Abstract:
A method and system to configure proximity detection and reporting in a wireless device during a transition of the wireless device from one cell state to another cell state in a third generation (3G) wireless communication system. In a first cell state, the wireless device is configured for proximity indication. The wireless device is transitioned from using the first cell state to using a second cell state. Upon the transition from the first cell state, the wireless device receives information from a base transceiver to reconfigure the proximity indication configuration based on the second cell state. The reconfiguration allows the mobile device to retain the existing proximity indication configuration, remove the proximity indication configuration, or stop reporting proximity indication. Additionally, the base transceiver also adjusts proximity configuration stored at the base station based on the second cell state.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is related and claims priority to Provisional Application No. 61/302,972, filed Feb. 10, 2010 and Provisional Application No. 61/303,671, filed Feb. 11, 2010, each of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Universal Mobile Telecommunications System (UMTS) is one of the third generation (3G) mobile telecommunications technologies and is also being developed into a 4G technology. UMTS terrestrial radio access network (UTRAN) is a collective term for a core network including base stations, known as Node Bs, and base station controllers, known as radio network controllers (RNCs), which make up a UMTS radio access network. A UTRAN can carry many traffic types, from real-time circuit-switched traffic to IP-based packet-switched traffic. A UTRAN allows connectivity between user equipment (UE) and the core network. The RNC provides control functionalities for one or more Node Bs. A Node B and an RNC may be combined in a single device, although typical implementations have a separate RNC located in a central office serving multiple Node Bs. 
     Recently the evolution of mobile access points within the mobile telecommunication industry has introduced femtocells into wireless communication systems. A femtocell is a small cellular base station, typically designed for use in a home or small business. Femtocells generally connect to the service provider&#39;s network via a customer&#39;s broadband connection, such as a Digital Subscriber Line (DSL) or cable broadband connection. A femtocell allows service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable. In 3G terms, femtocells are called Home Node Bs (HNBs). 
     HNBs are often arranged in uncoordinated large-scale deployments of several HNBs, and therefore the connection to the operator&#39;s core network needs to be realized efficiently. A closed subscriber group (CSG) is a specific group of UEs permitted access to a HNB. A CSG identifier (CSG-ID) is broadcast from the HNB in a system information block message (SIB), and only those UEs that are members of this group, as defined by a CSG whitelist of CSG IDs (generally stored on the UE), will attempt to select the cell. 
     Before deciding to hand over a UE to a HNB, a UTRAN generally needs to acquire UE measurement information related to the target HNB cell. The UTRAN can control what measurements the UE performs. In order to allow the UE to make those measurements efficiently, proximity detection can be configured within the UE via a radio resource control (RRC) measurement control message issued by the UTRAN. One type of measurement sent to a UE contains “CSG proximity detection” information, which is used by the UE to enable a proximity detection function to enter or leave one or more HNB cells within the UE&#39;s CSG whitelist. HNBs detected by the UE can be reported by the UE to the UTRAN via a proximity report in a measurement report message. 
     The 3rd Generation Partnership Project (3GPP) specifications define four RRC states in the connected mode: CELL_DCH, CELL_FACH, CELL_PCH, and URA_PCH. These states reflect the level of UE connection and the transport channels that can be used by the UE. For example, the CELL_FACH state, CELL_PCH state and URA_PCH state are characterized by the fact that there is no dedicated transport channel. In contrast, a UE in the CELL_DCH state has an assigned dedicated transport channel. A dedicated transport channel is not allocated in CELL_FACH, where a default common or shared transport channel is assigned. The descriptions for RRC layers are detailed in specification “3GPP TS 25.331 Radio Resource Control (RRC)” and hence are not repeated in detail. 
     SUMMARY 
     Current 3GPP specifications indicate that the UTRAN configures proximity detection in a UE by using the CELL_DCH state. While in the CELL_DCH state, the UE receives messages from the UTRAN instructing the UE as to what to measure, when to measure it, and how to report the measurement results. However, when the UE moves from CELL_DCH to CELL_FACH, CELL_PCH, or URA_PCH, there is no standard within current 3GPP specifications to instruct the UE when, where, and how to perform proximity detection and/or report proximity indication to the UTRAN. This creates inefficiencies resulting in decreased battery life of the UE, potential loss of transmitted data, degraded radio resource utilization, and erroneous configurations stored by the UTRAN and/or UE. 
     Introduced herein are methods and a system for configuring a UE for handling proximity indication and proximity detection in a wireless communication system. 
     In one embodiment, a UE configured with proximity detection stops reporting proximity indication to the UTRAN when the UE transitions from the CELL_DCH state to one of the CELL_FACH, CELL_PCH or URA_PCH states. Upon stopping the proximity indication reports, the UE stops performing proximity detection. 
     In some embodiments, a UE configured with proximity detection invalidates or deletes proximity detection configuration stored at a memory of the UE when the UE transitions from the CELL_DCH state to one of the CELL_FACH, CELL_PCH, or URA_PCH states. Upon invalidating or deleting the proximity detection configuration, the UE stops performing proximity detection. Additionally, the UTRAN can invalidate or delete proximity detection information stored by the UTRAN. 
     In a further embodiment, a UE configured for proximity detection retains proximity detection configuration information stored at a memory of the UE when the UE transitions from the CELL_DCH state to one of the CELL_FACH, CELL_PCH, or URA_PCH states. Upon retaining the proximity detection configuration information, the UE continues to perform proximity detection and to send proximity indication reports, based on the retained proximity detection configuration information. Additionally, the UTRAN retains proximity detection information used to configure the proximity detection at the UE. 
     In yet another embodiment, a UE configured for proximity detection retains proximity detection configuration information stored at a memory of the UE when the UE transitions from one of the CELL_FACH, CELL_PCH, or URA_PCH states to CELL_DCH. Upon retaining proximity detection, the UE continues to perform proximity detection and to send proximity indication reports, based on the retained proximity detection configuration information. 
     The solutions presented herein overcome the limitations of prior art, which defines configuring proximity indication in a UE by using CELL_DCH to establish procedural control to configure the UE to detect and to report proximity indication. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments of the disclosed method/apparatus are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements. 
         FIG. 1  illustrates a wireless communications system having a UTRAN, UE, and HNB. 
         FIG. 2  is a high-level block diagram showing an example of the hardware architecture of a UE. 
         FIG. 3A  is a timing diagram of an example communication between a UTRAN and a UE where proximity indication reporting is stopped when the UE transitions from using CELL_DCH to CELL_FACH, CELL_PCH, or URA_PCH. 
         FIG. 3B  is a timing diagram of an example communication between a UTRAN and a UE where proximity indication reporting is retained when the UE transitions from using CELL_DCH to CELL_FACH, CELL_PCH, or URA_PCH. 
         FIG. 3C  is a timing diagram of an example of communication between a UTRAN and a UE where proximity indication reporting is invalidated or deleted when the UE transitions from using CELL_DCH to CELL_FACH, CELL_PCH, and URA_PCH. 
         FIG. 3D  is a timing diagram of an example communication between a UTRAN and a UE where proximity indication reporting is retained when the UE transitions from using CELL_FACH, CELL_PCH, or URA_PCH to CELL_DCH. 
     
    
    
     DETAILED DESCRIPTION 
     References in this specification to “an embodiment,” “one embodiment,” or the like mean that the particular feature, structure, or characteristic being described is included in at least one embodiment of the disclosed system. Occurrences of such phrases in this specification do not necessarily all refer to the same embodiment. 
     Current implementations of 3G wireless communication systems configure proximity detection in a UE using only one of the four connected mode RRC cell states, CELL_DCH. A UE operating in, or transitioned to, CELL_FACH, CELL_PCH, or URA_PCH has no procedure within current 3GPP specifications to enable, disable, or otherwise configure proximity detection. Similarly, the UTRAN used to configure, via CELL_DCH, proximity indication at the UE lacks a standard operating procedure when the UE transitions to CELL_FACH, CELL_PCH, or URA_PCH. 
       FIG. 1  shows a wireless communications system having a UTRAN  110 , a UE  100 , and an HNB  116  in which the techniques introduced here can be implemented. It is noted that the UE described here is an illustration of one type of a wireless device in which the techniques can be implemented and that other wireless devices can be used for implementing the techniques. For example, UEs may include a cell phone, a personal digital assistant (PDA), a portable email device (e.g., a Blackberry® device), a portable media player (e.g., an Apple iPod Touch®), a tablet or slate computer (e.g., an Apple iPad®), a netbook computer, a notebook computer, an e-reader, or any other device having wireless communication capability. 
     The UE  100  includes a display  104  used to make and to receive telephone calls and to display data services. In some embodiments, the display  104  is a touch screen that allows for the direct manipulation of displayed data. The UE  100  has a multifunction input module  106  to operate the UE  100 , navigate the display, and perform selections on data. The input module  106  can be, for example, a keyboard, mouse, trackball, touch screen, or any other input module capable of communicating a user selection. Additionally, the UE  100  operates an antenna system  102  to send and receive information via wireless networks. 
     The UTRAN  110  is a wireless communication network used to communicate to the UE  100 . The UTRAN  110  contains one or more base transceiver stations (or “Node Bs” in 3G networks)  112  to communicate to other base transceivers (not shown) and other network core components within the UTRAN  110 , such as a base station controller or RNC  114 . The core components  112  and  114  of the UTRAN  110  can communicate to the UE  100  via an air interface  108 , such as the wideband code division multiple access (WCDMA) air interface defined within the 3GPP specifications. The air interface  108  is used to handle control plane signaling between the UE  100  and the UTRAN  110  by using RRC messages to control various functions in the UE  100 , such as connection establishment, measurements, radio bearer services, security, and handover decisions. 
     The Home Node B (HNB)  116  is a femtocell. HNBs  116  may broadcast IDs via a radio frequency  118  that are discoverable by a UE  100  that is configured for proximity detection. The UE  100  detects proximity using an autonomous search function. Network-controlled handover functionality is typically required for a UE  100  in an RRC connected state within the UTRAN  110 . Before making a decision to handover to a HNB  116 , the RNC  114  needs to acquire UE measurement information related to the HNB  116 . A UE  100  that is able to determine that it is proximate to a HNB  116  can inform the RNC  114  by sending a measurement report message containing proximity indication. The RNC  114  and the UE  100  use RRC configuration protocols to communicate the proximity indication. 
       FIG. 2  is a block diagram of one embodiment of the internal structure of the UE  100  that can implement one or more features of the disclosed system. In the illustrated embodiment, the UE architecture  200  is a computer system that includes a processor subsystem  202 , which further includes one or more processors. The UE architecture  200  further includes a memory  204  containing an operating system  208 , a storage module  210  containing data  218 , an input module  211 , a display module  214 , and a communication module  216 , each interconnected by an interconnect  206  and powered by a power supply  209 . 
     The UE architecture  200  can be embodied as a single- or multi-processor system that preferably implements a high-level module to receive the data  218  from the UTRAN  110 . The received data  218  is communicated via the communication module  216 , which includes a single or multiple antenna system capable of receiving and transmitting the data  218  using one or more frequencies. The data  218  can be stored in the storage module  210  for retrieval by the processor subsystem  202  and memory  204 . The processor subsystem  202  is configured by the data  218  to perform the features of the system, such as configuring proximity detection and transmitting indication reports. 
     For example, and as further explained below, upon the receipt of an RRC message containing proximity detection configuration information from the RNC  114 , the communication module  216 , in conjunction with the processor subsystem  202 , relays the message to the storage module  210  via the interconnect  206 . Based on the proximity detection configuration information contained in the message, the processor subsystem  202  is configured based on the data  218  of the message to enable/disable proximity detection of CSG cells, such as the HNB  116 , and/or report the proximity indication to the UTRAN  110 . 
     The display module  214  is configured to connect to the display  104  ( FIG. 1 ) for illustrating information to view on the display  104 . Information for display can consist of textual, graphical, and/or multimedia information and is presentable in a graphical user interface. In some embodiments, the display  104  includes a touch-sensitive component that allows for the direct manipulation of displayed information. The displayed information is additionally manipulable by the input module  106 . 
     The input module  211  is configured to receive the data  218  from a signal originating from the input module  106 . The signal may include a user selection transmitted to the input module  211 , which conveys via the interconnect  206  the signal to the processor subsystem  202  and the operating system  208 . 
     The memory  204  illustratively comprises storage locations that are addressable by the processor subsystem  202  and components  209 ,  210 ,  211 ,  214 , and  216  for storing software program code and data structures associated with the present system. The processor subsystem  202  and components may, in turn, comprise processing elements and/or logic circuitry configured to execute the software code and manipulate the data structures. The operating system  208 , portions of which are typically resident in the memory  204  and executed by the processor subsystem  202 , functionally organizes the UE architecture  200  by (among other things) configuring the processor subsystem  202  to invoke cell state selection and proximity indication related operations in support of the disclosed method/apparatus. It will be apparent to those skilled in the art that other processing and memory implementations, including various computer readable storage media, may be used for storing and executing program instructions pertaining to the technique introduced here. 
     One skilled in the art will appreciate that a similar structure may be used to operate the HNB  116  and Node B  112 . For example, the internal architecture of Node B  112  includes a communication module  216 , processor subsystem  202 , memory  204 , and storage module  210 , each configured to communicate via an interconnect  206 . 
     One skilled in the art will also appreciate that some or all of the disclosed method can be implemented using software stored on a computer-readable medium  204  and executed by a processor  202 . 
       FIG. 3A  is a timing diagram of an example communication between a UTRAN and a UE where proximity indication reporting is stopped when the UE transitions from using CELL_DCH to CELL_FACH, CELL_PCH, or URA_PCH. Initially, the UE  100  is configured to use the RRC CELL_DCH state at step  305 . At step  306 , the UTRAN  110  sends proximity indication configuration information via a measurement control message to enable the UE  100  to detect proximity of CSG cells, such as a HNB  304 . The purpose of the measurement control message at step  306  is to set up, modify, or release a measurement in the UE  100 . Upon reception of the measurement control message at step  306 , the UE  100  performs actions based on the contents of the message. If the message directed the UE  100  to enable proximity detection, it performs detection at step  308  on the HNB  304 . For example, the UE  100  may perform CSG proximity detection to detect the proximity of the UE  100  to one or more HNBs  304  broadcasting a CSG identity within the UE&#39;s CSG whitelist. The UE  100  then sends the results of the detection at step  308  to the UTRAN  110  as a measurement report at step  310 . In addition to the results of the detection, the measurement report at step  310  may include results of other measurements, such as intra-frequency measurement or traffic volume measurement, configured by the UTRAN. 
     In step  312 , the UTRAN  110  makes the decision to transition the UE from the CELL_DCH state to a different RRC connected state, such as CELL_PCH, CELL_FACH, or URA_PCH. The decision  312  may be based on a list of events including activity of data transmission from/to the UE monitored by the UTRAN, or the receipt of the measurement report at step  310 . The UTRAN  110  initiates the radio reconfiguration procedure to transition the UE from CELL_DCH by sending a radio bearer reconfiguration message at step  314 . The UE  100  responds with a radio bearer reconfiguration complete message at step  316 . After receiving an acknowledgement message from the UTRAN  110 , the UE  100  enters a new RRC connected state (CELL_PCH, CELL_FACH, or URA_PCH) at step  318  depending on the state specified in the radio bearer reconfiguration message at step  314 . Upon transitioning from CELL_DCH to the new state at step  318 , the UE  100  may also stop sending proximity indication reports at step  320  and the UE  100  may stop performing proximity detection at step  322 . The UE  100  and UTRAN  110  may retain the proximity indication configuration information  324  previously used to configure the UE  100  at step  306 . The UE  100  can optionally (not shown) resume performing proximity detection after the transition from CELL_DCH. The UTRAN  110  may initiate (not shown) a similar radio reconfiguration procedure to transition the UE from the new state to CELL_DCH by sending a radio bearer reconfiguration message. The UE  100  responds with a radio bearer reconfiguration complete message. The UE  100  enters a new RRC connected state (CELL_DCH). Upon transitioning from the new state to CELL_DCH, the UE  100  may also resume sending proximity indication reporting. Additionally the UE may enable the proximity detection if the UE disables the proximity detection from CELL_DCH to the new state at step  338  of  FIG. 3A . 
     In another embodiment (not shown), when the UE  100  transitions from CELL_FACH to CELL_PCH or URA_PCH, the UE  100  may stop sending proximity indication reports and the UE  100  may disable proximity detection. The UTRAN  110  may retain the proximity indication configuration information  324  previously used to configure the UE  100 . 
       FIG. 3B  is a timing diagram of an example communication between a UTRAN and a UE where proximity indication reporting is retained when the UE transitions from using CELL_DCH to CELL_FACH, CELL_PCH, or URA_PCH. Steps  305 - 316  are similar to steps  305 - 316  of  FIG. 3A . However, the UTRAN  110  decides to transition the UE  100  to CELL_FACH at step  311 . Upon transitioning from CELL_DCH to CELL_FACH, the UE  100  can determine whether it is configured for CELL_FACH measurement occasion information or high speed downlink shared channel (HS-DSCH) discontinuous (DRX) reception, at step  326 . 
     CELL_FACH measurement occasion information and HS-DSCH DRX reception in a CELL_FACH state define the times when the UTRAN  110  halts downlink transmissions to the UE  100  in the CELL_FACH state to allow the UE  100  to make measurements on other cells, such as the HNB  304 . Both CELL_FACH measurement occasion information and HS-DSCH DRX reception are configured by the UTRAN  110  using system information broadcasts sent to the UE  100 . 
     Upon transitioning the UE  100  from CELL_DCH to CELL_FACH and determining that the UE  100  is configured for CELL_FACH measurement occasion information or HS-DSCH DRX reception at step  326 , the UE  100  may continue to report proximity indication at step  328  by performing detection at step  330  and sending measurement reports at step  332  to the UTRAN  110 . The UTRAN  110  may retain the proximity indication configuration information previously used to configure the UE  100  at step  306 . 
       FIG. 3C  is a timing diagram of an example of communication between a UTRAN and a UE where proximity indication reporting is invalidated or deleted when the UE transitions from using CELL_DCH to CELL_FACH, CELL_PCH, and URA_PCH. Steps  305 - 318  are similar to steps  305 - 318  of  FIG. 3A . However, upon transitioning from CELL_DCH to the new state at step  318 , the UE may invalidate or delete proximity indication configuration information at step  336  and stop performing proximity detection at step  338 . The UTRAN  110  may also invalidate or delete at step  340  the proximity indication configuration information previously used to configure the UE  100  at step  306 . If the UTRAN  110  needs the UE to perform proximity reporting, the UTRAN  110  needs to send a second measurement control to configure the UE CSG proximity detection again. 
     An invalidation or deletion may be performed in any manner known in the art. For example, an invalidation may consist of an indication, such as a pointer, reference, or data flag, signaling that a current configuration of the UE  100  and/or the UTRAN  110  not be used. A deletion may be a removal of all or a portion of stored proximity indication configuration information stored at the UE  100  and/or the UTRAN  110 . 
     In another embodiment (not shown), when the UE  100  transitions from CELL_FACH to CELL_PCH or URA_PCH, the UE may invalidate or delete proximity indication configuration information and disable proximity detection. The UTRAN  110  may also invalidate or delete the proximity indication configuration information previously used to configure the UE. 
       FIG. 3D  is a timing diagram of an example communication between a UTRAN and a UE where proximity indication reporting is retained when the UE transitions from CELL_DCH to CELL_FACH, CELL_PCH, or URA_PCH. Steps  305 - 318  are similar to steps  305 - 318  of  FIG. 3A . However, upon transitioning from CELL_DCH to the new state at step  318 , the UE  100  retains the proximity indication configuration information at step  342  that was configured in step  306 . Additionally, the UE may maintain its ability to detect proximity indication at step  344  by performing detection at step  346  on one or more HNBs  304  and reporting the measurements to the UTRAN  110  at step  348 . The UTRAN  110  may also retain the proximity indication configuration information  350  previously used to configure the UE  100  at step  306 . 
     In some cases, the UE  100  may respond to the radio bearer reconfiguration message received at step  314  of  FIGS. 3A-3D  by transitioning to a state different from the state indicated by the message at step  314 . In these cases, the UE may invalidate or delete the proximity detection configuration information delivered in step  306 . For example, if the radio bearer reconfiguration message at step  314  contains information to configure the UE  100  to use cell state CELL_FACH, but the UE  100  selects cell state CELL_PCH, CELL_DCH, or URA_PCH, the UE  100  may delete or invalidate the proximity detection configuration information at the UE  100 . 
     Similarly, in another implementation of the embodiments described in  FIGS. 3A-3D , if the UE  100  transitions to a new state at step  318  due to the radio bearer reconfiguration message at step  314 , and the message does not indicate a cell state to which to transition, the UE  100  may invalidate or delete its proximity configuration information. 
     In another embodiment (not shown), when the UE  100  transitions from CELL_FACH to CELL_PCH or URA_PCH, the UE  100  retains the proximity indication configuration information. Additionally, the UE may maintain its ability to detect proximity indication by performing measurements on one or more HNBs  304  and reporting the measurements to the UTRAN  110 . The UTRAN  110  may also retain the proximity indication configuration information  350  previously used to configure the UE  100 . If the UE  100  transitions to CELL_PCH or URA_PCH due to the radio bearer reconfiguration message and the message does not indicate a cell state to which to transition, the UE  100  may invalidate or delete its proximity configuration information. 
     In yet another implementation of the embodiments described in  FIGS. 3A-3D , if the UE  100  transitions to a new state at step  318  not due to the radio bearer reconfiguration message at step  314 , the UE  100  may invalidate or delete the proximity configuration information at the UE  100 . For example, if the UE  100  cannot detect the UTRAN  110  due to a radio link failure, the UE  100  may perform a transition from one cell state to another. In this case, the UE may invalidate or delete its previously configured proximity indication. 
     The techniques introduced above can be implemented by programmable circuitry programmed or configured by software and/or firmware, or entirely by special-purpose circuitry, or in a combination of such forms. Such special-purpose circuitry (if any) can be in the form of, for example, one or more application-specific integrated circuits (ASICs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), etc. 
     Software or firmware for implementing the techniques introduced here may be stored on a machine-readable storage medium and may be executed by one or more general-purpose or special-purpose programmable microprocessors. A “machine-readable medium,” as the term is used herein, includes any mechanism that can store information in a form accessible by a machine (a machine may be, for example, a computer, network device, cellular phone, personal digital assistant (PDA), manufacturing tool, any module with one or more processors, etc.). For example, a machine-accessible medium includes recordable/nonrecordable media (e.g., read-only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.). 
     The term “logic,” as used herein, can include, for example, special-purpose hardwired circuitry, software, and/or firmware in conjunction with programmable circuitry, or a combination thereof. 
     Although the present invention has been described with reference to specific exemplary embodiments, it will be recognized that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense.