PATENT DOCUMENT

Publication Number: US-8340724-B2
Application Number: US-201113295123-A
Country: US
Kind Code: B2

Title: Feeder cable reduction

Abstract:
The present invention allows transmission of multiple signals between masthead electronics and base housing electronics in a base station environment. At least some of the received signals from the multiple antennas are translated to being centered about different center frequencies, such that the translated signals may be combined into a composite signal including each of the received signals. The composite signal is then sent over a single feeder cable to base housing electronics, wherein the received signals are separated and processed by transceiver circuitry. Prior to being provided to the transceiver circuitry, those signals that were translated from being centered about one frequency to another may be retranslated to being centered about the original center frequency.

Claims:
1. A method for receiving signals at a first electronics from a second electronics operatively connected to a first and second antenna, comprising:
 receiving, at the first electronics, a composite signal transmitted by the second electronics, the composite signal comprising a first signal centered about a first center frequency and a second signal centered about a second center frequency, wherein the method further comprises second electronics:
 receiving the first signal from the first antenna, wherein the first signal is centered about the second center frequency when received from the first antenna; 
 receiving the second signal from the second antenna, wherein the second signal is centered about the second center frequency when received from the first antenna; 
 translated translating the first signal to be centered about the first center frequency; and 
 combining the second signal with the translated first signal to form the composite signal; 
 
 wherein the method further comprises the first electronics, subsequent to receiving the composite signal, retranslating the first signal to be centered about the second center frequency for processing. 
 
     
     
       2. The method of  claim 1 , wherein the composite signal is received from a cable in a base station environment that is configured to transmit signals from the second electronics to the first electronics. 
     
     
       3. The method of  claim 2 , wherein:
 the first and second antennas are disposed on an antenna mast; 
 the second electronics are disposed on the antenna mast; and 
 the cable is disposed along the antenna mast between the first and second electronics. 
 
     
     
       4. The method of  claim 1 , wherein the first electronics is base housing electronics of a base station environment. 
     
     
       5. The method of  claim 1 , wherein the second electronics is mast housing electronics of a base station environment. 
     
     
       6. The method of  claim 1 , wherein: the second antenna is operable as a main antenna to transmit signals centered about the second center frequency; and the first antenna is operable as a diversity antenna. 
     
     
       7. The method of  claim 1 , wherein the second center frequency is associated with a first cellular band, and a third center frequency is associated with a second cellular band, and wherein the method further comprises the second electronics:
 receiving a third signal centered about the third center frequency from the first antenna; 
 translated translating the third signal to be centered about a fourth center frequency; and 
 combining the second signal with the translated first and third signals to form the composite signal. 
 
     
     
       8. The method of  claim 1 , wherein the first electronics comprises separation circuitry operable to separate the first and second receive signals from the composite signal. 
     
     
       9. The method of  claim 8 , wherein the first electronics comprises transceiver circuitry operable to receive the separated first and second signals from the separation circuitry. 
     
     
       10. A first electronics for receiving signals from a second electronics operatively connected to a first and second antenna, comprising:
 an input for receiving a composite signal transmitted by the second electronics comprising a first signal centered about a first center frequency and a second signal centered about a second center frequency, wherein the second electronics is configured to:
 receive the first signal from the first antenna centered about the second center frequency; 
 receive the second signal from the second antenna centered about the second center frequency; 
 translate the first signal to be centered about the first center frequency; and 
 combine the second signal with the translated first signal to form the composite signal; and 
 
 wherein the first electronics is configured to, subsequent to receiving the composite signal, retranslate the first signal to be centered about the second center frequency for processing. 
 
     
     
       11. The first electronics as recited in  claim 10 , wherein the composite signal is received from a cable in a base station environment that is configured to transmit signals from the second electronics to the first electronics. 
     
     
       12. The first electronics as recited in  claim 11 , wherein:
 the first and second antennas are disposed on an antenna mast; 
 the second electronics are disposed on the antenna mast; and 
 the cable is disposed along the antenna mast between the first and second electronics. 
 
     
     
       13. The first electronics as recited in  claim 10 , wherein the first electronics is base housing electronics of a base station environment. 
     
     
       14. The first electronics as recited in  claim 10 , wherein the second electronics is mast housing electronics of a base station environment. 
     
     
       15. The first electronics as recited in  claim 10 , wherein:
 the second antenna is operable as a main antenna to transmit signals centered about the second center frequency; and 
 the first antenna is operable as a diversity antenna. 
 
     
     
       16. The first electronics as recited in  claim 10 , wherein the second center frequency is associated with a first cellular band, and a third center frequency is associated with a second cellular band, and the second electronics is configured to:
 receive a third signal centered about the third center frequency from the first antenna; 
 translate the third signal to be centered about a fourth center frequency; and 
 combine the second signal with the translated first and third signals to form the composite signal. 
 
     
     
       17. The first electronics as recited in  claim 10  comprising separation circuitry operable to separate the first and second receive signals from the composite signal. 
     
     
       18. The first electronics as recited in  claim 10 , comprising transceiver circuitry operable to receive the separated first and second signals from the separation circuitry. 
     
     
       19. A wireless communication system, comprising:
 a first antenna operable to receive a first receive signal centered about a first center frequency; 
 a second antenna operable to receive a second signal centered about the first center frequency; 
 a first electronics operably connected to the first and second antennas and configured to:
 receive the first signal from the first antenna; 
 receive the second signal from the second antenna; 
 translate the first signal to be centered about a second center frequency; 
 translate the second signal to be centered about a third center frequency; 
 combine the translated first and second signals to form a composite signal; and 
 send the composite signal to second electronics via a cable; 
 
 wherein the wireless communication system further comprises the second electronics, wherein the second electronics is configured to, subsequent to receiving the composite signal, re-translate the first signal to be centered about the first center frequency for processing; 
 wherein the first electronics is a masthead electronics and the second electronics is a base station electronics. 
 
     
     
       20. The wireless communication system as recited in  claim 19 , wherein:
 the first and second antennas are disposed on an antenna mast; 
 the first electronics are disposed on the antenna mast; and 
 the cable is disposed along the antenna mast between the first and second electronics. 
 
     
     
       21. The wireless communication system as recited in  claim 20 , wherein:
 the second antenna is operable as a main antenna to transmit signals centered about the second center frequency; and 
 the first antenna is operable as a diversity antenna.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Continuation of U.S. patent application Ser. No. 12/768,515, filed Apr. 27, 2010, which was a continuation of U.S. Pat. No. 7,729,726, issued on Jun. 1, 2010, the disclosures of both applications are hereby incorporated by reference in its entirety; therefore, the present application claims priority to both the application and patent. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to radio frequency communications, and in particular to translating signals received at one frequency from multiple antennas to being centered about different frequencies, and combining these signals for delivery over a common antenna feeder cable. 
     BACKGROUND OF THE INVENTION 
     In cellular communication environments, the electronics used to facilitate receiving and transmitting signals is distributed between a base housing and a masthead, which is mounted atop a building, tower, or like mast structure. The actual antennas used for transmitting and receiving signals are associated with the masthead. The masthead will generally include basic electronics to couple the antennas to corresponding antenna feeder cables, which connect to transceiver and amplifier electronics located in the base housing. 
     Historically, the amount of electronics placed in the masthead has been minimized, due to inhospitable environmental conditions, such as lightning, wind, precipitation, and temperature extremes, along with the difficulty in replacing the electronics when failures occur. Maintenance of the masthead is time-consuming and dangerous, given the location of the masthead. Minimizing the electronics in the masthead has resulted in essentially each antenna being associated with a separate antenna feeder cable. 
     As time progressed, the cost of the electronics has been greatly reduced, whereas the cost of the antenna feeder cables has held relatively constant, if not increased. Thus, a decade ago the antenna feeder cables were an insignificant cost associated with a base station environment, whereas today the cost of the antenna feeder cables is a significant portion of the cost associated with the base station environment. Accordingly, there is a need to minimize the number of antenna feeder cables associated with a base station environment, without impacting the functionality or operability of the base station environment. Further, there is a need to minimize the increase in cost associated with the masthead and base housing electronics due to minimizing the number of antenna feeder cables required to connect the masthead electronics to the base housing electronics. 
     SUMMARY OF THE INVENTION 
     The present invention allows transmission of multiple signals between masthead electronics and base housing electronics in a base station environment. At least some of the received signals from the multiple antennas are translated to being centered about different center frequencies, such that the translated signals may be combined into a composite signal including each of the received signals. The composite signal is then sent over a single feeder cable to base housing electronics, wherein the received signals are separated and processed by transceiver circuitry. Prior to being provided to the transceiver circuitry, those signals that were translated from being centered about one frequency to another may be retranslated to being centered about the original center frequency. In one embodiment, the multiple antennas represent main and diversity antennas. In such an embodiment, the received signals from the diversity antenna(s) may be translated and combined with the signal received from the main antenna. The receive signal from the main antenna may or may not be translated prior to combining with the translated signals from the diversity antenna(s). The present invention is applicable in single mode and multi-mode environments. It is also applicable to systems which use four branch receive diversity. Future systems such as MIMO which may use two transmit signals and four receive signals per sector will also greatly benefit from this invention. In essence this invention can be leveraged in any deployment scenario where there are more receive signals than transmit signals. 
     Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a block representation of a base station environment according to one embodiment of the present invention. 
         FIG. 2  is a block representation of base housing electronics and masthead electronics according to a first embodiment of the present invention. 
         FIG. 3  is a graphical illustration of a frequency translation process according to the embodiment of  FIG. 2 . 
         FIG. 4  is a block representation of base housing electronics and masthead electronics according to a second embodiment of the present invention. 
         FIG. 5  is a graphical illustration of a frequency translation process according to the embodiment of  FIG. 4 . 
         FIG. 6  is a block representation of base housing electronics and masthead electronics according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. 
     The present invention facilitates the reduction of cabling required in a base station environment. In general, signals that were normally transmitted over separate cables are frequency shifted about different center frequencies, combined, and sent over a single cable. At a receiving end of the cable, the combined signals are recovered and processed in traditional fashion. The invention is particularly useful in a diversity environment, wherein multiple antennas are used to receive a common signal. In such an environment, certain of the signals received from the main and diversity antennas are shifted in frequency, combined with one another, and transmitted over a common cable. Accordingly, each sector, which includes a main and one or more diversity antennas, will need only one cable for transmitting the received signals from the antennas to electronics in a base housing. 
     Prior to delving into the details of the present invention, an overview of a base station environment  10  is illustrated in  FIG. 1  according to one embodiment of the present invention. The illustrated base station environment  10  is exemplary of the primary components in a cellular access network. A base housing  12  is provided in a secure location in association with a mast  14 , which may be a tower or other structure near the top of which is mounted a masthead  16 . Communications for the base station environment  10  are distributed between the masthead  16  and the base housing  12 . In particular, the base housing  12  will include base housing electronics  18 , which include the primary transceiver and power amplification circuitry required for cellular communications. The masthead  16  will include masthead electronics  20 , which generally comprise the limited amount of electronics necessary to operatively connect with multiple antennas  22 , which are mounted on the masthead  16 . The masthead electronics  20  and the base housing electronics  18  are coupled together with one or more feeder cables  24 . For the illustrated embodiment, there are six antennas  22  divided into three sectors having two antennas  22  each. For each sector, one feeder cable  24  is provided between the masthead electronics  20  and the base housing electronics  18 . Accordingly, there are three feeder cables  24  illustrated in  FIG. 1 . In traditional base station environments  10 , each antenna would be associated with one feeder cable  24 . 
     Turning now to  FIG. 2 , a block representation of the base housing electronics  18  and one sector of the masthead electronics  20  is provided according to one embodiment of the present invention. Notably, there are two antennas  22  illustrated. A first antenna is referred to as a main antenna  22 M, and the second antennas is referred to as a diversity antenna  22 D. For signals transmitted from the main antenna  22 M, a signal to be transmitted will be provided over the feeder cable  24  to a duplexer  26  in the masthead electronics  20 . The signal to be transmitted (MAIN TX) is sent to another duplexer  28  and transmitted via the main antenna  22 M. 
     For receiving, signals transmitted from remote devices will be received at both the main antenna  22 M and the diversity antenna  22 D. The signals received at the main antenna  22 M are referred to as the main receive signals (MAIN RX), and the signals received at the diversity antenna  22 D are referred to as the diversity receive signals (DIVERSITY RX). In operation, the main receive signal received at the main antenna  22 M is routed by the duplexer  28  to a low noise amplifier (LNA)  30 , which will amplify the main receive signal and present it to main frequency translation circuitry  32 . The main frequency translation circuitry  32  will effect a frequency translation, which is essentially a shift of the main receive signal from being centered about a first center frequency to being centered around a second center frequency. The main frequency translation circuitry  32  may take the form of a mixer, serrodyne, or the like, which is capable of shifting the center frequency of the main receive signal. 
     Similarly, the diversity receive signal received at the diversity antenna  22 D may be filtered via a filter  34  and amplified using an LNA  36  before being presented to diversity frequency translation circuitry  38 . The diversity frequency translation circuitry  38  will effect a frequency translation of the diversity receive signal from being centered about the first center frequency to being centered about a third center frequency. Preferably, the first, second, and third center frequencies are sufficiently different as to allow signals being transmitted or received at those frequencies to be combined without interfering with one another. 
     With reference to  FIG. 3 , a graphical illustration of the frequency translation process is provided. As illustrated, the main and diversity receive signals are centered about the first center frequency f C1 , wherein the translated main receive signal is centered about center frequency f C2  and the translated diversity receive signal is centered about center frequency f C3 . The center frequencies are sufficiently spaced along the frequency continuum to avoid any interference between the signals transmitted on those center frequencies. 
     Returning to  FIG. 2 , the translated main receive signal and the translated diversity receive signal provided by the main and diversity frequency translation circuitries  32  and  38  are then combined with combining circuitry  40  and presented to the duplexer  26 . The duplexer  26  will then transmit the composite signal to the base housing electronics  18 . 
     The composite signal will be received by a duplexer  40  and provided to separation circuitry  42 , which will effectively separate the translated main receive signal and the translated diversity receive signal and provide them to main frequency translation circuitry  44  and diversity frequency translation circuitry  46 , respectively. The translated main and diversity receive signals will be shifted back to being centered about the first center frequency f C1 , which was originally used for transmitting the main and diversity receive signals from the remote device. Accordingly, the main and diversity receive signals are recovered by the main and diversity frequency translation circuitries  44  and  46  and provided to transceiver circuitry  48 , wherein the receive signals are processed in traditional fashion and forwarded to a mobile switching center (MSC) or other device via an MSC interface  50 . 
     For transmitted signals, the base housing electronics  18  will generate a main transmit signal (MAIN TX) using the transceiver circuitry  48  and provide the main transmit signal to a power amplifier (PA)  52 . The amplified main transmit signal will then be transmitted to the duplexer  40 , which will send the amplifier main transmit signal over the feeder cable  24  toward the masthead electronics  20 , which will route the main transmit signal to the main antenna  22 M as described above. 
     The previous embodiment is configured to minimize the impact on the existing transceiver circuitry  48  in the base housing electronics  18 . In an alternative embodiment, the translated main and diversity receive signals may be presented directly to the transceiver circuitry  48 , which may be modified to be able to process the signals directly, instead of requiring them to be translated back to being centered about their original center frequency, f C1 . Further, the receive signals that are translated may be shifted up or down in frequency to varying degrees. For example, the receive signals may be shifted down to an intermediate frequency, to a very low intermediate frequency, or to a near DC frequency, such as that used in Zero IF architectures. 
     Although not shown, power may be fed from the base housing electronics  18  to the masthead Electronics  20  via the antenna feeder. Power would be coupled to the feeder cable  24  and off of the feeder cable  24  using a conventional Bias-T as is typically done for masthead electronics  20 . Furthermore, a communication link between the base housing electronics  18  and masthead electronics  20  may also be desirable and implemented. The communication link could be implemented at baseband or at an RF frequency other than those frequencies of interest to the wireless operator, using a low power RF transceiver. 
     Furthermore, if it is desirable to control the frequency translation to a high level of precision, a local oscillator (LO) signal in the form of a sine wave could be fed up the feeder cable  24  from the base housing electronics  18  and be extracted by the masthead electronics  20 . The LO signal could be a sine wave in the range of 100 to 200 MHz to facilitate separation from the RX and TX signals. 
     Redundancy is often an issue for the masthead electronics  20 . It is therefore desirable that a minimum amount of functionality be maintained in the event of a hardware failure with either the LNAs or frequency translation circuitry. It would therefore be advantageous in both the main and diversity receive paths be equipped with frequency translation circuitry. If one frequency translation circuit  32  should fail, the main signal would pass through the redundant circuitry unshifted and remain at its original frequency. In such an event the main receive signal could propagate downwards to the base housing electronics  18  at its original RF frequency and the diversity receive signal would continue to be propagated as described. 
     Turning now to  FIG. 4 , a second embodiment of the present invention is illustrated. In this embodiment, the main receive signal is not translated, while the diversity receive signal is translated. Thus, the main receive signal and a translated diversity receive signal are combined in the masthead electronics  20  and sent over the feeder cable  24  to the base housing electronics  18 . In particular, the main receive signal is received at main antenna  22 M, and forwarded to combining circuitry  40  via the duplexer  28 , and through an LNA  30 . The diversity receive signal is received at diversity antenna  22 D, filtered by the filter  34 , amplified by the LNA  36 , and translated from the first center frequency f C1  to a second center frequency f C2  by the diversity frequency translation circuitry  38 . The main receive signal and the translated diversity receive signal are combined by combining circuitry  40  and sent to duplexer  26  for delivery to the base housing electronics  18  over the feeder cable  24 . Upon receipt, the duplexer  40  at the base housing electronics  18  will send a composite receive signal to the separation circuitry  42 , which will provide the main receive signal to the transceiver circuitry  48 , and the translated diversity receive signal to the diversity frequency translation circuitry  46 , which will translate the translated diversity receive signal back to being centered about center frequency f C1  to effectively recover the diversity receive signal, which is then provided to the transceiver circuitry  48  for processing. The main transmit signal is transmitted from the main antenna  22 M as described in association with  FIG. 2 . 
     With reference to  FIG. 5 , a graphical illustration of the translation of the diversity receive signal is shown, as processed in the embodiment of  FIG. 4 . As illustrated, the translated diversity receive signal is shifted to be centered about center frequency f C2 , wherein both the main and the original diversity receive signals are centered about center frequency f C1 . 
     If a masthead LNA is not desired or needed for the main receive signal, the invention can be further simplified by removing the LNA  30  and Duplexer  28  and combining circuitry  40 . In such a case, both the transmit and main receive signals can be fed directly to the duplexer  26 , where they will be combined with a translated diversity receive signal. The duplexer  26  would be designed such that the main filter encompass both the main transmit and main receive frequencies, and the other filter would encompass a shifted diversity receive frequency. This implementation would provide a simpler and less costly module while minimizing transmit path loss. 
     The advantages of this embodiment are twofold. Firstly, the main receive path can be composed of only passive components, thereby improving reliability. Alternatively, if an LNA  30  is desired at the masthead  16  for both the main and diversity receive signals, this embodiment remains simpler since only the diversity receive frequency needs to be translated at the mast, simplifying the electronics and frequency plan. 
     Turning now to  FIG. 6 , a multi-band implementation of the present invention is illustrated. A multi-band communication environment is one in which the same or different cellular communication techniques are supported by a base station environment  10 . As illustrated, a single base housing  12  is used, but different base housings  12  may be used for the different frequency bands. In many instances, the different modes of communication, whether incorporating the same or different underlying communication technologies, are centered about different center frequencies. Two common frequencies about which cellular communications are centered are 800 MHz and 1900 MHz. Accordingly, the base station environment  10  must be able to transmit and receive signals at both 800 MHz and 1900 MHz, and may require diversity antennas  22 D to assist in receiving signals. In operation, received signals in the 800 or 1900 MHz bands (BAND 1 and BAND 2, respectively) may be received at diversity antenna  22 D, wherein a duplexer  54  will send 800 MHz receive signals (800 RXD) through LNA  56  to BAND 1 frequency translation circuitry  58 , which will translate the 800 MHz receive signal about a different center frequency. In this example, assume the BAND 1 frequency translation circuitry downconverts the 800 MHz receive signal to a first intermediate frequency (IF 1 ), wherein the downconverted signal is generally referred to as 800 RXD @ IF 1 . Similarly, 1900 MHz receive signals (1900 RXD) will be provided through LNA  60  to BAND 2 frequency translation circuitry  62 , which will downconvert the 1900 MHz receive signal to a second intermediate frequency (IF 2 ), wherein the downconverted signal is represented as 1900 RXD @ IF 2 . 
     The 800 RXD @ IF 1  and 1900 RXD @ IF 2  signals are combined using combining circuitry  64  to form a composite signal IF 1 +IF 2 , which is provided to combining circuitry  26 ′, which will combine the composite signal IF 1 +IF 2  with any signals received at the main antenna  22 M, and in particular, 800 MHz and 1900 MHz receive signals (800 RX and 1900 RX). Thus, the combining circuitry  26 ′ may combine the 800 and 1900 MHz receive signals with the composite IF 1 +IF 2  signal and present them over the feeder cable  24  to separation circuitry  42  provided in the base housing electronics  18 . The separation circuitry  42  will provide the 800 and 1900 MHz signals to the transceiver circuitry  48 , as well as send the 800 RXD @ IF 1  and 1900 RXD @ IF 2  (translated) signals to respective BAND 1 and BAND 2 frequency translation circuitry  66  and  68 . The BAND 1 frequency translation circuitry  66  may upconvert the 800 RXD @ IF signal to recover the original 800 RXD signal, and the BAND 2 frequency translation circuitry  68  will process the 1900 RXD @ IF 2  signal to recover the original 1900 RXD signal. The 800 RXD and 1900 RXD signals are then provided to the transceiver circuitry  48  for processing in traditional fashion. As noted for the previous embodiment, the transceiver circuitry  48  may be modified to process the downconverted or otherwise translated signals without requiring retranslations back to the original center frequencies, as provided by the BAND 1 and BAND 2 frequency translation circuitry  66  and  68 . 
     Accordingly, the present invention provides for translating signals from one or more antennas  22  in a base station environment  10  in a manner allowing the translated signals to be combined with one another and other untranslated signals for transmission over a common antenna feeder  24 . The present invention is applicable to single and multi-band communication environments, and is not limited to communication technologies or particular operating frequencies. In general, the translation of received signals need only operate such that when the signals are combined with other signals, there is no interference or the interference is otherwise minimal or manageable. Further, the receive signals may be from any spatially diverse array of antennas for one or more sectors. 
     As noted, two base housings  12  that operate in different bands may share the same feeder cables  24  and masthead  16 . 
     Redundancy is a key issue for masthead electronics  20 . Active components which are used in the LNA  30  and frequency translation circuitry  32 ,  38  are less reliable than passive components used to implement the duplexers  26 , combining circuitry  40 , and filters  34 . As such, it may be necessary to bypass the LNAs  30  within the module. An LNA bypass is standard practice for masthead LNAs  30 . 
     More important is redundancy in the frequency translation circuitry  32 ,  38 . Since the objective is to transmit two receive signals, main and diversity, down the same antenna feeder  24  to the base housing electronics  18 , loss of the frequency translation function means that only one of the receive signals can be relayed to the base housing electronics  18 . It is therefore important to consider redundancy schemes in practice. 
     One approach is to simply include multiple levels of redundancy within each circuit block. A more sophisticated scheme would be to further use frequency translation circuitry on both the main receive and diversity receive signals as shown in  FIG. 2 . However, the frequency translation circuitry  32 ,  38  should be designed as to allow a signal to pass through with relatively little attenuation in the event of a hardware failure. Such would be the case with a serrodyne implemented using exclusively shunt or reflection type switches. The combining circuitry  40  could be designed to accept a signal at the translated receive frequency or original receive frequency on either port. The frequency translation circuitry  32 ,  38  would only be used in one branch at any given time, and in the other branch the signal would be passed through the frequency translation circuitry with little or no effect. In the event that the active frequency translation circuitry  32 ,  38  should fail, the unused frequency translation circuitry  32 ,  38  could be turned on to implement the frequency translation on this branch, and the failed frequency translation circuitry  32 ,  38  would then allow the signal to pass through untranslated. 
     Finally, in cases where four-branch receive diversity is used, it is conceivable that each sector contain one transmit signal and four receive signals. In such a case the present invention could easily be expanded to translate the frequency of all receive signals or alternately on the three diversity receive signals to separate frequencies and combine them all onto one feeder cable  24  where they would be separated by another circuit at the base station housing  12 . 
     Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Metadata:
Filing Date: 20111114
Publication Date: 20121225
Grant Date: 20121225
Priority Date: 20040326
Inventors: BEAUDIN STEVE
EDWARDS KEITH RUSSELL
HU XIAOYUN
DEANE PETER
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/246", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W88/085", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/246", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W88/085", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B7/08", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 34990707