Patent Publication Number: US-2010128676-A1

Title: Carrier Channel Distribution System

Description:
This application claims the benefit of priority to U.S. provisional application having Ser. No. 61/117,469 filed on Nov. 24, 2008. This and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. 
    
    
     FIELD OF THE INVENTION 
     The field of the invention is wireless carrier channel technologies. 
     BACKGROUND 
     Wireless carriers utilize a number of frequency bands to carry voice, or other data, from one location to another. For example, the carriers can utilize bands around 800 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, or other frequencies as defined by standards or governing bodies. Commonly used techniques for wireless communication include CDMA, TDMA, or FDMA. Each carrier can utilize one or more carrier channels within the frequency bands to carry voice or other data for their services. 
     Unfortunately, geography of an area can severely limit the range in which wireless devices can operate and limit the efficiency of distributing the bands over a coverage area. The industry has responded by providing various cell networks to provide coverage for their services. In some deployments, remote transceiver units (RTUs) provide coverage for a cell area. The RTUs communicate with remote a base station, which can forward data in the channels to other locales or can interact with user equipment. The base station can also receive and digitize signals, which can then be forwarded one to the RTUs. Frequently, the RTUs lack wireless line-of-sight to the base stations due to geography. Rather than RTUs and base stations interacting wirelessly, they communicate with each other by digitized data over a backhaul fiber optic link. 
     Known carrier transport systems comprise terminals that digitize entire bands regardless of the carrier channels within in the band to ensure the terminals can operate with multiple carriers or standards. Such systems offer flexibility, but lack fine grained control over carrier channels, which results in many deficiencies. For example, a backhaul link can become unnecessarily congested because an entire band is digitized as opposed to only active carrier channels. Furthermore, such systems also lack the ability to allocate carrier channels from one cell region to another in response to various events or conditions. As examples, consider the following references describing effort directed toward providing support for carrier channel distribution:
         U.S. Pat. No. 5,642,405 to Fischer et al. titled “Cellular Communications Systems with Centralized Base Stations and Distributed Antenna Units”, filed on Aug. 31, 1994, and discusses aspects of digitizing and multiplexing signals within a Mobile Telecommunication Switching Office (MTSO).   U.S. Pat. No. 6,785,558 to Stratford et al. titled “System and Method for Distributing Wireless Communication Signals Over Metropolitan Telecommunication Networks”, filed on Dec. 6, 2002, describes a distributing wireless signal between a base station hotel and remote cell sites using separately digitized RF carrier signals.   U.S. patent application publication 2006/0258305 to Aschermann titled “Method and System for Transmission of Carrier Signals Between First and Second Antenna Networks” filed Jan. 30, 2002, discusses aspects of switching carrier signals among antenna networks.       

     A better carrier channel transport system would allow fine grained control over carrier channels from a single band or multiple bands by splitting carrier channels from their bands and routing the channels to RTUs as desired through a matrix switch according to a routing policy, possibly where the routing policy can be updated or reconfigured as desired. 
     Thus, there is still a need for a carrier channel distribution system. 
     SUMMARY OF THE INVENTION 
     The inventive subject matter provides apparatus, systems and methods in which a carrier channel distribution system can route individual carrier channels to Remote Transceiver Units (RTUs). The carrier channels can be routed according to a routing policy that can be reconfigured as desired. One aspect of the inventive subject matter includes a system comprising one or more multi-band transceivers configured to receive one or more frequency bands. Preferred frequency bands comprises more than one carrier channel per band. The contemplated system can also include a matrix switch in electrical bi-direction communication with the multi-band transceiver. The matrix switch can be configured to receive analog carrier channels and can include a combiner/splitter to separate out individual carrier channels from their respective bands. The switch preferably routes the individual channels, individually or combined, to RTUs according to a routing policy. The routing policy can be reconfigured as desired or can operate according to a priori defined rules based on circumstances including weather, events, traffic load, load balance, or other circumstances. 
     RTUs can be configured to distribute the carrier channels many different ways. In some embodiments, RTUs can be configured into a simulcast configuration where a host unit distributes the same carrier channels to multiple RTUs. In other embodiments, RTUs can be configured into a cascade configuration where a host unit distributes a carrier channel to a first RTU, which then forwards the carrier channel to another RTU. 
     Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a schematic of a carrier channel distribution system. 
         FIG. 2  is a schematic of a possible base transceiver station (BTS) having a matrix switch and host units. 
         FIG. 3  is a schematic of a possible remote transceiver unit (RTU). 
         FIG. 4  is a schematic of a carrier channel distribution system supporting different configurations of RTUs. 
         FIG. 5  is a composite image comprising  FIGS. 5-1  through  5 - 4  and presents a more detailed schematic overview of a possible carrier channel distribution system. 
         FIG. 5-1  is the upper left quadrant of  FIG. 5 . 
         FIG. 5-2  is the upper right quadrant of  FIG. 5 . 
         FIG. 5-3  is the lower left quadrant of  FIG. 5 . 
         FIG. 5-4  is the lower right quadrant of  FIG. 5 . 
         FIG. 6  is a composite image comprising  FIGS. 6-1  and  6 - 2  and presents a more detailed schematic overview of a possible host unit. 
         FIG. 6-1  is the left half of  FIG. 6 . 
         FIG. 6-2  is the right half of  FIG. 6 . 
         FIG. 7  is a composite image comprising  FIGS. 7-1  and  7 - 2  and presents a more detailed schematic overview of a possible RTU. 
         FIG. 7-1  is the left half of  FIG. 7 . 
         FIG. 7-2  is the right half of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     Throughout the following discussion, numerous references will be made regarding servers, services, interfaces, portals, platforms, or other systems formed from computing devices. It should be appreciated that the use of such terms is deemed to represent one or more computing devices having at least one processor configured to execute software instructions stored on a computer readable media. For example, a server can include one or more computers operating as a web server, database server, or other type of computer server in a manner to fulfill described roles, responsibilities, or functions. One should appreciate that the disclosed carrier channel distribution system offers several technical effects. One technical effect includes increasing the efficiency of carrier channel allocation to remote locations requiring additional bandwidth. 
     In  FIG. 1 , carrier channel distribution system  100  is deployed in an environment where cellular regions  120  require wireless coverage. A base transceiver station (BTS)  140  communicatively couples to one or more remote cell regions  120  via one or more host units  130  using physical communication links  115 . In a preferred embodiment, a BTS  140  is adapted to transmit and receive digitized signals from carrier channels within one or more bands through a multi-band wireless transceiver. Host units  130  relay digitized signals between BTS  140  and remote transceiver units (RTUs)  110  within the remote cell regions  120  using the physical links  115 , preferably fiber optic links. Distribution system  100  can support technologies or protocols including GSM, EDGE, CDMA, TDMA, FDMA, WCDMA, WiMAX, or other wireless technologies. 
     In a preferred embodiment, the communication links  115  between BTS  140  and remote units  110  employ one or more standards to exchange digitized signals. Suitable standards include those based on the Common Public Radio Interface (CPRI; http://www.cpri.info), the Open Base Station Architecture Initiative (OBSAI; http://www.obsai.org), or other known standards or those yet to be defined. 
     One should note that the number of elements within contemplated system  100  can vary to match requirements for a communication system. For example, the number of RTUs  110  within a remote region can vary, the number of host units  130  can vary, the number of BTS  140  can vary, or the number of links  115  among the various elements can vary. 
     In some embodiments, an RTU  110  is geographically separated from BTS  140  by at least 10 Km. It is also contemplated that a single host unit  130  associated with a BTS  140  could link to two or more RTUs  110  that are also geographically separated from each other by at least 10 Km. As used herein “geographically separated” is used euphemistically to represent that two devices are separated by significant distance as opposed to be trivially local to each other. Two devices can be geographically separated by 1 Km, 5 Km, 10 Km, 100 Km, 1000 Km, or further. Indeed such device can be separated across a city, a county, a state, a country, or even separated by continents or oceans. Although the devices can be separated geographically, they preferably communicate over fiber optic links. 
     In  FIG. 2 , BTS  240  is presented in more detail as a schematic of an exemplary embodiment of one aspect of the inventive subject matter. BTS  240  can include multi-band transceiver  260 , which is configured to receive a plurality of frequency bands. It is contemplated that a BTS  240  can be coupled to more than one of multi-band transceiver  260 , or a single multi-band transceiver  260  can coupled to more than one BTS  240 . For discussion purposes only BTS  240  can be considered to comprise multi-band transceiver  260  as illustrated. One should note that alternative configurations are possible while still falling within the scope of the inventive subject matter. For example, each BTS  240  can, itself, be transceiver  260  that is receptive to different bands, or could be remotely coupled to transceiver  260 . 
     Multi-band transceiver  260  is preferably configured to receiver or to transmit wireless signals within a plurality of frequency bands as represented by bands  263 A,  263 B, through  263 N, collectively referred to as bands  263 . Each of bands  263  preferably comprises multiple channels as illustrated. For example, band  263 A has four active channels; analog channels  270  illustrated as blocks  1 - 4 . Band  263 B has five active channels; analog channels  270  illustrated as blocks  5 - 9 , where there is a gap between channels  6  and  7 . Band  263 N has three active channels; analog channels  270  illustrated as blocks  10 - 12  where gaps exist between the channels. Preferred bands includes those around 800 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, or other frequencies as defined by standards or governing bodies. 
     The discussion regarding the routing of channels  1 - 12  from host units to RTUs is presented as channels flowing from transceiver  260 , through host units  230 , to RTUs. It should be noted that the disclosed system is considered to be bi-directional where carrier channel signals can be received by host units  230  from RTUs, then forwarded to multi-band transceiver  260  or a booster for transmission within bands  263 . 
     Although  FIG. 2  illustrates a specific arrangement of analog channels  270  within bands  263 , it should be appreciated that the number of channels and their distribution among bands  263  can vary. Furthermore, it should be appreciated that channels  1 - 12  do not necessarily consume the bandwidth available for their respective bands  263  as represented by the gaps between channels. 
     Received channels  1 - 12  from bands  263  are forwarded to matrix switch  250 . Matrix switch  250  can operate as a combiner/splitter, preferably an analog combiner/splitter, where bands  263  can have their individual channels  1 - 12  split into individual channels or groups of channels (e.g.,  1 - 4 ,  5 - 6 ,  7 - 9 , etc.). In a preferred embodiment, matrix switch  250  routes analog channels  270  to an appropriate host unit  230  according to a policy  255  for distribution to remote regions or RTUs. Host units  230  further distribute the channels to RTUs over links  215 . As referenced previously, matrix switch  250  can also receive channel signals from host units  230  and can combine the channels back into their proper form for transmission within bands  263  for transmission via multi-band transceiver  260 . 
     As an example, switch  250  could route channel  1  from band  263 A to a first host unit  230  while routing channel  2  from band  263 A to a second host unit where both channel  1  and  2  originate from the same band. It is contemplated that different carrier channels  270  from different bands  263  can also be treated separately and routed as desired. Such an approach provides for allocating carrier channels  270  to various remote regions to ensure proper coverage given various conditions. Contemplated conditions that could affect coverage include usage, load, weather, events, or other circumstances that could affect how channels are used. 
     Routing policy  255  can comprises one or more rules that govern behavior of switch  250  with respect to how analog channels  270  should be routed to host units  230  for further distribution to RTUs. Policy  255  is considered to include programmatic instructions stored on a computer readable memory  251  that can be executed within processor  253  that configures switch  250  to properly route the channels. 
     The rules of policy  255  can operate as functions of one or more metrics available to switch  250 . Metrics can be considered to be measures of circumstances associated with matrix switch  250  or its environment, local or global. The rules of policy  255  can include one or more criterion representing a trigger for an action that should be taken when the metrics satisfy the criteria of the rules. When the criteria are met, matrix switch  250  can take appropriate routing action. 
     Metrics include observed metrics, set metrics, calculated metrics, or other types of parameters or attributes of the system. Observed metrics are considered to be those having values that are measured by BTS  240 , matrix switch  250 , or other device associated with the system. Example observed metrics include a time (e.g., absolute, relative, date, etc.), a rate, a threshold, a quantity, a count, or other type of data that is measurable. It is contemplated that some metrics can include historical information relating to the system. Set metrics are considered to be parameters that have set values possibly comprising a geo-location of BTS  240  or RTUs, a flag, an authorization token or password, or other parameter that likely remains static unless directed to change by an authorized user. A calculated metric is considered to be a metric that has a value, or multiple values, as derived from a function operating on other metrics. Example, calculated metrics can include a traffic rate, a consumed bandwidth, an aggregated count, or other derived metrics. 
     As an example, consider a policy  255  that has rules governing the use of bandwidth allocated to different remote regions. A first region might have a significant number of commercial businesses that require additional bandwidth during business hours. The first region could be allocated a large number of channels during the business hours while a residential region might have a smaller number of channels during the same time frame. In such an embodiment, channels  270  can be routed, distributed, or allocated based on time-based metrics using simple rules. 
     Another example includes a policy  255  that routes, allocates, or distributes channels based on a current traffic load. Processor  253  can be configured to analyze traffic metrics (e.g., data rate, call rate, consumed bandwidth, etc.) and correlate various metrics with a signature of potential traffic issues, load balancing for example. If the current or recent historical traffic metric have a profile that satisfies criteria of a signature for a triggering condition, switch  250  can route, allocate, or distribute channels as defined by policy  255  to balance traffic load. 
     One aspect of the inventive subject matter is considered to include establishing one or more signatures of desirable triggering criteria. A signature can be represented by a plurality of metric values, either static value or time-varying vales, and relationships among the metric values. The relationships among metrics can include logical operates (e.g., AND, OR, XOR, etc.), programmatic instructions, threshold criteria, variances around average trends, or other types of relationship. Such signatures can be supplied to matrix switch  250  as part of policy  255 . 
     Yet another example includes a policy  255  that distributes or allocates channels to remote regions based on events. An event can include weather events, political events, trade shows, sporting events, government or police requests, emergencies, or other types of events outside the scope of BTS  240 . Allocating channels to remote regions based on events ensures that sufficient service coverage is available as conditions change. For example, if a weather disaster occurs, switch  250  can be instructed to allocate more channels to a victim region to increase the bandwidth available to victims or aid workers. Such an embodiment can be achieved through setting values to metrics (e.g., flags, Booleans, etc.) that indicate an event is taking place. It is also contemplated that allocating channels based on event could be achieved through a scheduled time as would be possible in a sporting event scenario. 
     Policy  255  can be configured to route, distribute, or allocate channels  270  collectively, as groups, individually, or in other desirable configurations. Matrix switch  250 , based on policy  255 , can allocate a first carrier channel to a first RTU while a second carrier channel from the same band can be routed to a second RTU. For example channel  1  from band  263 A could be routed as an individual, separate from channels  2 - 4  from band  263 A. Channels  5  and  6  could be grouped and routed together to an RTU, or could be split. Furthermore, individual channels from different bands could be split from their bands, and combined together. For example, channel  3  from band  263 A could be combined with channel  12  from band  263 N, which can then be routed together to an RTU as a group. 
     In more preferred embodiments, policy  255  is reconfigurable. A policy is considered reconfigurable if it can be externally updated or modified to reflect changes in its rules as opposed to having a static set of rules that are unchanging. Policy  255  can be reconfigured through numerous means. In some embodiments, BTS  240  or even matrix switch  250  include a network interface, through which policy  255  can be updated after required authentication or authorization. Matrix switch  250  could pull a new policy  255  from a remote server or a remote server or a user could push a new policy  255  to memory  251 . Policy  255  can be reconfigured by adding new rules, modifying existing rules, removing older rules, defining new metrics, setting metrics, or taking other management actions. It is also contemplated that more than one policy  255  could be updated across multiple BTS  240  spread over geographic regions. It is also contemplated that policy  255  could be reconfigured by physically replacing memory  251  storing policy  255  (e.g., flash card, hard drive, solid state driver, etc.). 
     Each host unit  230  can couple to switch  250  to send or receive channel signals. In a preferred embodiment, the host units  230  are configured to optimally digitize desirable channels as opposed to a complete band. For example with respect to illustrated band  263 B, a host unit can digitize, using an Analog to Digital Convert (ADC), a portion of band  263 B that is less than the full width of the band represented by the underline and that only corresponds to an envelope around one or more carrier channels (e.g., an envelope around channels  5  and  6  and/or an envelope around channels  7 - 9 ). Additionally, host unit  230  preferably filters out unused white space within bands  263  to reduce bandwidth utilization on links  215  between host units  230  and RTUs. Host units  230  preferably serialize digitized channels  273  and sends the digitized data over communications links to one or more RTUs. As shown all of channels  270  are transformed into serialized channels  275 . One should appreciate, as discussed previously, channels  270  can be routed or allocated according to policy  255  individually, collectively as shown, or in arbitrary groups. Serialized channel  275  can then be sent to the RTUs over links  215 . As previously discussed, preferred links  215  utilize a standard for exchanging data on channels  273  (e.g., CPRI, OBSAI, etc.). One should appreciate that host unit  230  can operate bi-directionally where it can received serialized channels  275  from an RTU, de-serialize the channels back into digitized channel  273 , restore analog channels  270 , and send the signals of the channels back to switch  250  within their proper channels  270 . It should be appreciate that digitizing or serializing carrier channels is considered to include digitizing or serializing data carried by the channels as desired. 
     In  FIG. 3 , RTU  310  receives serialized channels  375  from a host unit over link  315 . RTU  310  employs a reverse process as taken by host units with respect standards for exchanging data on carrier channels (e.g., CPRI, OBSAI, etc . . . ). RTU  310  de-serializes serialized channels  375  to obtain digitized channels  373 . Digitized channels can be converted back into analog channels  370  using suitable Digital to Analog Converters (DAC). Channels  370  can then be distributed to one or more boosters for re-transmission as represented by MCPA booster  383  or mBSC booster  385 . Suitable boosters include those produced by Bravo Tech Inc, of Cypress Calif. For example, the Bravo Tech Multi-Channel Power Amplifier (MCPA) series of products or Bravo Tech Multi-Band, multi-Standard &amp; multi-Carrier (mBSC) systems can be deployed in the contemplated environments, including indoor or outdoor environments. The channels  370  can be allocated to the boosters as desired: one band per booster, two bands per booster, etc. 
     In  FIG. 4 , RTUs  410  are arranged into different carrier channel distribution configurations. BTS  440  comprises two of host unit  430 , which route carrier channels to one or more of RTUs  410 . Configurations can include one-to-one couplings, one-to-many couplings, or even many-to-many couplings if an applications calls for such a configuration. Unicast configuration  491  represents a configuration where a single host unit  430  couples to a single RTU  410  at a remote location. Such a configuration represents a one-to-one configuration. Simulcast configuration  493  represents a configuration where a single host unit  430  couples to more than one RTU  410  in a one-to-many configuration. A single host unit  430  can duplicate serialized carrier channels as necessary and send the serialized data over more than one fiber optic link to multiple RTUs  410 . One should note that in a simulcast configuration  493 , multiple RTUs  410  could be in the same remote region or in different remote regions. Cascade configuration  495  also represents a one-to-many configuration where a host unit  430  couples to an RTU  410 , which in turn cascades the serialized carrier channels to another RTU  410 , preferably over another optic link. Cascade configuration  495  can include RTUs  410  within a single remote region or can be spread among multiple remote regions. 
     The illustrated examples in  FIG. 4  presents a few of many possible configurations. It is also contemplated that multiple host units  430  could connect to a single RTU  410  in a many-to-one configuration. Such embodiments can provide for redundancy of connectivity should one of BTS  440  fail, possibly due to a natural disaster. 
       FIGS. 5 ,  6 , and  7  are composite images comprising other figures as discussed below.  FIGS. 5 ,  6 , and  7  illustrate the relationship of the remaining figures relative to each other. 
       FIG. 5  is a composite image of  FIGS. 5-1 ,  5 - 2 ,  5 - 3 , and  5 - 4  and presents a more detailed schematic of a possible carrier channel distribution system where a matrix switch operating as a band combiner/splitter routes channels to one or more RTUs via a BTS&#39;s host units. The channels can be digitized using an ADC individually or as a group within an envelope as shown. The digitized channels and their encapsulated data can then be sent as a serialized stream to the RTUs, where the streams are de-serialized and converted back to analog signals for presentation to boosters. 
       FIG. 6  is a composite image of  FIGS. 6-1 , and  6 - 2  and provides a possible schematic of a host unit employing one or more FPGAs. FPGAs can be configured to communicate with a matrix switch to obtain signals from the respective bands supported by the system. An FPGA can also be used to frame, combine, divide, synchronize, or otherwise manage the carrier channels. In the example shown, the carrier channels are serialized using a CPRI standard. 
       FIG. 7  is a composite image of  FIGS. 7-1 , and  7 - 2  and provides a possible schematic of an RTU having similar structure of the host unit of  FIG. 6  and that mirrors a host unit&#39;s functionality. As mentioned previously, contemplated system can be bi-directional in nature. 
     It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.