Patent Abstract:
Methods and systems for making decisions regarding handing off a user-equipment device from a serving base station to a neighboring base station. Base stations in a wireless communication network measure parameters regarding forward-links from the base stations and reverse-links to the base stations. Each base station transmits its measured parameters to its neighboring base station(s). Each base station can determine differences between the parameters it measures and the parameters measured by a neighboring base station. The differences indicate whether the quality of service provided by the serving base station is greater than the quality of service provided by a neighboring base station. The servicing base station transmits the differences to user-equipment devices served by that base station. The user-equipment device compares the differences pertaining to the serving base station and multiple neighboring base stations and selects a neighboring base station to which the user-equipment device is to be handed over.

Full Description:
BACKGROUND 
     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. 
     A user-equipment (UE) device, such as a cellular phone, operating within a first radio frequency (RF) coverage area provided by a base station can be handed over from that base station to a base station providing a second RF coverage area. Handing over the UE device permits a communication session (such as voice call or internet browsing session) occurring via the UE device to continue as the UE device is moved from the first coverage area to the second RF coverage area. 
     RF signals transmitted from a base station within a coverage area to the wireless UE device can be referred to as forward-link signals. RF signals transmitted from the UE device to the base station can be referred to as reverse-link signals. Handing over the UE device from the first RF coverage area to the second RF coverage area can be based on a forward-link signal. 
     OVERVIEW 
     This application describes several example embodiments, at least some of which pertain to using reverse-link measurements to make decisions regarding whether to hand over a user-equipment device from a serving base station to another base station. 
     In one respect, an example embodiment can take the form of a method comprising (i) determining, at a first base station, a first reverse-link noise measurement pertaining to one or more reverse-links to the first base station, (ii) receiving, at the first base station, a second reverse-link noise measurement pertaining to one or more reverse-links to a second base station neighboring the first base station, (iii) determining, at the first base station, a difference between the first reverse-link noise measurement and the second reverse-link noise measurement, and (iv) transmitting, from the first base station to a user-equipment device served by the first base station, data indicating the difference between the first reverse-link noise measurement and the second reverse-link noise measurement. 
     In another respect, an example embodiment can take the form of a method comprising (i) determining, at a user-equipment device operating in an idle mode, a difference in reverse-link noise measured by a first base station currently serving the user-equipment device and reverse-link noise measured by a second base station that neighbors the first base station, (ii) selecting, based on the difference in reverse-link noise determined at the user-equipment device, the second base station to serve the user-equipment device instead of the first base station, and (iii) initiating, using the user-equipment device in response to selecting the second base station, handoff of the user-equipment device from the first base station to the second base station. 
     In yet another respect, an example embodiment can take the form of a user-equipment device comprising: (i) a wireless communication interface that receives first reverse-link noise data that indicates a difference in reverse-link noise measured by a first base station currently serving the user-equipment device and reverse-link noise measured by a second base station that neighbors the first base station, (ii) a processor, and (iii) a data storage device storing computer-readable program instructions executable by the processor to perform a set of functions. The set of functions comprises (i) selecting, based on the first reverse-link noise data received by the wireless communication interface, the second base station to serve the user-equipment device instead of the first base station, and (ii) initiating, in response to selecting the second base station, handoff of the user-equipment device from the first base station to the second 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 diagram depicting a system in accordance with one or more of the example embodiments; 
         FIG. 2  is a block diagram of a user-equipment device in accordance with one or more of the example embodiments; 
         FIG. 3  is a block diagram of a base station in accordance with one or more of the example embodiments; 
         FIG. 4  is a flowchart depicting a set of functions that can be carried out in accordance with one or more of the example embodiments; and 
         FIG. 5  is a flowchart depicting a set of functions that can be carried out in accordance with one or more of the example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     I. Introduction 
     In addition to handing over a user-equipment (UE) device performing a communication session, the UE device can be handed over from a serving base station to another base station while the UE device is operating in an idle mode. This description describes example embodiments that pertain to using reverse-link measurements to make decisions regarding whether to hand over a UE device. The reverse-link measurements can, for example, include parameters indicating reverse-link noise measurements made by base stations within a wireless communication network, Random Access Channel (RACH) capacity parameters, or Uplink Data Error rate parameters that indicate how well the reverse-link is performing. 
     In this 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 2 terms is to indicate that 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. For purposes of this description, the terms “hand off” and “hand over” can be used interchangeably as can the terms “handing off” and “handing over” and the terms “handed off” and “handed over.” 
     The diagrams 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) can be used instead. Furthermore, various functions 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. 
     II. Example Architecture 
       FIG. 1  is a diagram depicting a system  100  in accordance with one or more of the example embodiments. System  100  can be referred to as a communication network or, more particularly, a wireless communication network. System  100  includes multiple base stations, represented by base stations  102 ,  104 , and  106 . System  100  can include a different number of base stations than is shown in  FIG. 1 . Each base station shown in  FIG. 1  can include a transceiver to transmit and receive radio frequency (RF) signals. Each of those base stations can include a transceiver tower, as shown in  FIG. 1 , but is not so limited. 
     The RF signals transmitted by each base station provide a coverage area in which UE devices can carry out wireless communications over an air interface within the coverage area. In  FIG. 1 , the coverage areas provided by the base stations  102 ,  104 , and  106  are coverage areas  108 ,  110 , and  112 , respectively. The air interfaces within those coverage areas are air interfaces  114 ,  116 , and  118 , respectively. For simplicity, each coverage area is area is shown as a hexagon, but each coverage area is not so limited. For clarity of  FIG. 1 , none of the coverage areas of system  100  is shown as overlapping another coverage area. A person skilled in the art will understand that each coverage area can overlap or be overlapped by another coverage area. 
     System  100  includes multiple UE devices, represented by UE devices  120 ,  122 ,  124 ,  126 ,  128 , and  130 . In one respect, a UE device can be a mobile UE device. A mobile UE device can be moved from a first coverage area to a second coverage area and operate with a base station while moving between those coverage areas. In another respect, a UE device can be a stationary UE device that is configured for operating at a fixed location. The fixed location may be limited to a location at which the stationary UE device can receive electrical power to operate the UE device. 
     The RF signals transmitted via a UE device to a base station can be referred to as reverse-link signals or reverse-link communications. The RF signals transmitted from a base station to a UE device can be referred to a forward-link signals or forward-link communications. 
     In practice, each base station can communicate with a UE device over an air interface (for example, air interface  114 ,  116 , or  118 ) according to one or more air interface protocols, examples of which include LTE, CDMA, WiMAX, IDEN, GSM, GPRS, UTMS, EDGE, MMDS, WIFI, BLUETOOTH, and other protocols now known or later developed. The principles of the example embodiments may be applicable in various ones of these protocols. For simplicity, however, this description will focus specifically on implementation in LTE as described herein. 
     System  100  can include inter-base-station communication link  132  that connects each base station to at least one neighbor base station. In accordance with the LTE implementation, communication link  132  can comprise an X2 link. System  100  can include communication links  134  to provide base stations  102 ,  104 , and  106  with connectivity to one or more transport networks  136 , such as the public switched telephone network (PSTN) or the Internet for instance. With this arrangement, a UE device that is positioned within the coverage area of a base station and that is suitably equipped may engage in air interface communication with the base station and can thereby communicate with remote entities on the transport network(s) and/or with other UE devices served by a base station of system  100 . 
     Next,  FIG. 2  is a block diagram of a user-equipment (UE) device  200  in accordance with one or more of the example embodiments. UE device  200  includes a processor  202 , a wireless communication interface  204 , a user interface  206 , and a data storage device  208 , all of which can be linked together via a system bus, network, or other connection mechanism  210 . UE device  200  can operate within system  100 . One or more of the UE devices shown in  FIG. 1  can be configured as UE device  200 . UE device  200  can comprise or be configured as a cellular telephone, a personal digital, a tablet computing device, or a laptop computer. 
     Processor  202  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 instructions, such as computer-readable program instructions (CRPI)  212 . 
     Wireless communication interface  204  can include one or more components for transmitting data to a base station of a wireless communication network and for receiving data from a base station of the wireless communication network. Those components can include a transmitter and a receiver, distinct from one another, or a transceiver including both a transmitter and a receiver. Wireless communication interface  204  can be arranged as a multiple-input-multiple-output (MIMO) system including multiple transmit antennas (for example, 2 or 4 antennas) and multiple receive antennas (for example, 2 or 4 antennas). 
     User interface (UI)  206  can include one or more components for a user of UE device  200  to input data or information to UE device  200 . Those component(s) can be referred to as UI input component(s). As an example, the UI input components can include a touchscreen (for example, a capacitive touchscreen or a resistive touchscreen) to input selections made by the user. As another example, the UI input components can include a power switch to power on and power off UE device  200 . As another example, the UI input components can include a microphone to receive voice communication, spoken by the user, for transmission within system  100 . 
     User interface  206  can include one or more components to present data or information to the user of UE device  200 . Those component(s) can be referred to as UI output component(s). As an example, the UI output components can include an audio speaker to output audible sounds such as voice communications and streaming music received via wireless communication interface  204 . As another example, the UI output components can include a display device, such as a thin film transistor display, a thin film diode display, an organic light-emitting diode display, a capacitive touch screen, or a resistive touchscreen. 
     Data storage device  208  can comprise a non-transitory computer-readable storage medium readable by processor  202 . The computer-readable storage medium can comprise volatile and/or non-volatile storage components, such as optical, magnetic, organic or other memory or disc storage, which can be integrated in whole or in part with processor  202 . Data storage device  208  may also or alternatively be provided separately, as a non-transitory machine readable medium. Data storage device  208  can include CRPI  212  and a neighbor list  214 . 
     CRPI  212  can comprise a variety of program instructions, executable by processor  202 , to cause the elements of UE device  200  to perform one or more of the functions described herein, including one or more of the functions shown in  FIG. 5 . 
     CRPI  212  can comprise program instructions to allow a user to engage in communication sessions using UE device  200 , and to cause UE device  200  to operate in an idle mode while UE device  200  is not engaging in a communication session. Operating in the idle, mode can include UE device  200  performing discontinuous reception (DRX) to conserve power in a battery of UE device  200 . As an example, UE device  200  can operate in a low power mode and can wake up every 1.28 seconds (or other defined cycle period) to check for any page messages destined to UE device  200 . If UE device  200  detects a page message while awake during a DRX cycle, UE device  200  can then process the page message. Otherwise, UE device  200  can return to the low power mode before waking up again for the next DRX cycle. 
     CRPI  212  can comprise program instructions to receive reverse-link measurement parameters from a base station serving UE device  200 . While being served by base station  104 , wireless communication interface  204  can receive the reverse-link measurement parameters via the forward-link of air interface  116 . Execution of CRPI  212  can cause the reverse-link measurement parameters, received at wireless communication interface  204 , to be provided to processor  202  or data storage device  208 . Any data provided to data storage device  208  can be stored at data storage device  208 . In particular, the reverse-link measurement parameters provided to data storage device  208  can be stored with measurement parameters  216 . As an example, the reverse-link measurement parameters can include parameters for reverse-link noise measurements. 
     The reverse-link noise measurements received at UE device  200  can be arranged in various configurations. For example, the reverse-link noise measurements can indicate the noise measured on the reverse-links to the base station serving UE device  200  (RLN Serving ) and noise measured on the reverse-links to a base station neighboring the base station serving UE device  200  ((RLN Neighbor(x) ), where x=a number 1 to n, and n=the number of base stations considered to neighbor the base station serving UE device  200 . As another example, the reverse-link noise measurements can indicate a difference between reverse-link noise measurements of the base station serving UE device  200  and a neighboring base station. For instance, the difference can equal RLN Serving −RLN Neighbor(x)  or RLN Neighbor(x) −RLN Serving . The reverse-link noise measurements can, for example, be specified as a number of decibels (dB). 
     CRPI  212  can comprise program instructions to receive forward-link measurement parameters from a base station serving UE device  200 . Execution of CRPI  212  can cause the forward-link measurement parameters, received at wireless communication interface  204 , to be provided to processor  202  or data storage device  208  (for storing as measurement parameters  216 ). 
     CRPI  212  can include program instructions to provide the received reverse-link noise measurements to data storage device  208  and to determine an arithmetic mean (that is, average or mean) of a given number of most-recently received noise measurements for a base station or noise measurement differences. As an example, the given number can be 3. In that case, if the 5 most recent noise measurement differences for base stations  102  and  104  are 12 dB, 8 dB, 11 dB, 4 dB, and 3 dB, then execution of the CRPI  212  can cause processor  202  to determine the mean for those noise measurement differences to be 6 dB (that is, (11 dB+4 dB+3 dB)/3=6 dB). The arithmetic means can be provided to data storage device  208  and stored as aggregated parameters  218 . 
     Neighbor list  214  can comprise data indicating which base stations of system  100  are neighbors to the base station serving UE device  200 . In accordance with an embodiment in which base station  102  is serving UE device  200 , the neighbor base stations for UE device  200  can be base stations  104  and  106 . Tables 1 and 2 illustrate examples of neighbor list  214 . The data in Tables 1 and 2 identify that base station  102  is the base station serving UE  200  and base stations  104  and  106  are the neighbor base stations. The “Null” values in Tables 1 and 2 indicate that no data is stored in that field of the table. The “Null” values can change when or in response to UE device handing over to another base station. 
     Table 1 illustrates that neighbor list  214  includes the most-recent reverse-link noise measurements and an average of the most-recent reverse-link noise measurements for the serving and neighboring base stations. Table 2 illustrates that neighbor list  214  includes the most-recent differences in reverse-link noise measurements and an average of the most-recent differences in reverse-link noise measurements for the serving and neighboring base stations. 
     
       
         
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 BS Serving   
                 BS Neighbor   
                 RLN (1)   
                 RLN (2)   
                 RLN (3)   
                 RLN (Mean)   
               
               
                   
               
             
             
               
                 102 
                 Null 
                 15 dB 
                 10 dB 
                 9 dB 
                 11.3 dB 
               
               
                 Null 
                 104 
                  4 dB 
                  6 dB 
                 6 dB 
                  5.3 dB 
               
               
                 Null 
                 106 
                 13 dB 
                  3 dB 
                 6 dB 
                  7.3 dB 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 BS Serving   
                 BS Neighbor   
                 RLN DIFF(1)   
                 RLN DIFF(2)   
                 RLN DIFF(3)   
                 RLN DIFF(Mean)   
               
               
                   
               
             
             
               
                 102 
                 Null 
                 Null 
                 Null 
                 Null 
                 Null 
               
               
                 Null 
                 104 
                 11 dB 
                 4 dB 
                 3 dB 
                 6 dB 
               
               
                 Null 
                 106 
                  2 dB 
                 7 dB 
                 3 dB 
                 4 dB 
               
               
                   
               
             
          
         
       
     
     Referring to the data in Tables 1 and 2, the values of RLN DIFF(x)  are determined by subtracting the measured reverse-link noise for the neighbor base station from the measured reverse-link noise for the serving base station. The value of (x)=1 to n, wherein n=the number of measurements to be used to determine the arithmetic mean. The values of RLN DIFF(x)  can be negative. In accordance with other embodiments, the values of RLN DIFF(x)  can be determined by subtracting the measured reverse-link noise for the serving base station from the measured reverse-link noise for the neighbor base station. 
     The reverse-link noise measurement data in Tables 1 and 2 can be stored in area of data storage device  208  that is distinct from neighbor list  214 , such as measurement parameters  216 . CRPI  212  can comprise program instructions to calculate the values of RLN (Mean) , RLN DIFF(1) , RLN DIFF(2) , RLN DIFF(3) , and RLN DIFF(Mean)  from the values of RLN (1) , RLN (2) , and RLN (3)  received at wireless communication interface  204 . In response to UE device  200  being handed off from base station  102  to a neighbor base station, such as base station  104 , the data in the example neighbor lists shown in Tables 1 and 2 can be updated to indicate that base station  102  is a BS Neighbor  and base station  104  is the BS Serving . 
     CRPI  212  can comprise program instructions to select another base station to be the base station serving UE device  200 . Selecting another base station can be referred to as reselecting a base station. Executing the program instruction to select the other base station can include processor  202  determining the base station that, most recently, is experiencing the highest quality of service (for example, the lowest amount of reverse-link noise). Considering the reverse-link noise measurement data in Table 1, processor  202  can select base station  104  as the next base station to serve UE device  200  because the lowest average reverse-link noise was measured for base station  104 . 
     Considering the reverse-noise measurement data in Table 2, processor  202  can select base station  104  as the new serving base station since the largest difference in measured reverse-link noise is for the pair of base stations  102  and  104 . In accordance with the embodiments in which the values of RLN DIFF(x)  are determined by subtracting the measured reverse-link noise for the serving base station from the measured reverse-link noise for the neighbor base station, processor  202  can select a base station as the new serving base station if that base station has the smallest difference (or largest negative) value of RLN DIFF(x) . 
     Next,  FIG. 3  is a block diagram of a base station  300  in accordance with one or more example embodiments described herein. Base station  300  comprises a processor  302 , a network interface  304 , a wireless communication interface  306 , and a data storage device  308 , all of which can be linked together via a system bus, network, or other connection mechanism  310 . For the example embodiments using the LTE protocol, the base station serving a UE device can be referred to as “eNodeB” or “eNB.” 
     Processor  302  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, ASICs or DSPs). Processor  302  can execute computer-readable program instructions, such as computer-readable program instructions (CRPI)  312 . 
     Network interface  304  can comprise a wired or wireless interface for communicating with a network infrastructure (such as a switch, gateway, mobility manager, or the like), which provides connectivity or facilitates communication with one or more of the transport networks  136 . 
     Wireless communication interface  306  can engage in air interface communication with base stations such as those shown in  FIG. 1 . As such, wireless communication interface  306  can include an antenna structure and a chipset arranged to support wireless communication according to one or more air interface protocols, such as those discussed above for instance. The chipset can, for example, include a power amplifier and a cell site modem. 
     Data storage device  308  can comprise a non-transitory computer-readable storage medium readable by processor  302 . The computer-readable storage medium can comprise volatile and/or non-volatile storage components, such as optical, magnetic, organic or other memory or disc storage, which can be integrated in whole or in part with processor  302 . Data storage device  308  may also or alternatively be provided separately, as a non-transitory machine readable medium. 
     Data storage device  308  can include CRPI  312 , a neighbor list  314 , reverse-link measurement parameters  316 , reverse-link noise measurement differences, and UE device data  320 . Other examples of data that can be contained in data storage device  308  are also possible, some of which are described in other parts of this description. 
     CRPI  312  can comprise a variety of program instructions, executable by processor  302 , to cause the elements of base station  300  to perform one or more of the functions described herein, including one or more of the functions shown in  FIG. 4 . 
     CRPI  312  can comprise program instructions to receive reverse-link measurement parameters from one or more neighbor base station, such as one of the base stations shown in  FIG. 1 . The neighbor base station can transmit the reverse-link measurement parameters to network interface  304 . Execution of CRPI  312  can cause the reverse-link measurement parameters, received at network interface  304 , to be provided to processor  302  or data storage device  308 . Any data, such as reverse-link measurement parameters, provided to data storage device  308  can be stored at data storage device  308 . 
     In one respect, some or all of the reverse-link measurement parameters received at network interface  304  can be unsolicited. In another respect, some or all of the reverse-link measurement parameters received at network interface  304  can be received in response to base station  300  requesting the reverse-link measurement parameters. In that regard, CRPI  312  can comprise program instructions to generate a request for reverse-link measurement parameters to cause network interface  304  to transmit the request to one or more neighbor base stations. As an example, the reverse-link measurement parameters can comprise reverse-link noise measurement parameters that indicate reverse-link noise measured by a base station. 
     CRPI  312  can comprise program instructions to determine reverse-link measurement parameters for reverse links to wireless communication interface  306 , provide the determined reverse-link measurement parameters to data storage device  308  for storage as reverse-link measurement parameters  316 , generate a message comprising one or more of the determined reverse-link measurement parameters, and transmit, using network interface  304 , the message comprising one or more of the determined reverse-link measurement parameters to one or more neighbor base stations. Examples of the reverse-link noise measurement parameters are shown in Table 1 (for example, RLN (1) , RLN (2) , and RLN (3) ). 
     CRPI  312  can comprise program instructions to determine differences between reverse-link noise measurement parameters for reverse links to wireless communication interface  306  and reverse-link noise measurement parameters from a neighbor base station, provide the determined differences to data storage device  308  for storage as reverse-link measurement parameter differences  318 , generate a message comprising one or more determined differences, and transmit, using network interface  304 , the message comprising the one or more determined differences. Examples of the determined reverse-link parameter differences are shown in Table 2 (for example, RLN DIFF(1) , RLN DIFF(2) , and RLN DIFF(3) ). 
     UE device data  320  can comprise data that identifies the UE devices being served by base station  300  and whether each UE device is engaged in a communication session or is operating in an idle mode. UE device data  320  can include data that indicates or that can be used to determine when each UE device is operating in an idle mode and will transition to or operate in a discontinuous reception (DRX) mode. CRPI  312  can comprise program instructions that are executable to refer to UE device data  320  to determine when UE device  200  is operating in the idle mode and the DRX mode. Processor  302  can execute the program instructions to send reverse-link measurement parameters or differences to UE device  200  while UE device  200  is operating in the idle and DRX modes. 
     In addition to operating as a serving base station that serves UE device  200 , a base station, such as base station  300 , can operate as a neighbor base station to one or more other base stations. Those other base stations can transmit reverse-link measurement parameters obtained from base station  300  to UE devices serviced by those other base stations so that those UE devices can make a determination whether to select a new base station. Therefore, CRPI  312  can include program instructions to cause network interface  304  to transmit the reverse-link measurement parameters from base station  300  to another base station via inter-base-station communication link  132 . 
     III. Example Operation 
     Next,  FIG. 4  is a flow diagram depicting a set of functions  400  that can be carried out in accordance with one or more example embodiments. The functions identified in  FIG. 4  refer to a UE device, a first base station, and a second base station. For purposes of describing  FIG. 4 , the UE device is referred to as UE device  200 , the first base station is referred to as base station  102 , and the second base station is referred to as base station  104 . As indicated above, base stations  102  and  104  can be arranged like base station  300 , and therefore, contain the elements of base station  300 . 
     In  FIG. 4 , block  402  includes determining, at base station  102 , a first reverse-link noise measurement pertaining to one or more reverse-links to base station  102 . Processor  302  can execute program instructions  312  to determine the noise measurements. Execution of those program instructions can include referring to signals provided to base station  102  from UE devices via the reverse-links. Base station  102  may measure reverse-link noise while one or more UE devices serve by base station  102  are idle and operating in a DRX mode. 
     Block  404  includes receiving, at base station  102 , a second reverse-link noise measurement pertaining to one or more reverse-links to base station  104  neighboring base station  102 . Processor  302  can execute program instructions  312  to receive the second reverse-link noise measurement via network interface  304 . In that regard, network interface  304  can receive the second reverse-link noise measurement via transmission of that measurement via inter-base-station communication link  132  or a communication link  134 . 
     Block  406  includes determining, at base station  102 , a difference between the first reverse-link noise measurement and the second reverse-link noise measurement. Processor  302  can execute program instructions  312  to determine the difference. In one respect, processor  302  can execute CRPI  312  to determine the difference by subtracting the first reverse-link noise measurement from the second reverse-link noise measurement. In another respect, processor  302  can execute CRPI  312  to determine the difference by subtracting the second reverse-link noise measurement from the first reverse-link noise measurement. 
     A person skilled in the art will understand that the amount of noise experienced by the reverse-links to a base station can vary over time. As the noise on the reverse-links to base station  102  increases, the noise on the reverse-links to a neighboring base station can decrease. Providing a UE device with information regarding those noise levels can lead to the UE device selecting the base station experiencing less noise on the reverse-links to be a new serving base station for the UE device. 
     Base station  102  can be configured to determine additional differences of distinct reverse-link noise measurements. For example, base station  102  can determine multiple differences of distinct reverse-link noise measurements for a given pair of base stations, such as base stations  102  and  104 . As another example, base station  102  can determine differences of distinct reverse-link noise measurements for more than one pair of base stations. For instance, base station  102  can determine differences of reverse-link noise measurements for base stations  102  and  104  and differences for base stations  102  and  106 . 
     Block  408  includes transmitting, from base station  102  to UE device  200  served by base station  102 , data indicating the difference between the first reverse-link noise measurement and the second reverse-link noise measurement. Processor  302  can execute program instructions  312  to cause wireless communication interface  306  to transmit the data. In accordance with the LTE implementation, transmission of the data indicating the difference can occur over a physical downlink control channel (PDCCH) between UE device  200  and base station  102 , and that transmission can include transmitting a paging radio network temporary identifier (PRNTI) having the difference encoded within the PRNTI. 
     In an alternative arrangement, the base station serving UE device  200  can transmit the first and second reverse-link noise measurements to UE device  200 . In accordance with that alternative arrangement, UE device  200  can compare the first and second reverse-link noise measurements to determine whether UE device  200  should select a new base station to be the serving base station. Alternatively, UE device  200  can determine the difference between the first and second reverse-link noise measurements for use in determine whether a new serving base station should be selected. 
     In accordance with one or more example embodiments, transmitting data indicating the difference can occur while UE device  200  has awaken during a DRX cycle. Processor  302  can refer to UE device data  320  to determine when UE device  200  awakes for the DRX cycle and then transmit the data indicating the difference while UE device  200  is awake during the DRX cycle so that UE device  200  can receive the transmitted data. 
     Although  FIG. 4  provides an example of when the reverse-link measurement parameters are reverse-link noise measurements, a person having ordinary skill in the art will understand that the functions of  FIG. 4  can be carried out for other reverse-link measurement parameters as well or in addition to the reverse-link noise measurements. 
     Next,  FIG. 5  is a flow diagram depicting a set of functions  500  that can be carried out in accordance with one or more example embodiments. The functions identified in  FIG. 5  refer to a UE device, a first base station, and a second base station. For purposes of describing  FIG. 5 , the UE device is referred to as UE device  200 , the first base station is referred to as base station  102 , and the second base station is referred to as base station  104 . 
     In  FIG. 5 , block  502  includes determining, at UE device  200  operating in an idle mode, a difference in reverse-link noise measured by base station  102  currently serving UE device  200  and reverse-link noise measured by base station  104  that neighbors base station  102 . Processor  202  can execute program instructions  212  to determine the difference in the reverse-link noise measurements. 
     In order to determine the difference in reverse-link noise measurements, wireless communication interface  204  can receive the difference in reverse-link noise measurements, as determined by base station  102 . For instance, the difference in reverse-link noise can comprise data indicating a difference between a first reverse-link noise measurement and a second reverse-link noise measurement. In that regard, the first reverse-link noise measurement pertains to one or more reverse-links to the base station  102 , and the second reverse-link noise measurement pertains to one or more reverse-links to base station  104 . 
     Alternatively, in order to determine the difference in reverse-link noise measurements, wireless communication interface  204  can receive data indicating the first reverse-link noise measurement pertaining to the one or more reverse-links to base station  102 , and data indicating the second reverse-link noise measurement pertaining to the one or more reverse-links to base station  104 , and then determine the difference between those two measurements. 
     Execution of CRPI  212  to determine the difference in reverse-link noise measurements can occur during a DRX cycle. In that regard, UE device  200  can receive reverse-link noise measurement data while awake during a DRX cycle. Moreover, UE device can receive reverse-link noise measurements during a plurality of DRX cycles while UE device is operating in an idle mode. Data storage device  208  can be configured to store a plurality of the received noise measurements or a sum of a given number of the most-recently received noise measurements. 
     Furthermore, the base station serving UE device  200  (for example, base station  102 ) can have more than one neighboring base station. Each of those base stations neighboring base station  102  can measure reverse-link noise and provide the reverse-link noise measurements to base station  102 . Base station  102  can transmit the reverse-link noise measurements from the other neighboring base stations to UE device  200  to provide UE device with information for determining differences in reverse-link noise between base station  102  and those other neighboring base stations. Alternatively, base station  102  can determine the differences in reverse-link noise between base station  102  and those other neighboring base stations and transmit those differences to UE device  200 . 
     Block  504  includes selecting, based on the difference in reverse-link noise determined determined at UE device  200 , base station  104  to serve UE device  200  instead of base station  102 . Processor  202  can execute program instructions  212  to select base station  104 . Execution of those program instructions can cause UE device  200  to select a base station that can provide a greater quality of service than the serving base station. 
     In one respect, the greater quality of service can be based on the reverse-links to the selected base station relative to the quality of service that can be provided by reverse-links to the serving base station. The quality of service for each base station can be based, at least in part, on the noise measured on the reverse-links to that base station. In that regard, selecting the second base station based on the difference in reverse-link noise comprises can include determining that the first reverse-link noise measurement is greater than the second reverse-link noise measurement. 
     In another respect, the greater quality of service can be based on the forward-links to the selected base station relative to the quality of service that can be provided by forward-links to the serving base station. In addition to receiving parameters regarding reverse-links of the serving and neighboring base stations, UE device  200  can receive parameters regarding forward-links of the serving and neighboring base stations. The parameters regarding the forward-links can identify noise measured on the forward-links or some other parameter regarding quality of the forward-links. As an example, the forward-link parameters can comprise a Reference Signal Received Power (RSRP) parameter or a Reference Signal Received Quality (RSRQ) parameter. 
     Block  506  includes initiating, using UE device  200  in response to selecting base station  104 , handoff of UE device  200  from base station  102  to base station  104 . Processor  202  can execute program instructions  212  to initiate the handoff. Execution of those program instructions can cause processor  202  to generate a message to request handoff of UE device  200  from base station  102  to base station  104 , and to cause wireless communication interface  204  to transmit the message to request handoff to base station  102 . Execution of those program instructions can cause UE device  200  to synchronize to base station  104 . Synchronization to base station  104  can include decoding synchronization signals (such as a primary synchronization signal and a secondary synchronization signal) transmitted by base station  104 . Decoding the synchronization can allow UE device  200  to establish appropriate frequency and time synchronization with base station  104 . After initiating hand off, the user device can hand off to the other base station. 
     Although  FIG. 5  provides an example of when the reverse-link measurement parameters are reverse-link noise measurements, a person having ordinary skill in the art will understand that the functions of  FIG. 5  can be carried out for other reverse-link measurement parameters as well or in addition to the reverse-link noise measurements. 
     In accordance with one or more of the example embodiments, the UE device can continue to be served by the serving base station if the reverse-link measurement parameters, reverse-link measurement parameters differences, forward-link measurement parameters, or forward-link measurement parameters differences being compared indicate that the quality of service being provided by the serving base station exceeds or is not surpassed by the quality of service that might be provided by a neighbor base station by a threshold amount. Subsequent comparisons based on updated parameters or parameter differences may result in the UE device handing over to a neighbor base station. 
     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.

Technology Classification (CPC): 7