Abstract:
Methods and systems for using coverage or capacity classifications regarding a macro RF network to manage registration of femtocells with a service provider network (SPN) so as to avoid signaling overload are described herein. After a wide-scale power outage within an area where multiple femtocells are located, the femtocells can power on and attempt to register with the SPN at about the same time. The femtocells can scan RF signals received from the macro network and classify the received RF signals with respect to capacity or coverage of the macro network at the time of transmitting the RF signals. A device within the SPN can determine whether classification of the received RF signals is associated with dropping or accepting a registration request associated with the classified RF signals. The SPN device can accept the registration request or drop the registration request and request the femtocell to transmit another registration request.

Description:
RELATED APPLICATION 
     This application is a continuation of prior U.S. patent application Ser. No. 14/013,991, filed Aug. 29, 2013. U.S. Patent Application No. 14/013,991 issued on May 5, 2015 as U.S. Pat. No. 9,026,110. U.S. patent application Ser. No. 14/013,991 is incorporated herein by reference. 
    
    
     BACKGROUND 
     A wireless communication device, such as a cellular phone or a tablet device, can be used to perform various types of communications, such as making voice calls, transmitting or receiving textual messages, and transmitting or receiving computer-readable files. The various types of communications can be carried out by one or more communication networks. One of the communication networks can be a wireless network operated by a service provider that provides communication services to a user of the wireless communication device. 
     A service provider network can be configured in an arrangement that requires the wireless devices to register with the service provider network prior to the device using the service provider network. The service provider network can be overloaded if a large number of devices, such as wireless communication devices, request registration with the network simultaneously or close to simultaneously and the service provider network attempts to process all of the registrations requests. A quality of service provided by the service provider network can be degraded when the service provider network is overloaded by processing a high quantity of registration requests. 
     Unless otherwise indicated herein, the elements described in this section are not prior art to the claims and are not admitted to be prior art by inclusion in this section. 
     Overview 
     This application describes several example embodiments, at least some of which pertain to accepting or dropping registration requests at a service provider network connected to a femtocell base station that can provide one or more wireless communication devices with connectivity to the service provider network. Any or one or more of the example embodiments can also pertain to classifying macro radio frequency (RF) signals received at the femtocell base station, transmitting a registration request with data classifying the RF signals with respect to coverage and capacity of a macro base station, receiving the registration request from the femtocell base station, or determining whether to drop or accept a registration request based on the classification data or an activity level experienced by the femtocell base station. 
     In one respect, an example embodiment can take the form of a method comprising: (i) receiving, at a core network device of a core network, a registration request from a femto base station, wherein the registration request includes a classification of radio frequency (RF) signals from a macro base station connected to the core network, (ii) determining, by the core network device, whether the classification of the RF signals from the macro base station is associated with dropping or accepting the registration request, (iii) dropping, by the core network device, the registration request if the classification of the RF signals is associated with dropping the registration request, and (iv) accepting, by the core network device, the registration request if the classification of the RF signals is associated with accepting the registration request. In accordance with at least some embodiments, the core network device can determine an activity level of the femto base station. In accordance with those embodiments, dropping the registration request can be conditioned on the activity level of the femto base station being less than an activity level threshold and accepting the registration request can be conditioned on the registration request being greater than the activity level threshold. 
     In another respect, an example embodiment can take the form of a system comprising (i) a network interface configured to receive a registration request from a femto base station, wherein the registration request includes a classification of radio frequency (RF) signals from a macro base station connected to a core network, (ii) a processor, and (iii) a data storage device comprising computer-readable program logic. The computer-readable program logic is executable to determine whether the classification of the RF signals from the macro base station is associated with dropping or accepting the registration request, drop the registration request if the classification of the RF signals is associated with dropping the registration request, and accept the registration request if the classification of the RF signals is associated with accepting the registration request. In accordance with at least some embodiments, the computer-readable program logic can be executable to determine an activity level of the femto base station. In accordance with those embodiments, dropping the registration request can be conditioned on the activity level of the femto base station being less than an activity level threshold and accepting the registration request can be conditioned on the registration request being greater than the activity level threshold. 
     In yet another respect, an example embodiment can take the form of a method comprising: (i) detecting, by a processor of a femto base station, a reason to transmit a registration request to a core network device connected to a core network, (ii) scanning, by the femto base station, radio frequency (RF) signals from a macro base station connected to the core network, and (iii) transmitting, by the femto base station, the registration request to the core network device, wherein the registration request includes a classification of the RF signals from the macro base station. In accordance with at least some embodiments, the processor can determine an activity level of the femto base station. In accordance with those embodiments, the registration request can include data indicating the determined activity level of the femto base station. 
     These as well as other aspects and advantages will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings. Further, it should be understood that the embodiments described in this overview and elsewhere are intended to be examples only and do not necessarily limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments are described herein with reference to the drawings, in which: 
         FIG. 1  is a simplified block diagram of an example communication system; 
         FIG. 2  is a simplified block diagram of an example core network device; 
         FIG. 3  is a simplified block diagram of an example femtocell; 
         FIG. 4  is a simplified block diagram of an example wireless communication device; 
         FIG. 5  is a flowchart depicting a set of functions that can be carried out in accordance with one or more example embodiments described herein; and 
         FIG. 6  is a flowchart depicting another set of functions that can be carried out in accordance with one or more example embodiments described herein. 
     
    
    
     DETAILED DESCRIPTION 
     I. Introduction 
     This description describes several example embodiments and several figures accompanying the description. Within the description, the articles “a” or “an” are used to introduce elements of the example embodiments. The intent of using those articles is that there is one or more of the elements. The intent of using the conjunction “or” within a described list of at least two terms is to indicate any of the listed terms or any combination of the listed terms. The use of ordinal numbers such as “first,” “second,” “third” and so on is to distinguish respective elements rather than to denote a particular order of those elements. 
     The diagrams, depictions, and flow charts shown in the figures are provided merely as examples and are not intended to be limiting. Many of the elements illustrated in the figures or described herein are functional elements that can be implemented as discrete or distributed components or in conjunction with other components, and in any suitable combination and location. Those skilled in the art will appreciate that other arrangements and elements (for example, machines, interfaces, functions, orders, or groupings of functions or operations) can be used instead. Each element or components of an element shown in the figures or described in this description, alone or in combination with one or more other elements or components of the one or more other elements, can be referred to as a system. Furthermore, various functions or operations described as being performed by one or more elements can be carried out by a processor executing computer-readable program instructions or by any combination of hardware, firmware, or software. 
     This description refers to connecting or connection of multiple elements. Any connecting or connection of the elements described herein can occur using one or more wireless connections, one or more wired connections, or some combination of one or more wireless connections and one or more wired connections. Each wireless connection can occur by way of at least one wireless air interface, such as a wireless air interface that carries radio frequency signals. Each wired connection can include at least one conductor, such as, but not limited to a copper wire conductor, a coaxial cable, or a fiber optic cable. 
     II. Example System Architecture 
     A. Example Communication System 
     Referring now to the drawings,  FIG. 1  is a simplified block diagram of an example communication system  100 . At least a portion of communication system  100  is a wireless communication system. For purposes of explanation and example only, the wireless communication system shown in  FIG. 1  is generally arranged and described according to CDMA system architecture. It should be understood, however, that an LTE system architecture could be used instead or in addition, as could an architecture according to one or more other protocols mentioned herein or any others now known or later developed. 
     Communication system  100  includes a service provider network (SPN)  102 , a public switched telephone network (PSTN)  104 , a packet-data network (PDN)  106 , a mobile device (MD)  108 , and a femtocell (or femto base station (FBS))  110 . MD  108  is a wireless communication device. 
     Service-provider network  102  can include some or all of the network elements depicted in  FIG. 1  as being included in its dashed-cloud shape. In that regard, SPN  102  can include a macro base transceiver station (or more simply, “BTS” or a “macro base station”)  112 , a base station controller (BSC)  114 , a mobile switching center (MSC)  116 , and a core packet network (or more simply, “core network”)  118 . In general, there can be more or different communication links among the elements within SPN  102 , and there can be more or different connections between SPN  102  and outside entities. There can also be one or more other packet-data networks or elements, one or more circuit-switched networks or elements, one or more signaling networks or elements, or one or more of any other suitable network(s) or element(s). 
     Core network  118  can include some or all of the network elements depicted in  FIG. 1  as being included in its dashed-cloud shape. In that regard, core network  118  can include a VPN terminator (VPN-T)  120 , a session border controller (SBC)  122 , a femtocell controller  124 , a media gateway controller/media gateway (MGC/MG)  126 , and a femtocell switch  128 . Other elements that can be included within core network  118  include, but are not limited to, a security gateway, a device management system, or a session initiation protocol (SIP) registrar device. One or more of the security device, the device management system, or the SIP registrar device can be integrated into another device within core network  118 . 
     VPN terminator  120  can be arranged to establish secure VPN connections over PDN  106  with femtocells such as femtocell  110 , enabling the femtocells to securely communicate with devices on SPN  102  and beyond. VPN-T  120  can include or operate as a security gateway for core network for core network  118 . 
     SBC  122  can be arranged to perform call-control functions at or proximate to a border of SPN  102  or core network  118  so as to reduce loading on other elements of core network  118 . SBC  122  can be arranged to control a flow of bearer traffic, such as media signals, signaling traffic, such as voice over internet protocol (VoIP) call signaling, or registration requests from FBS  110 . SBC  122  can include or operate as a registrar, such as a SIP registrar. A registrar, such as a SIP registrar can accept registration requests, such as a SIP REGISTER message, and store the information contained in the registration requests for use by core network  118 . SBC  122  can be referred to as an SBC/IMS, where IMS refers to an IP multimedia system or subsystem. 
     Femtocell controller  124  can be arranged to communicate via VPN terminator  120  with femtocells such as femtocell  110 , perhaps to receive requests from various femtocells for configuration data, and to accordingly select various operational parameters for femtocells (e.g. carrier frequency, PN offset, whether to broadcast a pilot beacon, contents of any pilot beacon to be broadcast, transmission-power level), and to transmit those parameters to femtocells, perhaps along with other configuration data and messaging. Femtocell controller  124  can include or operate as a device management system. 
     Femtocell switch  128  can be arranged to act as a switch between MSC  116  and VPN terminator  120 , enabling wireless communication devices, such as MD  108 , communicating via femtocells to engage in calls over PSTN  104  via MSC  116 . 
     PDN  106  can be the well-known global packet-data network generally referred to as the Internet, but could also be or include one or more other packet-data networks. PDN  106  can include one or more wide area networks, one or more local area networks, one or more public networks, one or more private networks, one or more wired networks, one or more wireless networks, or one or more networks of any other type. Devices in communication with PDN  106  can exchange data using a packet-switched protocol such as the Internet Protocol (IP), and can be identified by an address such as an IP address. 
     MGC/MG  126  can be arranged to (a) receive packet-based communications from entities on SPN  102 , convert those to circuit-switched communications, and pass them to MSC  116  or PSTN  104  and (b) receive circuit-switched communications from MSC  116  or PSTN  104 , convert those to packet-based communications, and pass them to other entities on SPN  102 . 
     Communication system  100  can include other network elements as well, such as additional wireless communication devices, mobile or otherwise, in communication with BTS  112  and additional entities in communication with PSTN  104  or PDN  106 , etc. Also, there could be one or more devices or networks making up at least part of one or more communication links that carry communications within or between communication network  100 . For example, there could be one or more routers, cable modems, or other devices or networks on the link between femtocell  110  and PDN  106 . Mobile device  108  is described more fully in connection with  FIG. 2 , while FBS  110  is described more fully in connection with  FIG. 3 . And certainly many other configurations of communication system  100  are possible, as the described configuration is provided by way of example and not limitation. 
     RF signals  132  can be communicated between MD  108  and FBS  110 . RF signals  134  can be communicated between MD  108  and BTS  112 . RF signals  136  can be communicated between BTS  112  and FBS  110 . RF signals of RF signals  134  and  136  transmitted by BTS  112  can be referred to as forward-link RF signals. RF signals of RF signals  134  transmitted by MD  108  and RF signals of RF signals  136  transmitted by FBS  110  can be referred to as reverse-link RF signals. 
     B. Example Core Network Device 
       FIG. 2  is a simplified block diagram of a core network device  200  that includes a processor  202 , a data storage device  204 , and a network interface  206 , all of which can be coupled together by a system bus, network, or other communication mechanism  208 . In general, one or more devices within core network  118  can be configured like core network device  200 . In particular, and by way of example, VPN-T  120 , SBC  122 , femtocell controller  124  or another device referred to herein as a core network device can be configured like core network device  200 . 
     Processor  202 , or any other processor described in this description or used within any example embodiment, can comprise one or more general-purpose processors (for example, INTEL single core microprocessors or INTEL multicore microprocessors) or one or more special-purpose processors (for example, application specific integrated circuits (ASICs) or digital signal processors (DSPs)). Processor  202  can execute computer-readable program logic, which can include computer-readable program instructions (CRPI) stored in data storage device  204 . 
     Data storage device  204 , or any other data storage device described in this description or used within any example embodiment, can comprise a non-transitory computer-readable storage medium readable by a processor. Additionally or alternatively, the data storage device can comprise logic blocks or logic gates to perform various operations, such as operations described in this description as being executed by a core network device. Any computer-readable storage medium described in this description or used within any example embodiment can comprise volatile or non-volatile storage components, such as optical, magnetic, organic or other memory or disc storage, which can be, but is not required to be, integrated in whole or in part with a processor. 
     Network interface  206  can comprise an interface (for example, one or more interfaces) to at least one other element of communication system  100 . Network interface  206  can comprise a transmitter configured to transmit and a receiver configured to receive communications such as signaling and bearer communications to or from another element of communication system  100 . The transmitter and receiver can be separate or a combined transmitter and receiver in the form of a transceiver. A transmitter and receiver of network interface  206  that transmits RF signals can be referred to as a radio transmitter and radio receiver, respectively. The transmitter and receiver can transmit data to a wired network and receive data from the wired network. 
     Data storage device  204  can comprise computer-readable program logic (CRPL)  210  executable by core network device  200 . A person having ordinary skill in the art will understand that execution of program instructions of CRPL  210  can include executing some, but not all, of CRPL  210 . CRPL  210  can comprise computer-readable program instructions (CRPI)  212  executable by processor  202 . Any portion of CRPL  210  can be program instructions of CRPI  212 . In general, CRPL  210  can comprise program logic executable to perform any function described in the description or shown in the figures as being performed at least in part by a device in core network  118 . 
     Data storage device  204  can store various data that processor  202  can access (for example, read from data storage device  204 ) to use in performing one or more operations described herein. For example, data storage device  204  can store the data shown in Table 1, which can represent example classifications (for example, good, average, poor, and poor/absent) of the coverage and capacity provided by macro RF signals received at FBS  110 , and an example response (for example, drop or accept registration request) for each combination of classifications of the macro RF coverage and capacity. 
     
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Macro RF  
                 Macro RF  
                 Response to  
               
               
                 Coverage 
                 Capacity 
                 Registration Request 
               
               
                   
               
             
             
               
                 Good 
                 Good 
                 Dropped 
               
               
                 Good 
                 Average 
                 Dropped 
               
               
                 Good 
                 Poor 
                 Accepted 
               
               
                 Average 
                 Good 
                 Dropped 
               
               
                 Average 
                 Average 
                 Dropped 
               
               
                 Average 
                 Poor 
                 Accepted 
               
               
                 Poor/Absent 
                 Good 
                 Accepted 
               
               
                 Poor/Absent 
                 Average 
                 Accepted 
               
               
                 Poor/Absent 
                 Poor 
                 Accepted 
               
               
                   
               
             
          
         
       
     
     CRPL  210  can comprise program logic executable to receive a registration request from FBS  110 . The registration request can include a classification of RF signals from a macro base station connected to a core network, such as RF signals  136  transmitted by BTS  112 . Network interface  206  can receive the registration request and provide the received registration request to processor  202  by system bus  208 . 
     CRPL  210  can comprise program logic executable to determine whether a classification of RF signals from a macro base station is associated with dropping or accepting a registration request. Execution of that program logic can include comparing the classification information within the registration request to the data shown in Table 1. 
     CRPL  210  can comprise program logic executable to determine an activity level of FBS  110  from activity level information included within the registration request or otherwise transmitted to core network device  200  from FBS  110 . The activity level can indicate the last time activity from FBS  110  occurred. The activity from FBS  110  can be the last time a wireless communication device carried out a voice call or other type of communication using FBS  110 . 
     CRPL  210  can comprise program logic executable to determine the activity level of FBS  110  or another FBS using data stored within core network  118  regarding the activity level of FBS  110  or the other FBS. Determining the activity level of FBS  110  can include core network  118  or a device therein determining whether FBS  110  processed any voice calls within a predetermined amount of time occurring prior to core network  118  or the device therein receiving the registration request from FBS  110 . 
     CRPL  210  can comprise program logic executable to compare data indicating the last time a voice call or other activity occurred using FBS  110  to a current time so as to determine a time difference, and to compare the time difference to a time threshold. The result of that comparison can be used alone or in combination with the classification of RF signals received from the macro base station  112  to determine whether to accept or drop the registration request. 
     CRPL  210  can comprise program logic executable to drop a registration request if the classification of RF signals is associated with dropping the registration request. 
     CRPL  210  can comprise program logic executable to accept a registration if the classification of the RF signals is associated with accepting the registration request. 
     CRPL  210  can comprise program logic executable to cause a response to the registration request to be transmitted to a source of the registration request (for example, FBS  110 ). The response to registration request can notify the source of the registration request whether the registration request is accepted or dropped. For cases in which the registration request was dropped, a response to the registration request can include data indicating when FBS  110  should retry registering with SPN  102  or core network  118 . As an example, data indicating when FBS  110  should retry registering can include data that indicates a particular time, such as a particular coordinated universal time (UTC), a particular date and time, or an amount of time, such as ten minutes. 
     CRPL  210  can comprise program logic executable to cause core network device  200  to transmit updated data indicating when FBS  110  should retry registering with SPN  102  or core network  118 . The updated data can indicate FBS  110  should retry registering sooner or later than indicated by the data previously sent to indicate when the registration retry should occur. This CRPL  210  executable to transmit the updated data can, for example, be executed in response to core network device  200  determining a capacity for core network device  200  to handle more registration requests has increased or decreased by more than a threshold amount. 
     C. Example Femtocell 
       FIG. 3  is a simplified block diagram of femtocell (or femto base station (FBS))  110 , which includes a wireless-communication interface  300 , a global positioning system (GPS) receiver  302 , a PDN interface  304 , a processor  306 , and a data storage device  308 , all of which can be coupled together by a system bus, network, or other communication mechanism  310 . Note that femtocell  110  can have additional or different components, and that this structure is provided by way of example. 
     Wireless-communication interface  300  can include one or more antennas, one or more chipsets, a set of one or more channel elements, and/or one or more other components suitable for providing a wireless coverage according to a wireless-communication protocol such as CDMA or LTE (or one or more other technologies or protocols). GPS receiver  302  can be any known or hereafter-developed GPS receiver, suitable for receiving and decoding GPS signals for location and timing purposes, perhaps among other purposes. In some embodiments, a femtocell can have a location module in addition to or instead of a GPS receiver. 
     PDN interface  304  can provide a (e.g., wired) packet-data interface for communicating with a device such as a router or cable modem, and in general for communicating over one or more packet-data networks such as PDN  106 . 
     Processor  306  can comprise one or more general-purpose processors (for example, INTEL single core microprocessors or INTEL multicore microprocessors) or one or more special-purpose processors (for example, application specific integrated circuits (ASICs) or digital signal processors (DSPs)). Processor  306  can execute computer-readable program logic, which can include computer-readable program instructions (CRPI) stored in data storage device  308 . 
     Data storage device  308  can comprise a non-transitory computer-readable storage medium readable by processor  306 . Additionally or alternatively, data storage device  308  can comprise logic blocks or logic gates to perform various operations, such as operations described in this description as being executed by femtocell  110 . Data storage device  308  can comprise CRPL  312  executable by femtocell  110 . A person having ordinary skill in the art will understand that execution of program instructions of CRPL  312  can include executing some, but not all, of CRPL  312 . CRPL  312  can comprise CRPI  314  executable by processor  306 . Any portion of CRPL  312  can be program instructions of CRPI  314 . Executing CRPL  312  or CRPI  314  can include carrying out the femtocell functions described in this description, as well as any other operational, configuration, and/or other type of data deemed suitable in a given femtocell implementation. 
     CRPL  312  can comprise program logic executable to detect a reason to transmit a registration request and to cause wireless communication interface  300  or PDN interface  304  to transmit the registration request to a core network device within core network  118 . Examples of reasons to transmit the registration request are described elsewhere herein. 
     CRPL  312  can comprise program logic executable to determine the activity level of FBS  110 , such as the last time a wireless communication device carried out a voice call or other type of communication using FBS  110 . CRPL  312  can comprise program logic executable to determine whether FBS  110  processed any voice calls within a predetermined amount of time prior to FBS  110  detecting the reason to transmit the registration request or prior to a time when FBS  110  is embedding the registration request with the activity level information. Data storage device  308  can store time data for determining the activity level, such as time data indicating when the most recent communication performed using FBS  110  started or ended. 
     CRPL  312  can comprise program logic executable to embed (e.g., place within) the registration request with activity level information and the classification data pertain to RF signals FBS  110  receives from macro base station  112 . 
     D. Example Mobile Device 
       FIG. 4  depicts wireless communication device  400  as including a wireless-communication interface  402 , a user interface  404 , a processor  406 , and a data storage device  408 , all of which can be coupled together by a system bus, network, or other communication mechanism  410 . Mobile device  108  shown in  FIG. 1  can be configured like wireless communication device  400 . Wireless communication device  400  can be a mobile wireless communication device or otherwise. Wireless communication device  400  can comprise or be configured as a cellular phone, a laptop computer, a tablet device, or some other device. 
     Wireless-communication interface  402  can comprise one or more antennae and one or more chipsets for communicating with one or more base stations over respective air interfaces. As an example, one such chipset could be suited for LTE communication. As another example, one such chipset could be suited for CDMA communication. Wireless-communication interface  402  can also or instead be arranged to communicate according to one or more other types of wireless communication (e.g., protocols) mentioned herein and/or any others now known or later developed. User interface  404  can include one or more input devices such as a touchscreen, one or more buttons, a microphone, and the like for receiving inputs from users, as well as one or more output devices such as a display, one or more indicator lights, a speaker, and the like for communicating outputs to users. 
     Processor  406  can comprise one or more general-purpose processors and/or one or more special-purpose processors, and can be integrated in whole or in part with wireless-communication interface  402 . Data storage device  408  can comprise one or more volatile and/or non-volatile storage components (such as magnetic, optical, flash, or other non-transitory storage), and can be integrated in whole or in part with processor  406 . And certainly other configurations are possible. Data storage device  408  can contain CRPL or CRPI executable by wireless communication device  400  or processor  406  for carrying out various mobile-device functions described herein. 
     III. Example Operation 
       FIG. 5  depicts a flowchart showing a set of functions (for example, operations)  500  (or more simply, “the set  500 ”) that can be carried out in accordance with any or one or more of the example embodiments described herein. The functions of the set  500  are shown within blocks labeled with even integers between  502  and  510 , inclusive. Other functions described herein can be performed prior to, while, or after performing any one or more of the functions of the set  500 . Those other functions can be performed in combination with or separately from any one or more of the functions of the set  500 . 
     Block  502  includes performing power-on program logic. Femtocell  110  or processor  306  can perform the power-on program logic. The power-on program logic can be located within or as part of CRPL  312  or CRPI  314 . As an example, performing the power-on program logic can occur in response to electrical power being provided to femtocell  110  for an initial time or for an initial time after femtocell being installed at a new location. As another example, performing the power-on program logic can occur in response to electrical power being provided to femtocell  110  after electrical power was not provided for at least an amount of time during which femtocell  110  powered down to an off state. As yet another example, performing the power-on program logic can occur in response a femtocell  110  performing program logic that resets processor  306 . Other examples of events that trigger performance of the power-on program logic are also possible. 
     Next, block  504  includes detecting a reason to transmit a registration request to a core network device connected to a core network. Femtocell  110  or processor  306  can detect the reason to transmit the registration request. The core network device can be arranged like core network device  200 . The core network can be arranged like core network  118 . 
     As an example, detecting the reason to transmit the registration request can comprise femtocell  110  or processor  306  detecting execution of the power-on program logic is being performed by femtocell  110  or processor  306 . Detecting the power-on program logic is being performed can include, but is not limited to, detecting initiation of executing the power-on program logic or completing execution of the power-on program logic. 
     As another example, detecting the reason to transmit the registration request can comprise femtocell  110  or processor  306  detecting receipt of a message requesting femtocell  110  to send another registration request after a particular amount of time, and detecting that the amount of time has passed since receipt of the message or since a time the message was transmitted to femtocell  110 . 
     As yet another example, detecting the reason to transmit the registration request can comprise femtocell  110  or processor  306  detecting receipt of a message requesting femtocell  110  to send another registration request at or after a particular time or date and time, and detecting that the particular time or date and time is or has occurred. 
     Next, block  506  includes scanning radio frequency (RF) signals from a macro base station connected to the core network. Scanning the RF signals from macro base station  112  can include wireless communication interface  300  receiving the RF signals, measuring the received RF signals, and comparing the measured RF signals to RF signal thresholds. As an example, measuring the received RF signal can include measuring a signal to noise ratio of the received RF signal. The RF signal thresholds can include multiple thresholds so that FBS  110  can determine whether the RF coverage provided by macro base station  112  is classified as good (for example, the measured RF signal is above the greatest RF signal threshold), average (for example, the measured RF signal is less than the greatest RF signal threshold but greater than the least RF signal threshold, and poor/absent (for example, the measured RF signal is less than the least RF signal threshold. 
     Next, block  508  includes transmitting the registration request to the core network device. The registration request can include a classification of the RF signals from the macro base station. FBS  110 , wireless communication interface  300  or PDN interface  304  can transmit the registration request. Transmitting the registration request can include transmitting the registration request over PDN  106 . The registration request can be configured as a session initiation protocol (SIP) REGISTER message. The SIP REGISTER message can comprise an extensible markup language (XML) body including the classification of the RF signals from macro base station  112 . 
     The classification of the RF signals from macro base station  112  can comprise a classification of a coverage provided by the RF signals from macro base station  112 . That classification can, for example, indicate good, average, or poor/absent. Additionally or alternatively, the classification of the RF signals from macro base station  112  can comprise a classification of a capacity of the RF signals from macro base station  112 . This latter classification can, for example, indicate good, average, or poor. Other examples of what the various classifications are called are possible. Furthermore, more or fewer classifications of RF coverage or RF capacity can be defined. 
     Next, block  510  includes receiving a message requesting transmission of another registration request. FBS  110  can receive the message in response to transmitting a registration request that is dropped by core network  118  or a device therein. FBS  110  can transmit another registration request. Transmitting the other registration request can be conditioned on any of a variety of conditions, such as time conditions indicated in the message requesting retransmission of the other registration request. 
     Next,  FIG. 6  depicts a flowchart showing a set of functions (for example, operations)  600  (or more simply, “the set  600 ”) that can be carried out in accordance with any or one or more of the example embodiments described herein. The functions of the set  600  are shown within blocks labeled with even integers between  602  and  614 , inclusive. Other functions described herein can be performed prior to, while, or after performing any one or more of the functions of the set  600 . Those other functions can be performed in combination with or separately from any one or more of the functions of the set  600 . 
     Block  602  includes receiving a registration request from a femto base station. The registration request can include a classification of RF signals from macro base station  112  connected to core network  118 . Core network  118  or a device therein can receive the registration request. The registration request can include a classification of RF signals from macro base station  112  that is connected to core network  118 . 
     The classification of the RF signals from the macro base station can comprise a classification of a coverage provided by the RF signals from macro base station  112  or a classification of a capacity of the RF signals from the macro base station  112 . The classification of RF signals can be referred to as classification data. The classification data can comprise a macro RF coverage indication of good, average, or poor/absent, or some other indication of macro RF coverage. The classification data can comprise a macro RF capacity indication of good, average or poor, or some other indication of macro RF capacity. 
     In general, the registration request can be configured as any message a device sends to a core network for registering the device with the core network. That registration message can include the activity level information or classification data regarding the RF signals received by FBS  110 . As an example, the registration request can be configured as a session initiation protocol (SIP) REGISTER message. The SIP REGISTER message can comprise an extensible markup language (XML) body including the classification of the RF signals from macro base station  112 . Other examples of the registration message include an attach message, such as an LTE attach message, an H.323 registration message, or a SIP MESSAGE message. Those example messages can include the activity level information or classification data. 
     Next, block  604  includes storing classification data that associates classifications of RF signals to dropping or accepting a registration request. Core network  118  or a device therein can store the classification data that associates classifications of RF signals to dropping or accepting a registration request. The stored data can be arranged like the data in Table 1 or in another manner. Storing of the classification data can occur prior to receiving the registration request at block  602 . 
     Next, block  606  includes determining whether the classification of the RF signals from the macro base station  112  is associated with dropping or accepting the registration request. Making that determination can include core network  118  or a device therein comparing classification data with the registration request to classification comparison data, such as the classification comparison data shown in Table 1. Furthermore, making that determination may be conditioned on the result of comparing an activity level of the FBS  110  to an activity level threshold. 
     In accordance with any or one or more example embodiments, determining whether the classification of the RF signals from the macro base station  112  is associated with dropping or accepting the registration request is conditioned on core network  118  or a device therein receiving a number of other registration requests from other femto base stations during a time period occurring before core network  118  or the device therein receiving the registration request from FBS  110 . In accordance with that or those example embodiments, the number of other registration requests exceeds a threshold number of registration requests. Data indicating the threshold number of registration requests and the time period occurring before receipt of the registration request can be stored with data storage device  204 . 
     In accordance with any or one or more example embodiments, determining whether the classification of the RF signals from the macro base station  112  is associated with dropping or accepting the registration request is conditioned on core network  118  or a device therein operating in a state that exceeds a threshold congestion state. Data indicating the threshold congestion state for comparison to operating conditions of core network  118  or the device therein can be stored with data storage device  204 . The threshold congestion state can be for operating conditions of core network device  118  or the device therein other than receiving more than a threshold number of registration requests from femto base stations. 
     Next, block  608  includes determining an activity level of the femto base station. FBS  110 , or core network  118  or a device therein, can determine the activity level of FBS  110 . The activity level can indicate the last time activity from FBS  110  occurred. The activity from FBS  110  can be the last time a wireless communication device carried out a voice call or other type of communication using FBS  110 . Additionally or alternatively, determining the activity level of FBS  110  can include core network  118  or a device therein determining whether FBS  110  processed any voice calls within a predetermined amount of time occurring prior to core network  118  or the device therein receiving the registration request from FBS  110 . 
     The last time of the voice call or other activity can be compared to a current time to determine a time difference. The time difference can be compared to a time threshold, such as 60 minutes. The result of that comparison can be used alone or in combination with the classification of RF signals received from the macro base station  112  to determine whether to accept or drop the registration request. For example, if the time difference exceeds the time threshold, the activity level is less than the activity level threshold and the core network device can drop the registration request sent by FBS  110  without even considering the classification data. On the other hand, accepting the registration request at the core network device can be conditioned on the activity level being greater than the activity level threshold. The activity level can be considered to be greater than the activity level threshold if the time difference does not exceed the time threshold. 
     Next, block  610  includes counting a number of other registration requests received during a time period. The time period for counting registration requests can be thirty seconds, sixty seconds, or some other amount of time. Core network  118  or a device therein can count the number of other registration requests and can exclude any registration requests received by core network  118  prior to a start of the time period. The registration requests counted for block  610  can include registration requests from femto base stations connected to core network  118 . The counted registration requests can be used to determine whether more than a threshold number of registration requests have recently been received. If the counted registration requests exceed the threshold, the core network  118  can responsively execute CRPL or CRPI that causes core network  118  to operate in a state in which core network  118  makes determinations whether to drop registration requests from femto base stations. 
     Next, block  612  includes dropping the registration request if the classification of the RF signals is associated with dropping the registration request. Dropping the registration request can include core network  118  or a device therein transmitting to FBS  110  a registration request response indicating the registration request was dropped. The registration request response can include time data indicating a time, or a date and time, when FBS  110  should transmit another registration request to core network  118 . The registration request response can include time data indicating an amount of time FBS  110  should wait before transmitting another registration request to core network  118 . Core network  118  or a device therein can determine the time data based on the number of other registration requests received during the time period during which registration requests were counted. In at least some cases, the time data represents a time at which core network  118  determines another registration request from FBS  110  would be accepted rather than dropped. 
     Next, block  614  includes accepting the registration request if the classification of the RF signals is associated with accepting the registration request. A core network device of core network  118  can accept the registration request. In response to accepting the registration request, core network  118  or a device therein can register FBS  110  so as to allow FBS  110  to process communication sessions requests and communication sessions for wireless communication devices in proximity to FBS  110 . Various messages can be communicated between FBS  110  and core network  118  using PDN  106  to register FBS  110  with core network  118 . 
     IV. Conclusion 
     Example embodiments have been described above. Those skilled in the art will understand that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the present invention, which is defined by the claims.