# Patent

## Title
Pico-cell extension for cellular network

## Abstract

A pico-cell is located within a facility. The pico-cell has a wireless protocol for carrying calls placed to and from mobile devices in the facility. A call distributor is in communication with the pico-cell and handles calls carried by the pico-cell. The call distributor includes an embedded wireless switch for routing calls to and from mobile devices in the facility using the wireless protocol.

## Background
BACKGROUND
Enterprises want wireless communications for their employees within their work place (office buildings and warehouses, retail facilities, etc) and in the field. Cell phones are satisfactorily used by employees for wide area mobile communications, but coverage within buildings is not always adequate. Coverage problems arise when a user attempts to use a cell phone inside a building. For example, electromagnetic signals, such as radio frequencies used by cellular phones, are unable to fully propagate through walls, metalized glass and other common building materials that separate the inside of a building from an outside environment. As a result, the user may experience a degradation of service or may be precluded entirely from sending or receiving information while inside a building or other structure.
One solution to poor in-building cellular coverage has been to install a wireless private branch exchange (PBX) and to issue employees wireless WiFi enabled session initiated protocol (SIP) phones for mobile communications within buildings. However, this requires the enterprise to purchase two mobile devices for each employee—a cell phone for wide area communication, and a WiFi SIP phone for communication within the work place—which may be a substantial expense. In addition, this requires employees to carry multiple mobile devices, each typically having different contact number associated with it. Thus, callers must dial a different number to reach the employee, depending on the location of the employee (e.g., in the work place or in the field).
SUMMARY
This summary is provided to introduce simplified concepts of a pico-cell extension for a cellular network, which is further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.
In one implementation, a pico-cell is located within a facility. The pico-cell has a wireless protocol for carrying calls placed to and from mobile devices in the facility. A call distributor is in communication with the pico-cell and handles calls carried by the pico-cell. The call distributor includes an embedded wireless switch for routing calls to and from mobile devices in the facility using the wireless protocol.
In another implementation, a wireless pico-cell receives a request from a mobile device using a wireless protocol to access a wireless pico-cell extension. The request from the mobile device is transmitted to a call distributor of the pico-cell extension. The mobile device is registered with a registered visitor database of the call distributor of the pico-cell extension, and the pico-cell extension authenticates the mobile device to send and receive communications via the pico-cell extension.



BRIEF DESCRIPTION OF THE DRAWINGS
The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
FIG. 1 is a schematic diagram showing an exemplary environment, in which a pico-cell extension is coupled to a wireless network to extend wireless coverage within a building.
FIG. 2 is a block diagram showing details of an exemplary implementation of a pico-cell extension for a wireless network.
FIG. 3 is a block diagram showing details of another exemplary implementation of a pico-cell extension for a wireless network.
FIG. 4 is a block diagram showing the pico-cell of FIGS. 2 and 3 in more detail.
FIG. 5 is a block diagram showing details of another exemplary implementation of a pico-cell extension for a wireless network.
FIG. 6 is a block diagram showing the pico-cell of FIG. 4 in more detail.
FIG. 7 is a block diagram showing details of yet another exemplary implementation of a pica-cell extension for a wireless network.
FIG. 8 is a flow chart showing an exemplary method of providing wireless coverage within a facility.



DETAILED DESCRIPTION
Overview
FIG. 1 shows an exemplary environment 100, in which a pico-cell extension 102 is coupled to a wireless network, e.g., a cellular network 104 to extend and facilitate cellular coverage within a building 106, factory, warehouse, or other facility of an enterprise. Although a cellular network 104 and a cellular pico-cell extension 102 are shown and described in the following for ease of explanation, it should be appreciated that the invention is applicable to any type of wireless network and wireless pico-cell extension.
As shown in FIG. 1, in the field, a mobile device 108 is in wireless communication with the cellular network 104 via one or more cell towers in a known manner. The cellular network 104 may be based on the global system for mobile communications (GSM), code division multiple access (CDMA), and/or any other cellular protocol. Within the building 106, however, communication directly between the mobile device 108 and the cellular network may be limited or nonexistent. The pico-cell extension 102 uses cellular protocol and provides reception for the mobile device 108 within the building 106. In this way, employees of the enterprise or other users of the mobile devices 108 can use the same mobile device 108 in the field via the cellular network 104, and inside the enterprise facilities via the pico-cells extension(s) 102. Thus, the pico-cell extension 102 acts like an extension of the cellular network 104 within a structure, and provides or enhances cellular coverage within the structure.
Generally, the pico-cell extension 102 comprises one or more pico-cells 110 in communication with a call distributor, such as a private branch exchange (PBX) 112, and is connected to the cellular network 104 via the Internet 114 and/or the public switched telephone network (PSTN) 116. Additionally, the pico-cell extension 102 may include various other network components such as servers, local area network (LAN) switches, routers, memory, and processors, as described in more detail with respect to FIGS. 2-6 below. Pico-cells 110 approximate traditional cellular base stations, but are typically smaller and less powerful than a traditional cellular base station for serving smaller areas, such as buildings or portions thereof. The size and power of pico-cells 110 may vary depending on the desired coverage area and other needs of the enterprise. Examples of pico-cells usable with the pico-cell extensions include those described in U.S. patent application Ser. No. 11/276,269, filed Feb. 21, 2006, and entitled “Intelligent Pico-Cell for Transport of Mobile device Communications Over Wireless Networks,” now U.S. Pat. No. 7,623,857, which is incorporated herein by reference.
While the pico-cell extension 102 is shown comprising a single pico-cell 110 located within a single building 106, pica-cell extensions may in some implementations include plural pico-cells located in different rooms of a building, different locations within a room, and/or different buildings. Also, while a single PBX is shown, additional PBXs could be networked together to any number of one or more pico-cells, depending on the needs and resources of the enterprise.
In the exemplary implementations described herein, mobile devices 108 comprise cell phones and the pico-cells 110 comprise cellular pico-cells using the GSM protocol. However, mobile devices 108 could alternately comprise a variety of other types of computer and computer-like devices, such as, for example, Smartphones, tablet PCs, personal digital assistants (PDAs), workstations, or the like, which can transmit and/or receive voice, data, or a combination of voice and data. The pico-cells 110 may comprise pico-cells employing any cellular protocol capable of operating in conjunction with the mobile devices 108. Since the pico-cell extension 102 employs a cellular protocol, no inclusion of a bulky and/or costly client device in the mobile devices 108 is necessary to enable the mobile devices 108 to communicate with the pico-cell extension 102.
First Exemplary Pico-Cell Extension
FIG. 2 is a block diagram showing details of an exemplary implementation of a pico-cell extension 200 that might be used to improve wireless coverage in, for example, a facility of an enterprise. The pico-cell extension 200 includes one or more pico-cells 202, a base station controller (BSC) 204, and a PBX 206 coupled together by a local area network (LAN) or extension bus 208. The pico-cells 202 operate at cellular frequencies (these may vary from country to country) and include cellular protocols, such as GSM, CDMA, and the like. The pico cell extension 200 acts as a small extension of the cellular network 104 within the enterprise facility, and carries calls placed to and from mobile devices 108 in the facility in much the same way as a conventional macro cellular base station of the cellular network 104. That is, the pico cell extension 200 handles calls among mobile devices 108 in the facility, and between mobile devices 108 in the facility and mobile devices and/or wireline phones outside the facility.
The pico-cells 202 are connected to the other components on the extension bus 208 through an Internet protocol security (IPSEC) tunnel. The pico-cells 202 and other components of the pico-cell extension 200 may be connected to the extension bus 208 via an Ethernet port or any other conventional network connection, such as via a broadband modem, or the like.
The BSC 204 acts as a concentrator into which the pico-cells 202 attached to the pico-cell extension 200 are aggregated. The BSC 204 handles allocation of radio channels, receives measurements from the mobile phones, and/or controls handovers among the pico-cells 202 and between the pico-cells 202 and the cellular network 104. The BSC 204 may also include a database containing information about the pico-cells 202 that it controls, such as carrier frequencies, frequency hopping lists, power reduction levels, receiving levels for pico-cell border calculations, and the like.
In this implementation, the PBX 206 comprises an Internet protocol PBX (IP-PBX), which uses the Internet protocol to carry voice calls. The IP-PBX 206 includes an embedded softswitch 210 with cellular protocols corresponding to those of the connected pico-cells 202 (such as GSM, CDMA, and the like). A softswitch is a software program, which manages and connects calls from one phone to another. Generally, softswitches may provide features including call processing, measuring and monitoring capabilities, call detail reports for the IP endpoints, signaling notifications, flexible call routing and redirection, and the like.
The softswitch 210 in the IP-PBX 206 manages and connects calls to and from phones within the enterprise, including mobile devices 108. Also, the softswitch 210 may include the full GSM, CDMA, or other cellular feature set provided by the cellular carrier. Because the softswitch 210 is embedded in the IP-PBX 206, mobile devices 108 registered with the IP-PBX 206 retain their full functionality and host of features offered by or purchased from the cellular carrier on the cellular network 104. Thus, users can use all the functions of their cell phones or other mobile devices within the enterprise. This full functionality is provided without the need for a dual-mode handset or for enterprise employees to carry multiple devices. The IP-PBX 206 with the embedded soft switch 210 acts as a small standalone cellular switch, with functionality comparable to a standard cellular switch of a cellular network. The enhanced cellular coverage within the enterprise provided by the IP-PBX 206 with the embedded soft switch 210 may allow enterprises to eliminate the use of traditional wire line desk phones, which have limited functionality, and to replace them with readily available, feature-rich cell phones or other mobile devices 108.
The IP-PBX 206 also comprises a registered visitor database such as a visitor location register (VLR) 212, a registered home user database such as a home location register (HLR) 214, and an enterprise customer database 216. The VLR 212 maintains a list of all mobile devices 108 currently in the coverage area of the IP-PBX 206, regardless of whether the mobile devices are authorized to access the enterprise pico-cell extension 200. The HLR 214 maintains a list of subscriber profiles of enterprise wireless users and/or mobile devices 108 that are authorized to access the pico-cell extension 200. The HLR 214 may also maintain a rule set for determining how and whether to handle calls placed by visitors to the enterprise (i.e., mobile devices not registered with the enterprise IP-PBX 206). The rule set may, for example, specify whether to carry calls placed by visitors on the pico-cell extension 200, and if so, whether the visitor will be charged for using the pico-cell extension 200. The enterprise customer database 216 is a readily modifiable database of customer profiles administered by the enterprise, which is used to periodically populate information into the HLR 214. The customer database 216 may, for example, define a list of customers (e.g., employees, clients, etc.) and/or mobile devices that are authorized to access the enterprise pico-cell extension 200, define the features available to end users of the pico-cell extension 200, rule sets about what information end users can change about their profiles (e.g., PBX features, cellular features, etc.). Typically, the customer database 216 is updated by information technology (IT) staff of the enterprise, or directly by the end mobile users. The customer database 216 may be accessed and updated using any suitable interface, such as a web interface, a direct interface on the mobile device, or the like.
In practice, a cellular carrier still maintains a profile for each subscriber or mobile device 108 in a HLR of the cellular network 104. When a mobile device 108 enters the enterprise and attempts to access one of the enterprise pica-cells 202, the VLR 212 registers the mobile device 108 with its IP-PBX 206 as a “roamer.” The pico-cell extension 200 (specifically, the BSC 204 or IP-PBX 206) queries the HLR 214 to confirm that the mobile device 108 is authorized to access the pico-cell extension 200 and, if so, the level of services available to the mobile device 108. The pico-cell extension 200 also conveys to the HLR of the cellular carrier the current location of the mobile device and that the mobile device 108 has entered the coverage area of the specific pico-cell 202. While the VLR 212, HLR 214, and enterprise customer database 216 are shown and described as being part of the IP-PBX 206, they could instead be implemented as databases stored elsewhere in the pico-cell extension 200 and in communication with the IP-PBX 204 via the extension bus 208.
In addition to, or instead of, the BSC 204 on the extension bus 208, the IP-PBX 206 may include a local BSC 218. The local BSC 218 may be resident in the softswitch 210, the IP-PBX 206, or both. By way of example and not limitation, the local BSC 218 may be implemented as a module in the embedded softswitch 210 or as a card or other removable or non-removable memory in the IP-PBX 206.
The pico-cell extension 200 also includes a router 218 for connection of the pico-cell extension 200 to the cellular network 104 via the Internet 114 and/or a protocol gateway 220 for connection of the pico-cell extension 200 to the cellular network 104 via the PSTN 116. The media gateway 220 may include media gateway control protocol (MGCP), primary rate interface (PRI), session initiated protocol (SIP), combinations thereof, and the like. Alternatively, one or both of the router 218 amd gateway 220 could be integrated with one of the other components of the pico-cell extension 200 (e.g., the BSC 204, IP-PBX 206, pico-cell 202, or the like).
While the various components of the pico-cell extension are shown as being implemented on the enterprise premises, in some implementations, portions of the pico-cell extension could be located offsite, for example, at locations of the cellular carrier. In addition, while the various components of the pico-cell extension are shown as being separate components, these components could be rearranged and/or combined as desired.
In some instances, particularly for smaller enterprises, the enterprise may not have the resources or the desire to administer and update a HLR and/or enterprise customer database. Nevertheless, such enterprises may still want to be able to use their cell phones or other mobile devices within their facilities or other areas of poor cellular coverage. In that case, the enterprise could benefit from the installation of a pico-cell extension requiring minimal administration by the enterprise itself.
FIG. 3 shows another exemplary implementation of a pico-cell extension 300 for a cellular network, in which administration of user and/or mobile device profiles, feature rule sets, and the like is administered by a cellular carrier or other entity external to the enterprise. The pica-cell extension 300 of this implementation is a simplified version of the pico-cell extension 200 of FIG. 2. In this implementation, the pico-cell extension 300 is similar to that shown in FIG. 2, except for the configuration of the IP-PBX 302. The IP-PBX 302 in this implementation still includes an embedded softswitch 210 with cellular protocols corresponding to those of the connected pico-cells, and a VLR 212 that maintains a list of all mobile devices 108 currently in the coverage area of the IP-PBX 302. However, the IP-PBX 302 of this implementation does not include a HLR or an enterprise customer database. Instead, functionality of those components is implemented at least partially by a customer provisioning system 304 associated with the cellular carrier or other entity external to the enterprise. The customer provisioning system 304 may perform functions similar to the enterprise customer database described with respect to the implementation of FIG. 2. For example, the customer provisioning system 304 may define a list of customers (e.g., employees, clients, etc.) or mobile devices that are authorized to access the enterprise pico-cell extension 300, the features available to end users of the pico-cell extension 300, and/or rule sets about what information, if any, end users can change about their profiles (e.g., PBX features, cellular features, etc.). The customer provisioning system 304 may be updated by the cellular carrier at the direction of the enterprise and/or the end users. Alternatively, the end mobile users may be allowed to update at least some of the information on the customer provisioning system directly through, for example, a web interface, an interface on their mobile devices, or the like. Information input to the customer provisioning system 304 subsequently populates the HLR of the cellular network to update the HLR.
In order to benefit from a pico-cell extension 300 according to this implementation, all the enterprise needs to do is purchase and install the pica-cell 202, IP-PBX 302, and any other components of the pico-cell extension 300 that they do not already have installed. The pico-cell extension 300 then functions as a part of the larger cellular network, with the cellular carrier controlling who is allowed to access the pico-cell extension 300 in much the same way as they would any other conventional cell site at the direction of the enterprise. Thus, the enterprise can benefit from advantages of a pico-cell extension (e.g., reception within the enterprise facility, reduced costs for phones or mobile devices, reduced wireless service charges, and the like) without being required to administer and update a HLR or enterprise customer database.
FIG. 4 shows the pico-cell 202 of FIGS. 2 and 3 in more detail. As shown, the pico-cell 202 includes a network interface 400 for interfacing the pico-cell 202 with the extension bus 208, and a protocol converter 402 for converting between cellular protocol and Internet protocol for transmission over the extension bus 208. The network interface 400 and protocol converter 402 work together to convert protocols associated with mobile devices 108 (e.g., GSM, CDMA, and the like) into protocols suitable for transmission over the extension bus 208.
The pico-cell 202 also includes an interface 404 between the BSC 204 and base station transceiver subsystems (BTSs) associated with the pico-cell extension 200. The BSC-BTS interface 404 receives commands from the BSC 204 and converts them into signals understandable by the BTSs. Each BTS generally is comprised of one or more pico-cells. Thus, the pica-cell extension 200 could include one or more BTSs, each comprising one or more pico-cells. As one example, the pico-cell extension 200 might include two BTSs, each BTS corresponding to a building in the enterprise facility. One BTS might include a single pico-cell (e.g., if the BTS corresponds to a small single-room building), while the other BTS might include twenty or more pico-cells (e.g., if the BTS corresponds to an office building). The network interface 400, protocol converter 402, and BSC-BTS interface 404 all may be implemented as software or a combination of software and hardware. In the example shown, logic or processor 406 executes the functions of the network interface 400, protocol converter 402, and BSC-BTS interface 404 based on interface and conversions stored in memory 408.
The pico-cell 202 also includes a radio frequency (RF) transceiver 410 for wirelessly transmitting and receiving signals to and from the mobile devices 108 in the coverage area of the pico-cell 202. The RF transceiver is configured to transmit and receive on applicable cellular channels using cellular protocols, such as GSM, CDMA, and the like. The applicable cellular channels may vary from country-to-county, but in the United States may include, for example, the 850 megahertz and 1900 megahertz bands. The RF transceiver 410 may include its own onboard memory and/or processor or may use the processor 406 and memory 408 of the pico-cell 202.
Second Exemplary Pico-Cell Extension
FIG. 5 is a block diagram showing details of another exemplary implementation of a pico-cell extension 500. The pico-cell extension shown in FIG. 5 is similar in most respects to that shown in FIG. 2. Accordingly, for the sake of brevity, only those aspects of the pico-cell extension 500 which are different are described below for this implementation.
In the implementation of FIG. 5, the pico cell extension 500 again includes an IP-PBX 206, an enterprise customer database 214, an HLR 216, a router 218, and a protocol gateway 220 coupled together by a local area network (LAN) or extension bus 208. However, in this implementation, the pico-cell extension 500 includes one or more pico-cells 502 using the unlicensed mobile access (UMA) protocol. The pico-cell extension 500 also includes a UMA network controller (UNC) 504, which is a server connected to the extension bus 208 that acts as a pico-cell aggregator for all the pico-cells 502 within the enterprise. The UNC 502 aggregates the traffic from the pico-cells 502 and communicates with the cellular network 104 to facilitate handover of calls from the pico-cells within the enterprise to cell sites of the cellular network 104 and vice versa.
FIG. 6 shows the pico-cell 502 of FIG. 5 in more detail. As in the implementation of FIG. 4, the pico-cell 502 includes a network interface 600 for interfacing the pico-cell 502 with the extension bus 208. In this implementation, however, instead of a protocol converter and BSC-BTS interface, the pico-cell 502 includes a UMA protocol IPSEC tunnel 602, which provides a secure connection to the UNC 504 and other components on the extension bus 208. The network interface 600 and UMA protocol IPSEC tunnel 602 interface the pico-cell 502 with the extension bus 208. The pico-cell 502 also includes an intelligent channel selector 604, which determines which cellular frequency in the cellular frequency band for the pico-cell 502 to use to downlink signals to mobile devices. The intelligent channel selector 604 may determine what radio frequency (RF) channel to use from among the channels licensed by cellular carrier, depending on the frequencies used by other nearby cell sites, to minimize interference. In this manner, the intelligent channel-selector 604 can continuously or periodically monitor the channels that nearby cell sites are using, query a server on the cellular network to determine what other frequencies are available in the licensed frequency band that are not being used by any of the nearby cell sites, and then select one of the available frequencies to use for the pico-cell 502.
The network interface 600, UMA protocol IPSEC tunnel 602, and intelligent channel selector 604 all may be implemented as software, hardware, or a combination of software and hardware. In the example shown, processor 606 executes the functions of the network interface 600, UMA protocol IPSEC tunnel 602, and intelligent channel selector 604 based on interfaces and conversions stored in memory 608.
The pico-cell 502 also includes a radio frequency (RF) transceiver 610 for wirelessly transmitting and receiving signals to and from the mobile devices 108 in the coverage area of the pico-cell 502. The RF transceiver is configured to transmit and receive on applicable cellular channels using cellular protocols, such as GSM, CDMA, and the like. As discussed above, the applicable cellular channels may vary from country-to-county, but in the United States may include, for example, the 850 megahertz and 1900 megahertz bands. The RF transceiver 510 may include its own onboard memory and/or processor or may use the processor 506 and memory 508 of the pico-cell 502.
Third Exemplary Pico-Cell Extension
FIG. 7 is a block diagram showing details of another exemplary implementation of a pico-cell extension 700. The pico-cell extension 700 shown in FIG. 7 is similar in most respects to that shown in FIG. 2. Accordingly, for the sake of brevity, only those aspects of the pico-cell extension 700 which are different are described below for this implementation.
In the implementation of FIG. 7, the pico cell extension 700 again includes an IP-PBX 206, an enterprise customer database 214, an HLR 216, a router 218, and a protocol gateway 220 coupled together by a LAN or extension bus 208. However, in this implementation, the pico-cell extension 700 includes one or more pico-cells 702 with suitable protocol conversion, such as GSM, CDMA, UMA or the like. The pico-cell extension 700 also includes a UNC 704, which is a server connected to the extension bus 208 that acts as a pico-cell aggregator for all the pico-cells 702 within the enterprise. The UNC 702 aggregates the traffic from the pico-cells 702 and communicates with the cellular network 104 to facilitate handover of calls from the pico-cells within the enterprise to cell cites of the cellular network 104 and vice versa.
In addition, the implementation of FIG. 7 also includes additional network devices connected to the extension bus 208, including a LAN switch 706, a network management server 708, a domain name server (DNS) 710, AAA (authentication, authorization, and accounting) protocol 712, and various other backend services 714, such as, for example, the ability to allow end user to change his or her wireless profile, business-level policies for service-level agreements, customer relationship management services, transport services (e.g., transmission via the Internet), web policy services, distributed data bases and data storage, identification management services (e.g., meta directories and the like), calendar and administration policies. In some implementations, the softswitch 210 could be embedded in the LAN switch 706, rather than the IP-PBX 206, and may include any cellular protocol, such as GSM, CDMA, and the like.
The network management server 708 provides overall management of multiple devices in the customer's network (e.g., workstations, routers, and other network devices). The network management server 708 can schedule communications among devices based on priority of the communications, provide graphical reports (proactively or reactively) in real-time, analysis, polling and/or monitoring of the managed devices, and can send alerts or notifications when problems are detected, or thresholds exceeded. Other network management capabilities may include performance, configuration, accounting, fault, security, and device management.
The DNS 710 stores information associated with domain names and translates the domain names of devices on the LAN or extension bus 208 into corresponding IP addresses. The DNS 710 may also list exchange servers accepting email for each domain.
The AAA protocol 712 authenticates mobile devices 108 that request service on the pico-cell extension 700 by determining whether the mobile device requesting service is a valid user. Authentication may be accomplished, for example, by comparing an identifier of the mobile device (e.g., a phone number, international mobile subscriber identification (IMSI), or the like) to a list of such identifiers in the enterprise customer database 214. Once a mobile device is authenticated to the system, the AAA protocol 712 then authorizes the mobile device to use some or all of the services of the pico-cell extension 700 based on the end user's subscriber agreement with the cellular provider and/or the user's registration with the enterprise. Once the mobile device is authorized, the AAA protocol 712 accounts for (i.e., tracks) the network resources used by the mobile device 108 for management, planning, billing, or other purposes.
As discussed above, it should be understood that the elements discussed above with regard to the pico-cell extensions may be implemented by software, hardware or a combination thereof. If implemented by software, the software may reside on memory associated with any component of the pico-cell extension, standalone memory provided in communication with the LAN or extension bus, a remote memory storage device, removable/nonremovable memory, a combination of the foregoing, or any other combination of one or more computer-readable media. Any number of programs, program modules, data objects, or other data structures may be stored in memory including an operating system, one or more application programs, other program modules, and program data.
In some implementations, pico-cell extensions may also be configured such that a user may enter commands and information via input devices such as a keyboard, pointing device, serial port, and/or the like. These and other input devices may be connected to the one or more components of the pico-cell extension.
Security functions, such as determining user privilege to enter a cellular carrier's network, or defensive mechanisms against the passing of viruses, may also exist in one or more components of the pico-cell extension, such as the pico-cells, the PBXs, the UNC, the BSC, or another component of the pico-cell extension.
While several exemplary implementations have been described having a pico-cell extension with various different features and components, it should be understood that features and components of the various implementations could be rearranged, omitted, modified, and combined with one another and/or additional features and components. Moreover, while the pico-cell extension is described as being within an enterprise facility, pico-cell extensions may be distributed and at least some of the components may reside remotely from the enterprise facilities. For example, one or more components of the pico-cell extension may be provided by and/or reside with a cellular provider or other telecommunications company.
Exemplary Method of Operation
FIG. 8 is a flow chart showing an exemplary method 800 of providing cellular coverage within a facility. The method 800 may, but need not necessarily, be implemented using a system such as those described herein. In one implementation, the method 800 is implemented on a system having a pico-cell extension including one or more pico-cells coupled to an IP-PBX.
The method includes at 802 receiving at a cellular pica-cell a request from a mobile device using a cellular protocol to access a cellular pico-cell extension. Then, at 804, the pico-cell transmits the received request from the mobile device to an IP-PBX of the pico-cell extension. At 806, the pica-cell extension registers the mobile device with a VLR of the IP-PBX of the pico-cell extension. The pico-cell extension also queries a HLR of a remote cellular carrier at 808, to determine whether the mobile device is authorized to use a remote cellular network. At 810, the pico-cell extension populates the HLR from a customer database including a list of users authorized to access the pico-cell extension. In practice, the HLR will have been populated prior to being queried at 808, and may be repopulated continuously as information in the customer database changes, periodically at set intervals, and/or in response to manual instruction to repopulate the HLR.
If the mobile device is not authorized to access the pico-cell extension, the mobile device is not authenticated and is not allowed to access the pico-cell extension. However, if the mobile device is found based on the customer database to be authorized, at 812, the pico-cell extension authenticates the mobile device to the cellular pica-cell extension enabling the mobile device to send and receive calls via the pico-cell extension. The method may also include, at 814, conveying to the HLR of the cellular carrier that the mobile device is in the coverage area of the pico-cell.
Once the mobile device has been authorized to the pico-cell extension, it will be allowed to transmit and receive calls using the pico-cells of the pico-cell extension. Thus, at 816, the pico-cell extension connects a call between the mobile device and another line using an embedded cellular softswitch of the IP-PBX, which is in communication with the pico-cell. If the mobile device moves outside the coverage area of the pico-cell, then at 816, the pico-cell extension hands over the call from the pico-cell to another pico-cell associated with the pico-cell extension. In this manner, the mobile device functions properly as it is moved around the facility. A similar handover may be performed between a pico-cell of the pico-cell extension and an external cell site of the cellular network.
It should be understood that certain acts in method 800 need not be performed in the order described, may be modified and/or may be omitted entirely, depending on the circumstances and the needs of the enterprise. For example, the pico-cell extension need not necessarily query a customer database as in step 810 and might instead allow any mobile device in the facility to access the pico-cell extension.
Also, any of the acts described above may be implemented by a processor or other computing device based on instructions stored on one or more computer-readable media associated with the pico-cell extension.
CONCLUSION
Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the invention.

## Claims

1. A system comprising:
a pico-cell located within a building for carrying one or more calls placed to and from at least one mobile device in the building, the pico-cell having a wireless protocol for carrying at least the one or more calls placed to and from the at least one mobile device in the building using the wireless protocol; and
a call distributor in communication with the pico-cell for handling the calls carried by the pico-cell, the call distributor comprising:
an embedded wireless switch for routing the calls placed to and from the mobile devices in the building using the wireless protocol; and
a registered home user database in communication with the pico-cell for storing a list of user devices authorized to access the pico-cell and place the calls carried by the pico-cell.

2. The system of claim 1, wherein the system is in communication with at least one of the public switched telephone network (PSTN) and the Internet for transmission and reception of at least one call to and from locations outside the building.

3. The system of claim 1, wherein the registered home user database is disposed in the building or is disposed outside the building and is administered by a wireless carrier, the registered home user database comprises a home location register (HLR).

4. The system of claim 1, the call distributor further comprising a registered visitor database for storing information associated with at least one mobile device in the coverage area of the call distributor, wherein the registered visitor database comprises a visitor location register (VLR).

5. The system of claim 1, further comprising at least one additional pico-cell at another location within the building, the call distributor being in communication with each pico-cell in the building for handling calls carried by the pico-cells.

6. The system of claim 1, wherein the call distributor comprises an Internet protocol private branch exchange (IP-PBX), and the embedded wireless switch comprises a cellular softswitch.

7. The system of claim 6, further comprising a media gateway for converting session initiated protocol (SIP) signals from the IP-PBX to circuit time-division multiplexed (TDM) signals for communication with the public switched telephone network (PSTN).

8. The system of claim 1, further comprising a base station controller (BSC) for controlling handovers between the pico-cell and another pico-cell or cell site.

9. The system of claim 1, further comprising a customer database in communication with the pico-cell for storing at least one of a list of users authorized to use the pico-cell or a list of mobile devices authorized to be used with the pico-cell.

10. The system of claim 1, wherein the pico-cell comprises a network interface for interfacing the pico-cell with the call distributor, and for converting protocols associated with the mobile devices into protocols suitable for transmission to the call distributor.

11. The system of claim 1, wherein the pico-cell comprises a radio frequency (RF) transceiver for transmitting and receiving signals on cellular channels and using cellular protocols, and a protocol converter for converting between cellular protocol and Internet protocol.

12. The system of claim 1, wherein the pico-cell comprises a radio frequency (RF) transceiver for transmitting and receiving signals on cellular channels and using cellular protocols, an unlicensed mobile access (UMA) protocol Internet protocol tunnel, and an intelligent channel selector.