Abstract:
The present disclosure generally relates to wireless communication systems employing Distributed Antenna Systems (DAS) as part of a distributed wireless network. More specifically, the present disclosure relates to a DAS network that utilizes traffic monitoring of mobile devices of a distributed wireless network. Traffic monitoring may be used to monitor the DAS network performance and generate analytics of individual mobile devices.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 62/189,113, filed on Jul. 6, 2015, entitled “Distributed Antenna Network Analytics,” the disclosure of which is hereby incorporated by reference in its entirety for all purposes. 
     
    
     BACKGROUND 
       [0002]    Wireless network operators face a continuing challenge in building networks that effectively manage high data-traffic growth rates. To support the mobility and an increased level of multimedia content for end users, communication networks typically employ end-to-end network adaptations that support new services and the increased demand for broadband and flat-rate Internet access. 
         [0003]    One of the most difficult challenges faced by network operators is determining the performance of a DAS network. Remote units used in a DAS network may have limited functionality and may not have the capability of a base station for extracting all Key Performance Indicators (KPIs) available for each user. These KPIs determine the quality of service provided to each user. Users&#39; quality of service may inform network operators how to optimize their networks and may assist in determining problems as they arise. The separation of the base stations from remote units, which occurs in a DAS network, poses a problem in monitoring the network performance. In addition, identifying the location of a user in a DAS network—especially indoors—is a challenge. 
       SUMMARY 
       [0004]    The present disclosure generally relates to wireless communication systems employing Distributed Antenna Systems (DAS) as part of a distributed wireless network. More specifically, the present disclosure relates to a DAS network that utilizes traffic monitoring of mobile devices of a distributed wireless network. Traffic monitoring may be used to monitor the DAS network performance and generate analytics of individual mobile devices. 
         [0005]    According to one embodiment of the invention, a method for determining a geolocation of a mobile device in a DAS system is provided. The method comprises collecting first key performance indicator (KPI) data for the mobile device from a first digital remote unit (DRU). The first KPI data comprises at least one of a first power level and a first transmission time. The method further comprises obtaining a first location of the first DRU. The method further comprises collecting second KPI data for the mobile device from a second DRU. The second KPI data comprises at least one of a second power level and a second transmission time. The method further comprises obtaining a second location of the second DRU. The method further comprises collecting third KPI data for the mobile device from a third DRU. The third KPI data comprises at least one of a third power level and a third transmission time. The method further comprises obtaining a third location of the third DRU. The method further comprises determining the geolocation of the mobile device using (i) the first location and at least one of the first power level and the first transmission time, (ii) the second location and at least one of the second power level and the second transmission time, and (iii) the third location and at least one of the third power level and the third transmission time. 
         [0006]    Systems for performing the methods described herein are also provided. The system comprises a server computer comprising a processor and memory storing instructions, executable by the processor, the instructions comprising the steps of the methods described herein. The system may further comprise a mobile device, at least one DRU, at least one digital access unit (DAU), and/or at least one base transceiver station (BTS). 
         [0007]    These and other embodiments are described in further detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Further objects and advantages of the present invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0009]      FIG. 1  illustrates an example of a basic DAS network architecture, and also illustrates an example of a data transport network, KPI traffic monitoring, use KPI data and position information storage; 
           [0010]      FIG. 2  illustrates another example of DAS network architecture, in which a single base station is used to provide network coverage for a large geographic area when a frequency reuse pattern of N=1 is used; 
           [0011]      FIG. 3  illustrates an example of a DAS network architecture that includes a base station hotel with multiple base stations; 
           [0012]      FIG. 4  illustrates an example of the elements of a DAU, according to one embodiment; 
           [0013]      FIG. 5  illustrates an example of the elements of a DRU, according to one embodiment; 
           [0014]      FIG. 6  illustrates an example of a DAS network architecture, and further illustrates in greater detail an example of a base station hotel; 
           [0015]      FIG. 7  illustrates another example of a DAS network architecture, and further illustrates in greater detail an example of a base station hotel; 
           [0016]      FIG. 8  illustrates another embodiment of a DAS network architecture that includes a base station hotel; 
           [0017]      FIG. 9  illustrates an example of a process for obtaining KPIs for users on a DAS network; 
           [0018]      FIG. 10  illustrates an example of KPI data  1010  that may be collected and stored for each user, as well as an example of the organization of that data; 
           [0019]      FIG. 11  illustrates an example of a process for determining a user&#39;s position using KPI data; 
           [0020]      FIG. 12  illustrates an example of a process for determining a geolocation of a mobile device in a DAS network; 
           [0021]      FIG. 13  illustrates an example of the Long Term Evolution (LTE) channels; 
           [0022]      FIG. 14  illustrates an example of the LTE downlink receiver transport channels and control information; 
           [0023]      FIG. 15  illustrates an example of the LTE downlink transmitter transport channels and control information; 
           [0024]      FIG. 16  illustrates an example of the LTE uplink receiver transport channels and control information; and 
           [0025]      FIG. 17  illustrates an example of the LTE uplink transmitter transport channels and control information. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    A distributed antenna system (DAS) may efficiently utilize base station resources. The base station or base stations associated with a DAS may be located in a central location and/or facility, commonly known as a base station hotel. The DAS network may include one or more digital access units (DAUs, also referred to herein as host unit). DAUs function as an interface between the base stations and digital remote units (DRUs, also referred to herein as remote units). The DAUs can be collocated with the base stations. In some embodiments, the DAS network may further include one or more digital expansion units (DEUs) between the DAUs and the DRUs. DEUs provide routing between the DAUs and the DRUs. In some embodiments, the DEUs have a subset of the functionality of the DAUs, up to the full functionality of the DAUs. DRUs provide wireless network coverage for a given geographical area. The DRUs can be daisy chained together and/or placed in a star configuration. The DRUs may typically be connected with the DAUs using a high-speed optical fiber link. High-speed optical fiber links may facilitate transport of radio frequency (RF) signals from base stations, located at the base station hotel, to a remote location or area served by the DRUs. A base station may include a plurality of independent radio resources, commonly known as sectors. Each of these sectors may provide coverage to separate geographical areas. Each sector may be operable to avoid creating co-channel interference between users within each of the sectors. 
         [0027]    A network&#39;s performance may be measured by the quality-of-service, or QoS, provided to each user. Quality-of-service may be expressed using Key Performance Indicators (KPIs). KPIs may be derived from different parts of the network. Different network operators may have different defined business goals and/or different services of interest. The requirements for obtaining efficient and cost effective network performance management may thus vary from operator to operator. Therefore, quality-of-service metrics may be defined and mapped to a set of KPIs, as required by each operator. 
         [0028]    Remote units in a DAS network may not have the processing power of a base station, and thus may not be able to extract individual user KPIs. This creates a problem in determining the performance of a DAS network and further in identifying the position of mobile devices. Knowing the position of network users of mobile devices may be advantageous. For example, a user&#39;s position may be provided to an emergency service, such as the 911 emergency system. The user&#39;s position may also be used to obtain analytics about the mobile device. KPI metrics of individual mobile devices may also be used for monitoring the status of the DAS network, as well as optimizing the network in the event of failures. 
         [0029]    In various implementations, the systems and methods disclosed herein may use time-stamped snapshots of the network traffic at the various remote units in the DAS network. These snapshots may be transported to hosts units. At the host units, the snapshots may be stored in a server for post processing. A traffic snapshot may consist of complex in-phase and quadrature data (often referred to as I/Q data) of various cellular bands provided by a network. 
         [0030]    In some implementations, KPI data of the individual mobile devices may be scrambled and may be available only at a base station. As a result, KPI data may not be visible without access to proprietary encryption and/or decryption keys. The base station, however, may communicate with network mobile devices via control channels. These control channels may be readily available and provide limited information about KPIs. For example, downlink Long-Term Evolution (LTE) control channels and uplink LTE control channels may be composed of a Physical Broadcast Channel (PBCH), a Physical Downlink Control Channel (PDCCH), a Physical Downlink Shared Channel (PDSCH), a Physical Hybrid-Automatic Repeat Request (ARQ) Channel (PHICH), a Physical Uplink Control Channel (PUCCH), and a Physical Uplink Shared Channel (PUSCH). The control channels can provide information such as, for example, a transmission time, a power level, a user physical layer identifier, a number of allocated resource blocks, a bit-map of resource blocks, a modulation and coding scheme, an acknowledgement, a user channel, a base station channel, a signal-to-noise ratio (SNR), and/or a signal-to-interference-plus-noise ratio (SINR). Different telecommunication standards may provide different information that may be used as KPIs, and as standards evolve, additional KPI information may become available for use. 
         [0031]    In some implementations, the systems and methods disclosed herein can be used in public safety communications systems. Such public safety communications systems may use the LTE control channels discussed above and/or APCO-25 control channels. Thus, in some implementations, APCO-25 control channels may be used alternatively or additionally to LTE or other cellular control channels. 
         [0032]    As noted, KPI data from various remotes units and host units may be stored in a server for post processing. Control channel information for each network operator&#39;s channel may further be extracted from various signals. Furthermore, information associated with each mobile device may be tabulated. 
         [0033]    The commissioning phase of a DAS system is when the DAS system is installed. The commissioning phase may determine the position of each of the remote units, in many cases fairly accurately. Knowing the position of the remote units may assist in establishing the location of individual mobile devices on the DAS network. In many cases, a mobile device&#39;s signal may be received by multiple remote units. Snapshots may be taken of each mobile device&#39;s KPI data at each remote unit. Because the snapshots at the various remote units are time synchronized and time-stamped, these multiple snapshots may be used to triangulate the user&#39;s position. There are many triangulation techniques available to locate a user&#39;s position, such as, for example, Time Delay of Arrival, Power Level, Time Difference, etc. In cases where triangulation may not provide a sufficiently accurate result, the position of the user may be estimated from the location of the remote antenna that received the user&#39;s signal at the highest power. 
         [0034]    Floor plans of a venue that may be included in a DAS installation are generally available during the commissioning phase. These floor plans can be archived and used when tabulating KPI data. The remote units and host units of the DAS network can be identified with a position on the floor plans during the commissioning phase. The position of the remote units relative to a floor plan may further assist in quickly and accurately locating a user. This information may be advantageous, for example, to emergency responders. 
         [0035]      FIG. 1  illustrates an example of a DAS network architecture according to one embodiment. Also illustrated is an example of a data transport network, KPI traffic monitoring, user KPI data and position information storage. The example of  FIG. 1  illustrates a three-sector base station  100  (also referred to as a base transceiver station, or BTS), multiple DAUs  102 ,  108 ,  111  and multiple DRUs. In the illustrated example, the DRUs are connected in a daisy-chain configuration (meaning the DRUs are connected one after the other). In other implementations, the DRUs may be connected in a star configuration (meaning each DRU is independently connected to a central DAU). A daisy chain (or star) of DRUs may be referred to as a cell. Each cell provides network service coverage for a geographical area. The coverage area may be referred to as a sector. Each DRU may provide information associated with the DRU, which may uniquely identify uplink data received by the DRU. 
         [0036]    In various implementations, the base station  100 &#39;s resources may be shared among the DRUs, or among one or more groups of DRUs. To support this resource sharing, the DAUs  102 ,  108 ,  111  and/or DRUs may include routing tables. These routing tables may facilitate sharing of the base station  100 &#39;s resources. 
         [0037]    In various implementations, the DAUs  102 ,  108 ,  111  may be networked to each other to facilitate the routing of DRU signals among the multiple DAUs  102 ,  108 ,  111 . The DAUs  102 ,  108 ,  111  may be configured to transport radio frequency downlink and radio frequency uplink signals between the base station  100  and the DRUs. The architecture of the example DAS network of  FIG. 1  may enable various base station  100  signals to be transported to and from multiple DRUs. The DAUs may be interconnected using peer ports, that is, ports to connect the DAUs in a peer-to-peer network. A peer-to-peer network is distributed application architecture that partitions tasks or workloads between peer, or equally privileged, computing systems. Peer systems make a portion of their resources, such as processing power, disk storage or network bandwidth, directly available to other network participants, without the need for central coordination by servers or stable hosts. In some implementations, the DRUs may also be interconnected with peer ports. 
         [0038]    In some implementations, the DAUs  102 ,  108 ,  111  may have the ability to control the gain, in small increments over a wide range, of downlink and uplink signals that may be transported between the DAUs  102 ,  108 ,  111  and the base station  100 . This ability may allow the DAUs  102 ,  108 ,  111  to flexibly and/or simultaneously control uplink and downlink connectivity between any DRU, or a group of DRUs, and a particular base station  100  sector  101 ,  109 ,  110 . 
         [0039]    As noted above, routing tables may be used to configure the DAUs  102 ,  108 ,  111 . Routing tables of the DAUs may establish mappings between inputs to the DAUs  102 ,  108 ,  111 , and the DAUs&#39;  102 ,  108 ,  111  various outputs. Merge blocks internal to the DAUs  102 ,  108 ,  111  may be used in conjunction with downlink tables when inputs from an external port and a peer port may be merged into the same data stream. Similarly, merge blocks may be used in conjunction with uplink tables when inputs from Local Area Network (LAN) ports and peer ports may be merged into the same data stream. 
         [0040]    Routing tables at the DRUs may also be used establish mapping between inputs to the DRUs and the DRUs&#39; various outputs. Merge blocks internal to the DRUs may be used in conjunction with downlink tables when inputs from LAN ports and peer ports are to be merged into the same data stream. Similarly, merge blocks may be used in conjunction with uplink tables when the inputs from external ports and peer ports are to be merged into the same data stream. 
         [0041]    In the illustrated example of  FIG. 1 , the base station  100  includes three sectors, Sector  1   101 , Sector  2   109 , and Sector  3   110 . In the illustrated example, each sector  101 ,  109 ,  110 &#39;s radio resources may be a transported to a daisy-chained network of DRUs. Each sector  101 ,  109 ,  110 &#39;s radio resources may provide network service coverage to an independent geographical area, via the network DRUs. In the example of  FIG. 1 , three cells  115 ,  116 ,  117 , each comprising seven DRUs, provide coverage to a given geographical area. A server (not illustrated) may control switching of signals between the base station  100 , DAUs  102 ,  108 ,  111 , and the cells  115 ,  116 ,  117 . 
         [0042]    In the illustrated example of  FIG. 1 , DAU  1   102  receives downlink signals from Sector  1   101  of the base station  100 . The downlink signals may be received as radio frequency signals  118 . DAU  1   102  may translate the radio frequency downlink signals  118  from Sector  1   101  to optical signals. DAU  1   102  may further transport some or all of the downlink signals to DRU  1   104  in Cell  1   115 , using optical fiber cable  103 . The signals may be transported over additional optical fiber cable between the DRUs in Cell  1   115 , through each DRU in Cell  1   115 , to DRU  7   105 , the last DRU in the chain. In a similar fashion, DAU  2   108  may receive radio frequency downlink signals  118  from Sector  2   109  of the base station  100 . DAU  2   108  may translate the downlink signals to optical signal, and transport some or all of these downlink signals, using an optical cable  103  to DRU  8   106  in Cell  2   116 . The downlink signals may further be transported through each DRU in Cell  2   116  to DRU  14   107 , the last DRU in this chain. Similarly, DAU  3   111  may transport downlink signals from Sector  3   110  to DRU  15   112  in Cell  3   113 . The downlinks signals may further be transported through each DRU in Cell  3   117  to DRU  21   113 , the last DRU in this chain. Additional cells may be provided and connected to the DAS network. In some implementations, the DAUs  102 ,  108 ,  111  may interface with the base station  100  via a digital data link. In such implementations, radio frequency translation at the DAUs  102 ,  108 ,  111  may not be necessary. 
         [0043]    In the illustrated example, DAU  1   102  is networked with DAU  2   108  and DAU  3   111 . Networking the DAUs  102 ,  108 ,  111  allows the downlink signals from Sector  2   109  and Sector  3   110  to be transported to the DRUs in Cell  1   115 . Similarly, downlink signals from Sector  1   201  may be transported to the DRUs in Cell  2   116  and Cell  3   217 . Switching and routing functionality may control which sectors&#39;  101 ,  109 ,  110  signals are transmitted and/or received by each DRU in Cell  1   115 . 
         [0044]    In some implementations, one or more digital expansion units (DEUs) (not shown) are present between the DAUs  102 ,  108 ,  111  and their associated DRUs  104 ,  105 ,  106 ,  107 ,  112 ,  113 . The DEUs may provide routing between the DAUs  102 ,  108 ,  111  and their associated DRUs  104 ,  105 ,  106 ,  107 ,  112 ,  113 . In some embodiments, the DEUs have a subset of the functionality of the DAUs  102 ,  108 ,  111 , up to the full functionality of the DAUs  102 ,  108 ,  111 . 
         [0045]    Also illustrated in  FIG. 1  is, by way of example, a KPI traffic monitoring unit  121  and user KPI data and position storage  120 . The DAUs  102 ,  108 ,  111  may each be connected to the KPI traffic monitoring unit  121 . Alternatively, the KPI traffic monitoring unit  121  may be inside a particular DAU (e.g., DAU  102 ), or each DAU (e.g., DAUs  102 ,  108 ,  111 ) may be equipped with a KPI traffic monitoring unit  121 . The KPI traffic monitoring unit  121  may track user KPIs at each DAU  102 ,  108 ,  111  and DRU in the network. Time-synchronized snapshots of the traffic at the various DRUs and/or DAUs  102 ,  108 ,  111  may be collected and stored in a server for post processing. The traffic snapshots may include complex I/Q data from various cellular bands provided by the DAS network. The traffic snapshots may be collected and stored in the KPI Data and Position unit  120 . As with the KPI traffic monitoring unit  121 , the KPI Data and Position unit  120  may be separate from or a part of the DAUs (e.g., DAUs  102 ,  108 ,  111 ). The User KPI Data and Position unit  120  may extract KPI data for each user associated with the DAUs  102 ,  108 ,  111  and DRUs. This data may be extracted from control channels provided with uplink and downlink signals. 
         [0046]    Control channels may be readily available. Control channels may provide limited information about user KPIs. For example, downlink LTE channels and uplink LTE control channels may include a Physical Broadcast Channel (PBCH), a Physical Downlink Control Channel (PDCCH), a Physical Downlink Shared Channel (PDSCH), a Physical Hybrid-ARQ Channel (PHICH), a Physical Uplink Control Channel (PUCCH), and a Physical Uplink Shared Channel (PUSCH). Control channels may provide information such as for example transmission time, power level, user physical layer identifiers, a number of allocated resource blocks, a bitmap of resource blocks, a modulation and coding scheme, acknowledgements, a user channel, a base station channel, SNR, and/or SINR. 
         [0047]    The snapshots at the various DRUs may be time synchronized and time-stamped. These snapshots may be used to triangulate the user&#39;s position. Many triangulation techniques are available to locate a user&#39;s position, such as, for example, Time Delay of Arrival, Power Level, Time Difference at Arrival, etc. A time synchronized DAS network may provide the added advantage of relatively accurate time-stamped snapshots from a multitude of remote units and host units. In cases where triangulation may not provide a sufficiently accurate result, the position of user may be estimated from the location of the remote unit that received the highest signal power. User data may be provided over an Internet Protocol (IP)  119  connection to the Internet  130 , so that the data may be accessible for example on the World Wide Web. 
         [0048]      FIG. 2  illustrates another example of DAS network architecture, in which a single base station is used to provide network coverage for a large geographic area when a frequency reuse pattern of N=1 is used. The example of  FIG. 2  illustrates a three-sector base station  200 , multiple DAUs  202 ,  208 ,  211 , and multiple DRUs. The DRUs in this example are grouped into six cells  215 ,  216 ,  217 ,  231 ,  234 ,  237 . Within each cell, the DRUs are connected in daisy chained configuration. In this example, Cell  1   215  and Cell  8  share the radio resources of Sector  1   201  of the base station  100 . Similarly, Cell  2   216  and Cell  3   217  share the radio resources of Sector  2   209  of the base station  100 . Also similarly, Cell  3   217  and Cell  10   237  share the radio resources of Sector  3   210 . 
         [0049]    The DAUs  202 ,  208 ,  211  may control routing of data between the base station  100  and the DRUs. A data packet may be provided with a header that identifies the DRU with which it is associated. The DAUs  202 ,  208 ,  211  may be interconnected to allow data to be transported between them. The ability to route data between the DAUs  202 ,  208 ,  211  may be advantageous, because this allows flexible routing of signals between any of the sectors  201 ,  209 ,  210  and the individual DRUs. A server (not illustrated) may provide switching and routing functions. 
         [0050]    In the illustrated example of  FIG. 2 , DAU  1   202  receives downlink signals from Sector  1   201  of the base station  200 . DAU  1   202  may translate radiofrequency signals  218  from Sector  1   201  to optical signals. DAU  1   202  may further transport some or all of the downlink signals to DRU  1   204  in Cell  1   215 , using optical fiber cable  203 . The signal may be transported through additional optical fiber cable between the DRUs in Cell  1   115 , through each DRU in Cell  1   215  to DRU  7   205 , the last DRU in the chain. In the illustrated example, DAU  1   202  may also transport downlink signals to DRU  212  in Cell  3   217  over an additional optical cable  209 . The signals may further be transported over additional optical cable through each DRU in Cell  3   217  to DRU  21   213 , the last DRU in Cell  3   217 . Cell  3   217  may provide network service coverage to a different geographical area than is provided by Cell  1   215 . In this way, the services provided by Sector  1   201  may be distributed to a larger area. In some cases, Cell  3   217  may be a great distance away from Cell  1   215 . In other cases, Cell  3   217  and Cell  1   215  may be adjacent and/or coverage provided by them may be partially overlapping. 
         [0051]    In a similar fashion, DAU  2   208  may receive radio frequency downlink signals  218  from Sector  2   209  of the base station  200 . DAU  2   208  may translate the downlink signals to optical signals, and transport some or all of these downlink signals, using an optical cable  203  to DRU  8   206  in Cell  2   216 . The downlink signals may further be transported through each DRU in Cell  2   216  to DRU  14   207 , the last DRU in this chain. In this example, DAU  2   208  may also transport downlink signals to DRU  29   235  in Cell  4   234  over an additional optical cable  209 . The signals may further be transported through each DRU in Cell  4   234  to DRU  35   236 , the last DRU in this chain. Cell  4   234  may provide network service coverage to a different geographical area than is provided by Cell  2   216 . Furthermore, DAU  2   208  may selectively transport signals to either Cell  2   216  or Cell  4   234 , or both. In this way, network service coverage may be provided as needed in the geographical area covered by each cell  216 ,  234 . 
         [0052]    Similarly, DAU  3   111  may transport downlink signals from Sector  3   110  to DRU  15   112  in Cell  3   113 . The downlink signals may further be transported through each DRU in Cell  3   117  to DRU  21   113 , the last DRU in this chain. DAU  3   111  may also transport downlink signals, via an additional optical cable  209 , to DRU  42   239  in Cell  10   237 . The signals may further be transported through each DRU in Cell  10   237  to DRU  42   239 , the last DRU in this chain. 
         [0053]    Additional cells may be provided and connected to the DAS network. In some implementations, the DAUs  102 ,  108 ,  111  may interface with the base station  100  via a digital data link. In such implementations, radiofrequency translation at the DAUs  102 ,  108 ,  111  may not be necessary. 
         [0054]    In some implementations, DAU  1   202 , DAU  2   208 , and DAU  3   2111  may be networked to each other. In these implementations, downlink signals from Sector  2   209  and Sector  3   210  may be transported to some or all of the DRUs in Cell  1   215  and/or Cell  4   234 . Similarly, downlink signals from Sector  1   201  may transported to Cell  2   216  and/or Cell  4   234  by way of DAU  2   208 , and Cell  3   217  and/or Cell  10   237  by way of DAU  3   211 . 
         [0055]    In some implementations, one or more digital expansion units (DEUs) (not shown) are present between the DAUs  202 ,  208 ,  211  and their associated DRUs  204 ,  205 ,  206 ,  207 ,  212 ,  213 ,  232 ,  233 ,  235 ,  236 ,  238 ,  239 . The DEUs may provide routing between the DAUs  202 ,  208 ,  211  and their associated DRUs  204 ,  205 ,  206 ,  207 ,  212 ,  213 ,  232 ,  233 ,  235 ,  236 ,  238 ,  239 . In some embodiments, the DEUs have a subset of the functionality of the DAUs  202 ,  208 ,  211 , up to the full functionality of the DAUs  202 ,  208 ,  211 . 
         [0056]    Also illustrated in  FIG. 2  is, by way of example, a KPI monitor unit  221  and User KPI Data and Position storage  220 . The DAUs  202 ,  208 ,  211  may each be connected to the KPI monitor unit  221 . Alternatively, the KPI monitor unit  221  may be inside a particular DAU (e.g., DAU  202 ), or each DAU (e.g., DAUs  202 ,  208 ,  211 ) may be equipped with a KPI monitor unit  221 . The KPI monitor unit  221  may track user KPIs at each DAU  202 ,  208 ,  211  and/or DRU in the network. The KPI monitor unit  221  may collect time-synchronized snapshots of user data at any of the DAUs  202 ,  208 ,  211  and/or DRUs. The User KPI Data and Position storage  220  (which may be separate from or a part of one or more of DAUs  202 ,  208 ,  211 ) may extract KPI data from control channels provided in the user communication links. The User KPI Data and Positioning storage  220  may further use triangulation methods to determine a user&#39;s positon relative to the positon of the DRUs. User KPI data and/or position may be made provided over an IP  219  connection to the Internet  230 , so that the data may be accessible for example on the World Wide Web. 
         [0057]      FIG. 3  illustrates an example of a DAS network architecture that includes a base station hotel with multiple base stations  300 ,  350 . The number of base stations at the base station hotel may be represented as N base stations. Each base station  300 ,  350  may represent an independent wireless network operator. Alternatively or additionally, each base station  300 ,  350  may implement a different wireless standard (e.g. Wideband Code Division Multiple Access (WCDMA), LTE, etc.). Alternatively or additionally, each base station  300 ,  350  may provide additional radiofrequency carriers. Base station  300 ,  350  signals may be combined prior to these signals being transported to a DAU, as may be the case for a Neutral Host application. 
         [0058]    In the illustrated example of  FIG. 3 , DAU  1   302  receives downlink signals from Sector  1   301  of the base station  300 . The downlink signals may be received as radio frequency signals.  318 . DAU 1   302  may translate the radio frequency downlink signals  318  from Sector  1   301  to optical signals. DAU  1   302  may further transport some or all of the downlink signals to DRU  1   304  in Cell  1   315 , using optical fiber cable  303 . The signals may be transported over additional optical fiber cable between the DRUs in Cell  1   315 , through each DRU in Cell  1   315 , to DRU  7   305 , the last DRU in the chain. DAU  1   302  may also receive downlink signals from Sector  1   340  of base station N  350 . The downlink signals from base station N  350  may also be received as radiofrequency signals  318 . DAU  1   302  may also translate the downlink signals from Sector  1   340  of base station N  350  to optical signals, for transport to the DRUs in Cell  1   315 . 
         [0059]    In a similar fashion, DAU  2   308  may receive radio frequency downlink signals  318  from Sector  2   109  of the base station  300 , and Sector  2   341  of base station  350 . DAU  2   308  may translate the downlink signals to optical signals, and transport some or all of these downlink signals, using an optical cable  303  to DRU  8   306  in Cell  2   316 . The downlink signals may further be transported through each DRU in Cell  2   316  to DRU  14   307 , the last DRU in this chain. Similarly, DAU  3   111  may transport downlink signals from Sector  3   110  of base station  300  and Sector  3   342  of base station N  350  to DRU  15   312  in Cell  3   313 . The downlink signals may further be transported through each DRU in Cell  3   317  to DRU  21   313 , the last DRU in this chain. 
         [0060]    In some implementations, DAU  1   302  may be networked with DAU  2   308  and DAU  3   311 . Networking the DAUs  302 ,  308 ,  311  allows the downlink signals from Sectors  2   309  and Sector  3   310  from base station  300 , and Sector  2   341  and Sector  3   342  from base station N  350 , to be transported to some or all of the DRUs in Cell  1   315 . Similarly, downlink signals from Sector  1   301  of base station  300  and Sector  1   340  of base station  350  may be transported to some or all of the DRUs in Cell  2   316  and Cell  3   317 . 
         [0061]    In some implementations, the DAS network architecture of  FIG. 3  may achieve more efficient usage of base station resources. Routing functionality in the DAUs may be configured to redirect uplink and downlink signals associated with unique data streams to and from any of the base station  300 ,  350  sectors to and from any of the DRUs. 
         [0062]    In some implementations, one or more digital expansion units (DEUs) (not shown) are present between the DAUs  302 ,  308 ,  311  and their associated DRUs  304 ,  305 ,  306 ,  307 ,  312 ,  313 . The DEUs may provide routing between the DAUs  302 ,  308 ,  311  and their associated DRUs  304 ,  305 ,  306 ,  307 ,  312 ,  313 . In some embodiments, the DEUs have a subset of the functionality of the DAUs  302 ,  308 ,  311 , up to the full functionality of the DAUs  302 ,  308 ,  311 . 
         [0063]      FIG. 4  illustrates an example of the elements of a DAU, according to one embodiment. In this example, the DAU is composed of physical nodes  400  and a local router  401 . The physical nodes  400  may translate radio frequency downlink signals  404  to baseband downlink signals  409 , and baseband uplink signals  410  to radiofrequency uplink signals  405 . The physical nodes  400  may connect to one or more base stations at radio frequencies. Each physical node  400  may be used by a different network operator, for different frequency bands, for different channels, or any combination of operator, band and/or channel. In some implementations, the physical nodes  400  may combine downlink  404  and uplink  405  signals via a duplexer. In other implementations, the physical nodes  400  may keep downlink  404  and uplink  405  signals separate, such as, for example, for a simplex configuration. 
         [0064]    The local router  401  may direct traffic data between various LAN ports  403 , peer ports  408 , and external ports  411 . In some implementations, the local router  401  may also include (or alternatively, be coupled to) a KPI monitor  416 . The KPI monitor  416  may obtain time-synchronized snapshots of traffic data at each of the DAU ports. 
         [0065]    As illustrated in the example of  FIG. 4 , the physical nodes  400  have separate outputs for the uplink signals  405  and separate inputs for the downlink signals  404 . Each physical node  400  may be configured to translate the signals from radio frequency to baseband and vice versa. The physical nodes  400  may be connected to external ports  409 ,  410  on the local router  401 . The local router  401  may be configured to directed uplink data streams from the LAN  403  and peer  408  ports to external U ports  410 . Similarly, the local router  401  may be direct downlink data streams from the external D ports  409  to LAN  403  and peer  408  ports. 
         [0066]    In some implementations, the LAN ports  403  and peer ports  408  may be connected via optical fiber cable to a network of other DAUs and DRUs. Alternatively or additionally, a connection to this network connection may use copper interconnections, such as, for example, category-5 (cat-5) or category-6 (cat-6) cabling, or other suitable interconnection equipment. The DAU of  FIG. 4  may also be connected to the Internet  406  IP  412  capable connection. The DAU may also include an Ethernet connection  408  to communicate with a host unit or server  402 . The DAU may communicate with a remote operation control  407  center through the host unit  402 . In some implementations, the DAU may connect directly to the remote operational control  407  through the Ethernet port  408 . 
         [0067]      FIG. 5  illustrates an example of the elements of a DRU, according to one embodiment. In this example, the DRU is composed of physical nodes  501  and a remote router  500 . The remote router  500  may be configured to direct traffic data between LAN ports  502 , external ports  511 , and peer ports  510 . 
         [0068]    The physical nodes  501  may connect to a base station and/or antenna network at radio frequencies. Each physical node  501  may be used by different network operators, for different frequency bands, for different channels, or for any combination of operators, bands, and/or channels. In the illustrated example of  FIG. 5 , the physical ports  501  have separate inputs for uplink signals  504  and downlink signals  503 . The physical ports  501  may translate radiofrequency uplink signals  504  to baseband signals  507 , and baseband downlink  506  to radiofrequency downlink signals  503 . The physical ports  501  may be connected to the external ports  511  on the remote router  500 . 
         [0069]    The remote router  500  may be configured to direct downlink data streams from the LAN  502  and peer  510  ports to the External D ports  506 . Similarly, the remote router  500  may direct uplink data streams from the External U ports  507  to LAN  502  and peer  510  ports. The DRU may also include an Ethernet switch  505 . The Ethernet switch  505  may allow a remote computer  509  or one or more wireless access points  512  to connect to the Internet, by way of the DRU. In some implementations, the remote router  500  may also include (or alternatively, be coupled to) a KPI monitor  516 . The KPI monitor  516  may be configured to obtain time-synchronized snapshots of traffic data at each of the DRU&#39;s ports. 
         [0070]      FIG. 6  illustrates an example of a DAS network architecture, and further illustrates in greater detail an example of a base station hotel  610 . A base station hotel  610  may be composed of multiple picocells. Picocells may in most cases be wireless network operator dependent and/or frequency band dependent. In some implementations, picocells may be referred to as small cells. Picocells that operate in the same frequency band may be combined in the radio frequency domain, and the combined signal may be transported via a radio frequency connection  618  to a DAU  602 ,  608 ,  611 . Each DAU  602 ,  608 ,  611  may translate the combined signal to an optical signal, and transport the optical signal via an optical cable  603  to a daisy-chained cell  615 ,  616 ,  617  of DRUs. For example, the picocells numbered  11 ,  12 , . . .  1 N may be combined and transported to DAU  1   602 . DAU  1   602  may transport the signal over an optical cable  603  to the DRUs in Cell  1   615 . In this way, the DAUs  602 ,  608 ,  611 , and the DAUs&#39;  602 ,  608 ,  611  corresponding cells  615 ,  616 ,  617  of DRUs, may each provide network service coverage to a different geographical area. 
         [0071]    In some implementations, one or more digital expansion units (DEUs) (not shown) are present between the DAUs  602 ,  608 ,  611  and their associated DRUs  604 ,  605 ,  606 ,  607 ,  612 ,  613 . The DEUs may provide routing between the DAUs  602 ,  608 ,  611  and their associated DRUs  604 ,  605 ,  606 ,  607 ,  612 ,  613 . In some embodiments, the DEUs have a subset of the functionality of the DAUs  602 ,  608 ,  611 , up to the full functionality of the DAUs  602 ,  608 ,  611 . 
         [0072]    In some implementations, the DAS network architecture of  FIG. 6  may include a KPI monitor unit  621  and user KPI data and position storage  622 . The KPI monitor unit  621  may be connected to each of the DAUs  602 ,  608 ,  611 . Alternatively, the KPI monitor unit  621  may be inside a particular DAU (e.g., DAU  611 ), or each DAU (e.g., DAUs  602 ,  608 ,  611 ) may be equipped with a KPI monitor unit  621 . The KPI monitor unit  621  may capture time-stamped snapshots of user traffic data at each of the DAUs  602 ,  608 ,  611  and DRUs. User KPI data and position storage  622  (which may be separate from or a part of one or more of the DAUs  602 ,  608 ,  611 ) may store the snapshots, and may further use the snapshot data to determine the user&#39;s position. User KPI data and position information may be provided over an IP  619  connection to the Internet  630 , so that the data may be accessible for example on the World Wide Web. 
         [0073]      FIG. 7  illustrates another example of a DAS network architecture, and further illustrates in greater detail an example of a base station hotel  710 . A base station hotel  710  may be composed of multiple picocells. Picocells may in most cases be wireless network operator dependent and/or frequency band dependent. Picocells that operate in the same frequency band may be combined in the radio frequency domain, and the combined signal may be transported via a radio frequency connection  718  to a DAU  702 ,  708 ,  711 . Each DAU  702 ,  708 ,  711  may translate the combined signal to an optical signal, and transport the optical signal via an optical cable  703  to a daisy-chained cell  715 ,  716 ,  717  of DRUs. The DAUs  702 ,  708 ,  711 , and the DAUs&#39;  702 ,  708 ,  711  corresponding cells  715 ,  716 ,  717  of DRUs, may each provide network service coverage to a different geographical area. 
         [0074]    In some implementations, one or more digital expansion units (DEUs) (not shown) are present between the DAUs  702 ,  708 ,  711  and their associated DRUs  704 ,  705 ,  706 ,  707 ,  712 ,  713 . The DEUs may provide routing between the DAUs  702 ,  708 ,  711  and their associated DRUs  704 ,  705 ,  706 ,  707 ,  712 ,  713 . In some embodiments, the DEUs have a subset of the functionality of the DAUs  702 ,  708 ,  711 , up to the full functionality of the DAUs  702 ,  708 ,  711 . 
         [0075]    In some implementations, the DAS network architecture of  FIG. 7  may include a KPI monitor unit  721  and user KPI data and position storage  722 . The KPI monitor unit  721  may be connected to the picocells  741 ,  742 ,  743 . The KPI monitor unit  721  may capture time-stamped snapshots of user traffic data transmitted and received by each picocell  741 ,  742 ,  743 . User KPI data and position storage  722  may store the snapshots, and may further use the snapshot data to determine the user&#39;s position. User KPI data and position may be provided over an IP  719  connection to the Internet  730 , so that the data may be accessible for example on the World Wide Web. 
         [0076]      FIG. 8  illustrates another embodiment of a DAS network architecture that includes a base station hotel  810 . The base station hotel  810  may be composed of multiple picocells. Picocells may in most cases be wireless network operator dependent and/or frequency band dependent. In some implementations, the picocells may include a digital interface. In these implementations, the picocells may be connected to the DAUs  802 ,  808 ,  811  via a digital connection  830 , such as for an example an optical fiber cable. Each DAU  802 ,  808 ,  811  transports an optical signal via an optical cable  803  to a daisy-chained cell  815 ,  816 ,  817  of DRUs. The DAUs  802 ,  808 ,  811 , and the DAUs&#39;  802 ,  808 ,  811  corresponding cells  815 ,  816 ,  817  of DRUs, may each provide network service coverage to a different geographical area. 
         [0077]    In some implementations, one or more digital expansion units (DEUs) (not shown) are present between the DAUs  802 ,  808 ,  811  and their associated DRUs  804 ,  805 ,  806 ,  807 ,  812 ,  813 . The DEUs may provide routing between the DAUs  802 ,  808 ,  811  and their associated DRUs  804 ,  805 ,  806 ,  807 ,  812 ,  813 . In some embodiments, the DEUs have a subset of the functionality of the DAUs  802 ,  808 ,  811 , up to the full functionality of the DAUs  702 ,  708 ,  711 . 
         [0078]    In some implementations, the DAS network architecture of  FIG. 8  may include a KPI monitor unit  820  and user KPI data and position storage  840 . The KPI monitor unit  820  may be connected to the picocells. The KPI monitor unit  820  may capture time-stamped snapshots of user traffic data transmitted and received by each picocell. User KPI data and position storage  840  may store the snapshots, and may further use the snapshot data to determine the user&#39;s position. User KPI data and position may be provided over an IP  819  connection to the Internet  850 , so that the data may be accessible for example on the World Wide Web. 
         [0079]      FIG. 9  illustrates an example of a process for obtaining KPIs for users on a DAS network. The illustrated steps may be executed by a dedicated component in the DAS network, such as the KPI monitor unit described above. The KPI monitor unit may comprise a server computer. Alternatively or additionally, the steps may be executed individually by the DAUs and/or DRUs in the DAS network. Alternatively or additionally, the steps may be executed by one DAU or DRU that collects data from the other DAUs and/or DRUs. Alternatively or additionally, multiple DAUs and DRUs may operate cooperatively to collect and collate the KPI data. 
         [0080]    At step  910 , time-synchronized snapshots of traffic data may be collected from each remote unit (e.g., DRUs) and each host unit (e.g., DAUs). Timestamps indicate the time at which the snapshot was taken. A block of traffic data may be collected for each user presently associated with the DAS network. The snapshots may further be transported to a server for post-processing. 
         [0081]    At step  920 , the server may extract KPIs—that is, information about the user traffic data—from control channels associated with signals from the various network operators on the DAS network. At step  930 , the KPIs collected at step  910  may be transmitted to a User KPI Data Storage  960  to be stored. 
         [0082]    At step  940 , the server may analyze time-synchronized snapshots from multiple remote units and/or host units and apply a triangulation method to determine a user&#39;s position. At step  950 , the user&#39;s KPI data that is stored in the User KPI Data Storage  960  may be updated with the user&#39;s location information. The User KPI Data Storage  960  may be connected to the Internet  970 , such that the user&#39;s KPI data and/or location may be available for example on the World Wide Web. 
         [0083]      FIG. 10  illustrates an example of KPI data  1010  that may be collected and stored for each user, as well as an example of the organization of that data  1010 . In the illustrated example, KPI data  1010  may be first organized by user. Each user associated with the DAS network may be provided with a unique identifier (ID). For example, in this illustrated example, a first user has been assigned ID #1123 and a second user has been assigned ID #1345. KPI data  1010  may further be organized according to the point at which the data  1010  was collected. As noted above, KPI data  1010  may have been collected at a remote unit or a host unit. Each remote unit and host unit in the DAS network may be assigned a unique identifier. For example, in the illustrated example, various remote units and host units have been assigned the IDs #35, #44, and #54. At each of these remote units and host units, data may be collected for each user. Thus, for example, the data for the user ID #1123 may include a block of data for each of the remote/host IDs #35, #44, and #54. Similarly, the user ID #1345 may include a block of data for the remote/host ID #35, as well as the remote/host IDs #44 and #54 (not shown). A block of KPI data may further include, for example, a transmission timestamp, whether it is uplink or downlink data, a number of resource blocks, a bitmap of the resource blocks, a modulation scheme, an acknowledgment, a User Equipment (UE) channel, a Base Station (BS) channel, a signal-to-noise ratio (SNR), and/or a signal-to-interference-plus-noise ratio (SINR). 
         [0084]      FIG. 11  illustrates an example of a process for determining a user&#39;s position using KPI data. This example process may be executed by a dedicated component in the DAS network, such as, for example, a KPI monitor unit and/or a User KPI Data and Position storage component and/or a server connected to the DAS network. Alternatively or additionally, the steps may be executed by a DAU or DRU in the DAS network. Alternatively or additionally, the steps may be executed by multiple DAUs and/or DRUs working cooperatively. 
         [0085]    At step  1110 , KPI data may be collected from remote units and/or host units. At step  1120 , the user&#39;s stored information may be updated with the most recent KPI data collected at step  110 . The user&#39;s information may have changed since the last snapshots were taken and stored; for example, the user may have moved out of the range of one group of remote units and into the range of another group of remote units. In many cases, KPI data is collected for the user from multiple remote units and/or host units. At step  1120 , the user&#39;s stored information may be updated for some or all of the multiple remote units and/or host units. 
         [0086]    At step  1130 , user KPI data may be sorted according to the way in which the data may be analyzed. For example, the KPI data may first be sorted by user, then by the location of the remote unit and/or host unit where the data was collected, or by a transmission time of the data, or by the power level of the received signal, or by some other metric or by some combination of metrics. 
         [0087]    At step  1140 , the illustrated process may determine whether sufficient KPI data has been collected to perform triangulation, and determine a user&#39;s location. When an insufficient amount of data has been collected, the process may proceed to step  1180 . At step  1180 , the user&#39;s position may be determined from the position of the remote unit that was closest to the user. Whether a remote unit was closest to a user may be determined, for example, by finding the remote unit that received the user&#39;s signal at the highest power level. The remote unit&#39;s location may be known, for example, because the remote unit&#39;s location was stored at the time the remote unit was installed. Once the user&#39;s position has been estimated from the nearest remote unit to that user, the user&#39;s position may be stored at step  1170 . The user&#39;s information may also be updated at step  1120  with this estimated position. 
         [0088]    When, at step  1140 , the illustrated process determines that sufficient KPI data has been collected to perform triangulation, the process proceeds to step  1150 . At step  1150 , the process may apply a triangulation method, using the timestamps and power levels from the user&#39;s KPI data, and the position of the remote units. For example, the process may, at step  150 , determine which remote units received both the strongest and most recent signal from a user. The location of these remote units may be known, for example, because the location of the remote units was stored when the remote units were installed. The process may triangulate on the user&#39;s location using the location of these remote units. 
         [0089]    Having determined a position for a user, the process may, at step  1160 , update the user&#39;s position information. This information may be stored at step  1170 . The process may thereafter return to step  1110  and repeat. Repeating the process may provide updated information, as the user&#39;s information (including position) changes. 
         [0090]      FIG. 12  illustrates an example of a flowchart of a method for determining a geolocation of a mobile device in a DAS network. At step  1205 , first KPI data for the mobile device is collected from a first DRU. The first KPI data may be extracted from control channel information, such as that provided by the PDCCH for uplink or the PUCCH for downlink. The first KPI data comprises at least one of a first power level and a first transmission time (e.g., represented by a 32-bit timestamp). For example, the first power level may be −83 dBm. The mobile device may be associated with an identifier (e.g.,  1125 ). The identifier may be different than the phone number associated with the mobile device, which may be encrypted during transmission. 
         [0091]    At step  1210 , a first location of the first DRU is obtained. The first DRU may be identified by a code, such as “35”. The code may be used to obtain the location of the first DRU such as, for example, from a database. The location of the first DRU may have been stored when the first DRU was installed, for example. 
         [0092]    At step  1215 , second KPI data for the mobile device is collected from a second DRU. The second KPI data may be extracted from control channel information, such as that provided by the PDCCH for uplink or the PUCCH for downlink. The second KPI data comprises at least one of a second power level and a second transmission time (e.g., represented by a 32-bit timestamp). For example, the second power level may be −87 dBm. The mobile device may be identified by the same identifier used by the first DRU. 
         [0093]    At step  1220 , the second location of the second DRU is obtained. The second DRU may be identified by a code, such as “45”. The code may be used to obtain the location of the second DRU such as, for example, from a database. The location of the second DRU may have been stored when the second DRU was installed, for example. 
         [0094]    At step  1225 , third KPI data for the mobile device is collected from a third DRU. The third KPI data may be extracted from control channel information, such as that provided by the PDCCH for uplink or the PUCCH for downlink. The third KPI data comprises at least one of a third power level and a third transmission time (e.g., represented by a 32-bit timestamp). For example, the third power level may be −68 dBm. The mobile device may be identified by the same identifier used by the first DRU and the second DRU. 
         [0095]    At step  1230 , the third location of the third DRU is obtained. The third DRU may be identified by a code, such as “53”. The code may be used to obtain the location of the third DRU such as, for example, from a database. The location of the third DRU may have been stored when the third DRU was installed, for example. 
         [0096]    At step  1235 , the geolocation of the mobile device is determined using the first location and at least one of the first power level and the first transmission time, the second location and at least one of the second power level and the second transmission time, and the third location and at least one of the third power level and the third transmission time. For example, a triangulation algorithm may be applied using the first location and at least one of the first power level and the first transmission time, the second location and at least one of the second power level and the second transmission time, and the third location and at least one of the third power level and the third transmission time to determine the geolocation of the mobile device. As used herein, “at least one of [a] power level and [a] transmission time” is intended to mean the power level and/or the transmission time. In another embodiment, the geolocation of the mobile device may be estimated from the location of the DRU having the strongest power level. 
         [0097]    In one embodiment, the geolocation of the mobile device and the identifier of the mobile device may be transmitted to an emergency responder system (e.g., E911) or database. The emergency responder system may maintain or have access to a mapping between phone numbers and mobile device identifiers, such that the mobile device identifier can be used to tie a geolocation to a particular phone number of a mobile device. Thus, the geolocation of the mobile device may be used to determine the location of an emergency caller, for example. 
         [0098]      FIGS. 13-17  illustrate examples of Long Term Evolution (LTE) control channels from which user KPI data may be extracted. Although shown and described with respect to LTE, it is contemplated that embodiments of the invention may similarly extract user KPI data from control channels for other standards of wireless communication, such as 3G, 4G, GSM, etc. 
         [0099]      FIG. 13  illustrates an example of the LTE channels. User KPI data may be extracted primarily from the PDCCH on the downlink path and the PUCCH on the uplink path. The PDCCH channel is illustrated further in  FIG. 14 , which illustrates an example of the LTE downlink receiver transport channels and control information, and  FIG. 15 , which illustrates an example of the LTE downlink transmitter transport channels and control information. The PUCCH channel is illustrated further in  FIG. 16 , which illustrates an example of the LTE uplink receiver transport channels and control information, and  FIG. 17 , which illustrates an example of the LTE uplink transmitter transport channels and control information. 
         [0100]    It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.