data signals, and to receive one or more? respective uplink data signals; in which each transmitter ? configured to generate the respective transmit signal in response to a respective of the one or more? downlink data signals; and in which each receiver ? configured to generate a respective of the one or more? uplink data signals in response to the respective received signal.

[00323] Example 50 includes a method, comprising: imparting a first phase shift to a first transmission portion of a broadcast signal propagating from a transmitter to an antenna on a first transmission path; approximately imparting the first phase shift to a second transmission portion of the transmission signal propagating from the transmitter to the antenna on a second transmission path; imparting a second phase shift to a first dispersion portion of the transmission signal propagating from the transmitter to the receiver on a first dispersion path; and impart a third phase shift that ? approximately opposite the second phase shift to a second dispersion portion of the transmit signal propagating from the transmitter to the receiver on a second dispersion path.

[00324] Example 51 includes the method of Example 50, further comprising: making s? that the first and second transmission portions of the transmission signal have approximately the same signal strength at the antenna; and do yes? that the first and second dispersion portions of the transmission signal have approximately the same signal strength at the receiver.

[00325] Example 52 includes the method of any of Examples 50-51, further comprising electronically controlling the phase shift imparted to one of the first and second transmission portions of the transmission signal.

[00326] Example 53 includes the method of any of Examples 50-52, further comprising electronically controlling the phase shift imparted to one of the first and second dispersion portions of the transmit signal.

[00327] Example 54 includes the method of any of Examples 50-53, where the first phase shift ? approximately 90?.

[00328] Example 55 includes the method of any of Examples 50-54 where: the second phase shift ? approximately 180? and the third phase shift? approximately 0?.

[00329] Example 56 includes the method of any of Examples 50-55 where: the second phase shift ? approximately 270? and the third phase shift? approximately 90?.

[00330] Example 57 includes a method comprising: generating multiple dispersion components of a broadcast signal; and do yes? that the dispersion components interfere destructively to reduce interference in a received signal.

[00331] Example 58 includes a transmitter-receiver isolation circuit comprising: a transmit port configured to receive a transmit signal; a receive port configured to provide a receive signal; a first interference path disposed between the transmit port and the receive port and configured to carry a first component of a transmit signal; and a second interference path disposed between the transmit port and the receiver port and configured to carry a second component of the transmit signal and to condition the second component such that at the receiver port, the first and second component of the transmission signal destructively interfere with each other.

[00332] Example 59 includes the transmitter-receiver isolation circuit of Example 58 where: the first interference path ? configured to condition the first component of the transmit signal by imparting a first phase shift to the first component of the transmit signal; and the second interference path? configured to condition the second component of the transmit signal by imparting, to the second component of the transmit signal, a second phase shift that is approximately opposite to the first phase shift.

[00333] Example 60 includes a transmitter-receiver isolation circuit.

[00334] Example 61 includes a unit? of remote antenna.

[00335] Example 62 includes an interference canceling circuit.

[00336] Example 63 includes a unit? remote antenna that includes a transmitter-receiver isolation circuit.

[00337] Example 64 includes a unit? remote antenna that includes interference cancellation circuitry.

[00338] Example 65 includes a unit? of remote antenna which includes a transmitter-receiver isolation circuit and an interference cancellation circuit.

[00339] Example 66 includes a distributed antenna system that includes a unit of remote antenna.

[00340] Example 67 includes a distributed antenna system that includes a unit remote antenna that includes a transmitter-receiver isolation circuit.

[00341] Example 68 includes a distributed antenna system that includes a unit remote antenna that includes interference cancellation circuitry.

[00342] Example 69 includes a distributed antenna system that includes a unit of remote antenna which includes a transmitter-receiver isolation circuit and an interference cancellation circuit.

[00343] Yes? described a series of embodiments of the invention defined by the following claims. Nonetheless, can we understand? the possibility? to make various modifications to the described embodiments without departing from the spirit and scope of the claimed invention. Accordingly, other embodiments fall within the scope of the following claims.

Claims (12)

1. Transmitter-receiver isolation circuit, including: a transmitter port configured to receive a transmit signal; an antenna port configured to couple to an antenna; a receiver port configured to receive a receive signal; a first signal path between the transmitter port and the antenna port is configured to impart a first phase shift to a first transmission portion of the transmission signal; a second signal path between the transmitter port and the antenna port is configured to approximately impart the first phase shift to a second transmission portion of the transmit signal; a first leakage path between the transmitter port and the receiver port is configured to impart a second phase shift to a first leakage portion of the transmit signal; And a second leakage path between the transmitter port and the receiver port is configured to impart to a second leakage portion of the transmit signal a third phase shift which is approximately opposite to the second phase shift. 2. Transmitter-receiver isolation circuit according to claim 1, wherein: does the first signal path include a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator coupled between the first and second units? phase shift; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? phase shift configured to impart approximately the first phase shift to the second drive portion of the drive signal; and a second circulator coupled between the third and fourth unit? phase shift; ? does the first signal path include a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second door coupled to the second unit? phase shift, and a third port coupled to the receiver port; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? phase shift configured to impart approximately the first phase shift to the second drive portion of the drive signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second gate coupled to the fourth unit? phase shift and a third port coupled to the receiver port; ? does the first dispersal path include a first unit? phase shift configured to impart a first portion of the second phase shift to the first dispersion portion of the transmit signal; a second unit? of phase shift configured to impart to a second portion of the second phase shift to the first portion of transmission signal dispersion; and a first circulator coupled between the first and second units? phase shift; and does the second dispersal path include a third unit? phase shift configured to impart a first portion of the third phase shift to the second dispersion portion of the transmit signal; a fourth unit? phase shift configured to impart a second portion of the third phase shift to the second dispersion portion of the transmit signal; and a second circulator coupled to the third and fourth units? phase shift; ? does the first signal path include a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second door coupled to the second unit? phase shift, and a third port coupled to the receiver port; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? of phase shift configured to impart approximately the first phase shift to the second unit? signal transmission transmission; and a second circulator having a first door coupled to the third unit? of phase shift, a second gate coupled to the fourth unit? phase shift and a third port coupled to the receiver port; ? does the first dispersal path include a first unit? phase shift configured to impart a first portion of the second phase shift to the first dispersion portion of the transmit signal; a second unit? of phase shift configured to impart to a second portion of the second phase shift to the first portion of transmission signal dispersion; and a first circulator coupled between the first and second units? phase shift; and does the second dispersal path include a third unit? phase shift configured to impart a first portion of the third phase shift to the second dispersion portion of the transmit signal; a fourth unit? phase shift configured to impart a second portion of the third phase shift to the second dispersion portion of the transmit signal; and a second circulator coupled to the third and fourth units? phase shift; ? does the first dispersal path include a first unit? of phase shift to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; a second unit? of phase shift configured to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second port coupled to the antenna port and a third port coupled to the second unit? phase shift; and does the second dispersal path include a third unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; a fourth unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second port coupled to the antenna port and a third port coupled to the fourth unit? phase shift; ? does the first signal path include a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator having a first door coupled to the first unit? of phase shift, a second door coupled to the second unit? phase shift gate and a third gate; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? phase shift configured to impart approximately the first phase shift to the second drive portion of the drive signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second gate coupled to the fourth unit? phase shift gate and a third gate; does the first dispersal path include the first unit? phase shift configured to impart the first phase shift to the first dispersion portion of the transmit signal; a fifth unit? phase shift coupled to the third port of the first circulator and configured to impart approximately the first phase shift to the first distortion portion of the transmit signal; And does the second dispersion path include the third unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; and a sixth unit? phase shift coupled to the third port of the second circulator and configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; ? does the first dispersal path include a first unit? phase shift configured to impart a first portion of the second phase shift to the first dispersion portion of the transmit signal; a second unit? of phase shift configured to impart to a second portion of the second phase shift to the first portion of transmission signal dispersion; a third unit? phase shift configured to impart a third portion of the second phase shift to the first dispersion portion of the transmit signal; a first circulator coupled between the first and second unit? phase shift; and the second dispersion path includes a fourth unit? phase shift configured to impart a first portion of the third phase shift to the second dispersion portion of the transmit signal; a fifth unit? phase shift configured to impart a second portion of the third phase shift to the second dispersion portion of the transmit signal; a sixth unit? phase shift configured to impart a third portion of the third phase shift to the second dispersion portion of the transmit signal; and a second circulator coupled between the fourth and fifth units? phase shift; ? does the first dispersal path include a first unit? of phase shift configured to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; a second unit? of electronically adjustable phase shift configured to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; a third unit? of phase shift configurable to impart approximately 90? of phase shift at the first dispersion portion of the transmission signal; a first circulator having a first door coupled to the first unit? of phase shift, a second port coupled to the antenna port, and a third port coupled to the second unit? phase shift; and the second dispersion path includes a fourth unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; a fifth unit? of electronically adjustable phase shift configured to impart approximately 90? of phase shift to the second portion of the transmission signal; a sixth unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; and a second circulator having a first door coupled to the fourth unit? of phase shift, a second port coupled to the antenna port and a third port coupled to the fifth unit? phase shift; or ? does the first signal path include a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator having a first door coupled to the first unit? phase shift; a second door coupled to the second unit? phase shift gate and a third gate; and does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? of phase shift configured to impart approximately the first phase shift to the second transmission portion of the transmission signal; and a second circulator having a first door coupled to the third unit? of phase shift, a second gate coupled to the fourth unit? phase shift gate and a third gate; does the first dispersal path include the first unit? phase shift configured to impart the first phase shift to the first dispersion portion of the transmit signal; a fifth unit? an electronically adjustable phase shift device coupled to the third port of the first circulator and configured to impart approximately the first phase shift to the first dispersion portion of the transmit signal; and a sixth unit? of phase shift configurable to impart approximately the first phase shift to the first dispersion portion of the transmit signal; and does the second dispersion path include the third unit? phase shift configured to impart approximately zero phase shift to the second dispersion portion of the transmit signal; a seventh unit? electronically adjustable phase shift coupled to the third port of the second circulator and configured to impart approximately the first phase shift to the second dispersion portion of the transmit signal; and an eighth unit? phase shift configured to impart approximately zero phase shift to the second portion of the transmit signal. 3. Transmitter-receiver isolation circuit according to claims 1 or 2, wherein: does the first signal path include a first unit? phase shift configured to impart the first phase shift to the first transmit portion of the transmit signal; a second unit? phase shift configured to impart approximately zero phase shift to the first transmit portion of the transmit signal; and a first circulator coupled between the first and second units? phase shift; And does the second signal path include a third unit? phase shift configured to impart approximately zero phase shift to the second transmit portion of the transmit signal; a fourth unit? of phase shift configured to impart approximately the first phase shift to the second transmission portion of the transmission signal; and a second circulator coupled between the third and fourth units? phase shift; in which ? The transmitter-receiver isolation circuit further comprises a first coupling circuit which includes the first unit. of phase shift and the third unit? phase shift; and a second coupling circuit that includes the second and fourth units? phase shift; ? the first, second, third and fourth unit? of phase shift are configured to make s? that the first and second transmission portions of the transmission signal have approximately the same signal strength at the antenna port; or ? the transmitter-receiver isolation circuit further comprises a first coupling circuit which includes the first and third units? phase shift; a second coupling circuit that includes the second and fourth units? phase shift; and wherein the first and second coupling circuits are configured to cause s? that the first and second transmission portions of the transmission signal have approximately the same signal strength at the antenna port. 4. Transmitter-receiver isolation circuit according to claims 1 to 3, wherein: does the first dispersal path include a first unit? phase shift configured to impart a first portion of the second phase shift to the first dispersion portion of the transmit signal; a second unit? of phase shift configured to impart to a second portion of the second phase shift to the first portion of transmission signal dispersion; and a first circulator coupled between the first and second units? phase shift; And does the second dispersion path include a third unit? phase shift configured to impart a first portion of the third phase shift to the second dispersion portion of the transmit signal; a fourth unit? phase shift configured to impart a second portion of the third phase shift to the second dispersion portion of the transmit signal; And a second circulator coupled between the third and fourth unit? phase shift; in which ? the transmitter-receiver isolation circuit further comprises a first coupling circuit which includes the first and third units? phase shift; and a second coupling circuit that includes the second unit? of phase shift and the fourth unit? phase shift; ? the first, second, third and fourth unit? of phase shift are configured to make s? that the first and second transmission signal dispersion portions have approximately the same signal strength at the receiver port; or ? the transmitter-receiver isolation circuit further comprises a first coupling circuit which includes the first unit? of phase shift and the third unit? phase shift; a second coupling circuit that includes the second unit? of phase shift and the fourth unit? phase shift; and wherein the first and second coupling circuits are configured to cause s? that the first and second dispersion portions of the transmission signal have approximately the same signal strength at the receiver port. 5. Transmitter-receiver isolation circuit according to claims 1 to 4, wherein: ? does the first dispersal path include a first unit? phase shift configured to impart a first portion of the second phase shift to the first dispersion portion of the transmit signal; ? a second unit? of phase shift configured to impart to a second portion of the second phase shift to the first portion of transmission signal loss; ? a third unit? phase shift configured to impart a third portion of the second phase shift to the first dispersion portion of the transmit signal; And ? a first circulator coupled between the first and second unit? phase shift; And the second dispersal path includes ? a fourth unit? phase shift configured to impart a first portion of the third phase shift to the second dispersion portion of the transmit signal; ? a fifth unit? phase shift configured to impart a second portion of the third phase shift to the second dispersion portion of the transmit signal; ? a sixth unit? phase shift configured to impart a third portion of the third phase shift to the second dispersion portion of the transmit signal; And ? a second circulator coupled between the fourth and fifth unit? phase shift; in which: or the second unit? of phase shift? configured to alter the second portion of the second phase shift in response to a first control signal; and the fifth unit? of phase shift? configured to alter the second portion of the third phase shift in response to a second control signal; or ? the first, second, third, fourth, fifth and sixth unit? of phase shift are configured to make s? that the first and second dispersion portions of the transmit signal have approximately the same signal strength at the receiver port. 6. Unit? of remote antenna, including: a transmitter configured to generate a broadcast signal; a receiver configured to process a receive signal; an array of antennas that includes one or more? antennas coupled to the transmitter and receiver and each configured to output a respective downlink signal in response to a respective of the at least one transmit signal, and to generate a respective of the at least one receive signal in response to an uplink signal; And a transmitter-receiver isolation circuit coupled to one of one or more? antennas, to the transmitter and receiver, including the transmitter-receiver isolation circuit a first signal path between the transmitter and the antenna is configured to impart a first phase shift to a first transmission portion of the transmission signal; a second signal path between the transmitter and the antenna is configured to approximately impart the first phase shift to a second transmission portion of the transmission signal; a first leakage path between the transmitter and the receiver is configured to impart a second phase shift to a first leakage portion of the transmission signal; And a second leakage path between the transmitter and the receiver is configured to impart to a second leakage portion of the transmit signal a third phase shift which is approximately opposite to the second phase shift. 7. Distributed antenna system, including: a unit? master's degree; And at least one unit? of remote antenna coupled to the unit? master, each of at least one unit? of remote antenna, including a respective transmitter configured to generate a transmission signal; a respective receiver configured to process a receiving signal; a respective array of antennas that includes one or more? antennas, each coupled to the transmitter and receiver and each configured to output a respective downlink signal in response to a respective of the at least one transmit signal, and to generate a respective of the at least one receive signal in response to an uplink signal; and a respective transmitter-receiver isolation circuit coupled to one of the one or more? antennas, to the transmitter and receiver, including the transmitter-receiver isolation circuit a first signal path between the transmitter and the antenna is configured to impart a first phase shift to a first transmission portion of the transmission signal; a second signal path between the transmitter and the antenna is configured to approximately impart the first phase shift to a second transmission portion of the transmission signal; a first leakage path between the transmitter and the receiver is configured to impart a second phase shift to a first leakage portion of the transmission signal; and a second leakage path between the transmitter and the receiver is configured to impart to a second leakage portion of the transmit signal a third phase shift that is ? approximately opposite to the second phase shift. 8. The distributed antenna system of claim 7, further comprising: at least one base station paired with the unit? master and each configured to generate one or more? respective downlink data signals, e to receive one or more? respective uplink data signals; in which each transmitter ? configured to generate the respective transmit signal in response to a respective of the one or more? downlink data signals; and in which each receiver ? configured to generate one or more? uplink data signals in response to the respective received signal. 9. Method, including: imparting a first phase shift to a first transmission portion of a transmission signal propagating from a transmitter to an antenna on a first transmission path; approximately imparting the first phase shift to a second transmission portion of the transmission signal propagating from the transmitter to the antenna on a second transmission path; imparting a second phase shift to a first dispersion portion of the transmission signal propagating from the transmitter to the receiver on a first dispersion path; And impart a third phase shift that ? approximately opposite the second phase shift to a second dispersion portion of the transmit signal propagating from the transmitter to the receiver on a second dispersion path. 10. Method according to claim 9, wherein: ? the method also includes doing s? that the first and second transmission portions of the transmission signal have approximately the same signal strength at the antenna; and do yes? that the first and second dispersion portions of the transmission signal have approximately the same signal strength at the receiver; ? The method further comprises electronically controlling the phase shift imparted to one of the first and second transmission portions of the transmission signal; ? The method further comprises electronically controlling the phase shift imparted to one of the first and second dispersion portions of the transmission signal; the first phase shift? approximately 90?; the second phase shift? approximately 180? and the third phase shift? approximately 0?; or ? the second phase shift? approximately 270? and the third phase shift? approximately 90?. 11. Transmitter-receiver isolation circuit, including: a transmit port configured to receive a transmit signal; a receive port configured to provide a receive signal; a first interference path disposed between the transmit port and the receive port and configured to carry a first component of a transmit signal; And a second interference path disposed between the transmit port and the receiver port and configured to carry a second component of the transmit signal and to condition the second component such that at the receiver port, the first and second components of the transmission signal interfere destructively with each other. 12. Transmitter-receiver isolation circuit according to claim 11, wherein: the first interference path? configured to condition the first component of the transmit signal by imparting a first phase shift to the first component of the transmit signal; and the second interference path? configured to condition the second component of the transmit signal by imparting, to the second component of the transmit signal, a second phase shift that is approximately opposite to the first phase shift.