Abstract:
A new system for allowing PCS Providers to share cell sites, and more particularly multi-sector antennas, is provided. The present invention utilizes primarily passive, linear components to combine the transmit signals of PCS Providers which reside in non-adjacent frequency bands over a multi-sector antenna and to distribute from a multi-sector antenna the receive signals in all frequency bands of the PCS Providers.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical Field  
           [0002]    As a result of the growing number of providers of Personal Communication Services (PCS) coupled with the limited availability of prime real estate for new cell sites, an economically favorable option for PCS Providers is to share cell sites. The present invention allows multiple PCS providers to share cell sites, and, more particularly, cell site antennas.  
           [0003]    2. Description of the Prior Art  
           [0004]    As shown in FIG. 1, in prior art cellular systems, PCS Providers are able to transmit and receive signals among all users within a particular geographic area by ensuring that all of its users are within one of the cells  105  which surround each cell site  120 . Accordingly, as shown in FIG. 1, the cell sites  120  are systematically interspersed throughout a geographic area so that the cells  105  overlap just enough to allow a PCS provider to provide transmission and reception capabilities to its users throughout the entire geographic area. The cell sites  120  act as an interface between the users of the PCS network and those outside the network using the public telephone system.  
           [0005]    [0005]FIG. 2 shows how a multi-sector antenna  200  is used to provide the 360 degree horizontal coverage of the cell  105 . A multi-sector antenna  200  typically uses three 120 degree sector antennas  201  to obtain up to a full 360 degree horizontal coverage. However, a multi-sector antenna  200  could use two sector antennas  201 , four sector antennas  201 , or any number (n) individual sector antennas  201 . FIG. 3 provides a simplified representation of the multi-sector antenna  200  of FIG. 2, where the multi-sector antenna  200  may have any number (n) of these individual sector antennas.  
           [0006]    [0006]FIG. 4 shows the separate frequency bands currently allocated by the FCC for use by PCS Providers in the United States. In any one geographic area, six separate companies, or Providers, may hold a license to operate a PCS system on one of these frequency bands. With this arrangement, the Provider holding the license for Band A would be allowed to transmit signals from their cell site on the frequency band between 1930 MHz and 1945 MHz and receive signals at their cell site on the frequency band between 1850 MHz and 1865 MHz. Likewise, the Provider holding the license for Band B could transmit from their cell site on the frequency band between 1950 MHz and 1965 MHz and receive signals at their cell site on the frequency band between 1870 MHz and 1885 MHz. As is shown in FIG. 4, the Providers holding the license for Band C, D, E and F may also use their respective frequency bands to transmit and receive signals.  
           [0007]    [0007]FIGS. 5 and 6A illustrate two prior art cell site  120  architectures which allow a PCS Provider to provide its service. FIG. 5 shows a cell site  120  comprised of a transmitter system  500  and a separate receiver system  510  for transmitting and receiving signals, respectively, from and to the cell site. Here, the transmitter system  500  is comprised of a transmit multi-sector antenna  200 T and transmitter equipment  505 , including a high power amplifier  501  and a transmitter  502 . The receiver system  510  is comprised of a receive multi-sector antenna  200 R and receiver equipment  515 , including a receiver  512  and a low noise amplifier (LNA)  511 . In operation, the PCS provider transmits all signals over the transmitter system  500  and receives all signals over the receiver system  510 .  
           [0008]    [0008]FIG. 6A illustrates an alternative prior art cell site  120  architecture, which incorporates a diplexer  604  to allow a PCS Provider to transmit and receive from the same multi-sector antenna  200 T/R (a transmit/receive multi-sector antenna). This prior art embodiment allows the PCS Provider to receive the same signal from multiple paths via two spatially diverse antennas in order to, among other reasons, minimize multipath distortion, increase the sensitivity of the system, and increase the level of the desired signal. This cell site  120  architecture is similar to the embodiment of FIG. 5 in that the transmit system is comprised of multi-sector antenna  200 T/R, the addition of a diplexer  604 , and transmitter equipment  505 , including a high power amplifier  501  and a transmitter  502 . Further, the receiver system includes a primary receive path identical to that of FIG. 5, which is comprised of a receive multi-sector antenna  200 R and receiver equipment  615 , including a receiver  512  and an LNA  511 . However, the receiver system also includes a second receive path comprised of the transmit/receive multi-sector antenna  200 T/R, the diplexer  604 , and a second receiver  612  and LNA  611  included in the receiver equipment  615 .  
           [0009]    As shown in FIG. 6B, the diplexer  604  is a three port device which is capable of providing communication paths for one transmit path and one receive path only using a transmit bandpass filter  651  and a receive bandpass filter  652 . The diplexer  604  provides Radio Frequency (RF) isolation between the transmit and receive ports while maintaining a low power loss path for the transmit signals to the common antenna port and for the receive signals from the common antenna port.  
           [0010]    The above-described prior art systems are sufficient for PCS Providers who have adequate access to cell sites (towers) which allow the PCS Provider to provide cells throughout an entire geographic region as shown in FIG. 1. However, acquiring access to the real estate for these cell sites (towers) and building the towers, where needed, throughout a geographic region is extremely expensive. Moreover, citizens of many geographic regions have begun to make it known that they would like to eliminate as many cell sites (towers) as possible because they are extremely tall and somewhat unsightly.  
           [0011]    For that reason, some PCS Providers have considered sharing cell sites (towers). An obvious method for these PCS Providers to share the cell sites would be to have each install its own multi-sector antenna system. FIG. 7 illustrates six PCS Providers for bands A, B, C, D, E and F sharing a cell site using the cell site architecture of FIG. 5, and FIG. 8 illustrates the same six PCS Providers sharing a cell site and using the cell site architecture of FIG. 6A.  
           [0012]    A major drawback associated with sharing cell sites according to the embodiments of FIGS. 7 and 8 is that the cell sites would need extremely tall towers and the towers may have difficulty supporting the additional multi-sector antennas  200 . The reason for the difficulty is that the multi-sector antennas extend from the tower and tend to create torques of immense force, as a result of wind, storms and other environmental considerations. Accordingly, many such towers are limited to the number of multi-sector antennas they may support or PCS Providers are forced to spend large sums of money to enhance the supportability and height of the tower.  
           [0013]    To overcome the problems associated with having numerous multi-sector antennas on a tower, some in the PCS field may have considered sharing cell sites among PCS Providers by undertaking to develop a system to share multi-sector antennas. However, it is believed that no one in the PCS field has developed such a system because those of ordinary skill in the art believe that any such system would be extremely difficult and/or expensive to implement. More specifically, it is believed that those in the PCS field are of the common belief that any such system would be essentially a non-viable alternative to the prior art systems of FIGS. 7 and 8 because of their high cost, complexity and unreliability.  
           [0014]    For example, one method of sharing multi-sector antennas that would not likely be considered as a viable alternative is the use of radio frequency (RF) combiners and splitters to share transmit and receive antennas, respectively. As shown in FIG. 9A, a combiner system  900  typically includes an RF combiner  951  and a high power linear amplifier  952 . As shown in FIG. 9B, a splitter system  910  typically includes an RF splitter  953  and a low noise amplifier  954 . FIG. 10A illustrates the application of an RF combiner system  900  and splitter system  910  to the cell site  120  architecture FIGS. 5 and 7, and FIG. 10B illustrates the application of a combiner system  900  and splitter system  910  to the cell site  120  architecture of FIGS. 6A and 8.  
           [0015]    For the prior art system of FIG. 10A, PCS Providers could share a transmit antenna  200 T and a receive antenna  200 R. Likewise, for the prior art system of FIG. 10B, PCS Providers could share a transmit/receive antenna  200 T/R and a receive antenna  200 R. However, it is believed that this alternative has never been pursued because it has a substantial shortcoming in regards to the significant power loss which would be incurred in the RF combiner  951  component of the RF combiner system  900 . Referring to FIG. 9A, a majority of the power input from each PCS Provider transmit equipment to the RF combiner  951  would be dissipated internally within the RF combiner instead of being transferred to the output port. To compensate for this loss, the combiner system  900  must either include a high power linear amplifier  952  as shown, or each PCS Provider must increase their transmit output accordingly. In either case, providing an amplifier with sufficiently high power or increasing a PCS Provider&#39;s transmit output sufficiently would be extremely expensive. Another drawback of using active amplification to compensate for the power loss is the resulting intermodulation distortion which would occur as a result of amplifier non-linearities.  
           [0016]    Another example method of sharing multi-sectors antennas that would not likely be considered a viable alternative by those of ordinary skill in the field, is the typical application of multiplexers to share transmit and receive antennas. As shown in FIG. 11, a transmit multiplexer  1100  typically includes multiple bandpass filters  1101  tied to a common antenna port. The transmit bandpass filters  1101  would correspond to the cell site transmit bands illustrated in FIG. 4. Similarly, as shown in FIG. 11, a receive multiplexer  1105  typically includes multiple bandpass filters  1102  tied to a common antenna port. The receive bandpass filters  1102  would correspond to the cell cite receive bands illustrated in FIG. 4. The transmit multiplexer  1100  and a receive multiplexer  1105  and requisite amplifiers  952  and  954  could then be used in place of the RF combiner system  900  and RF splitter system  910 , respectively, in the cell site illustration of FIGS. 10A and 10B.  
           [0017]    The advantage of the multiplexers  1100  and  1105  relative to a combiner  900  and splitter  910  is that they typically exhibit a smaller power loss between each input and the common antenna port. FIG. 12 shows the six bandpass response curves for the typical implementation of a transmit multiplexer  1100 . The transmit signal from the Band A Provider would be filtered as shown by response curve  1210 , the transmit signal from the Band D Provider would be filtered as shown by response curve  1220 , the transmit signal from the Band B Provider would be filtered as shown by response curve  1230 , the transmit signal from the Band E Provider would be filtered as shown by response curve  1240 , the transmit signal from the Band F Provider would be filtered as shown by response curve  1250 , and the transmit signal from the Band C Provider would be filtered as shown by response curve  1260 .  
           [0018]    The shortcoming of the multiplexers  1100  and  1105  when used in this typical fashion is that due to the contiguous nature of the individual PCS transmit bands currently licensed by the FCC, the passband regions overlap for certain filters. For example, the transmit passband for the PCS Band D Provider  1220  is overlapped by the passband response of the Band A Provider  1210  and the Band B Provider  1230 . In these overlap regions, the power loss for a transmitted signal would increase significantly, thereby negating the benefits of the multiplexer. Due to the contiguous nature of the PCS receive frequency bands currently licensed by the FCC, as shown in FIG. 4, the receive multiplexer  1105  would also experience the same power loss in these overlapping regions. As a result, expensive and active amplification, which would include a high power amplifier  952  for the transmit multiplexer  1100  and a low noise amplifier  954  for the receive multiplexer  1105 , would again be required to compensate for these losses.  
           [0019]    Accordingly, a need exists for a system which allows PCS Providers to more economically, more reliably and more simply share cell sites. The above-described shortcomings, and other shortcomings of the prior art techniques for allowing PCS Providers to share cell sites are effectively overcome by the present invention, as described in further detail below.  
         SUMMARY OF THE INVENTION  
         [0020]    In accordance with the teachings of the present invention, a new system for allowing PCS Providers to share cell sites, and more particularly multi-sector antennas, is provided. The present invention provides a system which is much more economical, reliable and easier to install and use than those of ordinary skill in the PCS industry previously thought possible. The present invention utilizes primarily passive, linear components to combine the transmit signals of PCS Providers which reside in non-adjacent frequency bands over a multi-sector antenna and to distribute from a multi-sector antenna the receive signals in all frequency bands of the PCS Providers.  
           [0021]    The primary advantage of the present invention over the prior art embodiments in FIGS. 7 and 8 is that PCS Providers may share multi-sector antennas, rather than each having to add its own multi-sector antennas to the cell site (tower), thereby reducing the stress impacted on the cell site towers and potentially reducing the height of the tower. Further, the primary advantage of the present invention over systems that might use the RF combiner/splitters of FIGS. 9 and 10 and the multiplexers of FIGS. 11 and 12 is that no expensive high power amplifiers are necessary because the power loss in the system of the present invention is negligible. In addition, because the present invention utilizes primarily passive linear components, it is both comparatively inexpensive, highly reliable, and free of significant intermodulation distortion as compared to those systems requiring active high power amplification.  
           [0022]    The transmitter network  1300 , as shown in FIG. 13, preferably includes: a plurality of bandpass filters for filtering signals of a plurality of non-adjacent PCS frequency bands; a plurality of input lines coupled to the bandpass filters, where the input lines are connectable to the transmission equipment of a plurality of PCS Providers; and an output line coupled to the bandpass filters, where the output line is connectable to a transmit antenna. The bandpass filters are capable of filtering signals in the PCS transmit frequency bands of FIG. 4 and any other frequency bands that are made available to PCS Providers.  
           [0023]    The receiver network  1400 , as shown in FIG. 14, preferably includes: a single bandpass filter for passing the entire PCS cell site receive frequency band; an amplifier coupled to the bandpass filter; a splitter coupled to the amplifier; an input line coupled to the bandpass filters, where the input line is connectable to a receive antenna; and a plurality of output lines coupled to the splitter, where the output lines are connectable to receiver equipment of a plurality of PCS Providers. The bandpass filter is capable of filtering signals in the PCS receive frequency band of 1850 MHz to 1910 MHz as shown in FIG. 4 and any other frequency bands that are made available to PCS Providers.  
           [0024]    The transceiver network  1500 , as shown in FIG. 15, preferably combines the transmitter network  1300  and receiver network  1400 . More specifically, for the transceiver network  1500 , all of the components of the transmitter network  1300  and receiver network  1400  remain the same except that the output lines  1330  of the transmitter network  1300  and the input lines  1420  of the receiver network  1400  are preferably replaced with input/output lines  1510 , which may be connected to a transmit/receive antenna.  
           [0025]    In operation, each PCS Provider may transmit signals over the shared transmit antenna by transmitting their signals from their transmitter equipment via input line to the bandpass filter provided for the PCS Provider&#39;s frequency band. The bandpass filter then forwards the signal via the output line to the transmit antenna for transmission. Each PCS Provider may also receive signals over the shared receive antenna according to the following operations. Each PCS Provider&#39;s signal is received by the receive antenna and forwarded via the input line to the bandpass filter. Next, the bandpass filter forwards it to an amplifier for amplifying and the signal is then distributed to the PCS Provider&#39;s receiver equipment from a splitter via an output line.  
           [0026]    In another aspect of the present invention, the transmitter and receiver networks may be utilized with the standard transmitter/receiver PCS configuration of FIG. 7 and the diplexer configuration of FIG. 8. Further, the present invention includes built-in-test monitoring to detect failures and sense impending problems with the system. Moreover, the present invention provides high power handling capabilities, low insertion loss, non-specific modulation capabilities, high Q filters with steep roll-off characteristics, flat passband gain, flat passband group delay and connectorized components for easy installation and maintenance. The aforementioned and other aspects of the present are described in the detailed description and attached illustrations which follow.  
           [0027]    As described above in the Background of the Invention, it is believed that those in the PCS field have never seriously considered attempting to develop a PCS cell site system where multiple PCS Providers could share an antenna. Further, it is believed that, if those of ordinary skill in the PCS field considered sharing antennas among multiple PCS Providers. they would initially seek to employ the use of RF combiners and RF splitters. It is believed that this technique would be abandoned due to the expense and resulting intermodulation distortion of the high power amplifiers required to compensate for the combiner  900  and splitter  910  power losses.  
           [0028]    Further, it is believed that those of ordinary skill in the PCS field who abandon the technique of using combiners/splitters would not likely conceive of using multiplexers at all to share antennas among multiple PCS Providers. More specifically, given the fact that high power losses would occur in the filter passband overlap regions, as described by FIG. 12, those of ordinary skill in the art would likely readily conclude that extremely expensive high power amplifiers are necessary. Accordingly, the expensive amplifiers would be deemed a non-viable alternative to simply adding antennas and additional support to cell site towers.  
           [0029]    Furthermore, it is believed that those of ordinary skill in the PCS field have never considered attempting to develop a PCS cell site system using primarily passive components (e.g., no amplifiers) like that of the present invention because of the frequency band overlapping problem described above for FIG. 12. More specifically, because the PCS transmit frequency bands and receive frequency bands currently licensed by the FCC (See FIG. 4) are all respectively adjacent, those of ordinary skill in the art would have likely concluded that the use of primarily passive components in a PCS cell site system like that of the present invention was not a plausible solution to the above-described problem in the PCS field.  
           [0030]    However, by utilizing separate antennas at a cell site (tower) for groups of non-adjacent frequency band PCS providers, as set forth for the present invention, all PCS Providers may utilize and share a cell site much more economically, easily and reliably than previously believed possible. For example, referring to FIG. 4, by utilizing the system of the present invention, PCS Providers A, B and F could share a first antenna and PCS Providers D, E and C could share a second antenna. Accordingly, two pairs of transmit and receive antennas or two transmit/receive antennas could be attached to a cell site tower, as compared to the six sets of antennas shown in the prior art.  
           [0031]    By using primarily passive components, the reliability of the system of the present invention is much greater than a system which would require high power amplifiers such as the RF combiner and splitters of FIGS. 9 and 10 or multiplexers of FIGS. 11 and 12. Moreover, the cost to implement the same cell site is substantially less than the cost to implement a system employing the high power amplifiers which would be required for the combiner/splitter or multiplexer systems of FIGS. 9 through 12. Accordingly, for the above stated reasons and other reasons, the present invention is believed to be novel and non-obvious to one of ordinary skill in the art.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]    [0032]FIG. 1 depicts a diagram of a prior art cellular system.  
         [0033]    [0033]FIG. 2 depicts a block diagram of a multi-sector antenna.  
         [0034]    [0034]FIG. 3 depicts a simplified representation of the multi-sector antenna of FIG. 2.  
         [0035]    [0035]FIG. 4 depicts the frequency bands currently allocated by the FCC for use by PCS Providers in the United States.  
         [0036]    [0036]FIG. 5 depicts a diagram of a prior art multi-sector antenna system.  
         [0037]    [0037]FIG. 6 depicts a diagram of another prior art multi-sector antenna system utilizing a prior art diplexer.  
         [0038]    [0038]FIG. 6B depicts a prior art diplexer.  
         [0039]    [0039]FIG. 7 depicts six PCS Providers utilizing the prior art multi-sector antenna system of FIG. 5.  
         [0040]    [0040]FIG. 8 depicts six PCS Providers utilizing the prior art multi-sector antenna system of FIG. 6.  
         [0041]    [0041]FIG. 9A depicts a prior art combiner.  
         [0042]    [0042]FIG. 9B depicts a prior art splitter.  
         [0043]    [0043]FIG. 10A depicts six PCS Providers utilizing a combiner and splitter to share the multi-sector antennas of FIG. 5.  
         [0044]    [0044]FIG. 10B depicts six PCS Providers utilizing a combiner and splitter to share the multi-sector antennas of FIG. 6.  
         [0045]    [0045]FIG. 11 depicts a prior art active multiplexer.  
         [0046]    [0046]FIG. 12 depicts the filter passband response of the transmit multiplexer of FIG. 11.  
         [0047]    [0047]FIG. 13 depicts the transmitter network of the present invention.  
         [0048]    [0048]FIG. 14 depicts the receiver network of the present invention.  
         [0049]    [0049]FIG. 15 depicts the transmitter/receiver network of the present invention.  
         [0050]    [0050]FIG. 16 depicts the implementation of the present invention with six PCS Providers sharing two transmit multi-sector antennas and two receive multi-sector antennas.  
         [0051]    [0051]FIG. 17 depicts the implementation of the present invention with three PCS Providers sharing one transmit/receive multi-sector antenna.  
         [0052]    [0052]FIG. 18 depicts the implementation of the present invention with three PCS Providers sharing one receive multi-sector antenna and one transmit/receive multi-sector antenna.  
         [0053]    [0053]FIG. 19 depicts the implementation of the present invention with six PCS Providers sharing two transmit/receive multi-sector antennas.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0054]    The PCS cell site system of the present invention which allows PCS Providers to share cell sites preferably includes a transmitter network and a receiver network. The transmitter network allows two or more PCS Providers of non-adjacent frequency bands to transmit signals over a multi-sector antenna, and the receiver network allows two or more PCS Providers to receive signals over a multi-sector antenna.  
         [0055]    As shown in FIG. 13, the transmitter network  1300  consists of a transmitter sector  1305  for each antenna sector. Each transmitter sector  1305  preferably includes: a plurality of bandpass filters  1310  for filtering signals of a plurality of non-adjacent PCS frequency bands, including the PCS transmit frequency bands shown in FIG. 4 and any other frequency bands that are made available to PCS Providers; a plurality of input lines  1320  coupled to the bandpass filters  1310 , where each input line  1320  is connectable to the transmission equipment of a PCS Provider; and an output line  1330  coupled to the bandpass filters  1310 , where the output line  1330  is connectable to a transmit antenna.  
         [0056]    The transmitter network  1300  is preferably formed using cavity filter technology, though it may be formed using other filter technology, such as resistor/capacitor (RC) network technology. Cavity filter technology is preferred because it is relatively inexpensive, has a high power handling capability, and does not use active or other non-linear components which are susceptible to the creation of intermodulation distortion. The transmitter network  1300  includes bandpass filtering of particular PCS frequency bands and preferably includes the following characteristics for each transmission path: a maximum insertion loss of 1.0 dB over the passband, a maximum VSWR of 1.5:1 over the passband, a gain variation of less than 0.5 dB peak-to-peak over any 15 MHz segment within any passband, a group delay variation of less than 90 nsec. over any 15 MHz segment within the passband, an average power capacity of 200 Watts per input, a peak power capacity of 5000 Watts per input, steep filter roll-off characteristics, and a capability of handling all PCS modulation types (e.g., GSM, IS-95, etc.) FSY Microwave, Inc. of Columbia, Md. and Metropole of Stafford, Va. are manufacturers of bandpass cavity filter technology, who can manufacture such a transmitter network.  
         [0057]    Of note, the transmitter network  1300  of the present invention may include amplifiers and other components to potentially enhance the performance of the present invention. However, the cost to include any such components in the present invention should be comparatively inexpensive compared to the multiplexers and multicouplers described above in the Background of the Invention. This follows because the present invention does not have the same overlapping and power loss problems as a result of the use of non-adjacent frequency bands.  
         [0058]    The input lines  1320  and output line  1330  preferably include connectors, such as {fraction (7/16)} DIN connectors. The connectors of the input lines  1320  allow for easy connection to the PCS Provider&#39;s transmission equipment, and the connector for the output line  1330  allows for easy connection to a transmit antenna  200 T.  
         [0059]    In use, each input line  1320  of a transmitter sector  1305  is connected to the transmission equipment, including a transmitter, of PCS Providers that are operating in a frequency band which is not adjacent to the frequency band of other Providers using the same transmitter network  1300 , and the output line  1330  is connected to a single transmit antenna  201  for the transmitter sector  1305 . As described in the Background of the Invention for FIGS. 2 and 3, each transmit multi-sector antenna  200 T is comprised of multiple transmit antennas  201  which cover a horizontal sector (e.g., 32 degrees, 65 degrees, 90 degrees, 105 degrees, 120 degrees, etc.). Therefore, if, for example, each transmit antenna  201  covers only 120 degrees, then three transmit antennas  201  could be used to form a transmit multi-sector antenna  200 T covering 360 degrees. In this case, three sets of the transmitter sectors  1305  would be used where they could be packaged either separately or together.  
         [0060]    The transmission equipment for each PCS Provider is then connected to the input line  1320  associated with the respective bandpass filter  1310  on each one of the three transmitter sectors  1305 , and each output line  1330  for each transmitter sector  1305  is connected to a different 120 degree transmit antenna  201 . Accordingly, each PCS Provider may transmit its signals over the same transmit multi-sector antenna  200 T transmitting in all directions.  
         [0061]    In operation, each PCS Provider transmits its signals from its transmission equipment to one of the input lines  1320 . The input line  1320  used will be dependent on which transmit sector  1305  is connected to the desired transmit antenna  201  as well as which bandpass filter  1010  within the transmit sector  1305  corresponds to the Provider&#39;s transmit frequency band. The input line  1320  then forwards the signal to its respective bandpass filter  1310 , which forwards it to the output line  1330 . The signal is then forwarded to the transmit antenna  201  of the multi-sector antenna  200 T which is connected to the output line  1330 , and the signal is transmitted in the requisite direction with a certain beamwidth from the transmit antenna  201 .  
         [0062]    As shown in FIG. 14, the receiver network  1400  consists of a receiver sector  1405  for each antenna sector. Each receiver sector  1405  preferably includes: a bandpass filter  1410  for filtering all signals within the PCS receive frequency band for cell sites, including the PCS receive frequency bands shown in FIG. 4; an amplifier  1450  coupled to the bandpass filters  1410 ; a splitter  1440  coupled to the amplifier  1450 ; an input line  1420  coupled to the bandpass filters  1410 , where the input line  1420  is connectable to a receive antenna  201 ; and a plurality of output lines  1430  coupled to the splitter  1440 , where each output line is connectable to receiver equipment of a PCS Provider.  
         [0063]    Like those of the transmitter network  1300 , the bandpass filters  1410  of the receiver network  1400  are also preferably formed using cavity filter technology. Further, the bandpass filter  1410  preferably includes the same characteristics as described above for the bandpass filters  1310  of the transmitter network  1300 , with the exception that the power handling capability may be reduced. As described above, FSY Microwave and Metropole can manufacture such bandpass filters  1410 .  
         [0064]    The amplifier  1450  is preferably a low noise amplifier (LNA). Further, the amplifier  1450  preferably has a gain of greater than 20 dB, less than a 0.5 dB peak-to-peak gain variation across any 15 MHz band, a noise receive figure of less than 1.0 dB, a 1.85 GHz-1.91 GHZ frequency bandwidth, a one dB power compression point of greater than 15 dBm, and a group delay variation of less than 20 ns across any 15 MHz band. An amplifier  1450  having such characteristics is relatively inexpensive and, since normal operation will be well within the amplifier&#39;s linear response region, it does not produce the significant intermodulation distortion as described previously for high power amplifiers. Further, Miteq of Hauppauge, N.Y. manufacturers such an amplifier  1450  under part no. AFD3-018022-09LN, and MMI also manufactures such an amplifier  1450 .  
         [0065]    Of particular importance, because the receiver network  1400  preferably utilizes a high gain low noise amplifier  1450 , the receiver network  1400  is capable of receiving signals in both non-adjacent and adjacent frequency bands. More specifically, because the amplifier  1450  is able to compensate for any loss caused by the splitter  1440  without great expense or causing significant intermodulation distortion, all PCS Providers may share the receiver network  1400  of the present invention.  
         [0066]    The splitter  1440  may include any number of outputs necessary based on the number of output lines  1430  in the receiver network  1400 , and preferably can handle more than 1 Watt of power and provide minimal gain and phase variation. RLC of Mt. Kisco, N.Y. manufacturers such a splitter  1440 , including a four way splitter  1440  under part no. D-1530-4, as well as Narda and Mini-Circuits who also manufacturer such splitters  1440 .  
         [0067]    Also, like the transmitter network  1300 , the input line  1420  and the output lines  1430  of the receiver network  1400  preferably include connectors, such as {fraction (7/16)} DIN connectors. The connector of the input line  1420  allows for easy connection to a receive antenna  201 , and the connectors of the output lines allow for easy connection to the PCS Providers receiver equipment.  
         [0068]    In use, each output line  1430  of a receiver sector  1405  is connected to the receiver equipment, including a receiver, of a PCS Provider, and the input line  1420  is connected to a single receive antenna  201  for the receiver sector  1405 . As described in the Background of the Invention for FIGS. 2 and 3, each receive multi-sector antenna  200 R is comprised of multiple receive antennas  201  which cover a horizontal sector (e.g., 32 degrees, 65 degrees, 90 degrees, 105 degrees, 120 degrees, etc.). Therefore, if, for example, each receive antenna  201  covers only 120 degrees, then three receive antennas  201  could be used to form a receive multi-sector antenna  200 R covering 360 degrees. In this case, three sets of the receiver sector  1405  would be used where they could be packaged either separately or together.  
         [0069]    The reception equipment for each PCS Provider is then connected to the respective output lines of each receiver sector  1405 , and each receiver sector  1405  is connected to a 120 degree receive antenna  201  based on the desired direction of reception. Accordingly, each PCS Provider may receive its signals over the same receive multi-sector antenna  200 R which receives signals in all directions.  
         [0070]    In operation, the receive multi-sector antenna  200 R receives a signal in a PCS Provider frequency band on one of its receive antennas  201  with a certain beamwidth in a particular direction and forwards the signal to the bandpass filters  1410  of the particular receiver sector  1405  connected to the receive antenna  201 . The bandpass filter  1410  then filters the signal for all PCS receive bands and forwards it to the amplifier  1450  for amplifying. Finally, the signal is forwarded to the splitter  1440  which distributes the signal to individual PCS Provider&#39;s receiver equipment via an output line  1430 .  
         [0071]    As shown in FIG. 15, the transmitter network  1300  of FIG. 13 and receiver network  1400  of FIG. 14 may also be combined as a transceiver network  1500 . For this embodiment, all of the components remain and operate the same, except that output lines  1330  of the transmitter network  1300  and the input lines  1420  of the receiver network  1400  are preferably replaced with input/output lines  1510 , which may be connected to a transmit/receive antenna  201 .  
         [0072]    [0072]FIG. 16 illustrates an implementation of the present invention for a cell site accommodating all six PCS Providers which are to be licensed by the FCC. For this example, two transmit multi-sector antennas  200 T and two receive multi-sector antennas  200 R are utilized. Accordingly, PCS Providers A, B and F share one multi-sector transmit antenna  200 T and both receive multi-sector antennas  200 R, using one transmitter network  1300  and two receiver networks  1400  of the present invention. Further, PCS Providers D, E and C share another transmit multi-sector  200 T and both receive multi-sector antennas  200 R using a second transmitter network  1300  and the same two receiver networks  1400  of the present invention. For cell site situations where each PCS provider requires only a single receive input per sector, one receive multi-sector antenna  200 R and one receiver network  1400  could be eliminated from this illustration.  
         [0073]    In another example, FIG. 17 illustrates how PCS Providers A, B and C (three PCS Providers) may share a cell site using only one multi-sector antenna  200 T/R. Here, the Providers share one transmit/receive multi-sector antenna  200 T/R by using a transceiver network  1500  of the present invention.  
         [0074]    In yet another example, FIG. 18 illustrates how these same three PCS Providers can use the transceiver network  1500  and the receiver network  1400  of the present invention to share one transmit/receive multi-sector antenna  200  T/R and one receive multi-sector antenna  200 R.  
         [0075]    In yet a further example, FIG. 19 illustrates how all six PCS Providers using the FCC licensed frequency bands may utilize the present invention to share only two transmit/receive multi-sector antennas  200 T/R using two transceiver networks  1500  of the present invention. For this example, Providers holding a license to the PCS bands A, B, and F may share one transmit/receive antenna  200 T/R for their transmission path and the second transmit/receive antenna  200 T/R may be used to transmit signals from the Providers holding a license to the remaining three PCS bands D, E, and C. In this example, all six Providers would have access to the receive signal for their band from two different antenna sources. It may be further seen from this example that transmissions in any three non-adjacent frequency bands may use a single transmit/receive antenna  200 T/R for their transmission path and the second transmit/receive antenna  200 T/R may be used to transmit signals either for these same three frequency bands, the other three non-adjacent bands, or can be used to transmit the signals from any of the six frequency bands as long as the transmit signals occupy non-adjacent PCS transmit bands.  
         [0076]    Based on the above examples, it should be readily apparent to one of ordinary skill in the art that PCS Providers may share multi-sector antennas  200  in a variety of combinations as long as only transmit signals from non-adjacent PCS bands are routed to a single multi-sector antenna  200 . Referring to FIG. 4, such combinations include: Providers A and B; Providers A and E; Providers A and F; Providers A and C; Providers A, B and F; Providers A, B and C; Providers A, E and C; Providers D and E; Providers D and F; Providers D and C; Providers D, E and C; Providers B and F; Providers B and C; and Providers E and C.  
         [0077]    In another aspect of the present invention, the transmitter network  1300  of FIG. 13, receiver network  1400  of FIG. 14 and transceiver network  1500  of FIG. 15 may include built-in-test monitoring. For example, all networks  1300 ,  1400  and  1500  may include a means for over temperature sensing  1380 , and the receiver and transceiver networks  1400  and  1500  may include an amplifier failure detection means  1480 . Further, the transmitter network  1300 , receiver network  1400  and transceiver network  1500  may be packaged (e.g., in a metal box) in a variety of ways that allow for LEDs and remote monitoring connectors to be coupled to the different monitoring means and mounted to allow access from the outside of the package.  
         [0078]    What has been described above are preferred embodiments of the present invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present invention are possible.